THE INVISIBLE SOCCER BALL

Nothing exists except atoms and empty space; everything else is opinion.

— Democritus of Abdera

In the Very Beginning there was a void — a curious form of vacuum — a nothingness containing no space, no time, no matter, no light, no sound. Yet the laws of nature were in place, and this curious vacuum held potential. Like a giant boulder perched at the edge of a towering cliff ...

Wait a minute.

Before the boulder falls, I should explain that I really don't know what I'm talking about. A story logically begins at the beginning. But this story is about the universe, and unfortunately there are no data for the Very Beginning. None, zero. We don't know anything about the universe until it reaches the mature age of a billionth of a trillionth of a second — that is, some very short time after creation in the Big Bang. When you read or hear anything about the birth of the universe, someone is making it up. We are in the realm of philosophy. Only God knows what happened at the Very Beginning (and so far She hasn't let on).

Now, where were we? Oh yes ...

Like a giant boulder perched at the edge of a towering cliff, the void's balance was so exquisite that only whim was needed to produce a change, a change that created the universe. And it happened. The nothingness exploded. In this initial incandescence, space and time were created.

Out of this energy, matter emerged — a dense plasma of particles that dissolved into radiation and back to matter. (Now we're working with at least a few facts and some speculative theory in hand.) Particles collided and gave birth to new particles. Space and time boiled and foamed as black holes formed and dissolved. What a scene!

As the universe expanded and cooled and grew less dense, particles coalesced, and forces differentiated. Protons and neutrons formed, then nuclei and atoms and huge clouds of dust, which, still expanding, condensed locally here and there to form stars, galaxies, and planets. On one planet — a most ordinary planet, orbiting a mediocre star, one speck on the spiral arm of a standard galaxy — surging continents and roiling oceans organized themselves, and out of the oceans an ooze of organic molecules reacted and built proteins, and life began. Plants and animals evolved out of simple organisms, and eventually human beings arrived.

The human beings were different primarily because they were the only species intensely curious about their surroundings. In time, mutations occurred, and an odd subset of humans began roaming the land. They were arrogant. They were not content to enjoy the magnificence of the universe. They asked "How?" How was the universe created? How can the "stuff" of the universe be responsible for the incredible variety in our world: stars, planets, sea otters, oceans, coral, sunlight, the human brain? The mutants had posed a question that could be answered — but only with the labor of millennia and with a dedication handed down from master to student for a hundred generations. The question also inspired a great number of wrong and embarrassing answers. Fortunately, these mutants were born without a sense of embarrassment. They were called physicists.

Now, after examining this question for more than two thousand years — a mere flicker on the scale of cosmological time — we are beginning to glimpse the entire story of creation. In our telescopes and microscopes, in our observatories and laboratories — and on our notepads — we begin to perceive the outlines of the pristine beauty and symmetry that governed in the first moments of the universe. We can almost see it. But the picture is not yet clear, and we sense that something is obscuring our vision — a dark force that blurs, hides, obfuscates the intrinsic simplicity of our world.

HOW DOES THE UNIVERSE WORK?

This book is devoted to one problem, a problem that has confounded science since antiquity. What are the ultimate building blocks of matter? The Greek philosopher Democritus called the smallest unit the atomos (literally "not able to be cut"). This atom is not the atom you learned about in high school science courses, like hydrogen, helium, lithium, and proceeding all the way to uranium and beyond. Those are big, klunky, complicated entities by today's standards (or by Democritus's standards, for that matter). To a physicist, or even a chemist, such atoms are veritable garbage cans of smaller particles — electrons, protons, and neutrons — and the protons and neutrons in turn are buckets full of still smaller guys. We need to know the most primitive objects there are, and we need to understand the forces that control the social behavior of these objects. It is Democritus's a-tom, not your chemistry teacher's atom, that is the key to matter.

The matter we see around us today is complex. There are about a hundred chemical atoms. The number of useful combinations of atoms can be calculated, and it is huge: billions and billions. Nature uses these combinations, called molecules, to build planets, suns, viruses, mountains, paychecks, Valium, literary agents, and other useful items. It was not always so. During the earliest moments after the creation of the universe in the Big Bang, there was no complex matter as we know it today. No nuclei, no atoms, nothing that was made of simpler pieces. This is because the searing heat of the early universe did not allow the formation of composite objects; such objects, if formed by transient collisions, would be instantly decomposed into their most primitive constituents. There was perhaps one kind of particle and one force — or even a unified particle/force — and the laws of physics. Within this primordial entity were contained the seeds of the complex world in which humans evolved, perhaps primarily to think about these things. You might find the primordial universe boring, but to a particle physicist, those were the days! Such simplicity, such beauty, however mistily visualized in our speculations.

THE BEGINNING OF SCIENCE

Even before my hero Democritus, there were Greek philosophers who dared to try to explain the world using rational arguments and rigorously excluding superstition, myth, and the intervention of gods. These had served as valuable assets in accommodating to a world full of fearsome and seemingly arbitrary phenomena. But the Greeks were impressed too by regularities, by the alternation of day and night, the seasons, the action of fire and...