Kirjahaku

Thirty years ago Albert Einstein died, his dream of a theory that would unify the universe unfulfilled. He spent the last decades of his life searching for such a theory-a theory that would explain everything from elementary particles and their interac­ tions to the overall structure of the universe. But he failed, not because he didn't try hard enough, but because the attempt was ahead of its time. When Einstein worked on the problem liter­ ally nothing was known about black holes, white holes, sin­ gularities, the Big Bang explosion and the early universe, quarks, gauge invariance, and weak and strong nuclear forces. Today we know that all these things are important in relation to a unified theory, and that they must be incorporated in and explained by such a theory. Thus, in a sense, our problem is much more complex today than it was in Einstein's day. But scientists have persevered and as a result we are now tan­ talizingly close to achieving this long-sought goal. Important breakthroughs have been made. In this book we will look at these breakthroughs and at recent unified theories-theories that go by the names supergravity, superstrings, GUTs, and twistor theory. In order to understand the problem, however, we must begin at the beginning.

I remember sitting spellbound, watching the movie When Worlds Collide. Two planets hurled through space toward Earth while scientists and engineers frantically raced to complete a rocket­ ship that would take them to safety. In the final moments the spaceship lifted off as the occupants watched the Earth bulge, crack, then literally explode as one of the planets struck it. As I left the theater I wondered if it was really possible for another world to collide with Earth. Later I learned that while many catastrophic collisions no doubt occurred early in the his­ tory of the solar system, today they are exceedingly rare. I was relieved, but in another sense I was disappointed (not that I hoped a collision of this type would actually occur). A collision of two objects in space, say, two stars, I was sure would be a spectacular event. It is quite unlikely, however, that we will ever witness the collision of two stars. The event is just too rare. But collisions of systems of stars-galaxies-oddly enough, are relatively com­ mon. In fact, we see evidence of several in the sky right now.

'he year was 1889. The French physicist-mathematician Henry T Poincare could not believe his eyes. He had worked for months on one of the most famous problems in science-the problem of three bodies moving around one another under mutual gravita­ tional attraction-and what he was seeing dismayed and trou­ bled him. Since Newton's time it had been assumed that the problem was solvable. All that was needed was a little ingenuity and considerable perseverance, but Poincare saw that this was not the case. Strange, unexplainable things happened when he delved into the problem; it was not solvable after all. Poincare was shocked and dismayed by the result-so disheartened he left the problem and went on to other things. What Poincare was seeing was the first glimpse of a phe­ nomenon we now call chaos. With his discovery the area lay dormant for almost 90 years. Not a single book was written about the phenomenon, and only a trickle of papers appeared. Then, about 1980 a resurgence of interest began, and thousands of papers appeared along with dozens of books. The new science of chaos was born and has attracted as much attention in recent years as breakthroughs in superconductivity and superstring theory.