The Book of Nothing

by John D. Barrow

  Figure 8.17 Cosmic strings exchange loops when they intersect.

  Figure 8.18 A computer simulation of a network of cosmic strings in an expanding universe, provided by Paul Shellard.29

  The cosmic string scenario for the origin of galaxies is a natural rival to the inflationary theory. In the string theory, the initial non-uniformities in the density of the Universe from place to place are created by the appearance of string loops in different places, from the definite continuous vacuum structure of particular energy fields, whereas in the inflationary theory they arise from the zero-point fluctuations. The two ideas are not natural bed-fellows. Just as inflation sweeps away walls and monopoles that have formed in the Universe so it will sweep away the distribution of cosmic strings if they form before inflation happens. In that case they will play no further role in the formation of galaxies. Thus, if galaxies owe their existence to a population of cosmic strings forming in the very early Universe, either inflation did not happen, and we cannot appeal to any of its other benefits to explain mysterious properties of the Universe, like its proximity to the critical rate of expansion today, or the vacuum structure of the ultimate unified theory has a very peculiar double structure. That structure must undergo a slow change that first enables inflation to occur and then be followed by a further particular type of change which permits cosmic strings to appear without any walls or monopoles appearing along with them. Most cosmologists think that this is a tall order and rather unlikely. However, there is no proof of its impossibility.

  Individual cosmic vacuum strings are strange beasts. They could reveal their presence by bending rays of light that move close to them. The defining characteristic of a string is its mass per unit length. The larger this is, the greater will be the mass and gravitational effect of any piece of string on other masses. If a straight line of cosmic string were to pass through this page then its effect on neighbouring masses would be to make them move together. It is as if a wedge is cut out of space around the string and the remaining space pulled together to fill the gap (see Figure 8.19). Strings would be like nothing else we have ever encountered. If a piece of vacuum string extended across a part of space that astronomers were ob-serving then the effect of its gravity would be to behave like a lens. A star lying behind the string would have its image duplicated.30 A curving piece of string would create a tell-tale line of double images. Astronomers have looked for these tell-tale images but have yet to find them. Plenty of multiple images have been seen by the Hubble Space Telescope and they are clearly due to the lensing action of gravity fields. However, they seem to be caused by very large intervening objects like galaxies not cosmic strings.

  Figure 8.19 A long cosmic string passing into the page has the same effect as removing a wedge of space around the string. This creates a focusing of light rays as they pass by the string as if they are passing through a lens.

  These speculative possibilities show some of the unending richness of the physicists’ conception of the vacuum. It is the basis of our most successful theory of the Universe and why it has the properties that it does. Vacuums can change; vacuums can fluctuate; vacuums can have strange symmetries, strange geographies, strange histories. More and more of the remarkable features of the Universe we observe around us seem to be reflections of these properties of the vacuum. All that remains for us to ask about it is whether it had a beginning and whether it will ever have an end.

  “It has indeed been said that the highest praise of God consists in the denial of him by the atheist, who finds creation so perfect that it can dispense with a creator.”

  Marcel Proust1

  BEING OUT OF NOTHINGNESS

  “The human race, to which so many of my readers belong, has been playing at child’s games from the beginning … The players listen very carefully and respectfully to all that the clever people have to say about what is to happen in the next generation. The players then wait until all the clever men are dead and bury them nicely. They then go and do something else. That is all. For a race of simple tastes, however, it is great fun.”

  G.K. Chesterton2

  Why is there something rather than nothing? Some regard such questions as unanswerable, some go further to claim that they are meaningless, whilst others claim to provide the answers. Science has proved a reasonably effective way of finding out about the world because it confines itself, in the main, to questions about ‘how’ things happen. If it does ask the question ‘why’ it is generally about an aspect of things that can be answered if one is in possession of a full description of how a certain sequence of events occurs, what causes what, and so on. As one digs deeper to the roots of scientific theories one finds that there is a foundation of a sort that we call laws of Nature, which govern the behaviour of the most elementary particles of Nature. The identities of these particles, the things they are able to do, and the ways in which they can combine are like axioms whose consequences we can test against the facts of experience. To some extent we may find that it is very difficult to imagine how things could be otherwise because the properties of the laws become closely bound up with the nature of the populations of identical elementary particles that they govern. Some laws only act upon particles with particular attributes. But in other respects it is possible for us to envisage a universe that was slightly different from our own. So far, we have not found a theory that requires there to be only one possible universe. This question boils down to one about the nature of the vacuum landscape for the ultimate theory of the Universe. If there is a single valley in this landscape, then there is a single possible vacuum state and one possible set of values for the constants of Nature that define it. If there are many valleys, and so many vacua, then the constants of Nature are not uniquely specified by one possibility. They can exist with different values and, as we have seen in the last chapter, they may even do so elsewhere in our Universe now. Hence there has emerged a more modest version of the great ontological question, ‘Why is there something rather than nothing?’ which physicists are able to comment on in a meaningful way. From their perspective, certain aspects of the world may be inevitable or be necessary features of any universe that is going to contain living observers.

  The matters of science which are relevant to our great question are those studied by cosmologists and physicists. The study of the Universe has revealed it to be expanding. Tracing its history backwards for billions of years leads us to a moment when densities and temperatures would become infinite, and further backtracking using this description is impossible. This leads us to consider the serious possibility that it may have had a beginning at a finite time in the past. This is only an extrapolation and needs to be examined far more closely if it is to be taken seriously, but let us for the moment take it seriously enough to follow the argument a little further. If the expansion did have a beginning then we are faced with further questions: is this ‘beginning’ merely the start of the expansion of the Universe that we see today or is it the Beginning, in every sense, of the entire physical Universe? And, if it is the latter, does it include just the matter and energy in the Universe, or the entire fabric of space and time as well? And, if space and time come into being, what of the laws and symmetries and constants of Nature, as we like to call them; do they appear as well? Lastly, if some or all of these things must come into being at some identifiable moment of history, what do they come into being from, why, and how?

  There are ancient traditions of humans asking great ‘why’ questions about the nature and end of existence. A large fraction of the readers of these pages will live in societies that have been strongly influenced by the Judaeo-Christian tradition and the ideas that it generated in order to harmonise its writings and doctrines with our early knowledge of the physical world. The doctrine of the Universe having been created out of nothing (creatio ex nihilo) is almost unique to the Christian traditions. A survey of the mythological beliefs of the world reveals surprisingly few basic cosmological scenarios, despite a veneer of exotic acto
rs and fantastic memorable mechanisms.3

  The idea of a ‘created’ universe is most commonly found as a re-shaped or reconstructed universe, usually being fashioned out of a state of chaos or a structureless void. Alternatively, the world may ‘emerge’ from some other state, for which there are a multitude of candidates. It can spring new-born from some primeval womb, or be fished out of the dark waters of chaos by a heroic diver. It may hatch from a pre-existent egg or emerge from the union of two world parents. Elsewhere, we find versions of the story of a clash between some superhero and the forces of darkness and evil, out of which the world is born. All these pictures have close links to human experiences of human childbirth, battles with rivals, animal reproduction and fishing for food. The emergence of something from nothing, like the birth of a child, is accompanied by pain and effort. It is often opposed, but ultimately it succeeds. Not all these examples are straightforward. As time passes mythological accounts tend to become increasingly complex. More and more facts come to light about the world and new questions are asked. Answers can usually only be provided by embroidering the story further. Explanations grow more elaborate.

  Other traditions can be found in which the Universe does not begin at all: it always was. These traditions often have a cyclic picture of time and history that owes much to the seasonal cycles exploited by agricultural societies and the cycles of human life and death.4 Thus, while the ultimate reality continues from a past eternity to a future eternity, the Earthly world will die only to be reborn, rising like a phoenix from the ashes of its predecessor. The pattern of human cosmological stories is summarised in Figure 9.1.

  In these accounts the language of creation, in the artistic or practical sense, is often used to describe the bringing into being of the observed state of the world. In most cases the raw materials were given and the creative process fashioned order from chaos. No inquiry was made into the origin of the materials themselves. The origin of the world out of the union of two gods offers scope for contemplating the appearance of something where once there was nothing, in the same way that a new child is not just a rearrangement of pre-existing things. However, the idea of making something from nothing was compromised by the pre-existence of the gods. The offspring owed something to them just as the offspring of a human union displays characteristics of its parents. These stories always drew a veil over the question of how there could be a transition from absolutely nothing to something. No tradition addresses this question. All have something emerging from something else, usually aided by an act of will by a superhuman intermediary. The impression that one gets from these stories is that the idea that the world began was not too difficult to accept, but it was impossible to comprehend the idea that it could have ‘begun’ in any sense other than having changed from something else into what it now appears to be. Nothing, as we have seen, is a very difficult concept to grasp. Here, it was easy to sidestep it.

  Figure 9.1 The common patterns of cosmological traditions.

  CREATION OUT OF NOTHING

  “In the beginning there was Aristotle,

  And objects at rest tended to remain at rest,

  And objects in motion tended to come to rest,

  And soon everything was at rest,

  And God saw that it was boring.”

  Tim Joseph5

  There is a popular notion that the Christian tradition of the creation of the Universe out of nothing is simply that God made the Universe appear out of nothing at a moment in the finite past. Everything that constitutes the world – space, time, matter, laws of Nature – sprung into being at once out of nothing at all. These things were not fashioned out of some simpler, less ordered or chaotic mess. They were created, not formed out of something else.

  Almost all of the statements in the last paragraph have a number of different variants and interpretations. Yet the detailed nature of the traditional doctrine of creation out of nothing is far less specific and cosmological. One suspects that the religious ideas have gradually become far more specific and well defined with the advent of twentieth-century cosmology and the fairly precise picture that it gives of the expanding Universe and its apparent beginning. Although some modern theologians seek to reconcile the ancient tradition of creation out of nothing with contemporary cosmological ideas,6 it is good to recall that the doctrine of creation out of nothing did not arise in Christian tradition in order to make assertions about astronomy and cosmology as we now understand them. Its primary objectives were to make a statement about the relationship between God and the Universe; to assert that there was meaning and purpose to the world, that it was dependent upon God, and to distinguish clearly between Christian beliefs and those of other belief systems that were current at the time when the early Church was developing its theology.7 In particular, it proclaimed that Nature was not the same thing as God; this was an important distinction that served to make the worship of idols or nature-gods appear futile. It also sought to make a theological point about the power of God. Creation rather than formation out of pre-existing stuff asserted that no help was needed from other sources; God controlled matter’s existence as well as its orderly patterns.

  These aims were of far greater significance than any desire to underpin the idea that the world came into being at a definite moment in time.8 Yet it is this latter idea that often seems to be of primary interest to many modern apologists trying to reconcile science and Christianity.9 This polemical use of a doctrine of creation out of nothing is certainly not new. It was first developed in order to distinguish its adherents from other philosophies and beliefs, both current and inherited, in the Graeco-Roman worlds. Thus, whereas the followers of Plato subscribed to the shaping of some pre-existent world of matter into its present form by the action of a demiurge, Christianity affirmed a creation out of no pre-existent material at all. Aristotle, by contrast, argued for the past eternity of the world rather than its sudden appearance.

  One might imagine that early Christianity inherited the idea of creation out of nothing from Judaism, but the evidence for its presence in Jewish texts is by no means incontrovertible or unambiguous. There is no explicit statement in early Jewish writings about the creation of the Universe. It was not a doctrinal ingredient of its theology. There appears to have been little interest in the question. There was no doubt in anyone’s mind about the existence and omnipotence of Yahweh and so no motivation for proofs of His existence that appealed to the need for a Creator. Although no systematic position is explicitly worked out there is evidence that, if pressed on the issue, there was a clear defence of the concept of creation out of nothing. At the end of the first century, the influential Rabbi Gamaliel engaged in a debate10 with a philosopher on the question of whether the world was formed from pre-existent materials. The philosopher describes the work of God as that of a great artist using the materials (‘colours’) that are made available in the opening verses of Genesis. But Gamaliel counters this theory by arguing that all these ‘colours’ are explicitly described in the Bible as having been created by God. Thus he rejects an interpretation of the first two verses of Genesis as supporting the idea that the world was formed out of pre-existing material. Implicitly, he asserts creation out of nothing by declaring that anything you nominate as the raw material for creation was created by God. Here, as in other places, we seem to be seeing a theological affirmation that happens to use cosmological categories rather than the development of any explicit cosmological theory that can be used to deduce other properties of the Universe. There would have been religious views about the end of the world but they would not in any sense have been consequences of the teachings about its beginning.

  The Wisdom of Solomon11 speaks of the formation of the world out of formless matter that the Almighty ‘made’. The text most frequently cited as the earliest explicit statement of the idea of creation from nothing is in the second book of Maccabees,12 which speaks of the ‘Creator of the world’ bringing about ‘the beginning of all things’. The context is
a story in which a mother of seven martyrs encourages her youngest son to remain faithful by calling upon him to ‘look upon the heaven and the earth, and all that is therein, and consider that God made them of things that were not’ and be assured that ultimately he will awaken the righteous from death. But there is no philosophical purpose in the mother’s mind. She is just basing hope for resurrection upon her faith in the power of God. Other examples can be found of similar phraseology being used to express the coming of children into the world ‘out of non-being’.13 Again, there is no engagement with the sort of tricky philosophical problems for which the possibility of creation out of nothing would be a possible remedy or counter-example.