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Old 04-17-2017, 02:19 PM
Stranger On A Train Stranger On A Train is offline
Join Date: May 2003
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Originally Posted by Wesley Clark View Post
I don't understand physics well so I'm not sure if this is even a valid question. Point is, if we live in a multiverse of endless variations of physical laws, and assuming there are finite limits on physical laws, what percentage of universes relative to the whole could harbor life? Or is the answer 'an infinite minority of an infinite majority' or something?
I do know a bit about physics and a few things about biology, and not only do I think this is a question that informed speculation cannot begin to address, I'm not confident that it is a even meaningful question.

All life that we know--which, to date, is exclusively limited to life on Earth which as we observe has a single origin--is chemical in nature, and furthermore based on the six of the most abundant chemicals in the universe (hydrogen, carbon, nitrogen, oxygen, phosphorus, sulphur). Although living forms at even the monocellular level are formed of incredibly complex systems, the basic structures of those systems are formed from twenty amino acids, lipids, and bound and powered by carbohydrates, most of which we can synthesize in the lab (with relatively crude and inefficient methods). It seems likely to the point of statistical certainty that life based on organic chemistry will be found elsewhere and probably frequently in our universe and in any other universe which has similar chemical laws. (Those bemoaning that we have not yet found signs of extraterrestrial life and rationalizing that it must not exist should recognize that we have landed probes on only four extraterrestrial bodies in our own solar system (Luna, Venus, Mars, and the saturnian moon of Titan), only one of which could possibly support a biotic environment with a liquid medium and available hydrocarbons, and have about as much sense of the wider possibilities for life even in neighboring star systems much less the larger universe as a gnat does of Shakespeare.)

We naively assume that life would be chemical in nature and similar to our own fundamental construction of proteins and cellular organization which is reasonable given the lack of other examples but exclusionary to other possibilities of self-reproducing regulated net thermodynamic systems with large scale organization which could, depending on the qualifications you apply, be considered as life. As to universes with other laws of physics, perturbing basic parameters which appear to be arbitrary (to our current limited understanding of fundamental particle physics and quantum field theory) would certainly make chemistry that we know untenable but could be replaced by other organizing systems using different combinations of forces and an analogue to chemical elements, or perhaps even some more exotic combination of organized structures and interactions. It is entirely possible that there are additional forces beyond the four that we know that are suppressed or unmanifested in higher dimensional organizations which could come into play in a universe organized along different physical principles, and we honestly don't know enough to even begin to speculate on what that might look like.

So, in summary, we have no real evidence to base an estimate of the propensity of life to emerge even within our own solar system, even less to evaluate the vast expanse of the universe that is and will remain beyond our immediate reach for the foreseeable future, and not even a fundamental basis to speculate about life in hypothetical universes with alternative laws of physics and some kind of chemistry-like system of interactions.