Wednesday, June 13, 2012

Big Bang Cosmology- How Far Back?

The current scientific consensus is that the universe came into being following an event known as the ‘Big Bang’. Matter expanded rapidly from an extremely hot, extremely dense state, having transmuted from pure energy. Matter and energy then sprang forth to form the universe as we know it. This conclusion is drawn by interpreting certain observed information, notably two phenomena, the cosmic microwave background and the red shift of distant objects. 

The Big Bang is a generic expression for theories of this general nature but which may differ in the understanding of details. The prevailing detailed theory is the Lambda CDM model.

On the face of it there is reasonable evidence for some sort of Big Bang scenario. However as we probe into very early cosmological time, and try to evaluate what happened when matter first came into existence, we find there is little theory or consensus. There is an initial time, called the Planck Epoch, before which it is impossible, according to current understanding of fundamental physics, to probe. There are no firm ideas on what ‘seeded’ the Big Bang.  There is no understanding of what came before the Big Bang, or indeed whether there was a 'before'.

We are caught in the flow of time. Richard Feynman sets this out for those who have never considered it in his excellent book 'The Character of Physical Law'. When considering long gone events, we are left with our imagination and our ability to extrapolate backwards to form a view of the past. When we do this we rely on the assumption that there are no sudden changes or unexpected factors, other than the ones we already know about or have inferred. We often make many large jumps of conjecture. We assume we have all the information, all the relevant laws, all the correct theories, all the variables, all the significant factors. These are big assumptions.

It is certainly possible that God could have used a process similar to the Big Bang to create the Universe. The theory does have some widely acknowledged problems, such as the matter/anti-matter balance, and the dark matter/dark energy hypothesis/mystery. 

What the Big Bang Theory certainly does not do is rigorously explain how everything came from nothing. The prevailing lambda CDM model for cosmological origins requires the sudden appearance of expanding space-time. It does not tell us where space-time came from. It also requires immense radiation energy, again without rigorously explaining where it came from. It requires the background conceptual fabric of mathematics. Does that have an existence independent of any physical reality. If so, why?

If scientists are going to see scientific reductionism as a complete explanation of beginnings, to rid themselves of that word 'creation', then we will have to get beyond this point. I do not believe there are currently any meaningful leads on this one. 

Limitations of the Scientific Method in Probing Truth

Big Bang Cosmology relies on General Relativity. Fine so far. Einstein’s Theory of Relativity illuminates the fact that there can be previously unsuspected interactions between variables, between commodities we had taken to be separate, such as space, time, velocity, gravity, mass and energy. It shows that our day-to-day experience of space, time and matter are merely a parochial, subjective simplification of reality. In addition to those of general relativity, there may be other governing principles, involving interactions of variables, which the experiences of our day-to-day lives do not lead us to expect. We infer reality from the behind the blinkers of our own, parochial, mindset. Our mindset is derived from our own parochial experience. We extrapolate and hypothesize from behind the blinkers. Einstein brought the fact that we have these blinkers into sharp focus. Quantum Mechanics serves to show our blinkers again. It was eventually inferred from observed data, but is most certainly not obvious or intuitive from observed data. The scientific method needs data. It looks for patterns in the evidence, for laws behind events, for processes behind phenomena. However, the data is limited by our ability to perceive it, with and without instrumentation. Our capacity to evaluate patterns and explanations is also limited. It is limited by our best human brainpower and our best ability to perceive and conceptualize. We ourselves are an unavoidable filter on reality itself. The maths we use in day-to-day life, and the physics principles we use to design buildings, cars, boats, planes, etc, even Apollo spacecraft, are those discovered and derived by Sir Isaac Newton. They have served us well and continue to do so. However it turns out that Newtonian mechanics is a simplification of Relativistic 'mechanics'. Newtonian mechanics apply at speeds much lower than that of light. However they remain a simplification of the richness and sophistication of fuller physics models of reality. I say 'fuller' deliberately. It looks increasingly likely that Relativity is itself a simplification of reality which applies only within certain bounds. Can you see where this line of reasoning could take us? The further we step out of our little world, with its variables such as velocity and distance all within certain bounds, and with three-dimensional space and time, the more likely it is that the laws and behaviors we experience here will no longer be sufficient to explain and describe everything. I mention 3 dimensional space because, mathematically, you can have as many dimensions as you like. I mention time because we experience it as an unstoppable, irreversible flow. In maths, we can choose any time we like. It is entirely possible, perhaps even probable, that general relativity will turn out to be a simplification itself.