Sunday, 25 September 2016

Deep mystery of existence. 8. Critical mass of the early universe

Many people wonder why the universe is so massive. They say ‘what a wasteful God’.  The exact opposite applies. The importance of life in God’s scheme is highlighted by the need to create precisely the universe we have, in terms of mass and in many other ways which will not be dealt with in this post (e.g.the finest imaginable tuning of the physical constants and entropy of the universe at the Big Bang stage.)

Cosmologists and astrobiologists will confirm that it could not be any other mass and still sustain even bacterial life. Very slightly smaller in mass and life could not survive anywhere. Being marginally larger would also preclude life.  It has been calculated that if during the early expansion of the universe its mass had been out by the mass of a single coin the present universe could not harbour even bacteria. The precision is

 one part in a  trillion trillion trillion trillion trillion. ..

Why does the universe have to have this mass? Because otherwise  two life precluding phenomena would occur as the early universe expanded following the Big Bang (the creation event when space, time, matter and energy came into existence as a point source of everything).

A marginally smaller  mass would have resulted in less gravity and the matter of the universe flying apart too rapidly to form stars and planets – in particular our planet Earth, which has a uniqueness which led not just to bacteria but to human civilization.

A marginally larger mass would have resulted in the early cosmic material coalescing rather than forming stars and planets. Not a trace or promise of life could exist in this scenario – even the stuff out of which bacteria are built would not have existed.

This precision is, according to the latest cosmological theory, a consequence of our three dimensional space being almost totally flat, i.e. only curved to an extremely small but unimaginablyprecise degree,  to 

one part in a trillion trillion trillion  trillion trillion trillion trillion trillion trillion trillion.

 It is impossible to visualize what is meant by curved or flat three dimensional space. It is a mathematical concept, but an analogy which is often used is that of an inflated balloon, where the surface of the balloon represents the 3 dimensional space in which we live.  If the balloon is large enough the space is as near to flat as you can make it without the balloon becoming infinitely large. Space is curved to just the precise amount needed to enable bacterial life to survive. To repeat:

 one part in a trillion trillion trillion  trillion trillion trillion trillion trillion trillion trillion

 With space that close to flat the mass density of the universe will have the necessary value to the degree of precision required.

How did space get that flat? As usual in cosmology we have to turn to the mathematicians. The theory that has been proposed is known as cosmic inflation (in fact there is more than one version of this theory). The early universe, when it was only  a fraction of a second old, is postulated to have expanded at such an unimaginably high rate that space was forcefully smoothed out till it became virtually, but not quite, totally flat. This would explain why the universe as observed to today looks so isotropic (similar in structure in all directions) and is flat. But this would not explain why it dperts from absolute flatness to the ultra-fine degree required for a universe with living beings in it.

What could have made the universe expand so much so quickly before it was even a second old no one knows. It was probably not even dark energy (whatever that turns out to be) since that did not come into play until the universe was about 7 billion years old. At this stage it began to expand more rapidly, i.e. to accelerate, after being slowed down by gravitational forces. (If it had not accelerated in precisely the way it has that too would have precluded any kind of biological life. But that’s another story...).

One final point to bear in mind. The idea of increasing or decreasing the mass of the universe by the mass of a single coin having such huge existential significance for living systems applies only if this thought experiment is made at the very early stages of cosmic creation. If such a miniscule mass had been added or subtracted only, say, a million years ago, instead of 13.7 billion - i.e. after the elements, stars and planets had already  been formed - it would, as far as we know, have made no difference. Nevertheless, given that the total mass of the universe at its inception was the same as now, it is no less staggering to think that the mass of a single coin could mean the difference between life and no life some 13.7 billion years later.

As one who has only relatively recently become a follower of the cosmic Christ, the universal source of love,  I had not really understood what was meant when people talked about fearing God. Now I  am beginning to get the point.

 John Sears

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