William Jackson said:
I meant to imply that in my question. If the parameters make it impossible for stars to form, or even if they make it impossible for atoms to form, those are just the forms that we know from our own universe. If the universe had different parameters, then would it not take forms that are outside of our experience? And might it not be possible for complexity to evolve?
The fact that we can't imagine or know anything about that, it exactly the point. We are a product of our universe the way it is. The anthropic problem is only a problem if you insist that development must take the forms that we're familiar with. There is no anthropic conundrum, only a tautology.
(Phrased as a statement but meant more as a question.)
Hi William,
The anthropic coincidences are not just those that allow life on Earth to exist but any forms of exotic exobiological replicating species anywhere in this universe.
The one thing such a species would require is complexity, equal to the complexity of the simplest life forms on Earth. It needs complex molecular structure and the complex ordering of such molecular structure.
That requires a complex chemistry and a favourable ordering of the physical environment: a stable narrow temperature range, lack of severe ionising radiation, and a long, long time for any form of evolution to take place. Many possible universes would lack these things, for example if G were too large then those universes might collapse after only a few years or even after only a few seconds. As Chronos has said above one factor would be the existence of carbon as that alone in this universe is capable of sustaining a biochemistry; silicon is suggested as a possible alternative but it comes nowhere near in terms of complex silicon based chemistry comparable with carbon based organic chemistry.
These requirements for hyper-complexity place a severe constraint on the necessary conditions for life to exist anywhere in an otherwise habitable universe.
Now we can conjecture a different set of physical attributes in some other universe that could also produce a completely different complex life-form somewhere within it; but that life would also have to be hyper-complex and as equally unlikely as life on Earth. Like ours such a universe would be lost amongst the many many universes that would be completely hostile to 'life'.
Even if the conditions are suitable even then,
if life formed by chance, it would be incredibly unlikely. Fred Hoyle estimated the spontaneous
(stochastic - remember?) appearance of life from an ‘organic soup’ to the likelihood of a whirlwind going through a scrap yard and producing a Jumbo Jet in full working order. He estimated the odds to be somewhere between 10 to the power 140 (10
140) and up to 10
10,000 to one. He then proposed that if the universe were infinite in size and infinitely old (his
Continuous Creation model) then no matter how small the odds were it would have happened somewhere i.e. here on Earth or in nearby space (our neighbourhood of the galaxy).
To show how small these odds are take the smaller value, 10
140.
Take the rate of simple biochemical reactions as 10
5 per sec.
Now there are ~3 x 10
7 seconds in a year and ~1.4 x 10
10 years in the age of the universe, so each atom could have had ~10
23, (order of magnitude) reactions since the beginning of time!
Now there are about 10
80 atomic particles in the entire observable universe. Let each one be an atom undergoing random chemical/biological reactions.
There would have been a maximum of 10
23 x 10
80 =10
103 reactions since the universe began, a short fall of a factor of 10
37 before one "first self-replicating organism" arrived. And this is very much a lower bound, the real short fall is much larger.
Therefore
on those odds we would have to wait 10
37 or 10,000,000,000,000,000,000,000,000,000,000,000,000 times the present age of the universe until just one such organism arrived anywhere!
Now, there might be 10
37 other universes or 'patches' of this universe 'beyond our ken' in which the unlikely chemical reaction took place.
So one way to explain this is to say 'The multiverse did it'; no matter how improbable life may be it must happen somewhere in one of those universes/patches, and we are in this universe because we can be in no other.
But on the other hand, perhaps there are other ways rather than by pure chance of understanding how the first self-replicating organism appeared. For example, biologists are looking into there being a first self-replicating molecule, an evolving chemistry, which could develop by natural processes into a first replicating organism, such as a bacteria, in a relatively short period of time.
After all on Earth it seemed to have happened rather quickly, within a few hundred million years of the Earth becoming 'habitable'.
Now my point is this:
If we simply say 'the multiverse did it' then we would short-circuit that scientific investigation into the origin of life and hence get nowhere.
I use this as one example why I think the multiverse is not a good way to do science.
Garth