Essay Review

 

 Reflections on S.W. Hawking's A Brief History of Time

P. Hammond
Department Head & Professor of Electrical Power ngineering, retired
The University Southampton, SO9 5NH England

A BRIEF HISTORY OF TIME by S.W. Hawking. New York: Bantam Books, 1988. 198 pages. Hardcover; $18.95.

From PSCF 42 (March 1990): 47-52

It is commonly assumed in Christian circles that the conflict between science and faith has been more or less settled as far as physical science is concerned. It is thought that there still seems to be some conflict between the life sciences and faith, and clearly the social sciences remain intensely hostile to Christianity, but apparently physical science has reached a relatively easy accommodation with Christian belief. The more mathematical a scientific discipline becomes, the less does there seem to be an intersection between it and the Christian view of the world. Where there is no intersection there can be no conflict. Indeed, the mathematical structures of physics may even yield useful analogies for the Christian apologist.

Stephen Hawking's book is likely to cause these assumptions to be questioned. Although he is a professor of mathematics, he has deliberately written a non-mathematical book. Humourously, in the preface he writes that because equations would depress the sales of the book he has included only one, namely Einstein's famous equivalence of energy and mass. He hopes that this one equation will not halve the number of potential readers! Since the book is a best-seller even in a hardcover edition, there was no need to fear loss of sales. In any case, even Einstein's equation is not so much a piece of mathematics as a statement about physical phenomena, and the work is about such phenomena rather than about the logical connections between them. But the absence of mathematics is insufficient to account for the popularity of the work. Nor can that popularity be attributed entirely to the astounding lucidity with which complicated processes are made accessible to ordinary people. Even the altogether delightful sense of humour is insufficient to cause the man in the street to read such a profoundly serious book. The reason for Hawking's success as a writer is that he addresses the problems of meaning and purpose which bother all human beings, if not every day then every other day. Hawking has written a religious book in a scientific setting. It is a work which is more religious than many a church service, and it is explicit in its frequent use of the word God. The author speaks to modern readers who look for religious convictions, but who also look for them to carry the imprimatur of science.

Naturally, then, this book intersects with Christian belief and does so deliberately, but graciously and without rancour. It is an important book and needs to be treated by Christians with great respect and attention, although of course there is no need to agree with everything the author says.

The book starts with Aristotle's view of the universe and Ptolemy's development of it. The stationary earth is at the centre of the universe and the heavenly bodies attached to spheres rotate around it. This universe is finite because there is nothing to be observed beyond the outermost sphere which carries the fixed stars. This Aristotelian model was accepted by the Christian church as being in accordance with Scripture. Hawking surmises that the chief reason for this acceptance was that the model left plenty of space for the location of heaven and hell. Since he immediately replaces the Aristotelian model with the Copernican one of a stationary sun, there is here a gentle poking of fun at heaven and hell as well as their location in space. More seriously, the opposition of the church to the Copernican model is connected with its scientifically erroneous view of a central earth. Aristotle is rebuked for his mystical belief in circular motion and Christians for the use of Scripture, spelled respectfully with a capital  "S". Alongside these subjective notions, Hawking places the objectivity of Galileo's observations of the night sky and couples this with a side-swipe of the absurd notion of pretending that the difference between Ptolemy and Copernicus is merely arbitrary. In a few pages the scene has been set for conflict between scientific knowledge and nonscientific make-believe.

This does not mean that scientific thinkers get good marks throughout. Newton, for example, not only has a bad character reference in an appendix to the book, but is also shown to be in error about the possibility of a static universe of infinite extent. This leads to the first examination of the beginning of the universe and a mention of its expansion, which would seem to require an instant of creation. In this context there are frequent references to God, but in a very detached way. The first chapter concludes with a brilliant summary of the scientific method as seen by the author. In summary, he states that science is concerned with the construction of models, which are useful in making predictions. The eventual goal is to provide a single model to describe the whole universe. Although the models exist only in our minds, a universal model could be used to predict our thoughts and actions. Hawking regards this as a paradox, which cannot be resolved except perhaps by reference to Darwin's principle of natural selection, which favours correct theories.

The second chapter starts with Galileo's and Newton's clarification of the laws of motion. Hawking is particularly concerned with the absence of a unique standard of rest and therefore of position, and this leads him immediately to the impossibility of absolute time and the necessity of Einstein's postulate of relativity, in which the laws of science are the same for all freely moving observers. The exposition of both restricted and general relativity is concise and breathtaking in its mastery of the subject. The central feature of the universe is shown to be space-time interacting with matter. Hawking refers to his own early work, which led him to the conclusion that the general theory of relativity implies that the universe must have a beginning and perhaps an end in time.

Next, the book deals at some length with the expansion of the universe. Here the reader is confronted with the immense number of the heavenly bodies and the inconceivable distances between them. Not only is the earth no longer at the centre of the model, but the sun itself has no special position or size. The reader is unlikely to miss the implicit conclusion that mankind has little claim to being special or important. Yet, curiously, the ideas underlying the model are shown to be important, and throughout the book Hawking takes a roll-call of Nobel prizewinners who have contributed to the development of cosmology. There are even consolation prizes for people who failed to obtain the Nobel mark of approval. After a brief look at possible steady-state models of continuous creation, we are left in no doubt that the observed expansion together with other observations of radio astronomy lead inevitably to the conclusion that there must have been a Big-Bang singularity at the outset, unless the structure of that singularity were to be affected by the small-scale effects of quantum mechanics. The clue, that a combination of very large-scale with very small-scale effects may unravel the secret, is reminiscent of the very best kind of detective story.

But before he follows the clue the author has to resolve a number of philosophical and experimental problems. First amongst these is the question of how far scientific principles can be used to predict what happens in the universe. The doctrine of complete predictability has always been resisted by religious thinkers who felt that it infringed God's freedom to act. It has also been resisted by many scientific thinkers, but has been accepted by popular science as inevitable. Indeed, in popular writings a scientific description is almost identical with a deterministic one. Hawking describes how this identity was shown to be false with the discovery of the fact that energy is transferred in packets called quanta. This experimental fact led to the formulation of the Uncertainty Principle, which draws attention to the impossibility of knowing both the position and velocity of particles of matter. Philosophically, this points strongly to the result that all predictions of mechanical events are subject to uncertainty. Scientifically, particles are seen to have wave-like properties, and this means that the "singularity" of a particle is completely modified.

There follows a chapter dealing with the present state of the theory of elementary particles. Very skillfully, Professor Hawking hints that the apparent complications of the existence of many kinds of particles can be resolved by pointing to an underlying unity in terms of energy, force, and symmetry. Another important clue is inserted into the discussion by drawing attention to the fact that the laws of physics are not identical when the direction of time is reversed.

Since the book is primarily concerned with the origin (and end) of the universe, the author seeks to elucidate what happens at a singularity, such as the "Big-Bang" of creation. This makes him turn to existing partial singularities in the universe, which are known as black holes. The two chapters dealing with such regions of space are enormously exciting both intellectually and emotionally. Hawking is writing about his own discoveries, and his account must be read in his own words. A summary cannot attempt to recapture the mystery of regions of space which suck into themselves any matter or energy in their vicinity, and which allow these objects to send no signals of their fate when they are swallowed up. Hawking's scientific account is illuminated by colloquial expressions like: "to detect a black hole might seem like looking for a black cat in a coal cellar;" "a black hole has no hair;" and, "God abhors a naked singularity." The last statement provides another clue to Hawking's argument. Even black holes have some connection with the rest of the universe. They should slowly evaporate, because quantum mechanics should remove the singularities predicted by the general relativity theory.

The scene is now set for discussing the Big Bang singularity of the beginning of the universe and the Big Crunch singularity of its end. Black holes have been shown to have a less singular structure than might have been imagined. Could it be that something can be discovered from them about the beginning and end of the universe? Here the author has a dig at the Catholic Church, and claims that at a conference at the Vatican at which he gave a lecture, the Pope had warned the conference members to limit their investigations to events after the Big Bang so as to not intrude into the creative work of God. He expresses his relief that the Pope had not heard his lecture, because he did not wish to share the fate of Galileo!

There are four questions which Hawking wants to investigate. Why was the early universe so hot? Why is it now so uniform? Why did it start at the rate of expansion which we now observe? Why are there local irregularities like stars and galaxies? In the discussion of these questions there are repeated mentions of God. How did God choose the boundary conditions which set the universe on its present path? Are they incomprehensibly chosen and does the system afterwards continue by comprehensible laws? It could of course be that there are infinitely many universes, but that we observe only the one in which we live. The initial conditions for different universes could be different, so that the question of choosing particular conditions would not arise, but such possibilities do not fit easily into a framework of scientific law.

Here the author introduces the Anthropic Principle, which introduces the human observer as an essential constituent. The principle can be stated as: "We see the universe the way it is because we exist." This principle can be stated in either a strong or a weak form. The strong version is that our universe is such as to make human life possible. This comes close to the religious statement of a divine purpose in creation. Hawking dismisses the strong form of the Anthropic Principle, because it places the inhabitants of our small planet at the centre of importance and reverts to something like Ptolemy's geocentric cosmology. He is happier with a weak form, that the necessary conditions for intelligent life will be met only in certain regions of time and space. We should not be surprised to find that the conditions in our region are right for our existence.

However, such a bland statement does not by itself give a scientific explanation for the underlying order of the universe. So the author resumes the quest for an understanding of the Big Bang singularity. The book is close to its climax. Since even black holes are not as black as was first thought, Hawking now suggests that the Big Bang singularity may not after all be such as to cause the laws of physics to break down. In that case, there would be no need for boundary conditions at the instant of creation, or indeed at any instant.

The discussion is necessarily technical and mathematical. It involves the suggestion that quantum theory can be formulated by taking into account every possible path a particle might take in space-time. Coupled with this suggestion (due to Feynman), there is the proposal that the time coordinate should be modified in the equations in a manner which is familiar to electrical engineers, who prefer to work in the "frequency domain" rather than in "real time." These suggestions, together with Einstein's idea of curved space-time, lead to the possibility that space-time can be finite in extent but have no boundary or edge. The universe would then be completely self-contained and not affected by anything outside itself. It would have neither beginning nor end, nor, in Hawking's view, any need of a Creator.

But how can this be made to fit together with the observations which show that time has direction? The author tackles this question in a fascinating chapter on "The Arrow of Time." He reverts to the absence of symmetry when time is reversed. A film run backwards shows life very differently. In real life, a cup falling off a table breaks into pieces. When time is reversed, the pieces gather themselves off the floor and form an unbroken cup on the table.

In his view there are three arrows of time: the thermodynamic arrow, the psychological arrow, and the cosmological arrow. The thermodynamic arrow draws attention to the fact that there are many more disordered states than ordered ones, so that the probability is that disorder in a system will increase. The psychological direction of time is linked to the thermodynamic one by the structure of the brain, so that we remember things in the direction of increasing disorder. Lastly, the cosmological arrow of time, which is in the direction of an expanding universe, will reverse when the universe begins to contract, but at that time intelligent life will not be possible because of the high degree of disorder.

The final chapter is titled "The Unification of Physics." It contains a section on string theories in which the fundamental particles of physics are replaced by even more fundamental geometrical objects called strings. Here the author is leading his readers into the most recent thoughts of cosmologists and into unfamiliar territory. Nevertheless, the explanations reinforced by simple diagrams are extremely lucid. The purpose of string theories is to incorporate the Uncertainty Principle into General Relativity, and by this means to achieve a unified theory dealing with all of physics. Hawking is hopeful that such unification is both possible and not far away. He faces the question that there might be no such theory and that ultimately events occur in a random and arbitrary manner. It is interesting that he thinks that such a view appeals to some who want to defend the sovereignty of God, but he cites St. Augustine to show that no such defence is necessary. He also dismisses the possibility of an infinite succession of ever more accurate theories. Instead, he puts his faith in a single unified theory which is almost within our grasp. Such a theory would not of itself allow us to predict the behaviour of complicated systems, but it would be an important step to our understanding of the events around us and of our own existence.

A short conclusion summarises the arguments of the book. The search is for an understanding of the world around us and of ourselves. In early times, men thought that phenomena were governed by spirits who acted in an unpredictable manner. Gradually the orderliness of nature was observed and the underlying laws of science were discovered. The role of God was then confined to the act of creation. Now this role is in question because it is likely that the laws of physics apply even at the moment of creation. God had no freedom to choose the initial conditions which set the universe going. We are now close to the possibility of answering the question as to why the universe is the way it is. When we can do so, we shall "know the mind of God."

In spite of the apparent dismissal of God from activity in a universe completely described by scientific laws, the last words of Hawking's conclusion affirm a belief in God. Indeed, this is a religious book throughout, and it is important to discover what this religion is like. From a Christian point of view, one needs to know what the similarities and differences are between Christianity and the religious view of the book. Can Christians learn something from Hawking as a religious writer as well as from his brilliant powers of scientific explanation? Is there necessarily a conflict between the two religious views, or can they be reconciled with each other?

Let us first examine the strength of Hawking's point of view. Foremost among these is his commitment to rationality. We live in a time when reason is at a discount. The message of contemporary art and music is that life is essentially chaotic, and Christians as children of their age also stress the irrational in their faith and experience. Scientists and mathematicians, whose work depends on reason, often seem to lack the conviction that the domain of reason extends beyond their professional activities. Hawking will have none of this. He derides philosophers who, like Wittgenstein, reduce philosophy to the analysis of language. His philosophy is about the nature of the universe, and that includes everything. Nor does he admit that there are cracks and fissures in which unreason can hide. Unlike some Christian apologists, he does not insert God into the Uncertainty Principle. Rather, he pokes fun at the idea that God should seek to achieve his purposes through physical events described by uncertainty. The Uncertainty Principle is itself a part of rationality.

This spirited defence of reason is altogether admirable. Moreover, it also has a strong appeal to the man in the street. The brokenness of modern thought often contains a cry for help. Nonsense is not an option for normal human beings, and Hawking writes explicitly for ordinary people who can share the assurance that the world is reasonable.

The second strong feature of the religious view of the book is faith. Several times in the argument the question of the existence of scientific laws is posed, and every time it is answered by total faith in rationality. A layman can only guess at the intellectual effort involved in the search for the fundamental laws, for which there is no guaranteed success. Often there must be disappointment and always the work is incredibly demanding. Always the results have to be tested against observation and have to be adjusted to fit into each other. Faith has to be prepared to accept failure when a bright idea is shown to lead to a dead end. In the popular view, faith is contrasted with reason. Hawking shows faith cooperating with reason. One can even infer from the book that reason by itself is insufficient, because it has to be buttressed by faith.

All this is very positive, but there are also some remarkable weaknesses in this religion. A curiously weak section is the one which deals with the "arrow of time." The Second Law of Thermodynamics is unassailable, but the link between it and the psychological direction of time is unconvincing. It is common experience that a cup falls and breaks. It is also common experience that unbroken cups are for sale in the shops to replace the ones we have broken. It is curious to read that our memories act in accordance with increasing disorder. This is contrary to experience, and if it were to be correct, it is doubtful there would be a University of Cambridge and a Lucasian professorship for the author. The whole thrust of science and of the author's work is towards increasing order. Our lives between birth and death show both increasing order and increasing disorder, but the meaning is chiefly in the order. It is the human predicament that the Second Law of Thermodynamics prevails in death, but that is not the whole story or the more important part of the story. Similarly, the argument about the cosmological arrow of time does not carry conviction. The Anthropic Principle has a strangely unscientific flavour. Its weakness seems to lie in the fact that it is not a scientific law but a statement about the human observer. This brings us to the central difficulty of Hawking's religious as against his scientific views. How are human beings to be incorporated into the unified theory of physics?

In the first chapter, there is a very interesting discussion about the nature of scientific theory which has already been mentioned. Hawking states categorically that a theory is "just a model of the universe or a restricted part of it and a set of rules that relate quantities in the model to observations that we make. It exists only in our minds and does not have any other reality." The rest of the book and the triumphant final statement about knowing the mind of God suggest on the other hand that the unified theory which is its quest is "the" theory rather than "a" theory, and that its reality is rather more solid than the disclaimer at the beginning of the book implies. The author's many references to the progress of science sound a confident note. The model of the universe is speedily replaced by the actual universe itself. We need to enquire why he uses the word "model" and how far such a model can be coextensive with the object modelled. It is not obvious what is meant by "quantities in the model" or how such quantities are related to observations, which in the nature of things cannot be made on the model. It is also important to find out how such models are constructed.

Our enquiry can best start with an examination of Hawking's model of the universe. If we change the metaphor and regard the model and its activity as a play, we can ask for a list of the dramatis personae in this play.

The lead role is taken by a character called "space-time." This is a geometrical object which has the property of curvature. There is a married couple called energy and matter. Amongst the attendants of energy, there are gravity and force. Matter is attended by particles and strings. There is a space traveller, whose task is to send signals from the vicinity of black holes but who has no human features. The action of the play is moved forward by the comments of a chorus of a human scientists, many of whom are Nobel prizewinners.

Clearly the play, or model, has extremely few actors. None of the principle actors are recognisably human. The Anthropic Principle, which has been mentioned before, supplies stage lighting, but does not add human interest. The chorus however does consist of recognisable human beings, who take pleasure in being awarded the Nobel prize and are sad when this honour passes them by. The leader of the chorus is the author himself, and he is intensely human. So far I have made no reference to his illness, because it was irrelevant to a discussion of his scientific and religious views and it would have been impertinent to mention it. But in a discussion of the human element of the book, Hawking's amazing courage in the face of his disabilities must be included. It seems to me that the fallacy of equating the model of the universe with the universe itself is totally exposed by noting that this book was written by a man in a wheelchair, a married man with a family, a professor with colleagues and students, a man the very opposite of an unfeeling robotic look-a-like. It follows that however grand the unified theory of physics is in its grasp of inconceivable distances both small and great, and in its incorporation of the beginning and the end of time, it is not grand enough to incorporate human beings, and its God is not sufficient to answer the urgent questions arising from human experience. This is no appeal to an Anthropic Principle, but a direct appeal to observation of the world as it is and not of a model of that world.

A hint that Hawking himself has doubts about the completeness of his model arises in his discussion of what remains to be done in science once physics has been unified. He suggests that once the theory is complete it only remains to devise better means of calculation and of approximation. These might then lead to the prediction of human behaviour from mathematical equations, which so far has not been possible.

An alternative view of his complete model is that its very completeness shows its limitations. The glory of its completeness is bought at the price of excluding much of experience. The scientific method necessarily and rightly works by the reduction and separation of the variables. It is not surprising that a theory dealing with space-time gives results about space-time. That is why Hawking's proposal of unbounded space-time is so reasonable. It would surely be surprising if such a model could point to anything outside itself. A weakness of Christian apologetics has often been to try to insert God into a model instead of seeing him in the world itself. Hawking's God is also very much restricted to the model of physics. He seems to have no other characteristics than those from which the model is constructed.

In stressing the importance of human characteristics for a full understanding of the universe we might be accused of attaching undue importance to the inhabitants of an insignificant planet attached to an average star in an ordinary galaxy. But we cannot escape from having to make sense of our existence, and our existence is necessarily to do with our observations. Hawking's religion has the appearance of a proper humility in this respect, but it denies that humility by drawing attention to the marvels of a scientific theory which is said to exist only in the minds of human beings. One has to conclude that the God to whom he refers is similarly a human construct, and such an idea is as far from humility as is possible.

It therefore seems that the religion of this book cannot be reconciled with Christianity, in spite of its many admirable features. The arrow of time which points inexorably towards chaos is not the arrow of Christian thought, which points towards the coming kingdom of heaven. The Christian affirmation is that it was not possible for Christ to be held by death. There is a stronger law than the Second Law of Thermodynamics in God's providence.

However, there is much to be learned from the science in this splendid book, as indeed there is much to be learned from its very human author.

1990