Illustrated Theory of Everything: The Origin and Fate of the Universe

by Stephen Hawking

To ask deep questions about Nature is, ultimately, to want to know the mind of God.

Behind it all stood Heisenberg’s uncertainty principle, which stated that it is impossible to measure both the position and the velocity of a particle with arbitrarily high accuracy.

A proper scientific description of the big bang can only be obtained once we know how to combine quantum mechanics with Einstein’s theory of gravity. Unfortunately, so far we haven’t been able to do this.

“The universe would be neither created nor destroyed. It would just be,” he wrote. Parmenides would be proud. Here is a modern scientific version of the universe of being. Ironically, Hawking put forward this idea during a conference in the Vatican, not yet knowing that it would have serious theological implications. For one thing, a universe that is neither created nor destroyed, that is, a universe that is uncreated, does not need a Creator. What would be the role of God if science could explain creation itself?

In an infinite universe, every point can be regarded as the center because every point has an infinite number of stars on each side of it.

An expanding universe does not preclude a creator, but it does place limits on when He might have carried out his job.

Many people do not like the idea that time has a beginning, probably because it smacks of divine intervention. (The Catholic church, on the other hand, had seized on the big bang model and in 1951 officially pronounced it to be in accordance with the Bible.) There

Roger Penrose, in 1965. He used the way light cones behave in general relativity, and the fact that gravity is always attractive, to show that a star that collapses under its own gravity is trapped in a region whose boundary eventually shrinks to zero size. This means that all the matter in the star will be compressed into a region of zero volume, so the density of matter and the curvature of space-time become infinite. In other words, one has a singularity contained within a region of space-time known as a black hole.

There was a lot of opposition to our work, partly from the Russians, who followed the party line laid down by Lifshitz and Khalatnikov, and partly from people who felt that the whole idea of singularities was repugnant and spoiled the beauty of Einstein’s theory. However, one cannot really argue with the mathematical theorem. So it is now generally accepted that the universe must have a beginning.

And paradoxically, the more fuel a star starts off with, the sooner it runs out. This is because the more massive the star is, the hotter it needs to be to balance its gravitational attraction. And the hotter it is, the faster it will use up its fuel. Our sun has probably got enough fuel for another five thousand million years or so, but more massive stars can use up their fuel in as little as one hundred million years, much less than the age of the universe.

The idea was this: When the star becomes small, the matter particles get very near each other. But the Pauli exclusion principle says that two matter particles cannot have both the same position and the same velocity. The matter particles must therefore have very different velocities. This makes them move away from each other, and so tends to make the star expand. A star can therefore maintain itself at a constant radius by a balance between the attraction of gravity and the repulsion that arises from the exclusion principle, just as earlier in its life the gravity was balanced by the

These stars would be supported by the exclusion principle repulsion between the neutrons and protons, rather than between the electrons. They were therefore called neutron stars. They would have had a radius of only ten miles or so and a density of hundreds of millions of tons per cubic inch. At the time they were first predicted, there was no way that neutron stars could have been observed, and they were not detected until much later.

The event horizon is formed by rays of light that just fail to get away from the black hole. Instead, they stay forever, hovering on the edge of the black hole.

A precise statement of this idea is known as the second law of thermodynamics. It states that the entropy of an isolated system never decreases with time. Moreover, when two systems are joined together, the entropy of the combined system is greater than the sum of the entropies of the individual systems.

One such black hole could run ten large power stations, if only we could harness its output. This would be rather difficult, however. The black hole would have the mass of a mountain compressed into the size of the nucleus of an atom.

It would be very difficult to explain why the universe should have begun in just this way, except as the act of a God who intended to create beings like us.

However, the laws do not tell us what the universe should have looked like when it started. It would still be up to God to wind up the clockwork and choose how to start it off. So long as the universe had a beginning that was a singularity, one could suppose that it was created by an outside agency. But if the universe is really completely self-contained, having no boundary or edge, it would be neither created nor destroyed. It would simply be. What place, then, for a creator? SIXTH LECTURE The DIRECTION of TIME In his book, The Go Between, L.

There is one, and only one, arrangement in which the pieces make a complete picture. On the other hand, there are a very large number of arrangements in which the pieces are disordered and don’t make a picture.

The quest for such a theory is known as “the unification of physics.”

In string theories, what were previously thought of as particles are now pictured as waves traveling down the string, like waves on a washing line.

It is like the surface of an orange: if you look at it close up, it is all curved and wrinkled, but if you look at it from a distance, you don’t see the bumps, and it appears to be smooth. So it is with space–time. On a very small scale, it is ten–dimensional and highly curved. But on bigger scales, you don’t see the curvature or the extra dimensions. If this picture is correct, it spells bad news for would-be space travelers.

And who created Him?