Faster than the Speed of Light: The Story of a Scientific Speculationby Joao Magueijo
Nothing travels faster than the speed of light, and light travels at one fixed speed. This idea is considered a foundation of modern physics, but what if it is wrong?Theoretical physicist Magueijo presents the idea that light traveled faster in the early universe than it does today. The varying speed of light theory solves some of the most intractable problems in
Nothing travels faster than the speed of light, and light travels at one fixed speed. This idea is considered a foundation of modern physics, but what if it is wrong?Theoretical physicist Magueijo presents the idea that light traveled faster in the early universe than it does today. The varying speed of light theory solves some of the most intractable problems in cosmology, and could have major implications for the study of physics.
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FASTER THAN THE SPEED OF LIGHTTHE STORY OF A SCIENTIFIC SPECULATION
By JOÃO MAGUEIJO
Copyright © 2003 João Magueijo
All right reserved.
Chapter OneVERY SILLY
I AM BY PROFESSIONAL a theoretical physicist. By every definition I am a fully credentialed scholar-graduate work and Ph.D. at Cambridge, followed by a very prestigious research fellowship at St. John's College, Cambridge (Paul Dirac and Abdus Salam formerly held this fellowship), then a Royal Society research fellow. Now I'm a lecturer (the equivalent of a tenured professor in the United States) at Imperial College.
I mention this straight away not because I want to brag but because this book is about an extraordinarily controversial scientific speculation. Very few things in science are as rock solid as Einstein's theory of relativity. Yet my idea challenges nothing less-to extremes that could be perceived as a physicist's career suicide. Unsurprisingly, a well-known popular science tabloid used the title "Heresy" for an article about this work.
From the way the term speculation is so frequently used to dismiss ideas with which one disagrees, one might be led to believe that speculation has no role in science. In fact, the opposite is true. In theoretical physics, especially in cosmology, the branch in which I work, my colleagues and I spend a good part of each day trying to punch holes in existing theories and considering speculative new theories that may as well or better accommodate empirical data. We are paid to doubt everything that has been proposed before, to offer crazy alternatives, and to argue endlessly with each other.
I was introduced to this tradition when I became a graduate student at Cambridge in 1990. I soon realized that as a theoretical scientist you spend most of your time interacting with your peers: In a sense, your colleagues take the place of experiments. At Cambridge, semi-informal weekly meetings were convened, where we just argued about whatever had been occupying our minds. There were also the so-called U.K. itinerant cosmology meetings, where at the time, people from Cambridge, London, and Sussex got together to discuss projects that were driving them mad. More mundanely, there was the informal environment of my office, shared with five other people permanently disagreeing and constantly shouting at one another.
Sometimes these sessions would just be general discussions, perhaps focusing on a recent paper someone had just put out. Other times we would go around the room and, rather than talk about new ideas derived from experiments, mathematical calculations, or computer simulations, we would speculate. That is, we would discuss ideas based on no prior experimental or mathematical work, ideas that simply played out in our heads based on a broad knowledge of theoretical physics.
It is a lot of fun to do this, especially when, after arguing and arguing and finally convincing those around you that you are right, you suddenly slap your forehead and realize that some embarrassingly simple flaw mars your speculation, and that you have just been stupidly misleading everyone for the past hour-or vice versa: You have been childishly taken in by someone else's flawed speculation.
This argumentative tradition puts a lot of pressure on a new graduate student. It can be intimidating, especially when it becomes apparent in the middle of an argument that someone is much more skilled at it than you, and that you are hopelessly out of your depth. And Cambridge, within its ranks of permanent staff, had no shortage of very clever people who loved to show off-people who wouldn't just prove that you were wrong, but who would also let you know that the point you had missed was indeed rather trivial, and that any average Cambridge first-year undergraduate would easily have spotted the error. While these experiences unnerved me, they never depressed me. On the contrary, I found them motivating. You come to feel that unless you think up something truly new you have not earned your place in the community.
During these meetings, one of the topics that frequently came up for discussion was "inflation." Inflation is one of the most popular ideas in current cosmology, the branch of physics that endeavors to answer such profound questions as, Where did the universe come from? How did matter arise? How will the world end? These questions were for a long time a matter for religion, myth, or philosophy. Nowadays they have found a scientific answer in the form of the Big Bang theory, which posits an expanding universe born from a massive explosion.
Inflation is a theory that was first proposed by Alan Guth, a distinguished MIT physicist, and then further refined by several other scientists in response to what we theoretical physicists refer to as "the cosmological problems." Specifically, although virtually every cosmologist now accepts the idea that the cosmos began with a "big bang," there remain aspects of the universe that cannot be explained by the Big Bang theory as we currently understand it. Briefly these problems have to do with the fact that the Big Bang model is unstable. It can only exist as we see it today if its initial state, at the moment of the Bang, is very carefully contrived. Tiny deviations from the magic point of departure rapidly develop into disaster (such as an early death of the universe), and this very unlikely initial condition has to be "put in by hand," rather than deriving from any concrete and calculable physical process. Cosmologists find this very unsatisfactory.
Inflation, which argues that the baby universe expanded unimaginably faster than it does today (so that its size "inflated"), is currently the best answer to these cosmological problems, and to why the cosmos looks the way it does today. There is reason to believe it might be the correct answer; however, there is not yet experimental proof for inflation. And by the most rigorous scientific standards, this means that inflation is still a speculation.
While this does not stop most scientists from being enthusiastic about it, the British theoretical physics community never quite came to believe that the theory of inflation was the answer. Call it chauvinism (the theory was first advanced by an American), call it stubbornness, call it science, but if you sat around a table at one of these meetings, inevitably the topic of inflation would come up, and dominating the discussion would be the belief that inflation as we understood it did not resolve certain critical cosmological problems.
Initially, I didn't give all that much thought to inflation because my expertise was in a rather different area: topological defects, an explanation for the origin of galaxies and other structures of the universe. (Defects compete with the inflationary explanation for these structures, yet sadly cannot explain the cosmological problems.) But after hearing again and again that inflation had absolutely no grounding in the particle physics we know and that inflation was merely an American PR success-human nature being what it is-I, too, started to think of alternative explanations.
For the nonexpert it may not be clear why inflation would solve the cosmological problems. Even less obvious is why it is so difficult to solve them without inflation. But to a trained cosmologist, the great difficulty was there, and infuriatingly so, to the extent that no one had succeeded in finding an alternative theory. Inflation had won by default. And for many years, in the back of my mind, and at times even in the front, I puzzled over whether there might be another way, any other way, to solve the cosmological problems.
I was into my second year as a fellow of St. John's College (and the sixth of my stay in Cambridge), when one day the answer seemed to drop from the sky. It was a miserable rainy morning-typical English weather-and I was walking across the college's sports fields, nursing a bad hangover, when I suddenly realized that if you were to break one simple rule of the game, albeit a sacred one, you could solve these problems without inflation. The idea was beautifully simple, simpler than inflation, but immediately I felt uneasy about offering it as an explanation. It involved something that for a trained scientist approaches madness. It challenged perhaps the most fundamental rule of modern physics: that the speed of light is constant.
If there's one thing every schoolboy knows about Einstein and his theory of relativity, it is that the speed of light in vacuum is constant.* No matter what the circumstances, light in vacuum travels at the same speed-a constant that physicists denote by the letter c: 300,000 km per second, or as Americans refer to it, 186,000 miles per second. The speed of light is the very keystone of physics, the seemingly sure foundation upon which every modern cosmological theory is built, the yardstick by which everything in the universe is measured.
In 1887, in one of the most important scientific experiments ever undertaken, the American scientists Albert Michelson and Edward Morley showed that the apparent speed of light was not affected by the motion of the Earth. This experiment was very puzzling for everyone at the time. It contradicted the commonsense notion that speeds always add up. A missile fired from a plane moves faster than one fired from the ground because the plane's speed adds to the missile's speed. If I throw something forward on a moving train, its speed with respect to the platform is the speed of that object plus that of the train. You might think that the same should happen to light: Light flashed from a train should travel faster. However, what the Michelson-Morley experiments showed was that this was not the case: Light always moves stubbornly at the same speed. This means that if I take a light ray and ask several observers moving with respect to each other to measure the speed of this light ray, they will all agree on the same apparent speed!
Einstein's 1905 special theory of relativity was in part a response to this astonishing result. What Einstein realized was that if c did not change, then something else had to give. That something was the idea of universal and unchanging space and time. This is deeply, maddeningly counterintuitive. In our everyday lives, space and time are perceived as rigid and universal. Instead, Einstein conceived of space and time-space-time-as a thing that could flex and change, expanding and shrinking according to the relative motions of the observer and the thing observed. The only aspect of the universe that didn't change was the speed of light.
And ever since, the constancy of the speed of light has been woven into the very fabric of physics, into the way physics equations are written, even into the notation used. Nowadays, to "vary" the speed of light is not even a swear word: It is simply not present in the vocabulary of physics. Hundreds of experiments have verified this basic tenet, and the theory of relativity has become central to our understanding of how the universe works. And my idea was exactly a "varying speed of light" theory.
Specifically, I began to speculate about the possibility that light traveled faster in the early universe than it does now. To my surprise, I found that this hypothesis appeared to solve at least some of the cosmological problems without inflation. In fact, their solution appeared inevitable in the varying speed of light theory. It was as if the riddles of the Big Bang universe were trying to tell us precisely that light was much faster in the early universe, and that at some very fundamental level physics had to be based on a structure richer than the theory of relativity. The first time I threw my solution to the cosmological problems into discussion, an embarrassed silence followed. I was aware that a lot of work needed to be done before my idea could attract some respect; and that, as it was, my idea would look completely crackpot. But I was very enthusiastic about it. And so when I told it to one of my best friends (a physicist, now a lecturer at Oxford), I was not counting on a reaction of complete apathy. But that's what I got: not even a comment-just silence, and then a cautious "hmm...." No matter how hard I tried, I could not draw him into discussing my new idea in the same way that theorists are always discussing even their wildest speculations.
In the following few months, whenever I told my idea to people around me, the reactions were similar. People would shake their heads, at best say, "Shut up and don't be stupid," at worse just be very British and say noncommitally, "Oh, I don't know anything about that." Over the previous six years I had thrown into discussions more than my fair share of mad ideas. Never had I encountered this kind of reaction. When I started labeling my idea VSL (varying speed of light), someone suggested that it stood for "very silly."
You can't take anything that happens at these meetings personally. In fact, the easiest way to drive yourself crazy in science is to take challenges to your ideas as personal insults, even those that are expressed with contempt or venom, and even when you are absolutely sure that those around you think you are a fool. That's science. Every new idea is gibberish until it survives ruthless challenge. After all, what had motivated my idea was precisely my questioning the validity of inflation.
But no matter how many people thought the idea of a varying speed of light stupid, it continued to command my respect if not yet allegiance. The more I thought about it, the better I liked it. And so I decided to stay with it and see where it led.
For a long while it led me nowhere. It is often true in science that a given project does not take off until the right people get together. Most of modern science is done in collaboration. And what I desperately needed at the time was the right collaborator. On my own, I was just going round and round in circles, getting stuck on the same irrelevant details, so that no consistent whole ever seemed to emerge. The whole thing was driving me insane.
The rest of my research work was going well, though, and a year or so later I was overjoyed to find that I had been awarded a Royal Society fellowship. This fellowship is the most desirable junior research position available in Britain, perhaps anywhere. It gives you funding and security for up to ten years as well as the freedom to do whatever you want and go wherever you want. At this stage, I decided that I had had enough of Cambridge, and that it was time to go somewhere different. I have always loved big cities, so I chose to go to Imperial College, in London, a top university for theoretical physics.
The leading cosmologist at Imperial College then was Andy Albrecht. Although he was one of the creators of inflation, Andy had been wondering for years whether inflation really was the right theory.
Excerpted from FASTER THAN THE SPEED OF LIGHT by JOÃO MAGUEIJO
Copyright © 2003 by João Magueijo
Excerpted by permission. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Meet the Author
João Magueijo is a lecturer in Theoretical Physics at Imperial College, London, where he was for three years a Royal Society Research Fellow. He has been a visiting researcher at the University of California at Berkeley and Princeton University, and received his doctorate in Theoretical Physics at Cambridge University. Magueijo was featured in a British television documentary, "Einstein's Biggest Blunder," which was broadcast last year. Visit the author's website at http://theory.ic.uk/~magueijo/.
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