"...there is no way to know..."
"...that will likely not stop physicists from exploring the possibilities..."
I agree that there is no way to know. Therefore, there can be no "exploring." What they are doing is speculating about the existence of something which cannot be proven or disproven. How does this help us to "learn more about our own universe"? This is not science. It is not even science fiction. It is meaningless fantasy, a total waste of time.
Science is about disprovable hypotheseses.
But a many-Universe theory isn't disprovable. Moreover: it is strictly non-provable, which puts such a theory in a very special class of short-bus scientific endeavours. This is because - by definition - a different Universe must be orthogonal in all ways to this Universe.
So if you can detect or observe any part of a 'different Universe' then - by definition - what you have observed is actually part of your own Universe..
So for instance: different dimensions, different 'branes', phase-spaces of existance with different physical laws - if you can find them, then they are not a different Universe - they are simply proofs that the current Universe is more extended and more extraordinary than previously thought.
This is because it allows them to run from the glaringly obvious conclusions of the Strong Anthropic Principle.
In brief, the Strong Anthropic Principle concerns the colossal variable space that a Universe might have - and how the Universe in fact has exactly the correct variable set that allows:
* Three dimensional space to exist for 9+ Billion years
* Protonic matter to exist for 9+ Billion years
* Atoms to exist for 9+ Billion years
* Carbon and iron to exist
* Life to exist in any way, shape or form.
Example: vary one single nuclear resonance value by a vanishingly small fraction, and Carbon would be as rare as Mendelevium.
Because the Strong Anthropic Principle points directly to 'Intelligent Design', certain kinds of scientists instead insist that there must be quadrillions of different Universes sampling all parts of the Universe variable space - and that we happen to inhabit the only one of those quadrillions of Universes where life can exist.
Which is (as I say) non-disprovable, and also non-provable. Multiple Universe Theory requires a level of belief that e.g. Christian belief does not.
For instance: Christianity could be proved absolutely to all unbelievers in the next four minutes by the Second Coming. But Multiple Universe Theory cannot be proven - ever - not even after the last syllable of recorded time.
Can the existence of God be proven or disproven, demons, angels, elves, etc?
“It is meaningless fantasy, a total waste of time.”
And it’s a total waste of taxpayer money in a time when we are worse than broke. The government outlaws the use of tax money to support Christian religion in any way, but cheerfully supports billions of dollars of spending on the humanist delusions of scientists.
But as Mr. Llewellyn noted in the New York Review of Books all those years ago, they "cannot allow a Divine foot in the door." Therefore, these 'scientists' are compelled by their own denial of God to make up stories about how the Universe can exist without Him. Futile, and sad.
I was sorta thinking the same thing. What pays the bills?