Page 94 - A Brief History of Time - Stephen Hawking

A Brief History of Time - Stephen Hawking... Chapter 12
the fact that gravity is always attractive implies that the universe must be either expanding or contracting.
According to the general theory of relativity, there must have been a state of infinite density in the past, the big
bang, which would have been an effective beginning of time. Similarly, if the whole universe recollapsed, there
must be another state of infinite density in the future, the big crunch, which would be an end of time. Even if the
whole universe did not recollapse, there would be singularities in any localized regions that collapsed to form
black holes. These singularities would be an end of time for anyone who fell into the black hole. At the big bang
and other singularities, all the laws would have broken down, so God would still have had complete freedom to
choose what happened and how the universe began.

When we combine quantum mechanics with general relativity, there seems to be a new possibility that did not
arise before: that space and time together might form a finite, four-dimensional space without singularities or
boundaries, like the surface of the earth but with more dimensions. It seems that this idea could explain many
of the observed features of the universe, such as its large-scale uniformity and also the smaller-scale
departures from homogeneity, like galaxies, stars, and even human beings. It could even account for the arrow
of time that we observe. But if the universe is completely self-contained, with no singularities or boundaries,
and completely described by a unified theory, that has profound implications for the role of God as Creator.

Einstein once asked the question: “How much choice did God have in constructing the universe?” If the no
boundary proposal is correct, he had no freedom at all to choose initial conditions. He would, of course, still
have had the freedom to choose the laws that the universe obeyed. This, however, may not really have been all
that much of a choice; there may well be only one, or a small number, of complete unified theories, such as the
heterotic string theory, that are self-consistent and allow the existence of structures as complicated as human
beings who can investigate the laws of the universe and ask about the nature of God.

Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes
fire into the equations and makes a universe for them to describe? The usual approach of science of
constructing a mathematical model cannot answer the questions of why there should be a universe for the
model to describe. Why does the universe go to all the bother of existing? Is the unified theory so compelling
that it brings about its own existence? Or does it need a creator, and, if so, does he have any other effect on
the universe? And who created him?

Up to now, most scientists have been too occupied with the development of new theories that describe what
the universe is to ask the question why. On the other hand, the people whose business it is to ask why, the
philosophers, have not been able to keep up with the advance of scientific theories. In the eighteenth century,
philosophers considered the whole of human knowledge, including science, to be their field and discussed
questions such as: did the universe have a beginning? However, in the nineteenth and twentieth centuries,
science became too technical and mathematical for the philosophers, or anyone else except a few specialists.
Philosophers reduced the scope of their inquiries so much that Wittgenstein, the most famous philosopher of
this century, said, “The sole remaining task for philosophy is the analysis of language.” What a comedown from
the great tradition of philosophy from Aristotle to Kant!

However, if we do discover a complete theory, it should in time be understandable in broad principle by
everyone, not just a few scientists. Then we shall all, philosophers, scientists, and just ordinary people, be able
to take part in the discussion of the question of why it is that we and the universe exist. If we find the answer to
that, it would be the ultimate triumph of human reason – for then we would know the mind of God.

ALBERT EINSTEIN

Einstein’s connection with the politics of the nuclear bomb is well known: he signed the famous letter to
President Franklin Roosevelt that persuaded the United States to take the idea seriously, and he engaged in
postwar efforts to prevent nuclear war. But these were not just the isolated actions of a scientist dragged into
the world of politics. Einstein’s life was, in fact, to use his own words, “divided between politics and equations.”

Einstein’s earliest political activity came during the First World War, when he was a professor in Berlin.
Sickened by what he saw as the waste of human lives, he became involved in antiwar demonstrations. His

file:///C|/WINDOWS/Desktop/blahh/Stephen Hawking - A brief history of time/k.html (2 of 4) [2/20/2001 3:16:08 AM]