Illustrated Theory of Everything: The Origin and Fate of the Universe (9 page)

• There really is a complete unified theory, which we will somedaydiscover if we are smart enough.

• There is no ultimate theory of the universe, just an infinitesequence of theories that describe the universe more and moreaccurately.

• There is no theory of the universe. Events cannot be predictedbeyond a certain extent but occur in a random and arbitrary manner.Some would argue for the third possibility on the grounds that if there were acomplete set of laws, that would infringe on God’s freedom to change His mindand to intervene in the world. It’s a bit like the old paradox: Can God make astone so heavy that He can’t lift it? But the idea that God might want tochange His mind is an example of the fallacy, pointed out by St. Augustine, ofimagining God as a being existing in time. Time is a property only of theuniverse that God created. Presumably, He knew what He intended when Heset it up.

With the advent of quantum mechanics, we have come to realize that eventscannot be predicted with complete accuracy but that there is always a degreeof uncertainty. If one liked, one could ascribe this randomness to the interven-tion of God. But it would be a very strange kind of intervention. There is noevidence that it is directed toward any purpose. Indeed, if it were, it wouldn’tbe random. In modern times, we have effectively removed the third possibilityby redefining the goal of science. Our aim is to formulate a set of laws that willenable us to predict events up to the limit set by the uncertainty principle.The second possibility, that there is an infinite sequence of more and morerefined theories, is in agreement with all our experience so far. On many occa-sions, we have increased the sensitivity of our measurements or made a newclass of observations only to discover new phenomena that were not predictedby the existing theory. To account for these, we have had to develop a moreadvanced theory. It would therefore not be very surprising if we find that ourpresent grand unified theories break down when we test them on bigger andmore powerful particle accelerators. Indeed, if we didn’t expect them to breakdown, there wouldn’t be much point in spending all that money on buildingmore powerful machines.

However, it seems that gravity may provide a limit to this sequence of “boxeswithin boxes.” If one had a particle with an energy above what is called thePlanck energy, 1019 GeV, its mass would be so concentrated that it would cutitself off from the rest of the universe and form a little black hole. Thus, it doesseem that the sequence of more and more refined theories should have somelimit as we go to higher and higher energies. There should be some ultimatetheory of the universe. Of course, the Planck energy is a very long way fromthe energies of around a GeV, which are the most that we can produce in thelaboratory at the present time. To bridge that gap would require a particleaccelerator that was bigger than the solar system. Such an accelerator wouldbe unlikely to be funded in the present economic climate.However, the very early stages of the universe are an arena where such ener-gies must have occurred. I think that there is a good chance that the study ofthe early universe and the requirements of mathematical consistency will leadus to a complete unified theory by the end of the century-always presumingwe don’t blow ourselves up first.

What would it mean if we actually did discover the ultimate theory of the uni-verse? It would bring to an end a long and glorious chapter in the history ofour struggle to understand the universe. But it would also revolutionize theordinary person’s understanding of the laws that govern the universe. InNewton’s time it was possible for an educated person to have a grasp of thewhole of human knowledge, at least in outline. But ever since then, the paceof development of science has made this impossible. Theories were alwaysbeing changed to account for new observations. They were never properlydigested or simplified so that ordinary people could understand them.You hadto be a specialist, and even then you could only hope to have a proper grasp ofa small proportion of the scientific theories.Further, the rate of progress was so rapid that what one learned at school oruniversity was always a bit out of date. Only a few people could keep upwith the rapidly advancing frontier of knowledge. And they had to devotetheir whole time to it and specialize in a small area. The rest of the popula-tion had little idea of the advances that were being made or the excitementthey were generating.

Seventy years ago, if Eddington is to be believed, only two people understoodthe general theory of relativity. Nowadays tens of thousands of university grad-uates understand it, and many millions of people are at least familiar with theidea. If a complete unified theory were discovered, it would be only a matterof time before it was digested and simplified in the same way. It could then betaught in schools, at least in outline. We would then all be able to have someunderstanding of the laws that govern the universe and which are responsiblefor our existence.

Einstein once asked a question: “How much choice did God have in construct-ing the universe?” If the no boundary proposal is correct, He had no freedomat all to choose initial conditions. He would, of course, still have had the free-dom to choose the laws that the universe obeyed. This, however, may notreally have been all that much of a choice. There may well be only one or asmall number of complete unified theories that are self-consistent and whichallow the existence of intelligent beings.

We can ask about the nature of God even if there is only one possible unifiedtheory that is just a set of rules and equations. What is it that breathes fire intothe equations and makes a universe for them to describe? The usual approachof science of constructing a mathematical model cannot answer the questionof why there should be a universe for the model to describe. Why does the uni-verse go to all the bother of existing? Is the unified theory so compelling thatit brings about its own existence? Or does it need a creator, and, if so, does Hehave any effect on the universe other than being responsible for its existence?And who created Him?

Up until now, most scientists have been too occupied with the developmentof new theories that describe what the universe is, to ask the question why. Onthe other hand, the people whose business it is to ask why-the philoso-phers-have not been able to keep up with the advance of scientific theories.In the eighteenth century, philosophers considered the whole of humanknowledge, including science, to be their field. They discussed questions suchas: Did the universe have a beginning? However, in the nineteenth and twen-tieth centuries, science became too technical and mathematical for thephilosophers or anyone else, except a few specialists. Philosophers reduced thescope of their inquiries so much that Wittgenstein, the most famous philoso-pher of this century, said, “The sole remaining task for philosophy is the analy-sis of language.” What a comedown from the great tradition of philosophyfrom Aristotle to Kant.

However, if we do discover a complete theory, it should in time be understand-able in broad principle by everyone, not just a few scientists. Then we shall allbe able to take part in the discussion of why the universe exists. If we find theanswer to that, it would be the ultimate triumph of human reason. For then wewould know the mind of God.

Table of Contents

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

Chapter 1 - FIRST LECTURE - IDEAS ABO...

Chapter 2 - SECOND LECTURE - THE EXPA...

Chapter 3 - THIRD LECTURE - BLACK HOLES

Chapter 4 - FOURTH LECTURE - BLACK HO...

Chapter 5 - FIFTH LECTURE - THE ORIGI...

Chapter 6 - SIXTH LECTURE - THE DIREC...

Chapter 7 - SEVENTH LECTURE - THE THE...