Back to the Beginning

Article excerpt

Byline: Martin Rees

The possible discovery of the Higgs boson leads us one step closer to how the universe started--and where it may be headed.

The ancients believed that the world was made from four "elements"--earth, air, fire, and water--but that the heavens were something quite different; the "fifth essence." We have now learned that everything, from here on earth out to the remotest galaxies, is made of similar atoms, which are themselves each composed of smaller particles. And it's testimony to how far we've got that it takes a vast machine to disclose anything fundamentally new in the subatomic world.

While physicists probe ever smaller scales, astronomers deploy ever more powerful telescopes to search deeper into space and further back in time. Our cosmic horizons have vastly enlarged. Our sun is one of a hundred billion stars in our galaxy, which is itself one of many billion galaxies in range of our telescopes. This entire panorama emerged from a hot dense "beginning" nearly 14 billion years ago. One nanosecond after the big bang, every particle in the universe carried as much energy as can be generated by the Large Hadron Collider.

As always in science, each cosmological advance brings into focus some new questions that couldn't previously have even been posed--for instance, "Why is the universe expanding the way it is?" and "Why does it contain the particular 'mix' of atoms that we find in stars and galaxies?" The answers lie in the era when the universe was even less than a nanosecond old, and far hotter and denser than we can simulate in any laboratory.

According to a popular conjecture, our entire universe "inflated" from a hyper-dense blob no bigger than an orange. This universe is governed by the laws that Einstein discovered. But to confront the overwhelming mystery of what banged and why it banged, Einstein's theory isn't enough. It doesn't adequately describe the very beginning. That's because it "smooths out" space and time into a continuum. We know that no material can be chopped into arbitrarily small pieces because eventually you get down to discrete atoms. Likewise, even space and time can't be divided up indefinitely. Space has a grainy and "quantized" structure--but on a scale a trillion trillion times smaller than atoms. During the very earliest instants after the "big bang," everything was so immensely squeezed that quantum fluctuations could shake the entire "embryo universe."

If physicists achieved a complete understanding of all the particles and forces in the universe, it would be the summit of an intellectual quest that began with the Greeks, and continued with the insights of Newton, Einstein, and their successors. It would reveal a fundamental "order" in the world, describable by numbers and equations. It would supremely vindicate what the great physicist Eugene Wigner dubbed "The unreasonable effectiveness of mathematics in the natural sciences."

The very large and the very small--cosmos and microworld--are two great frontiers of science. Twenty-first-century scientists may successfully unify them. Until that is done we won't properly understand why the universe is expanding the way it is.

But this unification would not be the end of science; indeed, we could still be near the beginning. …