Sunday, 2 October 2016

Salvaging the Past Eternal

In WLC 2 – Cosmological Argument (“God Did It”), I wrote about Craig’s Argument from First Cause, focussing more on where he goes with assumption that the universe has a beginning rather than on that assumption itself.  In A Little Expansion on the Lightness of Fine-Tuning, I presented a perspective in which the expansion of the universe is time (that is not a typo, I mean “is time” not “with time”).

Now I understand that not everyone will be on-board with the idea that what we perceive as time is the expansion of the universe, so just take what follows as an explanation as to why I personally reject Craig’s claim that the universe began with the Big Bang (or if he’s sufficiently honest with himself, shortly before the Big Bang).

If universal expansion is time, then it would seem to make sense that if you ran everything backwards, you’d see the universe shrinking from its current size back to about something the size of a grapefruit.  There wouldn’t be a constant speed of shrinkage though, because the rate of expansion of the universe is inversely proportional to the age of the universe.  You’d see the shrinkage increasing in speed as you wound the clock back, right up until you got to the grapefruit and then … nothing.

Now, when I say “nothing”, I don’t mean that the grapefruit would have sprung into existence and if you continued winding the clock back there’d be nothing.  Remember that expansion of the universe is time, so if there is no universe there would be no time to wind back on the metaphorical clock.  Instead what I mean is that the universe would still be there, grapefruit sized and you could "wind the clock back" as far as you liked and the grapefruit would be there.

The expansion that we see in the universe is due to the fact that expansion is retarded around concentrations of mass-energy (we call this phenomenon “gravity”).  If the universe was not lumpy, but smooth instead, the expansion would be impossible to see – not only because we would not be here to see it, but because our rulers would be expanding at the same rate as the rest of the universe and the universe would always be a given number of cubic ruler lengths in size.  Time would still exist, since we’d still be expanding, but time as well would be impossible to detect – if the universe is smooth, there’d be no appreciable difference between moments.  Time would only become meaningful once change manifested, such as during an event such as the one that led to the Big Bang (let’s call it the Before Big Bang Event – 3BE).

So, sure, it makes sense to consider time as originating at 3BE and ignore all time before that, but it does not mean that time (or rather expansion) really commenced at that event.

I posed a puzzle in Hugging the World which may not have appeared to have been particularly relevant at the time.  In the answer (in the comments) Hausdorff and I note that if you increase the radius of a circle by 1 unit, you increase the circumference by 2π units.  This works if the units are attometres (very small) or exametres (very big).  In fact, you could take a circle of radius 1 attometre and increase the radius by 1 metre changing the circumference from about 6.283x10^-18m to about 6.283m.  To all intents and purposes, the expanded circle has a radius of 1m and it is as if there hadn’t been an original circle at all.

The expansion of the universe is analogous, it might not be strictly true to say that there was no time before 3BE, but to all intents and purposes it makes no difference if we assume there wasn’t.  Well, that is apart from a minor problem we get with this sort of flexibility, which is the fact that people like Craig come along and try to poke their gods into the very tiny gap.


If you don’t like my argument, you are welcome to try Victor Stenger’s (he has the benefit of being a published physicist).  Alternatively you can look at the document on which Craig hangs his argument (at least in his debates).  Note that the authors don’t draw the same conclusion that Craig does, they write:

What can lie beyond this boundary? Several possibilities have been discussed, one being that the boundary of the inflating region corresponds to the beginning of the Universe in a quantum nucleation event. The boundary is then a closed spacelike hypersurface which can be determined from the appropriate instanton.

They merely mention the quantum nucleation event as one of the options.  There are several other possibilities some of which are described by Stenger.  In some of these there is a discontinuity at the 3BE, which in my model isn’t as extreme as for some of Stenger’s options.  In my model, it’s just the transition from a(n effectively) smooth universe to a lumpy universe – which might cause a bit of a bang, but does not require any change to the underlying processes.

Penrose's Conformal Cyclic Cosmology model is also worth a look.

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