Can the multiverse hypothesis be an explanation for life on Earth?

[bland]

TL;DR Summary

Just finished David Lindley's new work called The Dream Universe where he has a bit of a dig at Smolin, Greene, Tegmark Rovelli and the like. Specifically he charges them with not even doing science up to a point.

Specifically he homes in on the multiverse and the 10^500 number that crops up. Basically he ends up saying that the whole concept of the multiverse virtually renders any TOE into pointless oblivion. So with this in mind I was wondering if I could also use the multiverse as an explanation for the rarity of life as far as we currently know.

Prior to Lindley's book I tended to take the position that it's as likely to be true that self conscious life, or indeed any life in the form that we recognise as life, could maybe only have a one in ten chance of forming in our entire known Universe. As opposed to the extreme diametrically opposed view that there are likely millions of advanced civilisations in our Universe.

Bearing in mind that each side of this debate along the entire spectrum has no actual supporting evidence and this will remain so until and unless life or actual solid evidence of life outside of that which appears to have originated on Earth, is discovered.

So I'm wondering if I am allowed to use the multiverse hypothesis to postulate that the spark or whatever it was that triggered life on Earth, was in fact so rare, so incredibly improbable that it would not be a one in ten chance in a single universe but it would in fact be a one in 10^500 chance.

Is this as scientifically valid a proposition if the multiverse itself is taken to be a scientific proposition? That is my question.

 

[Baluncore]

So with this in mind I was wondering if I could also use the multiverse as an explanation for the rarity of life as far as we currently know.

Our lack of knowledge of our universe is sufficient to explain what we see as a rarity of life. Occam's razor says we don't need to hypothesise a multiverse to explain our failure to observe something that has an unknown probability. We may need another 1000 years of observations before we have any idea of the real density of life in a universe. Maybe we are simply not sufficiently intelligent to recognise what is now in front of our instruments.

Adherence to unfounded belief systems will continue to obstruct our view of reality. There is still insufficient evidence to establish a science, so why bother to take sides or hypothesise anew?

 

[PeterDonis]

Lindley's book

Is not a valid reference for discussion here. It's a pop science book, not a textbook or a peer-reviewed paper, and, as your comments illustrate, it is his personal opinions, not mainstream science.

I'm wondering if I am allowed to use the multiverse hypothesis to postulate that the spark or whatever it was that triggered life on Earth, was in fact so rare, so incredibly improbable that it would not be a one in ten chance in a single universe but it would in fact be a one in 10^500 chance.

I don't see how this would follow; in fact it would seem on the face of it that the opposite would follow: that if the multiverse hypothesis is true, there are 10^500 times as many chances for life to evolve, so it becomes much harder to explain why Earth is the only place that has life (if that is in fact the case).

 

[PeroK]

So I'm wondering if I am allowed to use the multiverse hypothesis to postulate that the spark or whatever it was that triggered life on Earth, was in fact so rare, so incredibly improbable that it would not be a one in ten chance in a single universe but it would in fact be a one in 10^500 chance.

Where is the basis for $10^{500}$? If something can be shown to have occurred (evolution of life on Earth), then to say that effectively cannot happen elsewhere needs concrete evidence. There is no logic behind postulating a number like that in the first place.

 

[PeterDonis]

Where is the basis for $10^{500}$?

I'm assuming it comes from estimates of the size of the string theory "landscape".

 

[PeroK]

I'm assuming it comes from estimates of the size of the string theory "landscape".

As far as I can see Mars alone had a better chance than that of having intelligent life! And if you simply pick another Sun-like star, it's diffcult to justify a probability as small as that even for that one solar system. Let alone for them all put together.

That said, I'm not sure where string theory fits into all this.

 

[PeterDonis]

I'm not sure where string theory fits into all this.

$10^{500}$ is the most popularly quoted number of hypothetical "universes" in the string theory landscape, which is in turn the most popularly quoted type of "multiverse" hypothesis.

 

[Baluncore]

Foolishly simple statistics counts the known examples of life and divides by the number of possible environments. It is a big mistake to assume that life does not exist, just because you have not yet looked properly. That is a clear failure to sample sufficient environments.

There are two possibilities, either an environment has life, or it does not. Bayesian statistics starts with that probability estimate of 50%, then refines that as further data is acquired. We have almost no data, so the probability that any particular environment will have life must still be 50%.