Is there a real chance that there is a multiverse?

[Mister Agenda]

I am intimidated by the fine tuning argument.  In the past I subscribed to the "god of the gaps" view, but now I am more sensible.  I believe, or want to believe, that the universe has a natural beginning and it makes sense to me that the universe probably went through a many versions before this one originated.
Are there any people here who believe in the multiverse, or at least think it is a viable option?


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There are observations that multiple universes are a reasonable explanation for, but it remains a hypothesis for which there is insufficient evidence to consider it confirmed. It's an interesting possibility that doesn't contradict what we already know and for which the math works; but that's half of theoretical physics.

However, regarding the fine tuning argument; it's much weaker than it might appear at first. Note the local version of the fine tuning argument: The universe is so hostile to life that the existence of a planet just the right distance from its star with all the necessary elements for life is so unlikely that it is more likely to have been a product of design than chance. Then the general version: the universe is so accommodating to life that it is more likely to have been a product of design than chance.

More to the point, the argument in regards to the universe is that IF the universal constants could have had any value and IF the values are unrelated to each other (such that if one were different, another would have to have a particular value in relation to it) and IF any value is equiprobable, and IF only a universe with the exact same universal constants as ours could support life (including life very unlike ours); THEN it would be more likely to have been a product of design than chance.

A very large number of universes is one possible solution to the fine tuning argument. If you accept all of its premises, then a huge number of chances for a universe with the exact values ours has would be a sufficient explanation for our universe having them, and we would naturally be in the universe that allows our existence.

I don't think multiple universes is at all necessary as a rebuttal, though. The fine tuning argument is ultimately only a thought experiment based on things we do not know: we do not know that the universal constants could have been different, if they're unrelated to each other, if the values are equiprobable, or if different kinds of universes could allow different kinds of life. We've only got a sample size of one, and we can't really make an informed statement about the odds of it having turned out that way, except that one like ours is definitely possible.

If the universe is the result of a quantum vacuum fluctuation and must have a net energy budget of zero; that would put severe constraints on the range of possible values for the universal constants.

Here's an intriguing possibility: quantum foam spawns trillions of universes, most quite similar to ours in terms of their universal constants.