I have also heard that to get around the staggering statistics people have stated that there are many Universes that we just don't know about.
Not quite. This has been proposed, but
not, as you suggest, to answer the question of fine-tuning.
I believe that you are referring to the inflationary hypothesis, originally proposed by Alan Guth (whose book I have read, but some years ago, so I am not exactly an authority).
Guth's proposal was intended, originally, to solve problems in cosmology, the "horizon problem" and the "flatness problem". It is summarized
here.
quote:
Triggered by the symmetry breaking that separates off the strong force, models suggest an extraordinary inflationary phase in the era 10-36 seconds to 10-32 seconds. More expansion is presumed to have occurred in this instant than in the entire period ( 14 billion years?) since.
The inflationary epoch may have expanded the universe by 1020 or 1030 in this incredibly brief time. The inflationary hypothesis offers a way to deal with the horizon problem and the flatness problem of cosmological models.
Lemonick and Nash in a popular article for Time describe inflation as an "amendment to the original Big Bang" as follows: "when the universe was less than a billionth of a billionth of a billionth of a second old, it briefly went through a period of superchanged expansion, ballooning from the size of a proton to the size of a grapegruit (and thus expanding at many, many times the speed of light). Then the expansion slowed to a much more stately pace. Improbable as the theory sounds, it has held up in every observation astronomers have managed to make."
Now, what does this have to do with fine-tuning? Well, one of the physical implications of the inflationary hypothesis seems to be that our universe would be one of many universes in spacetime --- it is reasonable to call them different "universes" because we could never reach or observe another one. And these other universes would have physical constants different from our own. (This is a consequence of the absence of communication between the different universes.)
So then it is only necessary to invoke the Weak Anthropic Principle to see why we live in one of those universes that can support life --- no matter how unlikely they happen to be.
Is any of this true?
As I have said, we cannot observe these other universes --- by definition, that's what makes them other universes. So the reason to believe that they exist is because their existence is a logical consequence of the inflationary hypothesis --- we can't have the IH without having all these extra universes.
So it boils down to how much confidence you have in the inflationary hypothesis. As it says in the quotation above, it fits the astronomical observations.
But it also rests on certain ideas about particle physics: about symmetry breaking and the origin of the strong nuclear force. So far as I know, the current state of play with this is that scientists say that in order to test this aspect of the hypothesis, they need someone to buy them a much bigger steel donut. For a partial list of stuff which
might be true in this field, have a look
here.
You see the problem?
I hope this was informative --- welcome to the forums, by the way.
Edited by Dr Adequate, : 'Cos I found a missing link...
Edited by Dr Adequate, : No reason given.