Brief Answers to the Big Questions

Creation myths have sustained humans for a long time. One of them, popular among Western religions, asserts that the world was created about 6,000 years ago. Aristotle, meanwhile, considered the universe eternal. Both ideas are based on the notion that time exists outside the universe, but Einstein showed that time depends on space and gravity; it can’t exist on its own.

If the universe were infinite, the sky would long since have become as bright as the surface of the sun because the cosmos is filled with stars that shine light in every direction. That this hasn’t happened means that most of that light hasn’t yet reached us. Thus, the universe had a beginning.

A finite universe, on the other hand, must be older than a few thousand years because the light from galaxies that has reached our telescopes comes from extremely far away; thus, the universe is billions of years old. Moreover, that light shows that the universe is expanding. Thus, past galaxies were closer together and perhaps began their journey as a clump or even a point. This frustrated scientists, who believed that the laws of science would break down at the beginning and that a godlike being must therefore have started everything.

Astronomer Fred Hoyle and others developed the steady-state theory, which asserts that as the universe expands, it adds new material. Studies of radio sources in the universe, however, showed that the universe was denser in the past, so the steady-state theory was abandoned in favor of the expanding-universe theory.

Russian scientists proposed that the universe expands, then contracts, bounces off itself, and expands again. The author Roger Penrose proved instead that the universe must have a discreet beginning. In 1965, researchers discovered a faint microwave signal emanating from all directions. This is leftover energy from a very hot early universe, energy that’s since been cooled by the expansion of space, which helps prove the Big Bang theory.

At the Big Bang, the laws of physics break down. Relativity theory is a “classical” law that assumes objects follow exact paths, but in fact subatomic particles are somewhat random and therefore not perfectly predictable. Over vast areas of normal space, these random variations average out, and the laws of physics remain useful, but in considering the intense density of the Big Bang, calculations must use quantum mechanics and its understanding of particle uncertainty. Quantum mechanics and relativity don’t fit together well, and this remains a central problem of physics.

A recent idea, M-theory, proposes that an enormous number of possible universes exists. One way to whittle down the possibilities is the anthropic principle, which states that only certain types of universes are compatible with life forms like our own. This limits the possibilities for the early moments of the universe to a more manageable number. A universe with three dimensions of space, for example, seems to be required, or the evolution of galaxies and planets goes haywire.

The cosmic background radiation is remarkably smooth, which suggests that the universe inflated rapidly at its beginning. Small variations in that smoothness further suggest that quantum fluctuations at the outset were important to the later clumping of matter into galaxies. Meanwhile, satellites have begun searches for signs of “different fingerprints in the current structure of the universe” that might hint at the precise nature of the Big Bang (63). The Large Hadron Collider in Switzerland has begun to discover new subatomic particles that also may provide clues to the early universe.

Two other questions remain: whether our universe is unique and whether it will have an ending. It’s possible that the universe will contract and fall back in on itself in a Big Crunch. It’s also possible that the universe will expand indefinitely, long past when the last stars go out.