An Unfettered Mind
By Kitty Ferguson
St. Martin's Press Copyright © 2013 Kitty Ferguson
All rights reserved.
"The Quest for a Theory of Everything"
In the center of Cambridge, England, there are a handful of narrow lanes that seem hardly touched by the twentieth or twenty-first centuries. The houses and buildings represent a mixture of eras, but a step around the corner from the wider thoroughfares into any of these little byways is a step back in time, into a passage bending between old college walls or a village street with a medieval church and churchyard or a malt house. Traffic noises from equally old but busier roads nearby are barely audible. There is near silence, birdsong, voices, footsteps. Scholars and townspeople have walked here for centuries.
When I wrote my first book about Stephen Hawking, in 1990, I began the story in one of those little passageways, Free School Lane. It runs off Bene't Street, beside the church of St. Bene't's with its eleventh-century bell tower. Around the corner, in the lane, flowers and branches still droop through the iron palings of the churchyard, as they did twenty years ago and surely for centuries before that. Bicycles tethered there belie the antique feel of the place, but a little way along on the right is a wall of black, rough stones with narrow slit windows belonging to the fourteenth-century Old Court of Corpus Christi College, the oldest court in Cambridge. Turn your back to that wall and you see, high up beside a gothic-style gateway, a plaque that reads, THE CAVENDISH LABORATORY. This gateway and the opening beyond are a portal to a more recent era, oddly tucked away in the medieval street.
There is no hint here of the friary that stood on this site in the twelfth century or of the plants and trees of the gardens that later grew on its ruins. Instead, bleak, factory-like buildings, almost oppressive enough to be a prison, tower over grey asphalt pavement. The situation improves further into the complex, and in the two decades since I first wrote about it some newer buildings have gone up, but the glass walls of these well-designed modern structures are still condemned to reflect little besides the grimness of their more elderly neighbors.
For a century, until the University of Cambridge built the "New" Cavendish Labs in 1974, this complex housed one of the most important centers of physics research in the world. In these buildings, "J. J." Thomson discovered the electron, Ernest Rutherford probed the structure of the atom — and the list goes on and on. When I attended lectures here in the 1990s (for not everything moved to the New Cavendish in 1974), enormous chalk-boards were still in use, hauled noisily up and down with crank-driven chain-pulley systems to make room for the endless strings of equations in a physics lecture.
The Cockcroft Lecture Room, part of this same site, is a much more up-to-date lecture room. Here, on April 29, 1980, scientists, guests and university dignitaries gathered in steep tiers of seats, facing a two-story wall of chalkboard and slide screen — still well before the advent of PowerPoint. They had come for the inaugural lecture of a new Lucasian Professor of Mathematics, 38-year-old mathematician and physicist Stephen William Hawking. He had been named to this illustrious chair the previous autumn.
Hawking's friends and colleagues had learned to expect brash statements from him, and on this occasion he did not disappoint. The title announced for his lecture was a question: "Is the End in Sight for Theoretical Physics?" Hawking declared that he thought it was. He invited his audience to join him in a sensational escape through time and space on a quest to find the Holy Grail of science: the theory that explains the universe and everything that happens in it — what some were calling the Theory of Everything.
Watching Stephen Hawking, silent in a wheelchair while one of his research students read his lecture, no one unacquainted with him would have thought he was a promising choice to lead such an adventure. But most of his listeners knew that theoretical physics is for Hawking the great escape from a prison more grim than any suggested by the Old Cavendish Labs. Beginning when he was a graduate student in his early twenties, he had lived with encroaching disability and the promise of an early death. Hawking has amyotrophic lateral sclerosis, known in America as Lou Gehrig's disease after the New York Yankee first baseman, who died of it. The progress of the disease in Hawking's case had been slow, but by the time he became Lucasian Professor he could no longer walk, write, feed himself, or raise his head if it tipped forward. His speech was slurred and almost unintelligible except to those few who knew him best. He had prepared the Lucasian lecture by painstakingly dictating his text ahead of time, so that it could be read by the student. But Hawking certainly was and is no invalid. He is an active mathematician and physicist, whom some were even then calling the most brilliant since Einstein. The Lucasian Professorship is an extremely prestigious position in the University of Cambridge, dating from 1663. The second holder of the chair was Sir Isaac Newton.
It was typical of Hawking's iconoclasm to begin this distinguished professorship by predicting the end of his own field. He said he thought there was a good chance the so-called Theory of Everything would be found before the close of the twentieth century, leaving little for theoretical physicists like himself to do.
Since that lecture, many people have come to think of Stephen Hawking as the standard-bearer of the quest for that theory. However, the candidate he named for Theory of Everything was not one of his own theories but N=8 supergravity, a theory which many physicists at that time hoped might unify all the particles and the forces of nature. Hawking is quick to point out that his work is only one part of a much larger endeavor, involving physicists all over the world, and also part of a very old quest. The longing to understand the universe must surely be as ancient as human consciousness. Ever since human beings first began to look at the night skies as well as at the enormous variety of nature around them, and considered their own existence, they have been trying to explain all this with myths, religion, and, later, mathematics and science. We may not be much nearer to understanding the complete picture than our remotest ancestors, but most of us like to think, as does Stephen Hawking, that we are.
Hawking's life story and his science are rife with paradoxes. Things are often not what they seem. Here is a tale in which beginnings are endings; cruel circumstances lead to happiness, although fame and success may not; two brilliant and highly successful scientific theories taken together yield nonsense; empty space isn't empty after all; and black holes aren't black. In the twenty-first century, the effort to unite everything in a simple explanation is revealing, instead, a fragmented picture. And most paradoxical of all, a man whose physical appearance inspires shock and pity has led us joyfully to where the boundaries of time and space ought to be — but are not.
Everywhere we look in our universe, on all scales, reality (if Hawking will allow me to use this word) is astoundingly complex and elusive, sometimes alien, often not easy to take, and frequently impossible to predict. Beyond our universe there may be an infinite number of others. The close of the twentieth century has come and gone, and no one has discovered the Theory of Everything. Where does that leave Stephen Hawking's prediction? Can any scientific theory truly explain it all?
"Our Goal Is Nothing Less Than a Complete Description of the Universe We Live In"
The idea that all the amazing intricacy and variety we experience in the world and the cosmos may come down to something remarkably simple is not new or farfetched. The sage Pythagoras and his followers in southern Italy in the sixth century BC studied the relationships between lengths of strings on a lyre and the musical pitches these produced, and realized that hidden behind the confusion and complexity of nature there is pattern, order, rationality. In the two and a half millennia since, our forebears have continued to find — often, like the Pythagoreans, to their surprise and awe — that nature is less complicated than it first appears.
Imagine, if you can, that you are a super-intelligent alien who has absolutely no experience of our universe: is there a set of rules so complete that by studying them you could figure out exactly what our universe is like? Suppose someone handed you that rule book. Could it possibly be a short book?
For decades, many physicists believed that the rule book is not lengthy and contains a set of fairly simple principles, perhaps even just one principle that lies behind everything that has happened, is happening, and ever will happen in our universe. In 1980, Stephen Hawking made the daring suggestion that we might hold the rule book in our hands by the end of the twentieth century.
My family used to own a museum facsimile of an ancient board game. Archaeologists digging in the ruins of the city of Ur in Mesopotamia had unearthed an exquisite inlaid board with a few small carved pieces. It was obviously an elaborate game, but no one in the modern world knows its rules. The makers of the facsimile had tried to deduce them from the design of the board and pieces, but those like ourselves who bought the game were encouraged to make our own decisions and discoveries about how to play it.
You can think of the universe as something like that: a magnificent, elegant, mysterious game. Certainly there are rules, but the rule book didn't come with the game. The universe is no beautiful relic like the game found at Ur. Yes, it is old, but the game continues. We and everything we know about (and much we do not) are in the thick of the play. If there is a Theory of Everything, we and everything in the universe must be obeying its principles, even while we try to discover what they are.
You would expect the complete, unabridged rules for the universe to fill a vast library or supercomputer. There would be rules for how galaxies and clusters of galaxies form and move, for how the bodies of creatures living on earth work and fail to work, for how we humans relate to one another and to our environment, for what subatomic particles exist and how they interact, how water freezes, how plants grow, how and why dogs growl and bark — intricate rules within rules within rules. How could anyone think this could be reduced to a few principles?
American physicist and Nobel laureate Richard Feynman was amazingly skilled at explaining his science at a simple, understandable level. Here is his example of the way the reduction process happens: There was a time when we had something we called motion and something else called heat and something else again called sound.
But it was soon discovered, after Sir Isaac Newton explained the laws of motion, that some of these apparently different things were aspects of the same thing. For example, the phenomena of sound could be completely understood as the motion of atoms in the air. So sound was no longer considered something in addition to motion. It was also discovered that heat phenomena are easily understandable from the laws of motion. In this way, great globs of physics theory were synthesized into a simplified theory."
Life among the Small Pieces
If you are already familiar with the basics of general relativity and quantum mechanics, discussions about what makes a good scientific theory, and what is meant by a Theory of Everything, you may wish to skim the paragraphs that follow. If you are not, this simple overview will be extremely helpful for understanding the descriptions of Stephen Hawking's and others' work later in this book.
We begin on the level of the very small. All matter as we normally think of it in the universe — the matter making up you and me, air, ice, stars, gases, microbes, this book — is made up of minuscule building blocks called atoms. Atoms in turn are made up of smaller objects, called particles, and a lot of empty space.
Matter particles that orbit the nuclei of atoms are electrons, and the particles clustered in the nuclei are protons and neutrons, made up of even tinier particles of matter called "quarks." All matter particles belong to a class of particles called "fermions," named for the great Italian physicist Enrico Fermi. They have a system of messages that pass among them, causing them to act and change in various ways. A group of humans might have a message system consisting of four different services: telephone, fax, e-mail and "snail mail." Not all the humans would send and receive messages and influence one another by means of all four message services. Think of the message system among the fermions as four such message services, called forces. There is another class of particles that carry these messages among the fermions, and sometimes among themselves as well: "messenger" particles, more properly called "bosons." Apparently every particle in the universe is either a fermion or a boson.
One of the four fundamental forces of nature is gravity. One way of thinking about the gravitational force holding us to the Earth is as "messages" carried by bosons called gravitons between the particles of the atoms in your body and the particles of the atoms in the Earth, influencing these particles to draw closer to one another. Gravity is the weakest of the forces, but, as you'll see later, it is a very long-range force and acts on everything in the universe. When it adds up, it can dominate all the other forces.
A second force, the electromagnetic force, is messages carried by bosons called photons among the protons in the nucleus of an atom, between the protons and the electrons nearby, and among electrons. The electromagnetic force causes electrons to orbit the nucleus. On the level of everyday experience, photons show up as light, heat, radio waves, microwaves and other waves, all known as electromagnetic radiation. The electromagnetic force is also long-range and much stronger than gravity, but it acts only on particles with an electric charge.
A third message service, the strong nuclear force, causes the nucleus of an atom to hold together.
A fourth, the weak nuclear force, causes radioactivity and plays a necessary role in the formation of the elements in stars and in the early universe.
The gravitational force, the electromagnetic force, the strong nuclear force, and the weak nuclear force ... the activities of those four forces are responsible for all messages among all fermions in the universe and for all interactions among them. Without the four forces, every fermion (every particle of matter) would exist, if it existed at all, in isolation, with no means of contacting or influencing any other, oblivious to every other. To put it bluntly, whatever doesn't happen by means of one of the four forces doesn't happen. If that is true, a complete understanding of the forces would give us an understanding of the principles underlying everything that happens in the universe. Already we have a remarkably condensed rule book.
Physicists in the twentieth century were deeply involved in trying to understand how the four forces of nature operate and how they are related. In a human message system, we might discover that telephone, fax, and e-mail are not really so separate after all, but can be thought of as the same thing showing up in three different ways. That discovery would "unify" the three message services. In a similar way, physicists have sought, with some success, to unify the forces. Their ultimate goal is to find a theory that explains all four forces as one showing up in different ways — a theory that also unites both fermions and bosons in a single family. Such a theory would be a "unified theory."
A theory explaining the universe, the Theory of Everything, must go several steps further. Of particular interest to Stephen Hawking, it must answer the question, what was the universe like at the instant of beginning, before any time whatsoever had passed? Physicists phrase that question: what are the "initial conditions" or the "boundary conditions at the beginning of the universe"? Because this issue of boundary conditions has been and continues to be at the heart of Hawking's work, it behooves us to spend a little time with it. (Continues...)
Excerpted from Stephen Hawking by Kitty Ferguson. Copyright © 2013 Kitty Ferguson. Excerpted by permission of St. Martin's Press.
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