Human evolution: we are entirely improbable (Introduction)

by David Turell , Friday, January 15, 2021, 21:23 (1406 days ago) @ David Turell

A long discussion of the odds:

https://www.scientificamerican.com/article/our-improbable-existence-is-no-evidence-for-...

"...the universe we live in must be compatible with the existence of life. However, as scientists have studied the fundamental principles that govern our universe, they have discovered that the odds of a universe like ours being compatible with life are astronomically low. We can model what the universe would have looked like if its constants—the strength of gravity, the mass of an electron, the cosmological constant—had been slightly different. What has become clear is that, across a huge range of these constants, they had to have pretty much exactly the values they had in order for life to be possible. The physicist Lee Smolin has calculated that the odds of life-compatible numbers coming up by chance is 1 in 10^229.

"Physicists refer to this discovery as the “fine-tuning” of physics for life. What should we make of it? Some take this to be evidence of nothing other than our good fortune. But many prominent scientists—Martin Rees, Alan Guth, Max Tegmark—have taken it to be evidence that we live in a multiverse: that our universe is just one of a huge, perhaps infinite, ensemble of worlds. The hope is that this allows us to give a “monkeys on typewriters” explanation of the fine-tuning. If you have enough monkeys randomly jabbing away on typewriters, it becomes not so improbable that one will happen to write a bit of English. By analogy, if there are enough universes, with enough variation in the numbers in their physics, then it becomes statistically likely that one will happen to have the right numbers for life.

'...experts in the mathematics of probability have identified the inference from the fine-tuning to the multiverse as an instance of fallacious reasoning. Specifically, multiverse theorists commit the inverse gambler’s fallacy, which is a slight twist on the regular gambler’s fallacy. In the regular gambler’s fallacy, the gambler has been at the casino all night and has had a terrible run of bad luck. She thinks to herself, “My next roll of the dice is bound to be a good one, as it’s unlikely I’d roll badly all night!” This is a fallacy, because for any particular roll, the odds of, say, getting a double six are the same: 1/36. How many times the gambler has rolled that night has no bearing on whether the next roll will be a double six.

***

"Philosopher Ian Hacking was the first to connect the inverse gambler’s fallacy to arguments for the multiverse, focusing on physicist John Wheeler’s oscillating universe theory, which held that our universe is the latest of a long temporal sequence of universes. Just as the casino-visitor says “Wow, that person must’ve been playing for a long time, as it’s unlikely they’d have such good luck just from one roll,” so the multiverse theorist says “Wow, there must be many other universes before this one, as it’s unlikely the right numbers would have come up if there’d only been one.”

***

"But isn’t there scientific evidence for a multiverse? Some physicists do indeed think there is a tentative empirical evidence for a kind of multiverse, that described by the hypothesis of eternal inflation. According to eternal inflation, there is a vast, exponentially expanding mega space in which certain regions slow down to form “bubble universes,” our universe being one such bubble universe. However, there is no empirical ground for thinking that the constants of physics—the strength of gravity, the mass of electrons, etc.—are different in these different bubble universes. And without such variation, the fine-tuning problem is even worse: we now have a huge number of monkeys all of whom are typing English.

"?At this point, many bring in string theory. String theory offers a way to make sense of the possibility that the different bubbles might have different constants. On string theory, the supposedly “fixed” numbers of physics are determined by the phase of space, and there are 10500 different possible phases of space in the so-called “string landscape.” It could be that random processes ensure that a wide variety of possibilities from the string landscape are realized in the different bubble universes. Again, however, there is no empirical reason for thinking that this possibility is actual.

"The reason some scientists take seriously the possibility of a multiverse in which the constants vary in different universes is that it seems to explain the fine-tuning. But on closer examination, the inference from fine-tuning to the multiverse proves to be instance of flawed reasoning. So, what should we make of the fine-tuning? Perhaps there is some other way of explaining it. Or perhaps we just got lucky."

Comment: There seems no way out. Shades of John Leslie's discussion in "Universes". Multiverses is simply gambler's fallacy as the author points out. There is no substantive scrap of real evidence, only the attempt at anything but God the designer.