Planet Skyron

Fred Hoyle famously coined the term “Big Bang” to characterize the single creation theory of cosmology in a series of talks he gave on BBC radio broadcasts in the late 1940s. Equally famous was Hoyle’s own view of the universe wherein creation of matter was continuous without beginning or end. To his way of thinking, the “big bang” was counter-intuitive to nature and more at home to theology. As he said in the third programme broadcast in 1949:

[My theory] replaces a hypothesis that lies concealed in the older theories, which assume, as I have already said, that the whole of the matter in the universe was created in one big hang at a particular time in the the remote past. On scientific grounds this big bang hypothesis is much the less palatable of the two. For it is an irrational process that cannot be described in scientific terms.

See Hoyle’s entire script for the programme below.

Hoyle responds to a couple of questions about his theories.

Here’s the transcript of his “Big Bang” talk as heard on the Beeb some time ago.

CONTIGUOUS CREATION by Fred Hoyle
Monday, 28th March, 1949, 6.30-6.50 p.m. THIRD PROGRAMME

Tonight I want to tell you about some new work on the expanding universe. Together with two of my colleagues H. Bondi and T. Gold, I’ve reached the conclusion that the universe is in a state of continuous creation.

When we look at the sky on a clear night we see that the stars are mainly concentrated along the Milky Way. Astronomers infer from this simple observation that, here on Earth, we are situated inside a great disk-shaped system of stars. This system, which is usually referred to as the Galaxy, is of enormous size. To go right round it at the speed of light would take about two hundred thousand years.

Nor is this the end of the domain of the astronomer. In the nineteenth century the large telescope built by the Earl of Rosse showed that certain types of nebulae can be detected in all directions. For many years controversy raged as to whether these objects were small patches of luminous gas within our own Galaxy or whether they were great independent stellar systems having dimensions comparable with those of the Milky Way itself. The issue was finally settled by the American astronomers who found that they are indeed independent stellar systems. The number of these independent galaxies within the range of present observation is about a thousand million. It has also been found possible, largely through the work of Hubble, to establish a rough scale of distances. It turns out that light takes about two thousand million years to travel to us from the most distant galaxies visible in the largest telescopes. So the light we now receive from them must have started its journey at about the time the oldest known rocks on the Earth were laid down probably before the dawn of life on the earth.

At this stage it is natural to ask the question.

Where have these galaxies come from? It now seems very probable that they have condensed out of a uniform background of diffuse gaseous material.

Is this background exhausted?

Or can new galaxies still condense out of it?

It is my own view that the background is a very far from being exhausted. I would estimate only about one part in a hundred has been used up to form the galaxies. It is therefore to be expected that new condensations are continually being formed out of it.

What is the density of the background material?

Compared with everyday experience it is remarkably small, amounting to an average of about one atom in a volume of about 10 litres. At first sight this density might seem too little to account for all the matter present in the galaxies. But this is not so. The essential point is that, whereas the galaxies occupy only a small fraction of space, the background material is distributed throughout the whole of space.

We now come to the expansion of this universe of galaxies. Observations shows that they are moving away from each other. You might like to know how this has been discovered. Well, perhaps you’ve noticed that a whistle from an approaching train has a higher pitch, and from a approaching train a lower pitch, than a similar whistle from a stationary train. Light emitted by a moving object has the same property. In particular the pitch of the light is lowered, or as we say reddened, if the object is receding from us. Now we observe that light from the galaxies is reddened. And the degree of reddening increases proportionately with the distance of a galaxy. The natural explanation of this is that the galaxies are rushing way from each other at enormous speeds, which for the most distant galaxies become comparable with the speed of light itself.

My non-mathematical friends often tell me that they find it difficult to picture this expansion. Short of a mathematical treatment which obviously is out of place in a broadcast, I can’t do better than use the analogy of a balloon with a large number of dots marked on its surface. If the balloon is blown up the distances between the dots increase in the same way as the distances between the galaxies. Here I would like to give a warning that the analogy between the balloon and the universe must not be taken too strictly. There are several important respects in which it is misleading. For example, the dots on the surface of a balloon would themselves increase in size as the balloon was blown up. This is not the case for the galaxies which remain of approximately constant size the distances between them increase. A further weakness of our analogy is that the surface of an ordinary balloon is only two dimensional – that is to say, the points on its surface can be described by two coordinates; for example, by latitude and longitude. In the case of the universe we must think of the surface as possessing an additional dimension. This is not so difficult as it may sound. We are all familiar with pictures in perspective. Pictures where artists have represented three dimensional scenes on two dimensional canvases. So it’s not really a difficult conception to imagine the three dimensions of space as being confined to the surface of a balloon. But what does the radius of the balloon then represent, and what does it mean to any that the balloon is being blown up? The answer is that the radius of the balloon is a measure of time, and the passage of time has the effect of blowing up the balloon. The space in which the galaxies are confined expands, so to speak into time. This gives a rough, but useful, picture of the type of theory investigated by the mathematician.

The recession of the galaxies does not give the only observational test that a theory of the expanding universe must satisfy. During the past few years astronomers have developed a number of further requirements. Although I don’t wish to go into these in detail, I might mention that it is now possible to determine the ages of our own Galaxy and of several neighbouring galaxies with a substantial degree of accuracy. The result is about five thousand million years. A satisfactory theory must provide for this age, neither more nor less.

We now come to the question of applying the observational tests to earlier theories. These theories were based on the hypothesis that all the matter in the universe was created in one big bang at a particular time in the remote past. It now turns out that in some respect or other all such theories are in conflict with the observational requirements. And to a degree that can hardly be ignored. Investigators of this problem are like a party of mountaineers attempting an unclimbed peak. Previously it had seemed as if the main difficulty was to decide between a number of routes, all of which seemed promising lines of ascent. But now we find that each of these routes peters out in seemingly hopeless precipices. A new way must be found. The new way I am now going to discuss involves the hypothesis that matter is created continuously.

How are the difficulties facing former theories overcome by introducing continuous creation of matter?

I cannot deal fully with this question, but perhaps you may like to hear one of many possible examples. According to the majority of the earlier theories the density of the matter which composes the background, the background which I’ve already described, must in the distant past, have been vastly greater than it is at present. This is an effect arising from the expansion, which in these theories produces a decrease of background density as we go forwards into the future but an increase of density as we go back into the past. The galaxies that were formed in the remote past should on these theories have average densities enormously greater than that of the present background. But this is not the case. The galaxies are all found by observation to have mean densities not greatly in excess of the present background. This difficulty when stated in proper mathematical form is the death-knell of a large number of theories.

How can this objection be avoided in a theory that includes the continuous creation of matter?

Simply because it is no longer a valid conclusion that expansion produces a marked change of background density with time. Indeed according to the work I am now going to describe the continuous creation takes place in such a way that the background density remains constant with time, neither decreasing into the future nor increasing as we go back into the past.

The first step in constructing a theory of continuous creation was to find a suitable representation of the creation properties. Fortunately the groundwork had already been prepared by H. Weyl, a German mathematician now resident in Switzerland. So it wasn’t particularly difficult to build a theory in which the consequences of the creation process could be worked out and compared with observation. A natural question at this stage is this.

If matter is created continuously why don’t we observe the creation process going on?

Detailed investigation shows that the creation is not concentrated in small localised regions but is spread throughout the whole of space. It proceeds at a rate sufficient to replenish the general background in about two thousand million years. This means you will remember that in a volume equal to 10 litres about one atom is created in two thousand million years. I think you will agree that there is no chance of observing this directly.

Although the rate of creation is so small the creation process is nevertheless responsible for the expansión of the universe. Newly created matter has the effect of producing an outward pressure that leads to a steady expansion of the background material. The galaxies are then carried along in the general expansion through the action of gravitational forces.

We may now pass on to the question.

According to the creation theory is space finite or infinite? In terms of our picture of the galaxies as being confined to the surface of a balloon this simply means:

Is the radius of the balloon finite or infinite?

Remembering that the radius of the balloon is a measure of the age of the universe this amounts to answering the additional query.

Is the universe of finite or infinite age?

I shall simply quote the results of a good deal of mathematical work. Both the age of the universe and the volume of space turn out to be infinite. Moreover the universe has an infinite future in which all the present very large scale features will be preserved.

It is, important however, to realise that reference to an infinite future refers to the universe as a whole and not to individual details such as the Earth or the Sun. The future of the Earth and the stars, although probably far more than adequate for the needs of the human species, will be limited. The point is that as the stars and even the galaxies burn out they are replaced by new stars and by new galaxies. The situation is analogous to our common experience. Although no individual person lives for more than about seventy years the human species maintains itself through the births of new individuals replacing the deaths of others. So it appears to be with the universe.

It is perhaps not out of place to compare these conclusions with the theories that have been much popularised during the last twenty five years. These theories fall into the class I have already described as being in contradiction with present observational requirements. Both Eddington and Jeans are concerned with model universes of finite age and volume, and containing a fixed finite amount of matters. This led Jeans, on the basis of a thermodynamic argument, to proclaim that the ultimate fate of the universe was a featureless heat death. Every physical process was supposed to hasten this end. But the type of argument used by Jeans becomes invalid when applied to a universe with continuous creation of matter. The creation of new material prevents thermodynamic degeneration, and there is no running down at all. In other words the universe remains permanently wound up.

Eddington, on the other hand, was much impressed by a certain coincidence between a number that arose out of his theory of the expanding universe and a number obtained from atomic physics. This apparent connexion between very large scale and very small scale phenomena was unique in the history of science and was undoubtedly very perplexing. One of the reasons why I am favourably disposed towards the creation theory is that this coincidence now appears as a relation between the rate of creation of matter and a number derived from atomic theory. Since the rate of creation could in principle be determined without reference to very large scale phenomena, the relation simply connects quantities that refer to small volumes. This agrees with all scientific precedent, and goes far towards clearing up what once looked like a very awkward question.

I should like to end by discussing an objection that has been raised to the continuous creation theory. This objection is of a philosophical rather than a scientific nature. It has been argued that continuous creation introduces an additional hypothesis into the discussion – and a very startling hypothesis at that. Now I don’t agree that there is an additional hypothesis. Continuous creation, in the sense I have described it, is certainly a new hypothesis. But it replaces a hypothesis that lies concealed in the older theories, which assume, as I have already said, that the whole of the matter in the universe was created in one big hang at a particular time in the the remote past. On scientific grounds this big bang hypothesis is much the less palatable of the two. For it is an irrational process that cannot be described in scientific terms. Continuous creation, on the other hand, can be represented by precise mathematical equations whose consequences can be compared with observation. On philosophical grounds too I cannot see any good reason for preferring the big bang idea. Indeed it seems to me to be in the philosophical a distinctly unsatisfactory notion, since it puts the basic assumption out of sight where it can never be challenged by a direct appeal to observation.

But it is far from being my main purpose to advocate the continuous creation of matter as an end in itself. The upshot of my remarks is that the observations at present available give a preference for a universe with continuous creation. Explicit reference to present observations leaves room for the possibility that future observations may turn out to be in opposition to continuous creation, just as the observations of the last few years are opposed to the theories that were constructed about twenty years ago. New developments may well arise as new observational discoveries are made.