Time

Time

C) Introduction

Scientific revolutions, almost by definition, defy common sense.

If all our common-sense notions about the universe were correct, the science would have solved the secrets of the universe thousands of years ago. The purpose of science is to peal back the layer of the appearance of objets to reveal their underlying nature. In fact, if appearance and essence were the same thing, there would be no need for science.

Perhaps the most deeply entrenched common-sense notion about our world is that it is three dimensional. It goes without saying that length, width, and breadth suffice to describe all objects in our visible universe. Experiments with babies and animals have shown that we are born with an innate sense that our world is three dimensional. But to record all events in the universe, we need another dimension. If we include time as another dimension, then four dimensions are sufficient. No matter where our instruments have probed, from deep within the atom to the farthest reaches of the galactic cluster, we have only found evidence for these four dimensions.

Time is a very complex dimension. So not only in science, thus also in common usage, time is hard to understand. There are so many possible meanings implied.

If you just say the word time when you enter different situations, it depends on which room you have entered. When you enter a restaurant, you will receive the time of the time zone you are right now, which is the usual answer. But there are many different answers possible. Like if you enter a soccer stadion. Everybody will yell at you the score, how much time there is left, and to shut up. If you sit in a plane, and you ask the captain will tell you several times you haven't even thought of: The time of your arrival and departure in the time zone you left and will arrive, how long your flight was since now and how long it will take in miles per hour or km per second. Which speed the plain in that moment has, and which average speed it needs for take off or landing. If you enter a fast-food restaurant and you just ask 'time?', you will hear how long it takes to finish the fries or the burger. If you are in a university and you ask for 'time?', the answer depends again in what room you are. In the dorms you will get a tired 'too late' or a curse like 'damn it! I'm late.' as answer. On the foodcourt a hectically 'just five more minutes' is the usual answer. And during a physics class, the answer is a long precise definition of time.

What time really is, nobody truly can tell, but scientists try their hardest to find answers to their unanswered questions. In this Special Topic 'Time' I would like to give an idea of the momentary situation science is now, and show some possible answers from some of the brightest minds of mankind.

But also scientists do not agree in every respect. They try to fit all their observations in formulas they again try to combine all to get a unifying theory about the smallest and the largest things in our universe we live in.

The aim of science is to penetrate into smaller and bigger dimensions and not to stop until humankind has a complete theory of all forces and particles that appear in nature.

Like Thomas H. Huxley once said,

The known is finite, the unknown infinite; intellectually we stand on an islet in the midst of an illimitable ocean of inexpl- icability. Our business in every generation is to reclaim a little more land.

On the next pages I would like to give an easy understandable, brief description of what time is considered to be and want to try to uncover some secrets of         Time

1) Time is an Arrow

Seeing Things Different

The Last Century

Before the 20^th century, Newton's laws belonged to the basis of physics. But at the end of the 19^th century there were discovered two conflicts, with thermodynamics and electro-magnetism, that ultimately led to the formulation of first the theory of relativity and then the quantum theory. Einstein told us that space and time were part of a four-dimensional space-time and both relative. He was the first to count these to physics instead of accepting it as simply "existing". When it was later discovered that the universe is expanding, scientists quickly realised that everything had to start existing at a certain point in the past, known as the "Big Bang".

The Beginning of Time

At the Big Bang the universe's density was infinite. Under such conditions all the laws of science, and therefor all ability to predict the future, would break down. If there were events earlier than this time, then they could not affect what happens at the present time. Their existence can be ignored because it would have no observational consequences. One may say that time had a beginning at the big bang, in the sense that earlier times simply would not be defined.

Sensing Time

We are creatures in time and this has a very great effect on how we think about time and the temporal aspect of what is real.

The psychological time is very much different from the physical one. It seems that we are not able to perceive too short events, and that our brain manipulates our perceptions before they become conscious. Based on experiments, psychologists therefore suggest that our consciousness is a whole bunch of parallel processes.

People seem to sense time in a very subjective way, a fact that is in conflict with an universal time. In other cultures, like the Aborigines, there is not even a clear distinction between past, present and future. But the latter vanished in physics too, with the invention of relativity.

Many religions and philosophers believe in a cyclic time, and they are consistent with some scientific theories. Laplace first realised that when everything is predictable, knowledge of the moment is enough to know the situation in every moment, also in the future, thus making time obsolete.

The Arrows of Time

With the laws of thermodynamics physicists then realised that the universe is developing towards maximal entropy, or chaos. This made the perpetuum mobile impossible and put an end to Newton's linear time. It also brought an arrow of time into physics. Based on Boltzmann´s work Poincaré then proved the possibility of a cyclic universe, but with cycles being incredibly long.

Religions like to believe in creation, which cannot be proven to be wrong. The P'an Ku myth of China's third century describes the time before creation like that:

In the beginning, was the great cosmic egg. Inside the egg was chaos , and floating in chaos was P ' an Ku, the divine Embryo.

In India's ninth century, the Mahapurana, one of the most important books was written. In this book, the beginning of time is described as follows:

If God created the world, where was He before Creation? Know that the world is uncreated, as time itself is, without beginning and end.

It is not entirely impossible that we all live only since some minutes ago, created with memories of past times. Seen out of this respect, the flow of time can never be proven, and time itself may as well be an illusion.

Which Direction?

The increase of disorder or entropy with time is one example of what is called an arrow of time, something that distinguishes the past from the future, giving a direction to time. There are at least three different arrows of time.

First, there is the thermodynamic arrow of time, the direction of time in which disorder or entropy increases. Then, there is the psychological arrow of time. This is the direction in which we feel time passes, the direction in which we remember the past but not the future. Finally, there is the cosmological arrow of time. This is the direction of time in which the universe is expanding rather than contracting.

The psychological arrow is essentially the same as the thermodynamic arrow, so that the two would always point in the same direction.

Intelligent Life

The no boundary proposal for the universe predicts the existence of a well defined thermodynamic arrow of time because the universe must start off in a smooth and ordered state. And the reason why we observe this thermodynamic arrow to agree with the cosmological arrow is that intelligent beings can exist only in the expanding phase of our universe.

However, a strong thermodynamic arrow is necessary for intelligent life to operate. In order to survive, human beings have to consume food, which is an ordered form of energy, and convert it to heat which is a disordered form of energy. Thus intelligent life could not exist in a contracting phase of the universe. This is the explanation of why we observe that the thermodynamic and cosmological arrows of time point in the same direction.

The contracting phase will be unuitable because it has no strong thermodynamic arrow of time.

A fourth Arrow?

Some scientists interpose a fourth arrow, an arrow that helps to explain the causal asymmetry. We use 'cause' to mark the earlier and 'effect' to mark the later of a pair of events which are related this way. Cause-effect relation is itself asymmetric - that is, that causes and effects can be distinguished in some way.

Scientists are everything else but the same opinion in which direction they themselves should research to find answers to the questions the arrows and the asymmetry of time pose to us. In the respect of the increasing disorder in the course of time, James Thurber was right as he said:

'It is better to know some of the questions than all of the answers.'

Because the more answers we find the more questions arise.

Summary

Up to the beginning of our century people believed in an absolute time.

Newton considered time to be moving like a straight arrow, which unerringly flies forward toward its target. Nothing could deflect or change the course of this arrow once it was shot. Einstein, however, abandoned the idea of an absolute time and showed that time was more like a mighty river, moving forward but often meandering through twisting valleys and plains created through matter on a space-time surface. The presence of matter or energy might momentarily shift the direction of the river, but overall the river's course was smooth: It never abruptly ended or jerked backward.

However, successors like Kurt Gödel or Louis Tamburino showed that the river of time could be smoothly bent backward into a circle. Rivers, after all, have eddy currents and whirlpools. In the main, a river may flow forward, but at the edges there are always side pools where water flows in a circular motion.

2) Relativity of Time

Newton's laws of motion put an end to the idea of absolute position in space. The theory of relativity put an end to the idea of absolute time, so any observer can work out precisely what time and position any other observer will assign to an event, provided he knows the other observer's relative velocity. (they are related)

Nowadays we use just this method to measure distances precisely, because we can measure time more accurately than length. In effect, the meter is defined to be the distance travelled by light in vacuum in 0.000000003335640952 seconds, as measured by a caesium clock. So, we must accept that time is not completely separate from and independent of space, but is combined with it to form an object called space-time. (more later)

The Beginning

I want to know how God created this world. I am not interested in this or that phenomenon. I want to know His thoughts, the rest are details.

Albert Einstein

Einstein's Start

When Einstein was born, Newton's theory led to absurd results for the movement of light, leading him to postulate the relativity of time and to set the speed of light as the highest one possible.

Early on in physics, scientists invented an ether to explain the characteristics of light. But Michelson and Morley proved this idea ultimately wrong. This led Einstein to the idea that neither space nor time are fixed. His theory of relativity has been proved often since, as an example with the help of pulsars, and turned out to be right. The speed of light being the absolute top causes time dilatation effects, which allow us to observe myons. But this effect also causes the twin paradoxon, which is absolutely possible on closer examination, and it puts an end to a definite present.

The Twin Paradoxon

This paradoxon is one of the best known world-wide. It describes twins, one staying on earth the other twin making a journey in a rocket travelling with a velocity near the speed of light. They were exactly the same age when the brother departs but when he comes back after 50 years, the brother that stayed is older than the one that went with the rocket. For the one that lived on earth all the time, 50 years had gone by, whereas for the other one in the rocket, just 5 or 10 or 13 years had passed. (dependent on the velocity he travelled)

It is not that the one in the rocket lived 50 years and got only 13 years older; He lived just 13 years in the rocket. For him and all the watches on board only 13 years passed. And for his brother and all the watches placed on earth 50 years passed. Both of them are right.

That time is not a constant but dependent on the velocity of the system in which it is measured, is an assumption of Albert Einstein. Meanwhile there are very exact atomic clocks that proof his assumption as true.

Einstein's idea was that if the speed of light appeared the same to every observer, no matter how he was moving, another factor has to be variable, what led him to the theory of relativity. And this factor is the velocity with which time goes by, to say, time itself. Out of this thought follows that clocks, carried by different observers, would not necessarily agree.

Seen from an observer outside of the moving system, this interesting effect in the flow of time is called time dilatation. The nearer to the speed of light you get, the slower time goes by.

If an object moves with 100% lightspeed, time would stand still; and the mass would get infinite. That is the reason why travelling with speed greater than the one of light is impossible. The spaceship would have to get through the barrier of infinite mass and no time passing by, the so-called light barrier. The second problem is the slightest problem for the person travelling in the rocket. For his point of view the flow of time is constant all the journey long! He just would not find the same persons he left when he comes back. They will all be dead since millions of centuries.

So if one does not like his century, travelling near the speed of light would offer a realistic possibility to jump into the next without a worth mentioning loss of time.

In this respect the advertisement slogan of Swatch, now seen from another background, gets a completely new meaning:

'Time is what you make of it!'

It's all Relative

Both Aristotle and Newton believed in absolute time. That is, they believed that one could unambiguously measure the interval of time between two events, and that this time would be the same whoever measured it, provided they used a good clock. Time was completely separate from and independent of space. This is what most people would take to be the common-sense view. However, we have had to change our ideas about space and time. Although our apparently common-sense notions work well when dealing with things like apples and planets that travel comparatively slowly they do not work at all for things moving at or near the speed of light.

Einstein

Einstein had worked as a patent officer in Berne, in Switzerland, to earn a living and pay for his academic work while he wrote up his ideas about the laws of physics. In doing this he was rapidly becoming known as the visionary scientist of his time. His first major work was published in 1905, the first of two Theories of Relativity. It is called special Relativity; and the later theory, published in 1915, is called General Relativity. The fundamental postulate, we recall from our time at school, was that the laws of science should be the same for all freely moving observers, no matter what their speed. Both deal with the way an observer and the event he or she observes are related; Special Relativity essentially spells out what happens when there is a constant movement linking the event and the observer, and General Relativity brings in gravity. It also suggests what happens as the speed of any movement increases or decreases. The idea included also the speed of light: all observers should measure the same speed of light, no matter how fast they are moving. This simple idea has some remarkable consequences which I will describe later on.

Day-to-Day Experiences

They are both still very difficult theories to understand fully, but they are nevertheless widely acknowledged as the ideas which placed Einstein on the scientific world stage. Einstein did not set out specifically to explain the nature of time or the universe, but his theories inevitably interested many scientists, because he was in effect rewriting the laws of physics which had been left unchallenged since the time of Newton.

Einstein argued that the laws of physics must be the same, from whatever position they happened to be observed. This idea stemmed from the insight that the same event can appear different to two different observers, depending on their relative positions.

Several day-to-day examples have been suggested to help illustrate the point. One that most of us have experienced at some time or another is when two trains stop alongside each other in a railwaystation. You can be sitting on one train, looking out of the window at the other train, when it seems to move off. For a second or two you are not sure whether it has in fact started to move, or whether it is your own train which is moving off. All you know is that one train must be moving relative to the other; hence Relativity.

Now imagine a situation where one observer is on board a train another is on a railway station platform as the train rushes by. A cup on a table in front of the man on the train will appear to stay 60 centimetres in front of him. So, from his point of view, it will not be moving. However, to the man on the platform who watches the passing carriage windows, the cup will be seen to rush past at great speed as the train hurtles through the station.

A Clue

Einstein's great insight was that the laws of physics had to be rewritten in such a way that the laws of motion would be recognised as being consistent. They would have no account for related concepts such as acceleration and momentum, which were involved in these apparently different views of the cup. And this meant understanding the nature of time and space, and how they affect things.

After all, what causes two different views of the cup are the different positions of the observers relative to the cup in time and space. One is travelling through time and space alongside the cup, so that its relative position is always 60 centimetres in front of him; it stays in his field of vision as long as they are both travelling through time and space in an identical fashion. The other observer is, by comparison, stationary in time and space relative to the moving cup, so that it comes into and moves out of his field of vision in a very short time.

The Solution

Einstein developed mathematical equations to describe these kinds of relationships. Taken together, they defined the nature of time and space; and they had momentaneous consequences for cosmologists. To begin with, it emerged that time and space were mathematically one and the same thing. And, as a consequence, Newton's explanation of gravity had to be totally revised, accurate as it seemed to be.

But more to this in the next chapter about 'Space and Time'.

Light

Contemporary physics states that no object should be able to travel faster than the speed of light

c = 299'792'458 metres per second.

Although the value of c appears enormous when compared with conventional travelling speeds, it suggests a limit which renders a practical realisation of interstellar travel improbable. Whereas another planet in our solar system is reachable within minutes or at least hours at the speed of light, a journey to the nearest star system Alpha Centauri would already demand a travelling time of several years (4,2 Light-years). Surely, the question remains: Are faster-than-light speeds possible? At the present time most scientists believe that the correct answer should be 'no'. However, it has to be emphasised that there is no definite proof for this claim. Actually, whether superluminal speeds are possible in principle depends on the real structure of the space-time continuum. (more later)

Einstein's Dreams[1]

This book shows what would happen if time was no longer an arrow but anything else. There are several examples of different kinds of appearances of time like being like a stream of water, a circle or even parted in regions where in each time runs at a different speed.

Plot

It is a fiction book, endearingly short, airy and irrational, in simple and beautiful language. The science is gentle and it is cast in language to bring the flush of envy to any one of the many famous writers alive today who has coaxed himself into the delusion that scientists cannot write. It is a celebration of a world in which time does not march brutally through people's lives, but rather skips and gambles, forever quirky and unpredictable. Lightman is exploring fiction's deep space, taking us further than we are used to being taken.

The setting of the story is located in Berne, in Switzerland.

In this book Alan Lightman describes the dreams of Albert Einstein, a young patent clerk had between 14th April 1905 and 28th June 1905. Although the characters and situations in this book are entirely imaginary and bear no relation to any real person or actual happening, it is a breathtaking synthesis of science and imagination.

One witnesses Einstein's dreams of new worlds: extraordinary visions of the effect on people's lives when the direction and the flow of time changes to circular or flows backwards, slows down or takes the form of a nightingale.

In all dreams there are given examples, of how life changes when time is different, and most of them play in Berne, the city Einstein used to live.

The whole book is a flashback that starts after Einstein has finished his work. He reflects back on his time of creating the new theory of time. This ends two hours later. In those two hours Einstein reflects on the past several months, where he had many dreams about time. The book describes some of the dreams and tells the reader that those have taken hold of his research.

Out of many possible natures of time, imagined in as many nights, one seems compelling. Not that the others are impossible. The others might exist in other worlds.

Results

The result of all those dreams was the special theory of relativity. It was a completely new point of view. Although it cost Einstein a lot of energy, he believed that it was worth it. The picture of time that got its final shape while it was dreaming, was so obvious, so clear to him. Other people might also have such visions, but Einstein had the ability to write it down as a physical concept.

New Findings

Consequences

The essence of Einstein's equations is that the matter and energy content of an object determines the amount of curvature in the surrounding space and time.

Faster than Light

The question whether the speed of light is a true physical limit has no definite answer yet. It depends on the real structure of space-time. If there is an absolute time preserving causality (by preventing time-travel paradoxes), then faster-than-light speeds - and even faster-than-light travel - are possible, at least in principle. On the other hand, if superluminal processes are to be discovered, then absolute time will

probably have to be reintroduced in physics. Although the theory of special relativity states against absolute time and superluminal phenomena, it does it not by proof, but only by assumption.

Are there indications that absolute time and faster-than-light processes

exist ? My opinion is 'yes' !

The theory of relativity does not make faster-than-light moving completely impossible, it only forbids the crossing of the light barrier, thus principally allowing tachyons that always move faster than light, but are not manipulatable by us. Based on the equivalency principle and the Doppler effect Einstein concluded that also gravity influences light, putting an end even to sub-atomic perpetuum mobiles.

Another example where particles can travel faster than light is given in the quantum theory. There exists a phenomenon called the tunnel effect. It turned out that it is impossible to measure the length of the tunnelling time. Some other experiments also showed that one cannot determine which way a photon has taken in an experiment. The photons even seemed to communicate to each other faster than light! Quantum theory therefore proposes the concept of multiple realities.

General Relativity

A Solution

In 1949, Einstein was concerned about a discovery by one of his close colleagues and friends, the Viennese mathematician Kurt Gödel. Gödel found a disturbing solution to Einstein's equation that allowed for violation of the basic tenets of common sense: His solution allowed for certain forms of time travel. For the first time in history, time travel was given a mathematical foundation.

If one followed the path of a particle in a Gödel universe, eventually it would come back and meet itself in the past. He wrote, 'By making a round trip on a rocket ship in a sufficiently wide curve, it is possible in these worlds to travel into any region of the past, present, and future, and back again.'

His solution let time bend into a circle, called a closed timelike curve (CTC).

The Trojan Horse

Einstein's equations, in some sense, were like a Trojan horse. On the surface, the horse looks like a perfectly acceptable gift, giving us the observed bending of starlight under gravity and a compelling explanation of the origin of the universe. However, inside lurk all sorts of strange demons and goblins, which allow for the possibility of interstellar travel through wormholes and time travel. (more later)

The price we had to pay for peering into the darkest secrets of the universe was the potential downfall of some of our most commonly held beliefs about our world - that its space is simply connected and its history is unalterable.

Questions

But the question still remained: Could these CTCs be dismissed on purely experimental grounds, as Einstein did, or could someone show that they were theoretically possible and then actually build a time machine?

3) Space and Time

Because of the non-existence of an absolute rest, the lack of an absolute position in space and time is explained !

A Brief History of Time[2]

'A Brief History of Time' is a book that tries to explain the main theories of today physics in a quite 'non-technical' language so everybody can understand them. This book starts at the beginning of science with the Greek philosopher Aristotle and goes on until the youngest theories about our universe like the superstring-theory which needs 10dimensions.

We go about our daily lives understanding almost nothing of the world. We give little thought to the machinery that generates the sunlight that makes life possible, to the gravity that glues us to an Earth that would otherwise send us spinning off into space, or to the atoms of which we are made and on whose stability we fundamentally depend. Except for children, few of us spend much time wondering why nature is the way it is; where the cosmos came from, or whether it was always here; if time will one day flow backward and effects precede causes; or whether there are ultimate limits to what humans can know. Was there a beginning of time? Could time run backwards? Is the universe infinite or does it have boundaries? These are just some of the questions considered in an internationally acclaimed masterpiece which begins by reviewing the great theories of the cosmos from Newton to Einstein, before diving into the secrets which still lie at the heart of space and time.

This book tries to answer at least some of these questions that can be answered now. To get some answers we can only follow the theories of Stephen Hawking, which are very good explained in his best-seller.

Sinking into space-time

Einstein

As I already mentioned, Einstein developed mathematical equations to define the nature of time and space. These equations had momentous consequences for cosmologists. To begin with, it emerged that time and space were mathematically one and the same thing. And, as a consequence, Newton's explanation of gravity had to be totally revised, accurate as it seemed to be. Einstein argued that two objects do not directly attract each other as Newton has thought; rather, each of the two objects affects time and space, and any gravitational effects are a consequence of this. That was the moment when he found out that space and time are warped.

The Universe as a Sheet

If this concept is difficult to grasp, imagine a heavy object (such as a cannon ball), representing the sun, being placed in the middle of a taut rubber sheet [], creating a cone-shaped dent all around it - rather reminiscent of the surface of a vortex of swirling water rushing down a plunge hole.

Einstein argued that whenever something heavy bent space-time like this, it would naturally affect the path of anything lighter travelling nearby. So a smaller ball representing the Earth or one of the other planets could be rolled across the stretched rubber sheet representing space-time, towards the dent around the cannon ball sun.

If it was travelling too slowly, it would fall directly into the dent and quickly reach the surface of the sun (just like Newton's apple falling to the surface of the Earth). If it was travelling too fast, it would have its path deflected towards the cannon ball sun, but would only dip into the dent then climb out of the other side, before continuing on its journey. But at just the right speed, the small planet ball would be going fast enough not to fall right into the dent, but too slowly to escape it completely. With nothing else to stop it or slow it down, it would find its level on the 'side' of the dent in space-time, rather like a motorcycle stunt rider going round and round the 'wall of death'. It would have found its static orbit around the sun.

Einstein as Idol

The mathematical formula of Einstein could apart from even describe the orbit of Mercury, what was not possible with Newton's rather simpler equation. This was impressive evidence that Einstein's theory was correct, or at least an improvement on Newton's explanation of gravity. It was natural for physicists to begin to think: if it fits in with Einstein's theories, it is probably going to be true.

Dynamic Space and Time

It was while studying these equations of Einstein's that Lemaitre, a priest and Belgium's most famous astronomer, discovered something which really excited him. One of the consequences of Einstein's maths was that the universe was not static; it was dynamic.

It is simply enough to see why. If time and space are 'dented' by anything with mass, then, as one body passes another, it will be drawn closer to it.

If the universe is static, then all objects will eventually be drawn to each other; all mass will congregate together at the bottom of the largest dent in space and time.

This was the same problem which had worried Newton when he came up with his theory of gravity; how could all the matter in the universe still be widely spread out after billions of years? Why hadn't it been pulled together by gravity into one conglomerate lump? But, whereas Newton's idea had confined itself to the attraction of objects, Einstein's theory involved the mathematics of how space and time change when an object with mass affects them. Thus Newton's system had no way for the coming together of all objects to be avoided but Einstein's maths did. Einstein needed space and time to be able to change in the presence of mass. So space and time had to be dynamic, rather than static.

Consequently, space-time, and so the universe, could not remain still; and if it had to change it could only really get bigger or smaller. Hence it ought to be gently expanding or contracting.

Gravitational Effects

It is gravity that governs and shapes the large-scale structure of the universe and thus even time.

The laws of gravity were incompatible with the view held until quite recently that the universe is unchanging in time: the fact that gravity is always attractive implies that the universe must be either expanding or contracting.

According to general theory of relativity, there must have been a state of infinite density in the past, the big bang, which would have been an effective beginning of time. (Scientists today generally agree on an age of the universe of about 13 billion years.)

Similarly, if the whole universe recollapsed, there must be another state of infinite density in the future, the big crunch, which would be an end of time. Even if the whole universe did not recollapse, there would be singularities in any localised regions that collapsed to form black holes. These singularities would be an end of time for anyone who fell into the black hole.

In every case there are certain locations in space that effect time, seen from an different, innocent, and independent observer.

Solutions?

Schwarzschild calculated a solution to Einstein's equations where the time dilatation is infinite from a certain radius on, out of which evolved the idea of black holes. Wheeler found out that Schwarzschild´s solution included a singularity, but also proved its possibility. (The first black hole was found in 1964 in the system Cygnus X-1.)

Hubble proved the even expanding of space, which allowed to calculate the Big Bang. Einstein therefore introduced a new term into his theory of relativity, the "cosmic term", which he later thought of as his biggest error, because it would have caused the universe to become unstable.

In the search for "theories of everything", which try to unite relativity and quantum mechanics, the possibility of a cosmic term returned.

A Unifying Theory

When scientists like Stephen Hawking combine quantum mechanics, with general relativity, there seems to be a new possibility for him that did not arise before: that space and time together might form a finite, four-dimensional space without singularities or boundaries, like the surface of the earth but with more dimensions. It seems that this idea could explain many of the observed features of the universe, such as its large-scale uniformity and also the smaller-scale departures from homogeneity, like galaxies, stars, and even human beings. It could even account for the arrow of time that we observe.

At the end of A Brief History of Time Stephen Hawking concludes that, if we do discover a complete theory that could describe everything, its basic principles and implications should in time be understandable by everyone. And once we all understand the true nature of the universe, we all, philosophers, scientists and just ordinary people, can take part in the discussion of the question of why it is that we and the universe exist. Should we ever resolve this question, he suggests, it will be 'the ultimate triumph of human reason - for then we would know the mind of God'.

Perhaps, for many of us, that challenge will seem a step too far. There are millions of us who have never before got close to discovering the nature of the universe. We may just have not tried; more likely we were convinced that it was beyond our limited capacity to understand.

But I think that our opinion is changing. Changing towards knowing more and more about the world and universe we live in. And that is the reason for me to belief that in no way research in this field will find a sudden end.

Already Yogi Berra said :

"It ain't over till it's over"

Dreams

I think that these concepts will come to seem as natural to the next generation as the idea that the world is round. Imaginary time is already a commonplace of science fiction. But it is more than science fiction or a mathematical trick. It is something that shapes the universe we live in.

An example of how the human race could cope with the progress made in all scientific directions is given in Star Trek. It shows how much we know already and how much we will be able to do with our knowledge in the near future.

The Physics of Star Trek[3]

It is a popular science book, trying to tell most modern science in a simple language. ' The Physics of Star Trek' is a book to be read many times as long it is up-to-date with our time (till we cross the milky ways of our and other galaxies). It offers a lot of exotic science to anyone who wants to make a small investment of imagination. Perhaps accidentally, Krauss also does a useful job in explaining some important physics, using Star Trek as a pop culture example: the physics of Newton, Einstein and Stephen Hawking all figure in the highly successful analysis. It is a book on physics, but it is written in such a spirit of fun, it might even make you want to watch Star Trek. This book is fun, and Mr. Krauss has a nice touch with a tough subject. Krauss is smart, but speaks and writes the common tongue.

In this entertaining book the physics professor Lawrence Krauss looks at how the imaginary science of the Star Trek universe stacks up against the real thing. Krauss speculates on the possibility of alien life, touching on whether any kind of life is such an improbable phenomenon.

There are impressively clear explanations of difficult and up-to-date concepts in information theory, quantum mechanics, particle physics, relativity, mechanics and cosmology. The book goes where not even the show's laudable tradition of scientific evangelism has gone before.

4) To Build a Time Machine

The First Thoughts

Change Time

Since ever, humans wanted to change the past and know about the future. Just to know the results of a bet of tomorrow today or to mend a decision, made in the past.

Since it was not possible for scientists to build machines to look or travel through time, it was the duty of science fiction authors to speculate about possible ways, how a time machine would look and work like.

The Time Machine[4]

It is a science fiction novel about the Victorian future which is more than a fantastical yarn. It raises chilling questions about progress, social orders, so called civilisation and the ultimate fate of the world. It tells the story from the present until the end of our sun-system, a cold, almost lifeless earth with a dying sun.

Wells wrote this novel mainly because Charles Darwin published and proved his theory of Evolution, which was the greatest scientific rumpus since the trial of Galileo.

It is a story about evolution brought to the reader as an adventure of an old scientist, who has invented a time machine. Although Wells doesn't tell the reader the names of the Victorian scientist and the Narrator, he creates a personal relationship with the reader, which is very difficult and proves again that H.G.Wells is one of the best writers.

The Time Traveller lives in a house in London, in Richmond. In the cellar he has his laboratory, his workshop. The Time Traveller shows his disbelieving dinner guests a device he claims is a Time Machine.

He tries to convey his dinner guests that he found a machine to interrupt the floating time stream an though have the possibility to move through time as one wants.

In real time a week later the dinner guests visit the Time Traveller again, but instead of a settled old man they find him raged, exhausted and garrulous. The tale he tells is of the year 802,701 AD of life as it is lived on exactly the same spot, what once had been London. He has visited the future, he has encountered the future -race -elfin, beautiful, vegetarian, helpless, leading a life of splendid idleness.

But this is not the only race, these are not our only descendants. In the tunnels beneath the new Eden there lurks another life form.

The end of the book is open because the Time Traveller disappears in front of the eyes of the Narrator and hasn't come back for three years although he said he'll need only half an hour for his journey.

Time Travel

Can we go back in time?

Like the protagonist in H.G. Wells's The Time Machine, can we spin the dial of a machine and leap hundreds of thousands of years to the year 802,701? Or, like Michael J. Fox, can we hop into our plutonium-fired cars and go back to the future?

The possibility of time travel opens up a vast world of interesting possibilities. With time travel, we could go back to our youth and erase embarrassing events from our past, choose a different mate, or enter different careers; or we could even change the outcome of key historical events and alter the fate of humanity.

For example, in the climax of Superman, our hero is emotionally devasted when an earthquake ravages most of California and crushes his lover under hundreds of tons of rock and debris. Mourning her horrible death, he is so overcome by anguish that he rockets into space and violates his oath not to tamper with the course of human history. He increases his velocity until he shatters the light barrier, disrupting the fabric of space and time. By travelling at the speed of light, he forces time to slow down, then to stop, and finally to go backward, to a time before Lois Lane was crushed to death.

This trick, however, is clearly not possible. Although time does slow down when you increase your velocity, you cannot go faster than the speed of light ( and hence make time go backward ) because special relativity states that your mass would become infinite in the process. Thus the faster-than-light travel method preferred by most science fiction writers contradicts the special theory of relativity.

Einstein himself was well aware of this impossibility.

Most scientists, who have not seriously studied Einstein's equations, dismiss time travel as poppycock, with as much validity as lurid accounts of kidnappings by space aliens. However, the situation is actually quite complex.

To resolve the question, we must leave the simpler theory of special relativity, which forbids time travel, and embrace the full power of the general theory of relativity, which may permit it. General relativity has much wider validity than special relativity. While special relativity describes only objects moving at a constant velocity far away from any stars, the general theory of relativity is much more powerful, capable of describing rockets accelerating near supermassive stars and black holes. The general theory therefor supplants some of the simpler conclusions of the special theory. For anyone who has seriously analysed the mathematics of time travel within Einstein's general theory of relativity, the final conclusion is, surprisingly enough, far from clear.

Proponents of time travel point out that Einstein's equations for general relativity do allow some forms of time travel. They acknowledge, however, that the energies necessary to twist time into a circle are so great that Einstein's equations break down. In the physically interesting region where time travel becomes a serious possibility, quantum theory takes over from general relativity.

Einstein's equations state that the curvature or bending of space and time is determined by the matter-energy content of the universe. It is, in fact, possible to find configurations of matter-energy powerful enough to force the bending of time and allow for time travel.

However, the concentrations of matter-energy necessary to bend time backward are so vast that general relativity breaks down and quantum corrections begin to dominate over relativity. Thus the final verdict on time travel cannot be answered within the framework of Einstein's equations, which break down in extremely large gravitational fields, where we expect quantum theory to become dominant. But quantum corrections, in turn, may actually close the opening of the wormhole, making travel through the gateway impossible.

Introducing a New Theory

This is when the ten dimensional hyperspace theory can settle the question. Because both quantum theory and Einstein's theory of gravity are united in ten dimensional space, scientists expect that the question of time travel will be settled decisively by the hyperspace theory. But wormholes and dimensional windows which could be used for time travel might only be understood completely when one incorporates the full power of the hyperspace theory.

Because of this reason it will take some time until enough scientists can research in this direction and decide whether these wormholes are physically relevant or just another crazy idea.

However, the most bizarre consequence of wormholes is that physicists can not only show that wormholes allow for multiply connected spaces, but that they allow for time travel as well. This is the most fascinating, and speculative, consequence of multiply connected universes. (more later)

Problem: Time Travel

Logical Paradoxon

If what one does could be predicted, then the fact of making that prediction could change what happens. It is like the problems one would get into if time travel were possible. If you see what is going to happen in the future, you could change it. But that action would change the odds. One only has to see Back to the Future to realise what problems could arise.

The Risks of Time Travel

The peculiar risk lies in the possibility of the time traveller finding some substance in the space which he, or the machine, occupies. As long as the traveller travels through time at a high speed, this scarcely matters, but to come to a stop would involve the jamming of him, molecule by molecule into whatever lies in his way. That would result in a far reaching explosion and would blow him and the apparatus out of all possible dimensions into the 'Unknown'.

Here one could raise the question weather air or water is also a substance which leads to an explosion or if these substances are exceptions because of their low density. Another interesting case that could happen would be if a feather is just gliding through the air, exactly at the place in space where the time traveller stops. When he stops and the feather is exactly under his nose, he will sneeze. When he stops and it is there where his lounges are, he will cough it up. But what will happen when the feather is there where his leg or head is going to be?

Avoidable but risky problems are also posed by time paradoxes, but more to this later on.

Another risk is that you never know the exact situation in which you stumble in stopping the machine. At your destination a suddenly appearing earthquake could surprise and kill you without giving you a chance to flee through time in the last moment.

In the movie Time Cop one of the greatest risks is described very vivid. The same object cannot exist in the same place, at the same time! It would erase itself out of the universe. From that time on it would stop to exist as matter.

But already while the time traveller is making or entering the machine, he has to accepted these possibilities as unavoidable risks, some of the risks a time traveller has to take.

Time Paradoxes

To understand the problem with time travel, it is first necessary to classify the various paradoxes. In general, most can be broken down into one of two principal types:

1. Meeting your parents before you are born

2. The man with no past

The first type of time travel does the most damage to the fabric of space-time because it alters previously recorded events. For example, remember that in Back to the Future, our young hero goes back in time and meets his mother as a young girl his age, just before she falls in love with his father. To his shock and dismay, he finds that he has inadvertently prevented the fateful encounter between his parents. To make matters worse, his young mother has now become amorously attracted to him! If he unwittingly prevents his mother and father from falling in love and is unable to divert his mother's misplaced affections, he will disappear because his birth will never happen.

The second paradox involves events without any beginning. For example, let's say that an impoverished, struggling inventor is trying to construct the world's first time machine in his cluttered basement. Out of nowhere, a wealthy, elderly gentleman appears and offers him ample founds and the complex equations and circuitry to make a time machine. The inventor subsequently enriches himself with the knowledge of time travel, knowing beforehand exactly when stock-market booms and busts will occur before they happen. He makes a fortune betting on the stock-market, horse races, and other events. Decades later, as a wealthy, ageing man, he goes back in time to fulfil his destiny. He meets himself as a young man working in his basement, and gives his younger self the secret of time travel and the money to exploit it. The question is: Where did the idea of time travel come from?

My Favourite

My favourite time travel paradox is one of the second type. It was cooked up by Robert Heinlein in his classic short story All You Zombies--.

A baby girl is mysteriously dropped off at an orphanage in Cleveland in 1945. 'Jane' grows up lonely and dejected, not knowing who her parents are, until one day in 1963 she is strangely attracted to a drifter. She falls in love with him. But just when things are finally looking up for Jane, a series of disasters strike. First, she becomes pregnant by the drifter, who then disappears. Second, during the complicated delivery, doctors find that Jane has both sets of sex organs, and to save her life, they are forced to surgically convert 'her' to a 'him.' Finally, a mysterious stranger kidnaps her baby from the delivery room.

Reeling from these disasters, rejected by society, scorned by fate, 'he' becomes a drunkard and drifter. Not only has Jane lost her parents and her lover, but he has lost his only child as well. Years later, in 1970, he stumbles into a lonely bar, called Pop's Place, and spills out his pathetic story to an elderly bartender. The sympathetic bartender offers the drifter the chance to avenge the stranger who left her pregnant and abandoned, on the condition that he join the 'time travellers corps.' Both of them enter a time machine, and the bartender drops off the drifter in 1963. The drifter is strangely attracted to a young orphan woman, who subsequently becomes pregnant.

The bartender then goes forward 9 months, kidnaps the baby girl from the hospital, and drops off the baby in an orphan age back in 1945. Then the bartender drops off the thoroughly confused drifter in 1985, to enlist in the time travellers corps. The drifter eventually gets his life together, becomes a respected and elderly member of the time travellers corps, and then disguises himself as a bartender and has his most difficult mission: a date with destiny, meeting a certain drifter at Pop's place in 1970.

The question is: Who is Jane's mother, father, grandfather, grandmother, son, daughter, granddaughter, and grandson? The girl, the drifter, and the bartender, of course, are all the same person.

And the reason why it is my favourite is because it makes your head spin, especially if you try to untangle Jane's twisted parentage. If You draw Jane's family tree, we find that all the branches are curled inward back on themselves, as in a circle. You will come to the astonishing conclusion that she is her own mother and father! She is an entire family tree unto herself.

Creating the Impossible?

Special warpings of space-time would make time travelling possible. In warped space-time also wormholes are possible, although all current models require exotic matter, to say imaginary matter, to generate negative pressure and so negative gravity.

Theoretical Basis

Using Einstein's equations, it is perfectly possible to predict changes to the shape of space and time which would affect us in ways we have so far found no way to experience - like time warps.

Most people imagine the universe to be a bit like an ever-inflating balloon, with us somewhere inside it. But perhaps the balloon is hardly inflated at all, and is instead a loose and flexible bag. Perhaps we are inside a universe where time and space can be so bent and flexed that the balloon can be folded back on itself. Eventually two parts of the outer skin could somehow get close enough to each other to be linked by wormholes - strange tunnels through space and time through which we might one day be able to move from one end of the universe to the another.

Multiply Connected Universes

Multiply connected is the opposite to simply connected what means, that our windows and doorways are not entrances to wormholes connecting our home to a far-away universe.

Although the bending of our universe in an unseen dimension has been experimentally measured, the existence of wormholes and whether our universe is multiply connected or not is still a topic of scientific controversy.

Many physicists, who once thought multiply connected spaces in which regions of space and time are spliced together, are now seriously studying multiply connected worlds as a practical model of our universe.

These models are the scientific analogue of Alice's looking glass. When Lewis Carroll's White Rabbit falls down the rabbit hole to enter Wonderland, he actually falls down a wormhole.

One can visualise a wormhole as the tube between two sheets of paper, connected through holes.

If you fall into the wormhole, you are instantly transported to a different region of space and time. Only by retracing your steps and falling back into the wormhole can you return to your familiar world.

Time Travel and Baby Universes

Although wormholes provide a fascinating area of research, perhaps the most intriguing concept to emerge from this discussion is the question of time travel.

Wormholes may connect not only two distant points in space, but also the future with the past.

Since travel through the wormhole is nearly instantaneous, one could use the wormhole to go back in time. Unlike the machine portrayed in H.G.Wells's The Time Machine, however, which could hurl the protagonist hundreds of thousands of years into England's distant future with the simple twist of a dial, a wormhole may require vast amounts of energy for its creation, beyond what will be technically possible for centuries to come.

Another bizarre consequence of wormhole physics is the creation of 'baby universes' in the laboratory. We are, of course, unable to re-create the Big Bang and witness the birth of our universe. However, a few years ago some physicists of the Massachusetts Institute of Technology shocked many physicists, when they claimed that the physics of wormholes may make it possible to create a baby universe of our own in the laboratory. By concentrating the intense heat and energy in a chamber, a wormhole may eventually open up, serving as an umbilical cord connecting our universe to another, much smaller universe. If possible, it would give a scientist an unprecedented view of a universe as it is created in the laboratory.

One could then find out how the starting conditions of a universe look like; if time is already one of those conditions or if it is just a product, created by chance.

Evading the Light Barrier

When Carl Sagan wrote a novel called Contact, he wanted to make his book as scientifically accurate as possible and though wrote to the well known physicist Kip Thorne weather there was any scientifically acceptable way of evading the light barrier.

Sagan's request piqued Thorne's intellectual curiosity. A serious request that demanded a serious reply. Fortunately, because of the unorthodox nature of the request, Thorne and his colleagues approached the question in a most unusual way: They worked backward. Normally, physicists start with a certain known object and then solve Einstein's equation to find the curvature of the surrounding space.

However, Thorne and his colleagues started with a rough idea of what they want to find. They wanted a solution to Einstein's equations in which a space traveller would not be torn apart by the tidal effects of the intense gravitational field. They wanted a wormhole that would be stable and not suddenly close up in the middle of the trip. They wanted a wormhole in which the time it takes for a round trip would be measured in days, not millions or billions of earth years, and so on. In fact, their guiding principle was that they wanted a time traveller to have a reasonably comfortable ride back through time after entering the wormhole. Once they decided what their wormhole would look like, then, and only then, did they begin to calculate the amount of energy necessary to create such a wormhole.

They did not care if the energy requirements were well beyond twentieth-century science. To them, it was an engineering problem for some future civilisation actually to construct the time machine. They wanted to prove that it was scientifically feasible, not that it was economical or within the bounds of present-day earth science.

Much to their delight, they soon found a surprisingly simple solution that satisfied all their rigid constrains. It was not a typical black hole solution at all. They christened their solution the 'transversible wormhole,' to distinguish it from the other wormhole solutions that are not transversible by spaceship.

They were so excited by their solution that they wrote back to Sagan, who incorporated some of their ideas in his novel. (and this year in the identically named film Contact.)

Inside Out

Scientists are not quite sure what happens inside a black hole. There are solutions of the equations of general relativity that would allow one to fall into a black hole and come out of a white hole somewhere else. A white hole is the time reverse of a black hole. It is an object that things can come out of but nothing can fall into. The white hole could be in another part of the universe. This would seem to offer the possibility of rapid intergalactic travel. The trouble is it might be too rapid. If travel through black holes were possible, there would seem nothing to prevent you from arriving back before you set off. You could then do something, like kill your mother before you were born. You must then cease to exist. But if you cease to exist, you could not have gone back and killed your mother. But if you didn't kill your mother, then you have not ceased to exist. To put it another way: if you exist, then you cannot exist, while if you don't exist, you must exist.

This is the most famous paradox to be found in both science fiction and physics. (It belongs to the first type)

Perhaps fortunately for our survival ( and that of our mothers), it seems that the laws of physics do not allow such time travel. What seems to happen is that the effects of the uncertainty principle would cause there to be a large amount of radiation if one travelled into the past. This radiation would either warp space-time so much that it would not be possible to go back in time, or it would cause space-time to come to an end in a singularity like the big bang or the big crunch. Either way, our past would be save from evil-minded persons.

But the best evidence that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future.

But, are we alone?

I) Conclusion

Why it matters

In what sense do these issues matter? Why shouldn't we ignore the view from nowhen, and go on in physics, philosophy, and ordinary life just as we always have? After all, we cannot actually step outside time, in the way in which we can climb a tree to alter our viewpoint. Isn't it better to be satisfied with the viewpoint we have?

We cannot step outside time, but we can try to understand how the way in which we are situated within time comes to be reflected in the ways in which we talk and think and conceptualise the world around us. What we stand to gain is a deeper understanding of ourselves and of what is external to us. This is a reflective kind of knowledge: we reflect on the nature from the standpoint from within, and thereby gain some sense, a sense-from-within, of what it would be like from without.

If the reflexivity were viscous the whole project would be self-defeating, but is it vicious? Our understanding seems to be enhanced, not overturned. With each advance comes a new picture of how the world would look like from nowhere, and a new appreciation of the limits of our own standpoint.

Our culture has been as surely shaped by the miracles of modern physics as it has by any other human intellectual endeavour. And while it is an unfortunate modern misconception that science is somehow divorced from culture, it is, in fact, a vital part of what makes up our civilisation. Our explorations of all dimensions of the universe, represent some of the most remarkable discoveries of the human intellect, and it is a pity that they are not shared among as broad an audience as enjoys the inspiration of great literature, or painting, or music.

The campaign for a view from nowhen is a campaign for self-improvement, and not a misguided attempt to do the impossible. It promises only to enhance our understanding of ourselves and our world, and not to make us gods.

A proof for this kind of argumentation is the increasing number of still present a new question: Why is the future so different from the past? Why does the past affect the future and not the other way round? The universe began with the Big Bang - will it end with a 'Big Crunch'?

To try to answer these questions we adopt some 'world picture.' Each answer and each new theory we humans find, lets us feel that mankind could bring the world totally under his control. But until now, none of the known theories results in a completely determined picture of our universe.

This paper presents an innovative and controversial view of time and contemporary physics. I especially pondered on time in space, the paradoxes of time and time travel to throw a fascinating new light on some of the great mysteries of the universe and to give all the readers the opportunity to look at the world from a fresh perspective.

II) Glossary

big bang: The singularity at the beginning of the universe.

big crunch: The singularity at the end of the universe.

black hole: A region of space-time from which nothing, not even light, can escape, because gravity is so strong.

Chandrasekhar limit: The maximum possible mass of a stable cold star, above which it must collapse to a black hole.

cosmological constant: A mathematical device used by Einstein to give space-time an inbuilt tendency to expand.

event: A point in space-time, specified by its time and place.

field: Something that exists throughout space-time, as opposed to a particle that exists at only one point at a time.

general relativity: Einstein's theory based on the idea that the laws of science should be the same for all observers, no matter how they are moving. It explains the force of gravity in terms of the curvature of a four-dimensional space-time.

grand unified theory: A theory that unifies the electromagnetic strong and weak forces.

imaginary time: Time measured using imaginary numbers.

light cone: A surface in space-time that marks out the possible directions for light rays passing through a given event.

light-second (light-year): The distance travelled by light in one second (year).

no boundary condition: The idea that the universe is finite but has no boundary (in imaginary time).

primordial black hole: A black hole created in the very early universe.

quantum mechanics: The theory developed from Planck's quantum principle and Heisenberg's uncertainty principle.

singularity: A point in space-time at which the space-time curvature becomes infinite.

space-time: The four-dimensional space whose points are events.

special relativity: Einstein's theory based on the idea that the laws of science should be the same for all freely moving observers, no matter what their speed.

III) Bibliography

V) Bookreports

i)     Einstein's Dreams page 30

ii) The Time Machine page 37

iii) A Brief History of Time page 45

iiii) The Physics of Star Trek page 61

Marcus Meisel,8C

Einstein's Dreams by Alan Lightman

Author:

'Einstein's Dreams' was written by Alan Lightman, who was born in Memphis, Tennessee, in 1948 and was educated at Princeton and at the California Institute of Technology. He has written for Granta, Harper's, The New Yorker, and The New York Review of Books.

His previous books include 'Time Travel and Papa Joe's Pipe ', 'A Modern-Day Yankee in a Connecticut Court ', 'Origins ', 'Ancient Light ', 'Great Ideas in Physics ', and 'Time for the Stars '.

'Einstein's Dreams ' is his first work of fiction. He teaches physics and writing at the Massachusetts Institute of Technology and currently directs the MIT programme in writing and humanistic studies.

Published :

It´s a Sceptre Book, published by Hodder and Stoughton in Great Britain in 1994. It was first published in Great Britain in 1993 by Hodder and Stoughton, a division of Hodder Headline PLC.

Type of book:

It is a fiction book, endearingly short, airy and irrational, in simple and beautiful language. It is an accomplished first novel and a beautiful book. The science is gentle and it is cast in language to bring the flush of envy to any one of the many famous writers alive today who have coaxed themselves into the delusion that scientists cannot write. 'Einstein's Dreams ' is the sort of book to be read many times and hored and treasured for bleak times and empty spaces.

' A joy to read. It is a celebration of a world in which time does not march brutally through people's lives, but rather skips and gambols, forever quirky and unpredictable' - The Times

'Original, beautifully written light, amusing, fresh a bit of scintillating intellectual daring' - The Observer

'Lightman is exploring fiction's deep space, taking us further than we are used to being taken. It is payful, poignant, intimate cool, languid, intelligent and quotable.Lightman writes movingly and with great precision'-The Sunday Times
Subject:

The setting of the story is located in Bern in Switzerland.

In this book Alan Lightman describes the dreams of Albert Einstein, a young patent clerk, which he had between 14th April 1905 and 28th June 1905. Although the characters and situations in this book are entirely imaginary and bear no relation to any real person or actual happening, it is a breathtaking synthesis of science and imagination.

One witnesses Einstein's dreams of new worlds: extraordinary visions of the effect on people's lives when the direction and the flow of time changes to circular or flows backwards, slows down or takes the form of a nightingale.

The whole book is a flashback that starts after Einstein has finished his work. He reflects back on his time of creating the new theory of time. This ends two hours later. In those two hours Einstein reflects on the past several months, where he had many dreams about time. Most of the dreams take place in Berne, where Einstein lives, while he is dreaming. So in each dream a typical situation out of everyday life of the dream persons, is described. The book describes some of the dreams and tells the reader that those have taken hold of his research.

Out of many possible natures of time, imagined in as many nights, one seems compelling. Not that the others are impossible. The others might exist in other worlds.

The most important persons:

Einstein: a young, 26 years old patent clerk in Berne, dreaming about time while he is discovers a new theory of time. Already this year, he has completed his Ph.D. thesis, finished one paper on photons and another on Brownian motion. The current project actually began as an investigation of electricity and magnetism, which, Einstein suddenly announced one day, would require a reconception of time.

Besso: a close friend to Einstein. They have known each other since their student days in Zürich, and still meet to talk and dine. He is married.

a typist: she has already typed several of his personal papers for him in her spare time. She likes Einstein.

Plot synopsis:

It is six o'clock in the morning and Einstein has finished with his new theory of time, which he will mail to the German journal of physics that day. It cost him a lot of strength and energy, but now he has finished. But not completely. While he waits for the typist in the patent office in Berne he works in, he begins to reflect on the dreams he had.

14th April 1905

Suppose time is a circle, bending back on itself. The world repeats itself precisely, endlessly. Every movement and thought, every flapping of a butterfly's wing, each touch, each smile, every kiss, every birth and every word will be repeated an infinite number of times. But how would humans living in such a world know that nothing is temporary, that everything happened and is going to happen again and again?

There are some few people in every town, who, in their dreams, are vaguely aware that all has occurred in the past. These are the people with unhappy lives who fill up the vacant streets with their moans at night. They are unable to rest because they have the knowledge that they cannot change a simple action or mistake they or anyone else has made.

16th April 1905

In this world time is like a flow of water. Now and then, some cosmic disturbance will cause a rivulet of time to turn away from the mainstream, to make connection backstream.

When this happens, birds, soil, people caught in the branching tributary find themselves suddenly carried to the past. Persons who have been transported back in time are easy to identify because of their fear that any change they make in the past, could have drastic consequences for the future.

There is an example given, of such a traveller from the future. She huddles in a corner, creeps across the street and cowers in another darkened spot. For if she makes the slightest alteration in anything, she may destroy the future. Like kicking up dust while she crossed the street just as Peter Klausen is making his way to the apothecary in Berne on Spitalgasse this afternoon of 16^th April 1905. Klausen hates to have his clothes sullied. If dust messes his clothes, he will stop and brush them off, regardless of waiting appointments. If Klausen is sufficiently delayed, he may not buy the ointment for his wife, who has been complaining of leg aches for weeks. In that case, Klausen´s wife, in a bad humour, may decide not to make the trip to Lake Geneva .

And if she does not go to Lake Geneva on June 23rd, 1905, she won´t meet a Catherine d'Épinay walking on the jetty of the east shore and will not introduce Mlle. d'Épinay to her son Richard. In turn, Richard and Catherine will not marry on 17th December 1908, will not give birth to Friedrich on 8th July 1912. Friedrich Klausen will not be father to Hans Klausen on 22nd August 1938, and without Hans Klausen the European Union of 1979 will never occur.

The woman from the future knows the Klausen story and a thousand other stories, waiting to unfold, dependent on the birth of children and the movement if people in the streets.

19th April 1905

In this world time has three dimensions, like space.

Just as an object may move in three perpendicular directions, corresponding to horizontal, vertical, and longitudinal, so an object may participate in three perpendicular futures. Each future moves in a different direction of time.

Each future is a real one. At every point of decision the world splits into three worlds, each with the same people but with different fates for these people. In time, there are an infinity of worlds.

24th April 1905

There are two times at the same time. There is a mechanical time and there is a body time. The first is like a pendulum that swings back and forth, regularly and without anything disturbing it. The second wriggles like a bluefish in a bay. It makes up its mind as it goes along.

All people who are convinced that mechanical time does not exist, never look at a clock. They eat when they are hungry, sleep, whenever they want and go to their jobs, whenever they wake from their sleep. The others live like machines, they think their bodies don´t exist. They rise at seven a.m., eat their lunch at noon, supper at six, and make love between eight and ten at night.

You can live in either time, but not in both times. Each time is true, but the truths are not the same.

26th April 1905

This is an odd world. Everybody lives on Dome, the Matterhorn, Monte Rosa, and other high ground. No one would buy or build a home elsewhere.

And all this because some time in the past, scientists discovered that time flows more slowly the further from the centre of the earth. The effect, produced by the rotation of the earth , is minuscule, but it can be measured with extremely sensitive instruments. Once the phenomenon was known, the people got anxious to stay young and moved to the mountains. To get the maximum effect, they have constructed their houses on stilts.

Height has become status. In time people have forgotten the reason why higher is better. Nevertheless, they continue to live on the mountains. They tolerate cold, thin air and discomfort for staying younger.

28th April 1905

Time is visible in all places. Clock towers, wristwatches, church bells divide years into months, months into days, days into hours, hours into seconds, each increment of time marching after the other imperfect succession.

In this world a second, is a second. Time is equal for all, it´s an infinite ruler.

Time is absolute. A world in which time is absolute, is a world of consolation. For while the movements of people are unpredictable, the movement of time is predictable.

3rd May 1905

Consider a world in which cause and effect are erratic.

Sometimes the first precedes the second, sometimes the second the first.

Or perhaps cause lies forever in the past while effect in the future, but future and past are entwined.

It is a world of impulse. It´s a world of sincerity. It´s a world in which every word spoken speaks just to that moment, every glance given, has only one meaning, each touch has no past or no future, each kiss is a kiss of immediacy.

4th May 1905

In this world, time does pass, but little happens. Just a s little happens from year to year, little happens from month to month, day to day.

If time and the passage of events are the same, then time moves barely at all. If time and events are not the same, then it is only people who barely move. If a person holds no ambitions in this world, he suffers unknowingly. If a person holds ambitions, he suffers knowingly, but very slowly.

8th May 1905

The world will end on 26th September 1907. Everyone knows it. In Berne, it is just as in all cities and towns. One year before the end, schools close their doors. Why learn for the future, with so brief a future?

One month before the end, businesses close. What need is there for commerce and industry with so little time left? People are not afraid . They sit and sip coffee and talk easily of their lives. What is there to fear now?

One day before the end the streets swirl in laughter. Neighbours who have never spoken greet each other as friends. What do their past stations matter? In a world of one day they are equal.

One minute before the end of the world everyone in Bern gathers on the grounds of the Kunstmuseum. No one moves. No one speaks.

In the last seconds, it is as if everyone has leaped off Topaz Peak, holding hands. The end approaches like approaching ground. Cool air rushes buy, bodies are weightless. The silent horizon yawns for miles. And below, the vast blanket of snow hurtles nearer and nearer to envelope this circle of pinkness and life.

There are a lot more dreams described, and in each dream time has a completely different character and behaviour.

Here are some other examples:

Each village is fastened to a different time and this is because the texture of time is not smooth but it happens to be sticky.

In another dream the passage of time brings increasing order. If time is an arrow, that arrow points toward order.

This book is about the things in life, life, and the humans living in the world. But not only a simple description of their places , behaviours or themselves, it is a description of what happens to them if time has another appearance as we know it.

If there is a world with a centre of time, the time would stand still in the centre. The further one moves away, the faster time goes by. Or imagine a world without any time at all. There would be only images.

A world without memory, as a world in which time flows not evenly but fitfully also occurs in Einstein's dreams. As a consequence of the fitful flow of time, the people receive fitful glimpses of their future.

In another dream all the buildings are built on wheels and race through the cities. Instead of standing still they move fast. Everybody is fixed on speed and this only because some time in the past scientists discovered that time passes more slowly for people in motion. Thus everyone travels at a high velocity, to gain time.

In other worlds the time runs backwards, or the lifetime is compressed to the space of one turn of the earth on its axis, or that time is a sense some people have, and some not.

There are some interludes between these chronologically ordered dreams in which the real time and though Einstein's actions in real live, like meetings with his best friend Besso are described. In such meetings they talk about Einstein's progress with his work, but the reader also gets a glimpse of Einstein's lifestyle in Berne.

Other dreams are about worlds where people live forever, or that time is not a quantity but a quality so that it exists but cannot be measured, or about a world without future where no person can imagine the future.

In another dream, time is a visible dimension which everybody is able to use like all the other dimensions in space, or in another world, time is not continuos, its a local phenomenon. This world is split up in zones of time.

In another dream there is a world where every moment of time is determined.

Other examples of the behaviour of time in the worlds of Einstein's dreams are a world in which time is like the light between two mirrors, a world of countless copies, or a world in which time is a nightingale. For everyone who catches a nightingale, time stands still.

This was the last dream of Einstein before he finished his 'Special Theory of Relativity'.

Ideas, opinions and comments:

This is my favourite book. As I read the book the first time, I was able to understand the meaning of everything what was written, but as I read it the second time, I could enter the plot and really live in the thoughts of Einstein. It was such a fantastic and extraordinary experience, to be relaxed and excited the same time while reading this book. I truly can recommend this book to any person who want's to get a short but deep insight in the thoughts of a genius. It will be an enlarging experience.

Marcus Meisel,7C

The Time Machine by H.G.Wells

Author:

'The Time Machine' was written by H.G.Wells, who was born in Bromley, Kent in 1866, to a working class family. His mother worked as a maid and housekeeper.

After working as a draper's apprentice and pupil-teacher, he won a scholarship to the "Normal School of Science" in South Kensington, where he began to write. The first published work appeared in May 1887 in the Science Schools Journal -"A Tale of the Twentieth Century". After his studies he worked in poverty in London as a cramer and published his first book "A Textbook of Biology" (1893), which was to remain in print for over forty years. Wells had been in print as a professional writer, since 1891 when the Fortnightly Review published his article "The Rediscovery of the Unique". He lived on his writing in those times. But not until he published his first novel "The Time Machine" (1895) did his literary career start.

H.G.Wells died in London, on 13^th August 1946 at the age of 79 years, after having survived the First and Second World War.

Published :

It´s an Everyman Book, published by J.M.Dent, and edited by John Lawton in 1995. It was first published on paperback by J.M.Dent in Everyman's Library 1935.The first publication as book was 1895 by Heinemann in Britain and in the USA by Holt.

Type of book:

It is a science fiction novel about the Victorian future which is more than a fantastical yarn. It raises chilling questions about progress, social orders, so called civilisation and the ultimate fate of the world. It tells the story from the present until the end of our sun-system, a cold, almost lifeless earth with a dying sun.

Wells wrote this novel mainly because Charles Darwin published and proved his theory of Evolution, which was the greatest scientific rumpus since the trial of Galileo. Although the theory shocked society, and Wells had created another "prove" with "The Time Machine", he got positive critics like:

"The Time Machine - considered by the majority of scientific readers to be Mr. Wells's best work" - Nature Magazine.

"The Time Machine - A new thing under the sun" - The Daily Chronicle.

Subject:

It´s a story about evolution brought to the reader as an adventure of an old scientist, who has invented a time machine. Although Wells doesn't tell the reader the names of the Victorian scientist and the Narrator, he creates a personal relationship with the reader, which is very difficult and proves again that H.G.Wells is one of the best writers.

The Time Traveller lives in a house in London, in Richmond. In the cellar he has his laboratory, his workshop, where he invents a miniature and a full- size time machine. The Time Traveller shows his disbelieving dinner guests a device he claims is a Time Machine.

In real time a week later the dinner guests visit the Time Traveller again, but instead of a settled old man they find him raged, exhausted and garrulous. The tale he tells is of the year 802,701 AD of life as it is lived on exactly the same spot, what once had been London. He has visited the future, he has encountered the future -race -elfin, beautiful, vegetarian, helpless, leading a life of splendid idleness.

But this is not the only race, these are not our only descendants. In the tunnels beneath the new Eden there lurks another life form.

The end of the book is open because the Time Traveller disappears in front of the eyes of the Narrator and hasn't come back for three years although he said he'll need only half an hour for his journey.

The most important persons:

The Time Traveller He is an old but lively grey-eyed man who usually has a pale face. He is very learned and wise. The Time Traveller is as reliable as all inventors of new things that weren't proved properly. He thinks un- happily of the Advancement of Mankind, and sees in the growing pile of civilisation only a foolish heaping that must inevitably fall back upon and destroy its makers in the end.

The Narrator He is one of the most constant guests of the Time Traveller. He is a young man, who believes the Time Traveller because of the things he saw ( the flowers, the Time Traveller disappearing). But he also has his own point of view of the future. For him future is still black and blank - is a vast ignorance, lit at a few casual places by the memory of the Time Traveller's story.

A Psychologist: He always tries to destroy a theory with facts that are universally accepted.

A Medical Man: He is a very realistic thinking man. He trusts his eyes but doesn't make premature decisions.

A Provincial Mayor: He doesn't really understand the matters of science, but tries hard to do so.

Filby: He is an argumentative person with red hair.

A Very Young Man: Smokes cigars, is very young and gullible

A Journalist: He thinks the same as the Editor.

A Editor: He believes that the Time Traveller is only an old man who made "telling fantastic stories" to his aim.

A Silent Man: plays his part perfectly. Silent in action and sound.

The Eloi and the Morlocks Those were the two species that resulted from the evolution of man. Those two were now in the year 802,701 AD sliding down towards, or had already arrived at, an altogether new relationship. The Eloi who were the Upperworld people, might once have been the favoured aristocracy, and the Morlocks, their mechanical servants. But that had been long ago. The Eloi, like Carlovingan kings, had decayed to a mere beautiful futility. They still possesed the earth on sufferance, since the Morlocks, subterranean for innumerable generations, had come at last to find the daylight surface intolerable.

In contrast to the Upper-worlders, to whom fire is a novelty to watch and play with, the Morlocks fear any light because their eyes were that sensible that they could see under the surface of earth.

Weena One of the Eloi women. She fell in love with the Time Traveller because he saved her life. Weena had the oddest confidence in the Time Traveller. She followed him everywhere he went and tried to delight him when he got upset. The Eloi feared the darkness like the Morlocks the light but nevertheless Weena followed the Time Traveller into the darkness. After one week queer friendship for about a week, during a journey, the Time Traveller and Weena got attacked by Morlocks and Weena died.

All characters are only related to one another because of their meetings with the Time Traveller.

Plot synopsis:

The action of the book plays in two main settings. One is the house of the Time Traveller in the Victorian age. The other one is on exactly the same place, on an area from Richmond until Wimbledon (in London), but in the year 802701, where everything but-physical rules-has changed. The action, if one sees it in the perspective of the Time Traveller, is strictly chronological, but in the view of all other involved persons in real time, the action has a long and exact foreshadowing.

The novel is gradually built up. It starts with an open beginning, where the Time Traveller, Provincial Mayor, Very Young Man, Psychologist, Filby and the Narrator discuss the existence and nature of a fourth dimension. The Time Traveller explains, that he found out that the fourth dimension, time, is only another dimension of space. He also tries to convey to the dinner guests that man is only able to move in two dimensions without technical help (like a balloon as technical help for the third dimension, heighth). He compares time with some sort of gravitation which limits our movements up or down. The Timetraveller visualises with that example, if it is like that, that it is possible, with technical help, to interrupt the floating time stream, or even move through time as one wants. To prove that to his guests, he experiments with a miniature time machine and shows his guests his lifework, the full-size version of the nearly completed Time Machine.

After a week real time, the Psychologist, Medical Man, Journalist, Editor, Silent Man and Narrator gather at the Time Traveller's. As they can't find him, they start to eat dinner. When he suddenly appears, dishevelled and lame, he washes himself, eats dinner and begins his story.

There is one disruption in the tale of the Time Traveller in chapter seven while he puts the flowers of Weena on the table. This should be a significant sign for the reader that there were two actions at the same time. And that the Time Traveller is only telling a story which is told like a very long direct speech. Except for that very long direct speech the whole book is narrated like a diary by the Narrator who is not named.

"At ten o'clock this day, real time," the Time Traveller begins his hardly believable story about his journey. He tells about his sensations as he travelled through time, that one gets a bit sick of it, that years pass like seconds for him, and he tells about the risks of time travelling.

The peculiar risk lies in the possibility of him finding some substance in the space which he, or the machine, occupies. As long as he travels through time at a high speed, this scarcely matters, but to come to a stop would involve the jamming of him, molecule by molecule into whatever lies in his way. That would result in a far reaching explosion and would blow him and the apparatus out of all possible dimensions into the Unknown.

But already while he was making the machine, he accepted it as an unavoidable risk, one of the risks a man has to take.

When continuing the story, the Timetraveller says that when he halted, he saw some creatures, friendly, smiling, human, vegetarian, but degenerated. Their behaviour was comparable to children's, not to adult's. He says that he had dined with the creatures he met and comments on their nature and way of life. Eg. that they spoke a very sweet and liquid tongue. They didn't know what fear during sunshine was, their hair, which was uniformly curly, came to a sharp end at the neck and check, their mouths were small, with bright red, rather thin lips and their eyes were large and mild, etc.

The Time Traveller considers how the world of his own time could have changed to that in which he finds himself after the journey. After dinner he discovered that his machine had disappeared. He met Weena. In the early dawn of one night he caught a glimpse of creatures other than those he first met and concluded that there were two distinct peoples, those who lived above ground, and those who existed below.

Convinced the under-world creatures which he named Morlocks had hidden his machine, the Time Traveller descended to their underground caves but had to escape, empty- handed.

But that action was not useless. From that moment on he knew that the Morlocks feared light and the Eloi, like he named the upperworlders, feared the dark. He considered the relationship between the two races and realised that the once- subservient Morlocks now dominated the Eloi. So he took Weena to explore a large place , which had been a museum in former times.

During the journey Weena put some flowers into his pocket. While he tells the story he puts the flowers onto a table in his smoking room. After a short break he continues and says that it was further than he thought. With the darkness approaching, his and Weena's fear of Morlocks grew. They spended the night in safe. In the ruined museum the Time Traveller found matches, camphor and a metal bar to use against the Morlocks as a weapon.

As the Time Traveller and Weena returned from the museum, they were forced by tiredness to rest in a forest. Although the Time Traveller had set fire to the trees to fend off the Morlocks, the two were attacked and Weena disappeared which gave the Time Traveller a keen stab of pain directly into his heart. The Morlocks, however, were blinded by the raging fire.

On the next day the Traveller returned to the Eloi and found his time machine in a trap of the Morlocks, but he escaped through time. He went on into the future. During his journey he recognised that the changing of day and night got more slowly although he drove at a constant speed, which could only mean, that the earth was spinning more and more slowly. He also saw that the sun got bigger. When he stopped, he discovered a cold and almost lifeless earth with a dying sun. That shocked him that much, that he returned immediately into his own time, where he was greeted with scepticism.

As the Narrator visits the Time Traveller on the next day again, he, the Time Traveller disappears with a camera in his Time Machine.

In the Epilogue the Narrator reflects on what might have befallen the Time Traveller, he also considers his own view of the future, as black and blank as ever.

Ideas, opinions and comments:

This book is very interesting because since I was in Kindergarten, I wanted to build a Time Machine, so I really could easily identify with the Time Traveller, as an excellent scientist and inventor. I really enjoyed that science fiction novel because it is not that unrealistic, how time works and what will happen to our earth. I think many writers of science fiction novels have gathered material from the fairy- land of science, and have used it in their construction of literary fabrics, but none have done it more successful than H.G.Wells.

Marcus Meisel,8C

A Brief History of

Time by Stephen W. Hawking

Author:

'A Brief History of Time' was written by Professor Stephen Hawking, who was born in Oxford, Great Britain, on 8^th January 1942.

He studied physics at Oxford University and went on to pursue his graduate studies at Cambridge. In his early twenties he was diagnosed as having ALS (Amyotrophic Lateral Sclerosis), known in the UK as Motor Neurone Disease. He holds Newton's chair as Lucasian Professor of Mathematics at Cambridge and is widely considered to be the greatest scientific thinker since Newton and Einstein. In 1989 he received an Honorary Doctor of Science degree from Cambridge University and was made a Companion of Honour.

Published :

It´s a Bantam Books Book, published by Bantam Press. It was first published by Bantam Books in 1988. 'A Brief History of Time' remained on The New York Times best-seller list for fifty-three weeks; and in Britain, as of February 1993, it had been on The Sunday Times list for 205 weeks. (At week 184, it went into the Guinness Book of Records for achieving the most appearances on this list.) The number of translated editions is now thirty-three.

Type of book:

'A Brief History of Time' is a book that tries to explain the main theories of today physics in a quite 'non-technical' language so everybody can understand them. Stephen also explains also the basics to these theories so that the reader has to know almost nothing about physics to understand them. This book starts at the beginning of science with the Greek philosopher Aristotle and goes on until the youngest theories about our universe like the superstring-theory which needs 10dimensions.

The book is divided into 11 chapters and 3 epilogues about Einstein, Newton and Galileo Galilei. There is also a glossary that explains the main technical verbs that are used in this book.

' This book marries a child's wonder to a genius intellect. We journey into Hawking's universe, while marvelling at his mind ' - Sunday Times

Subject:

We go about our daily lives understanding almost nothing of the world. We give little thought to the machinery that generates the sunlight that makes life possible, to the gravity that glues us to an Earth that would otherwise send us spinning off into space, or to the atoms of which we are made and on whose stability we fundamentally depend. Except for children few of us spend much time wondering why nature is the way it is; where the cosmos came from, or whether it was always here; if time will flow backward one day and effect precede causes; or whether there are ultimate limits to what humans can know. Was there a beginning of time? Could time run backwards? Is the universe infinite or does it have boundaries? These are just some of the questions considered in an internationally acclaimed masterpiece which begins by reviewing the great theories of the cosmos from Newton to Einstein, before delving into the secrets which still lie at the heart of space and time.

This book tries to answer this question, but a lot of these questions can not be answered now and so we can only follow the theories of Stephen Hawking, which are very well explained here.

The most important persons:

Albert Einstein: He is a German-born American physicist and Nobel laureate, best known as the creator of the special and general theories of relativity and for his bold hypothesis concerning the particle nature of light. He is perhaps the most well-known scientist of the 20th century.

Einstein was born in Ulm on March 14, 1879. At the age of 12 he taught himself Euclidean geometry.

In 1902 he secured a position as an examiner in the Swiss patent office in Bern. After 1919, Einstein became internationally renowned. He accrued honours and awards, including the Nobel Prize in physics in 1922, from various world scientific societies. His visit to any part of the world became a national event.

When Hitler came to power, Einstein immediately decided to leave Germany for the United States. He took a position at the Institute for Advanced Study at Princeton, New Jersey. Einstein died in Princeton on April 18, 1955.

He often said, only the discovery of the nature of the universe would have lasting meaning.

Galileo Galilei: Galileo was born near Pisa, on February 15, 1564. He was a Italian physicist and astronomer, who, with the German astronomer Johannes Kepler, initiated the scientific revolution that flowered in the work of the English physicist Sir Isaac Newton. Born Galileo Galilei, his main contributions were, in astronomy, the use of the telescope in observation and the discovery of sunspots, lunar mountains and valleys, the four largest satellites of Jupiter, and the phases of Venus. In physics, he discovered the laws of falling bodies and the motions of projectiles. In the history of culture, Galileo stands as a symbol of the battle against authority for freedom of inquiry.

In 1589 he became professor of mathematics at Pisa. Only the Copernican model supported Galileo's tide theory, which was based on motions of the earth. He discovered mountains and craters on the moon. He also saw that the Milky Way was composed of stars. By December 1610 he had observed the phases of Venus, which contradicted Ptolemaic astronomy and confirmed his preference for the Copernican system.

He died in 1642.

Sir Isaac Newton: He was born on January 4, 1643 at Woolsthorpe, near Grantham in Lincolnshire. He was an English mathematician and physicist, considered one of the greatest scientists in history, who made important contributions to many fields of science. His discoveries and theories laid the foundation for much of the progress in science since his time. Newton was one of the inventors of the branch of mathematics called calculus. He also solved the mysteries of light and optics, formulated the three laws of motion, and derived from them the law of universal gravitation.

Later, in the summer of 1661, he was sent to Trinity College, at the University of Cambridge. Newton received his bachelor's degree in 1665. He received his master's degree in 1668.

Newton is probably best known for discovering universal gravitation, which explains that all bodies in space and on earth are affected by the force called gravity. He published this theory in his book Philosophiae Naturalis Principia Mathematica in 1687. This book marked a turning point in the history of science. Newton died in 1727.

Plot synopsis:

In the introduction Stephen Hawking explains that he left out all but one equation, the most famous found by Albert Einstein because someone told him every equation would halve the sales of the book. He also describes how he got help from friends, who donated a communication programme and a speech synthesiser to him, which in combination with a small personal computer mounted on his wheelchair, allows him a better communication than before he lost his voice.

In the beginning Hawking tells an anecdote on how a well-known scientist once gave a public speech on astronomy and in the end an old lady got up and said that he´d talked rubbish, because in reality the world would be a flat plate supported on the back of a giant tortoise that stands on the back of another tortoise and so on. He points out that most people would find this picture rather ridiculous, but why do we think to know better?

Only recent breakthroughs in physics suggest answers to our questions about the history of the universe, which may seem as obvious as the earth orbiting our sun, or as ridiculous as a tower of tortoises. Only time (whatever that may be) will tell.

The Greek philosopher Aristotle was the first to point out that earth was a round sphere. Nevertheless the Greek still believed in the earth being the stationary centre of the universe. This idea was elaborated by Ptolemy into a complete cosmological model, which was generally accepted and adopted by the Christian church as the picture of the universe that was in accordance with the Scriptures, for it had the great advantage that it left lots of room outside the sphere of the fixed stars for heaven and hell.

A simpler model suggesting that the sun was stationary at the centre and the earth and the planets moved in circular orbits around the sun, was proposed by Nicholas Copernicus. Nearly a century passed before this idea was taken seriously by two astronomers, the German, Johannes Kepler and the Italian, Galileo Galilei. Galileo observed the moons of Jupiter with a just invented telescope, which was the deathblow to the old theory. An explanation was provided only much later, in 1687, when Sir Isaac Newton published his 'Philosophiae Naturalis Principia Mathematica', probably the most important single work ever published in the physical sciences. In there, he postulated the law of universal gravitation and developed the complicated mathematics needed to analyse the motions of planets and calculus.

The beginning of the universe has been discussed long then, because according to religious traditions the universe started at a finite, and not very distant time in the past. Nowadays we take it for granted that we live in a lacy spiral disk galaxy and that there are many other galaxies more or less like it in the universe. But early in our century not everyone accepted this picture.

It was the American astronomer Edwin Hubble who, in the 1920s, showed that there are indeed many galaxies besides our own. It was Hubble again who showed that distant galaxies, wherever you look, are all moving away from us. In other words, the universe is expanding. The most helpful way to think of the expansion of the universe is not as things rushing away from one another but as space between them swelling. Imagine a balloon with dots on its surface being inflated. When the balloon swells, the dots move apart.

This discovery finally brought the question of the beginning of the universe into the realm of science. If galaxies move apart from each other, they used to be much closer together at some moment in the past, ten or twenty thousand million years ago. They all have been in exactly the same place. All the enormous amount of matter in the universe packed in a single point, infinitely dense and infinitesimally small. Such a situation is called the 'big bang'. One may say that time had a beginning at the big bang, in the sense that earlier times simply would not be defined.

But this is not the only possible history of an expanding universe.

The second chapter describes the non-existence of absolute rest and therefore the lack of an absolute position in space and time.

The fact that light travels at a finite, but very high, speed ( 186,000 miles per second) was first discovered by the Danish astronomer Roemer. He measured the motion of Jupiter and the eclipses of its moons. A better theory of the locomotion of light did not come until the 19^th century when the British physicist Maxwell managed to unify the partial theories that till then had been used to describe the forces of electricity and magnetism. Maxwell's theory predicted that radio or light waves should travel at a certain fixed speed. In order to fit Newton's theories he introduced a substance called 'ether' that was present also in empty space.

Finally in 1905 Albert Einstein came to the conclusion that the whole idea of an ether was unnecessary, providing one was willing to abandon the idea of absolute time. Based on this Einstein worked out first the special, then the general theory of gravity, presenting the famous equation and the law that nothing can travel faster than the speed of light.

The theory of relativity describes that any observer can work out precisely what time and position any other observer will assign to an event, provided he knows the other observer's relative velocity. Nowadays we use just this method to measure distances precisely, because we can measure time more accurately than length. In effect, one meter is defined to be the distance travelled by light in 0.000000003335640952 seconds, as measured by a caesium clock.

So, we must accept that time is not completely separate from and independent of space, but is combined with it to form an object called 'space-time'.

Einstein spent several years attempting to find a theory of gravity that would work with what he had discovered about light and motion at near light speed. In 1915 he introduced the theory of general relativity where he thinks of gravity not as a force acting between two bodies but in terms of the shape, the curvature, of four-dimensional space-time itself. In general relativity, gravity is the geometry of the universe. According to Einstein the curvature is caused by the presence of mass. Every massive body contributes to the curvature of space-time. Things going 'straight ahead' in the universe are forced to follow curved paths. Imagine a heavy object, such as a cannon ball, representing the sun, being placed in the middle of a taut rubber sheet, creating a cone-shaped dent all around it.

Einstein argued that whenever something heavy bent space-time like this, it would naturally affect the path of anything lighter travelling nearby. If you now try to roll a smaller ball representing the Earth or one of the other planets across the stretched rubber sheet representing space-time, it will certainly change direction slightly when it meets the dent caused by the cannon ball sun.

It will probably do more than that: it may describe an ellipse and roll back in your direction. Something like that happens as the earth tries to continue in a straight line past the sun. The sun warps space-time as the canon ball warps the rubber sheet. The earth's orbit is the nearest thing to a straight line in warped space-time. At just the right speed, the small planet ball would be travelling fast enough not to fall right into the dent, but too slowly to escape it completely. With nothing else to stop it or slow it down, it would find its level on the 'side' of the dent in space-time.

The speed of light in space time can be seen like the ripples that spread out on the surface of a pond when a stone is thrown in. The ripples spread out as a circle that gets bigger as time goes on. If one thinks of a three-dimensional model consisting of the two-dimensional surface of the pond and the one dimension of time, the expanding circle of ripples will mark out a cone whose tip is at the place and time at which the stone hit the water. Similarly the light spreading out from an event forms a three-dimensional cone in the four-dimensional space-time. This cone is called the future light cone of the event. In the same way we can draw another cone, called the past light cone, which is the set of events from which a pulse of light is able to reach the given event.

Einstein's theory predicts that not only planets, also Photons are affected by the warp of space-time. If a light ray is travelling from a distant star and its path takes it close to our sun, the warping of space-time near the sun causes the path to bend inward towards the sun for a few degrees. Perhaps the path of light bends in such a way that the light finally hits the earth. Our sun is too bright for us to see such starlight; except during an eclipse of the sun.

If we see it then and do not realise the sun is bending the path of the stars light, we would get the wrong idea about which direction the beam of light is coming from and where that star actually is in the sky. Astronomers make use of this effect. They measure the mass of objects in space by measuring how much they bend the paths of light from distant stars. The greater the mass , the greater the bending.

Einstein made the revolutionary suggestion that gravity is not a force like other forces, but is a consequence of the fact that space-time is not flat, as had been previously assumed: it is curved, or warped, by the distribution of mass and energy in it. Roger Penrose and Stephen Hawking showed that Einstein's general theory of relativity implied that the universe must have a beginning and, possibly, an end.

Chapter three begins with the observation that even fixed stars in fact change their position, and all visible to us are concentrated in one band, which we call the Milky Way. Our modern picture of the universe dates back to Hubble, who demonstrated that ours was not the only galaxy. There were in fact many others, with a lot of empty space between them. We live in a galaxy that is about one hundred thousand light-years across and is slowly rotating. The stars in its spiral arms orbit around its centre about once every several hundred million years. Our sun is just an ordinary, average-sized, yellow star, near the inner edge of one of the spiral arms.

The characteristics of a stars, we get by observing the spectra, which not only tells us the temperature, but also the elements it consists of.

Friedmann started with two assumptions in his model: 1^st: The universe looks much the same in whatever direction you look (except for nearby things like our Solar System and the Milky Way); 2^nd: The universe looks like this from wherever you are in the universe.

Friedmann's first assumption is fairly easy to accept. The second isn't. We do not have any scientific evidence for or against it.

From these two ideas alone, Friedmann showed that we should not expect the universe to be static. In fact, in 1922, several years before Edwin Hubbell's discovery, Friedmann predicted exactly what Hubble found! In 1965 two American physicists at the Bell Telephone Laboratories in New Jersey, discovered the microwave background of the universe and thereby proved Friedmann´s theories.

Although Friedmann found only one, there are in fact three different kinds of models that obey Friedmann´s two fundamental assumptions. In the first which Friedmann found, the universe is expanding too slowly so that the gravitational attraction between the different galaxies causes the expansion to slow down and eventually to stop. The galaxies then start to move toward each other and the universe contracts until the big crunch. In the second kind of solution, the universe is expanding so rapidly that the gravitational attraction can never stop it, though it does slow it down a bit. Finally, there is a third kind of solution, in which the universe is expanding only just fast enough to avoid recollapse. However, the speed at which the galaxies are moving apart gets smaller and smaller, although it never quite reaches zero. Because of insufficient measuring methods and some uncertainty about dark matter we cannot exactly figure out which Friedmann model describes our universe. All the Friedmann solutions have the feature that at some time in the past, the distance between neighbouring galaxies must have been zero. At that time, which we call the big bang, the density of the universe and the curvature of space-time would have been infinite. Because mathematics cannot really handle infinite numbers, this means that the general theory of relativity (on which Friedmann´s solutions are based) predicts that there is a point in the universe where the theory itself breaks down. Such a point is an example of what mathematicians call a singularity.

In 1965 the British mathematician and physicist Roger Penrose discovered the existence of black holes, which also contain singularities.

The idea, that stars may end up and can become a black hole, is based on the gravitational effect of mass. Imagine a star that has ten times the mass of the sun. The star's radius is about 3 million kilometres, about five times that of the sun. Escape velocity is about 1,000 kilometres per second. Such a star has a life span of about a hundred million years. On one side the sun has to fight against gravity: the attraction of every particle in the star for every other. On the opposing side is the pressure of the gas in the star. This pressure comes from heat released when hydrogen nuclei in the star collide and merge to form helium nuclei what is called the fusion process. The heat makes the star shine and creates enough pressure to resist gravity and prevent the star from collapsing.

For a hundred million years this balance is held. Then the star runs out of hydrogen that it could convert into helium. Some stars then convert helium into heavier elements, but that gives them only a short reprieve.

When there's no more pressure to counteract gravity, the star shrinks. As it does, the gravity on its surface becomes stronger and stronger because the mass gets more and more compressed. It won't have to shrink to a singularity to become a black hole. When the 10-solar-mass star's radius is about 30 kilometres, escape velocity on its surface will have increased to 300,000 kilometres per second, the speed of light. And out of these facts rises the definition of a black hole: When light can no longer escape the star is a black hole.

Stars with less than 8 solar masses probably don't shrink all the way to form black holes. Such stars are then called brown dwarfs. The limit, beyond that a star can become a black hole, is called the 'Chandrasekhar limit'.

Whether our star goes on shrinking to a point of infinite density or stops shrinking just within the radius where escape velocity reaches the speed of light, gravity at that radius is going to feel the same, as long as the star's mass doesn't change. Escape velocity at that radius is the speed of light and will stay the speed of light. Such a border of a black hole is called 'event horizon'. Light coming from the star will find escape impossible. Nearby beams of light from distant stars may curl around the black hole several times before escaping or falling in.

A black hole, with its event horizon for an outer boundary, is shaped like a sphere, or if it is rotating, a bulged-out sphere, a convex lens. The event horizon is marked by the paths in space-time of rays of light that hover just on the edge of that spherical area, not being pulled in but unable to escape. Gravity at that radius is strong enough to stop their escape, but just not strong enough to pull them back in. We can't see them because the photons of those rays can't escape from that radius, they can't reach our retina.

General relativity predicts the existence of singularities, but in the early 1960s only a few took this prediction seriously. Until Hawking and Penrose showed that if the universe obeys general relativity, a star of great enough mass undergoing gravitational collapse must form a singularity.

Hawking realised that if he reversed the direction of time so that the collapse became an expansion, everything in the theory would still hold. If general relativity tells us that any star which collapses beyond a certain point must end in a singularity, then it also tells us that any expanding universe must have begun as a singularity therefore as a Friedman model.

With newly developed mathematical techniques and other technical conditions from the theorems that singularities must occur, Penrose and Hawking at last proved that there must have been a big bang singularity provided only that general relativity is correct and the universe contains as much matter as we observe. It is perhaps ironic that now, having changed his mind, Hawking actually is trying to convince other physicists that there was in fact no singularity at the beginning of the universe - as you will see later, it can disappear once quantum effects are taken into account.

The fourth chapter begins with the theory of determinism proclaimed by the French scientist the Marquis de Laplace at the beginning of the 19^th century.

To avoid that a hot object, or body, such as a star, must radiate energy at an infinite rate, the German scientist Planck suggested in 1900 that light, X rays, and other waves could not be emitted at an arbitrary rate, but only in certain packets that he called quanta. 1926 another German scientist, Heisenberg, formulated his famous uncertainty principle. In order to predict the next position and velocity of a particle, one has to be able to measure its present position and velocity exactly.

This led Heisenberg, Schrödinger, and Dirac to reformulate mechanics into a new theory called quantum mechanics, based on the uncertainty principle. It predicts a number of different possible outcomes and tells us how likely each of these is. Quantum theory also led to the theory of wave-particle duality.

The fifth chapter deals with elementary particles and the forces of nature. Just thirty years ago, it was thought that protons and neutrons were elementary particles, but experiments in which protons were shot on one another at high speeds had shown that they were in fact made up of smaller particles which were named quarks. There are different types of quarks: there are thought to be at least six 'flavours', which we call: up, down, strange, charmed, bottom, and top. Each flavour comes in three 'colours', red, green, and blue. These colours and names are just a creative invention of physicist, quarks are much smaller than the wavelength of visible light and so do not have any colour in the normal sense.

A proton or neutron for instance, is made up of three quarks, one of each colour. We can create particles made up of the other quarks, but these all have a much greater mass and decay very rapidly into protons and neutrons.

The wave-particle dualism leads to a characteristic of particles, called spin. Since particles have no well-defined axis, the spin really tells us what the particle looks like seen from different directions. A particle of spin 0 is like a dot: it looks the same from every direction. A particle of spin 1 has to be turned round a full revolution to look the same, a particle of spin 2, half a revolution. But there are particles that do not look the same if one turns them through just one revolution: you have to turn them through two complete revolutions! Such particles are said to have spin ½. All the known particles in the universe can be divided into two groups: particles of spin ½, which make up the matter in the universe, and particles of integer spin which give rise to forces between the matter particles. The matter particles obey what is called Pauli´s exclusion principle. This was discovered in 1925 by an Austrian physicist, Wolfgang Pauli.

There exist just four groups of force-carrying particles. You can sort them according to the strength of the force they carry and the particles with which they interact. These four are: gravitational force, electromagnetic force, weak nuclear force, and strong nuclear force. The last three are combined into what is called a Grand Unified Theory (GUT), but these contain a number of parameters whose values cannot be predicted from the theory. That's the reason why this theory is not the ultimate theory up to now.

Till 1956 it was believed that the laws of physics obeyed each of three separate symmetries called C, P, and T. The symmetry C(charge) means that the laws are the same for particles and antiparticles. The symmetry P(parity) means that the laws are the same for any situation and its mirror image (the mirror image of a particle spinning in a right-handed direction is one spinning in a left-handed direction). The symmetry T(time) means that if you reverse the direction of motion of all particles and antiparticles, the system should go back to what it was at earlier times; in other words, the laws are the same in the forward and backward directions of time. However, in 1964 two Americans, J. W. Cronin and Val Fitch proved this believe to be wrong.

The sixth chapter gets a little bit more practical and explains the mystery of black holes. In 1969 the term 'black hole' was put into the world by the American scientist John Wheeler as a graphic description of an idea at least two hundred years old. Roemer´s discovery that light travels at a finite speed meant that gravity might have an important effect on it, following the wave-particle duality of quantum mechanics. However, a consistent theory of how gravity affects light did not come along until Einstein proposed general relativity.

The possible final states are 'white dwarfs', neutron stars or black holes. Chandrasekhar had shown that the exclusion principle could not halt the collapse of a star more massive than the Chandrasekhar limit, but the problem of understanding what would happen to such a star, according to general relativity, was first solved by a young American, Robert Oppenheimer. He found that at this singularity the laws of science and our ability to predict the future would break down.

Anybody who remained far enough away of the black hole would not be affected by this failure of predictability, because neither light nor any other signal could reach him from the singularity.

There are some solutions of the equations of general relativity in which occur so-called 'wormholes'. These are 'highways' of transport through space. You can get from one region of the universe to another in no time at all. This would offer great possibilities for travel through space and time, but unfortunately, it seems that these solutions may all be highly unstable.

The extra attraction of a large number of black holes could also explain why our galaxy rotates at the rate it does: the mass of the visible stars is insufficient to account for this. We also have some evidence that there is a much larger black hole, with a mass of about a hundred thousand times that of the sun, at the centre of our galaxy.

As in the case of Cygnus X-1, a very possible candidate for a black hole, the gas will spiral inward and will heat up. It will not get hot enough to emit X-rays, but it could account for the very compact source of radio waves and infrared rays that is observed at the galactic centre. It is thought that similar but even larger black holes, with masses of about a hundred million times the mass of the sun, occur at the centres of quasars. Matter falling into such a supermassive black hole would provide the only source of power great enough to explain the enormous amounts of energy that these objects are emitting.

As the matter spirals into the black hole, it would make the black hole rotate in the same direction, and though producing a magnetic field like that of the earth. Very high energy particles would be generated near the black hole by the in-falling matter. The magnetic field would be so strong that it could focus these particles into jets ejected outward along the axis of rotation of the black hole. Such jets are really observed in a number of galaxies and quasars.

The seventh chapter is about light rays in the event horizon. If the rays of light that form the event horizon can never approach each other, the area of the event horizon might stay the same or increase with time but it could never decrease - because that would mean that at least some of the rays of light in the boundary would have to be approaching each other. In fact, the area would increase whenever matter or radiation fell into the black hole. The nondecreasing behaviour of a black hole's area was very significant for the behaviour of a physical quantity called entropy, which measures the degree of disorder of a system. It is a matter of common experience that disorder will tend to increase if things are left to themselves.

This idea combined with the second law of thermodynamics, leaded to a fatal law. If a black hole has entropy, then it ought also to have a temperature! But a body with a particular temperature must emit radiation at a certain rate. This radiation is required in order to prevent violation of the second law. So black holes ought to emit radiation. But by their very definition, black holes are objects that are not supposed to emit anything. It therefore seemed that the area of the event horizon of a black hole could not be regarded as its entropy.

But calculations showed that black holes in fact emitted radiation. The spectrum of the emitted particles was exactly that which would be emitted by a hot body, and the black hole was emitting particles at exactly the correct rate to prevent violations of the second law.

So there occurred a new question: How is it possible that a black hole appears to emit particles when we know that nothing can escape from within its event horizon? The answer, quantum theory tells us, is that the particles do not come from within the black hole, but from the 'empty' space just outside the black hole's event horizon.

What we think of as 'empty' space cannot be completely empty because that would mean that all the fields, such as the gravitational and electromagnetic fields, would have to be exactly zero. There must be a certain minimum amount of uncertainty, or quantum fluctuations, in the value of the field. One can think of these fluctuations as pairs of particles of light or gravity that appear together at some time, move apart, and then come together again and annihilate each other. These particles are virtual particles like the particles that carry the gravitational force of the sun: unlike real particles, they cannot be observed directly with a particle detector, but their indirect effects, like small changes in the energy of electron orbits in atoms, can be measured. And those measurements agree with the theoretical predictions with a high accuracy.

Heisenberg's uncertainty principle also predicts that there will be similar virtual pairs of matter particles, such as electrons or quarks. In this case one member of the pair will be a particle and the other an antiparticle. Out of the reason that energy cannot be created out of nothing, one of the partners in a particle/antiparticle pair will have positive energy, and the other partner negative energy. The one with negative energy is condemned to be a short-lived virtual particle because real particles always have positive energy in normal situations. It must therefore seek out its partner and annihilate with it. Normally, the energy of the particle is still positive, but the gravitational field inside a black hole is so strong that even a real particle can have negative energy there. If a black hole is present, it is possible for the virtual particle with negative energy to fall into the black hole and become a real particle or antiparticle. In this case it no longer has to annihilate with its partner. Now there are two possibilities what could happen: The second partner could also fall into the black hole and disappear forever, or it might also escape from the black hole as a real particle or antiparticle. To an observer at a distance, like us humans, it will appear to have been emitted from the black hole. And this is the radiation we can observe.

Because of this radiation, the black hole therefore reduces its mass, very slowly, but it does.

Moreover, the lower the mass of the black hole, the higher its temperature. So, as the black hole loses mass, its temperature and rate of emission increase, so it loses mass more quickly. What happens when the mass of the black hole eventually becomes extremely small, is not quite clear, but the most reasonable guess is that it would disappear completely in a huge final burst of emission, equivalent to the explosion of millions of H-bombs.

The eighth chapter is about the origin and fate of the universe as general relativity predicts it and when quantum effects are taken into account. Hawking first gives us an opportunity to think about the role the church had played in the picture of the universe, and then goes on with new theories science has uncovered.

We don´t yet have a complete and consistent theory that combines quantum mechanics and gravity, but we are fairly certain of some features that such a unified theory should have.

One is that it should incorporate Feynman´s proposal to formulate quantum theory in terms of a sum over histories. In this approach, a particle does not have just a single history, as it would in a classical theory. Instead, it is supposed to follow every possible path in space-time, and with each of these histories there are associated a couple of numbers, one representing the size of a wave and the other representing its phase. The whole thing works with probabilities of the sums of waves, associated with every possible history that a particle has.

To avoid technical problems, one must add up the waves for particle histories that are not in the 'real' time that you and I experience but take place in what is called imaginary time. Imaginary time may sound like science fiction but it is in fact a well-defined mathematical concept. There are special numbers, called imaginary, that, unlike ordinary numbers, give negative numbers when multiplied by themselves. So for the purposes of the calculation of Feynman's theory, one must measure time using imaginary numbers, rather than real ones. This has an interesting effect on space-time: the distinction between time and space disappears completely.

A second feature that we believe must be part of any ultimate theory, is Einstein's idea that the gravitational field is represented by curved space-time. When we apply Feynman´s sum over histories to Einstein's view of gravity, the analogue of the history of a particle is now a complete curved space-time that represents the history of the whole universe.

In the classical theory of general relativity, there are many different possible curved space-times, each corresponding to a different initial state of the universe. If we knew the initial state of our universe, we would know its entire history!

Similarly, in the quantum theory of gravity, there are many different possible quantum states for the universe. Again, if we knew how the Euclidean curved space-times in the sum over histories behaved at early times, we would know the quantum state of the universe now and in the future.

In the classical theory of gravity, which is based on real space-time, there are only two possible ways the universe can behave: either it has existed for an infinite time, or else it had a beginning at a singularity at some finite time in the past. In the quantum theory of gravity, a third possibility arises. Because it is possible for space-time to be finite in extent and yet to have no singularities that formed a boundary or edge. Space-time would be like the surface of the earth, only with two more dimensions.

The ninth chapter discusses the arrow of time and its direction. There are at least three different arrows of time. First, there is the psychological arrow of time. This is the direction in which we feel time passes, the direction in which we remember the past but not the future. Then, there is the thermodynamic arrow of time, the direction of time in which disorder or entropy increases. Finally, there is the cosmological arrow of time. This is the direction of time in which the universe is expanding rather than contracting.

Chapter ten speculates about the unification of physics. To remove infinities, one uses a process called renormalization, but this leads to many errors conflicting with observation. The introduction of 'supergravity' caused problems, too. So, in 1984 there was a change of opinion in favour of string theories. In these theories the basic objects are not particles, which occupy a single point of space, but things that have a length but no other dimension, like an infinitely thin piece of string. These strings may have ends or they may join with themselves in closed loops. A particle occupies one point of space at each instant of time. Thus its history can be represented by a line in space-time, the 'world-line'. A string, on the other hand, occupies a line in space at each moment of time. So its history in space-time is a two-dimensional surface called the world-sheet. Any point on such a world-sheet can be described by two numbers: one tells the time and the other the position of the point on the string.

But, string theories seem to be consistent only if space-time has either ten or twenty-six dimensions, instead of the usual four. The suggestion is, therefore, that the other dimensions are curved up into a space of very small size.

The eleventh, final chapter, tries to draw a conclusion. The history of science (and time) is once again briefly summed up, and Stephen Hawking ends with the hope of finally gain understanding of everything that happens in our universe.

Ideas, opinions and comments:

I liked this book very much, for it is one of the very best I´ve ever read. Stephen Hawking points out the most complicated scientific facts in an easily understandable and very fascinating way. This book will attract the interest of any reader, and probably everyone willing to think about it will have no problems to understand it.

At the end I just want to mention that Stephen's book has sold 8 million copies world-wide and familiarised a whole generation with complex but intensely exciting scientific theories. I think that he has a very good ability to explain complicated things in an easy understandable way. I really loved to read this book and I can only strongly recommend this book to anyone!

Marcus Meisel,8C

The Physics of

Star Trek           by Lawrence M. Krauss

Author:

'The Physics of Star Trek' was written by Lawrence M. Krauss. He is Ambrose Swasey Professor of Astronomy and Chairman of the Department of Physics at Case Western Reserve University. He is the author of two acclaimed books, Fear of Physics: A Guide for the Perplexed and The Fifth Essence: The Search for Dark Matter in the Universe, and over 120 scienific articles. He is the recipient of several international awards for his work, including the Presidential Investigator Award, given by President Reagan in 1986. He lectures extensively to both lay and professional audiences and frequently appears on radio and television.

Published :

It´s a Flamingo Book, published by HarperCollinsPublishers in 1997. It was first published in the USA by Basic Books, a division of HarperCollinsPublishers in 1995.

It was first published in the UK by HarperCollinsPublishers in 1996.

Type of book:

It is a popular science book, trying to tell most modern science in a simple language.

' The Physics of Star Trek' is a book to be read many times as long it is up-to-date with our time (till we cross the milky ways of our and other galaxies). It offers a lot of exotic science to anyone who wants to make a small investment of imagination. Perhaps accidentally, Krauss also does a useful job in explaining some important physics, using Star Trek as a pop culture example: the physics of Newton, Einstein and Stephen Hawking all figure in the highly successful analysis.

It is a book on physics, but it is written in such a spirit of fun, it might even make you want to watch Star Trek.

'Always enlightening this book is fun, and Mr Krauss has a nice touch with a tough subject Krauss is smart, but speaks and writes the common tongue.' - New York Times Book Review

' Entertaining and fascinating' - Manchester Evening News

' A brilliant book' - Cambridge Evening News

' Highly recommended' - SFX

Subject:

This entertaining book from the popular professor for physics and astronomy at the Case Western University, Cleveland, Ohio deals with the physical backgrounds of Star Trek and looks at how the imaginary science of the Star Trek universe stacks up against the real thing. Krauss speculates on the possibility of alien life, touching on whether any kind of life is such an improbable phenomenon.

There are impressively clear explanations of difficult and up-to-date concepts in information theory, quantum mechanics, particle physics, relativity, mechanics and cosmology. The book goes where not even the show's laudable tradition of scientific evangelism has gone before.

The most important persons:

This book is about science from the past through the present into the future. Because of this enormous frame of time it is not possible to give a brief description of every important scientist or character of the Star Trek series.

Plot synopsis:

In the foreword famous Lucasian Professor and one-time Star Trek guest star Stephen Hawking points out that the main purpose of science fiction is to expand the imagination of all people. He says that 'Science fiction suggests ideas that scientists incorporate into their theories'. Star Trek literally takes us "where no one has gone before", and the science fiction of today may become the science of tomorrow.

In the first four chapters the author takes us on a guided tour through the history of physics, always with an eye on some Star Trek adventures that fit to this special part of physics.

He starts with seventeenth-century mathematician and physicist Isaac Newton, continues with Albert Einstein and Stephen Hawking until he finally reaches Trek's 24^th century, with Data as the temporary end of knowledge. A main objective of these first four chapters is faster-than-light travel, called 'warp drive' in Star Trek. Lawrence M. Krauss notices that the authors of Star Trek had a brilliant imagination with the word "warp", because for almost all scientists warping space seems to be the only possibility to move faster than light.

His next objective is the transporter, probably one of the most fascinating technics in Star Trek. At the beginning he asks the question of whether to transport atoms or Bits, because this has never become clear in Star Trek until today. A big problem in dematerialising a man would be how to get rid of the body. Following Einstein's famous equation , the atoms of only one man would transform to the energetic equivalent of about one thousand hydrogen bombs. On the other hand, the energy needed to dematerialise someone is gigantic, because to convert matter into energy you have to heat it up to about 1000 billion degrees like in a fusion-reactor. To 'save' a human body on a hard disk of a computer you need to save the position, kind and movement of every single atom in that moment. If you try to remember only the position, you would need about 10²⁸ Kilobytes of RAM for the storage of a single human. Another question that rises at this point is if the 'soul' of someone is, or would be transported too. In addition, Heisenberg's uncertainty principle also sets limits for just scanning somebody. Based on this, Krauss considers a transporter to beam someone, is nearly impossible to realise.

Another problem for the Enterprise is the energy she needs to survive and move through the universe. The engines of the Enterprise are constructed to use anti-matter to produce energy. But the huge amounts needed are much more than we can today even imagine to produce. One very informative detail of this book is to reveal the formula for dilithium crystals: 2<5>6 dilithium 2<:>1 diallosilikat 1:9:1 heptoferranid. These dilithium crystals are the most important part in a warp drive, and it seems that the theoretical method could work with today's understanding of nuclear physics.

The next part of the Enterprise the author examines is the so-called 'holodeck'. Though three dimensional touchable holograms are possible, but this device suffers from the same problems as the transporter, the almost infinite memorycapacity it would need.

A very interesting chapter is the one about the possibility of extraterrestrial life, one of the most important points in Star Trek. It´s a pity that this one allows only speculations until we have the first contact to any kind of species of another planet (also in our own solar system).

Near the end the author tells us about perspectives of modern physics in connection with Star Trek, which is very interesting for somebody with knowledge on these issues.

The last chapter then reveals the ten biggest mistakes in the history of Star Trek. This starts with the fact that it is absolutely silent in space, and goes on with the second fact, that an event horizon is a mathematical border in which it is impossible to shoot a hole with a phaser. Other funny mistakes are technical terms used in a wrong way. As an example, in one episode the Enterprise is cleaned from Baryons. But the only Baryons are protons and neutrons. If you clean a ship from them, there isn´t much left The last error is a very specialised one, because in one episode the Neutrinos have a wrong spin. I guess that only a few people even know what Neutrinos are.

The author ends with a quote from Gene Roddenberry: ' The human race is a remarkable creature, one with great potential, and I hope that Star Trek has helped to show us what we can be if we believe in ourselves and our abilities.'

Ideas, opinions and comments:

I liked this book because I am very interested in physics, all the explained theories in this book and especially the future of mankind. I was not a Star Trek freak before I read this book and I won't get one now, but I am sure I will watch more if I have more time.

It is generally very easy to read, but a few parts are specialised. For that reason I would recommend a basic knowledge in physics for reading this book.