The Big Bang theory was first described, but not so named, by the French Jesuit Georges Lemaître in the late 1920s. His picture of the universe expanding from a single point was certainly controversial but has now become scientific orthodoxy. The exploration of its implications is today the preoccupation of many of the world’s physicists. I like to mention his name when I hear the Church being accused of opposing science.
But Big Bang theory has itself expanded in the most remarkable and bizarre ways; it is an interesting story.
The universe has from its first micro instant expanded with enormous speed and power. But there is a problem. In order for our universe to have developed there are, I am informed, some 25 parameters which have to be correct in order for our universe to support life. Gravity must be just right, the electron’s charge must be of the strength needed. The “strong nuclear force” requires the right level in order for there to be carbon or life, and so on. There is even a tiny “cosmological constant” without which the universe would not enjoy accelerating expansion.
The universe is supremely finely tuned. And that is a problem because it suggests a fine tuner. Embarrassment upon embarrassment: it seems to hint at God.
But resourceful physicists are not daunted. They argue thus: suppose there is a million-to-one chance against all these factors being exactly as they are. Then we only have to presume that there are a million different universes to make it reasonable to expect that one universe will have the characteristics to support intelligent life. And of course we happen to be that intelligent life. I am told that the chances are a great deal larger than a million to one. The figure is uncertain – even the exact number of parameters is uncertain. We would need many millions of universes to meet the challenge, and it just so happens that millions of universes are exactly what we have.
Where are they all? They are, in principle, beyond our capacity to detect because the universe is not only expanding, it is accelerating beyond the speed of light. Thus no information can ever get back to us. These further universes are, as they say, beyond our “event horizon”. However, it may be possible to make predictions of the effect of this extended cosmos, and then check whether these predictions are verified. There is now a growing speculation about universes existing before the Big Bang – if that actually happened, and even the idea that we are simply the construct of the inhabitants of a superior universe.
How many universes? That depends on which of the several multiverse theories you adopt. You could, for example, go for an infinite number of universes. And literally so – I am reproduced in them an infinite number of times, sitting at my computer typing this. In another I am being decorated with the VC; in yet another, I am shot for cowardice.
But that may be over the top. String theorists are content with worlds numbering 10 to the power of 500. This is a very large number, and I would have thought abundant for the task in question. String theory could be the backing for the “theory of everything”, which links quantum effects with gravity. And some believe that the fluctuations which take place at the quantum level relate through inflation to fluctuations on the cosmic scale.
Some observers take a cynical view of this profusion, but the physicists are busy developing their various models and trying to discover at least indirect ways of verifying them. We should take an interest in this search since the existence of multiverses about which we can by definition know nothing is apparently of little value to the man on the Clapham omnibus – who is ultimately funding the investigation.
Nor should we assume that this quest is solely to answer the possibility that there is a fine tuner responsible for our universe, although it may have been a motivation. There are great minds working away at this question, and reporting fruitful results. That the various theories suggest different models is only to be expected when the problem is so large and the evidence so far beyond us – and getting further with every second.
But one might at least ask whether this is a truly scientific discipline since science is concerned with hypotheses which can be tested through just the sort of empirical evidence, which is excluded in this case. It has been suggested that this is not physics but mathematics – where the only multiverse we can know is to be found in an equation.
But perhaps the most outstanding irony is that, while multiverses might obviate the need for a fine tuner, they do not address the question of creation ex nihilo. Indeed their existence could only lead to a deeper perception of God’s creative power. While belief in God is of a different order from a belief in reductionist physical theories, and indeed they can both be true in their own terms, I wonder why so many scientists who are incredulous of the former can be so childishly credulous of the latter.
I keep an open mind. I am untroubled by universes I cannot see. If there are duplicates, triplicates or infinicates of me, I can only think that to be a good thing. But mastering the Clapham omnibus is as much an intellectual stimulus as I need for the time being.
Visit Secondsightblog.net (which was visited 34,000 times, internationally, in 2011) and tell us about your universe.
New Scientist 28 November 2011 Ultimate Guide to the Multiverse
Scientific American August 2011 Does the Multiverse really Exist?