I am told that contemporary models are not of infinite comoving space. Not being an expert, I have no ground to assert otherwise. So yes, I backtracked.Well yeah, that's my point. You claimed there's a dup earth, I asked you to support your claim, and you have apparently backtracked. Yes? — fishfry
Clear, and it makes no sense. Any infinite sequence cannot be a specific one. That seems to be the point on which we differ. An infinite sequence is not 'some number' any more than its length is.I pointed out that ANY specific infinite sequence has probability zero. Are you unclear on this point? — fishfry
So yes, I backtracked. — noAxioms
An infinite sequence is not 'some number' — noAxioms
You take a stab at a number line with a pointer and you will hit a 'typical number' as I call it. That number cannot be expressed with any amount of digits. It has zero probability of being hit, and yet it was hit.
Is that more what you're after? — noAxioms
Edit: I wrote that before reading your last post. Creepy...
No, I would say it is impossible to hit a computable (or expressible) number, except to say 'this one'. — noAxioms
Well, I hit a different one that cannot be hit, so I'm on thin ice to counter this. But having hit this computable number, I must in addition throw infinite coins and come up heads on them all, or else I just got close to it. I don't need to do that with the 'typical number'. Is there a term for that? I made that up.It's not impossible. The computable numbers exist. You might hit one. — fishfry
I would suggest 'possibly not'. If someone has infinite copies, I probably do as well. But I must back off the 'definitely' stance.Getting back to our original point, this is why even if there are infinitely many universes, SOME state must recur infinitely many times, but not necessarily any particular one. SOME person might exist infinitely many times, but probably not you or me. — fishfry
YesSo at best, the "in an infinite universe there must be two earths" is false in an absolute sense, and is at best a probabilistic argument. Which I think we already agreed on.
Well, I hit a different one that cannot be hit, so I'm on thin ice to counter this. But having hit this computable number, I must in addition throw infinite coins and come up heads on them all, or else I just got close to it. I don't need to do that with the 'typical number'. Is there a term for that? I made that up. — noAxioms
Multiverse theory, string theory, speculative theories that have zero experimental basis and that can't be experimentally verified even in theory. — fishfry
Many Worlds is at least 60 years old, and has not only passed every test, but has led to the discovery of decoherence and the quantum computer. Every quantum interference experiment is a test of Many Worlds, as are interaction free measurements and many other technological examples. — tom
Perhaps I stand corrected. Are we talking about interpretations of QM? Or actually proven multiverses? — fishfry
Many Worlds is the only known interpretation of quantum mechanics. — tom
Well, you list others, so there are other known interpretations. Support of MWI is growing among physicists, but it has yet to reach a majority. For the record, my opinion rests with the MWI guys, but without a falsification test, it remains an interpretation, not a theory.Many Worlds is the only known interpretation of quantum mechanics. — tom
Why are hidden variables disallowed? I think you're right actually in that it was proved somewhere that there can be no hidden variables, but its supporters obviously don't think the proof carries weight.Bohmian mechanics - adds hidden variables to QM, thus a different theory. Doesn't work.
These are new ones to me, but again, why does this addition disqualify them?GRW - ads stochastic collapse to QM, thus a different theory. Doesn't work.
Transactional - I really don't care.
My personal aversion to most of the other interpretation is non-locality. Bohmian doesn't necessarily have it, but the others do. The ability to alter the past seems a nastier pill to swallow than the (mostly religious) implications of what MWI does to one's biased ideas of personal identity. — noAxioms
Well, you list others, so there are other known interpretations. Support of MWI is growing among physicists, but it has yet to reach a majority. For the record, my opinion rests with the MWI guys, but without a falsification test, it remains an interpretation, not a theory. — noAxioms
Why are hidden variables disallowed? I think you're right actually in that it was proved somewhere that there can be no hidden variables, but its supporters obviously don't think the proof carries weight. — noAxioms
My personal aversion to most of the other interpretation is non-locality. Bohmian doesn't necessarily have it, but the others do. The ability to alter the past seems a nastier pill to swallow than the (mostly religious) implications of what MWI does to one's biased ideas of personal identity. — noAxioms
Non-locality doesn't necessarily have to violate causality. — Mr Bee
Unitary Quantum Mechanics is a local theory. It is only when you ad-hoc modify it or burden it with metaphysical baggage like collapse, hidden variables, and unreality that are you forced to appeal to acausal interactions from beyond spacetime. — tom
How does the second sentence follow from the first? Do the [level-I multiverse] universes share the same history? Why should they do that? — fishfry
because the level-1 multiverse notion assumes that this universe is infinite. In an infinite amount of space, with an infinite number of solar-systems and planets, there inevitably, somewhere, will be an identical copy of Earth, with, of course, a copy of you. ...an infinite number of exact Earth copies, in fact. — Michael Ossipoff
Unconvinced we disproved it. I left convinced that a random stab will hit a zero-probability 'typical number' which are uncountably infinite. There are also infinite specific numbers, and they are countable. An exact copy of Earth is a specific number. The odds of it being never copied in infinite space is thus zero, with certainty. Of course it was also posted that contemporary physics puts a finite size on the universe, which dispells the whole infinite data-set thingy. Still level 1 places, but not necessary a copy of us.NoAxioms and I just had a lengthy conversation disproving this very point. — fishfry
It means there will never be enough time. It requires the expansion to be accelerating since steady expansion still allows light to travel from anywhere to anywhere else eventually.Secondly, the level-1 multiverse only requires a finite universe sufficiently large that light hasn't had time to get from one point to some other point in the age of the universe.
How do you get this? It seems, especially in the context of this thread, to follow from an assumption that other civilizations must be essentially identical to us to be, well, civilizations.By the way, I'd expect that if an infinite universe means that there are other civilizations in the universe, then the nearest one is so far away that, for all practical purposes, including communication or transportation, it's the same, for us, as if it weren't there. — Michael Ossipoff
You just got finished saying there is an exact copy of us out there, given infinite space.Could there not be any other civilizations in this universe, if the universe is infinite?
This statement is quite a break from the usual stance I've seen from you. You gone all ID on us? Tegmark for instance described a universe not in need of creation, not designed, nor one where we are special.Maybe, if, as a form of high-tech quarantine, our belligerent and aggressive species, along with its planet, has been re-located into a universe that was specifically designed, by an advanced technology, to not have any life other than us.
Which is good, because contemporary physics holds that the universe is finite. — fishfry
We now know (as of 2013) that the universe is flat with only a 0.4% margin of error. This suggests that the Universe is infinite in extent; however, since the Universe has a finite age, we can only observe a finite volume of the Universe. All we can truly conclude is that the Universe is much larger than the volume we can directly observe. — NASA
you would be hard-pressed to find many cosmologists who dismiss the possibility of an infinite universe — SophistiCat
I can see now that an infinitely large number of planets is not needed for the argument, so thanks for correcting me on that.
I remained unconvinced, though, that an infinite number (can there be more than one?) could be specified; because it would seem that any specifiable number must be finite. This is not to deny that an unspecifiable number might be useful for mathematical operations. In any case I see no reason to believe there are infinitely many planets; but admittedly I am no expert on cosmology. — Janus
... I offer you to play a game: give me any number and I can give you an even bigger (but still finite) number. It turns out that that's all we need to get going. — SophistiCat
Without the axiom of infinity, each number has a successor but there is no set of all the numbers; no infinite set; and no calculus — fishfry
I never dismissed the possibility. I pointed out -- correctly -- that current theory says that the universe is finite. Your own examples support this. — fishfry
This does not change what I was saying though: like it or not, most of modern physics does use calculus. — SophistiCat
You can claim that most of modern physics is misguided — SophistiCat
And this is why I don't usually engage this person. — SophistiCat
Which is good, because contemporary physics holds that the universe is finite. — fishfry
A bit off topic, but I've always noted that the orientation of the three spatial axes (X, Y, and Z) is arbitrary. If there is an actual x axis, which way is it? But if the universe is a 3-torus, all three axes have a preferred orientation, and this defines a preferred frame as well, even if not an inertial one. If the spatial axes are fixed, the temporal one, orthogonal to the others, is fixed as well.A locally flat(tish) universe is compatible with some finite topologies, such as a 3-torus. These guys did some serious number-crunching with WMAP data and came to the conclusion that out of several likely topologies that they considered, a certain compact (finite) topology provided a better fit than the infinite flat topology. — SophistiCat
MWI is not an ontological stance. No creation of new universes or new material ('somewhere' as fishfry puts it) occurs, and energy conservation laws are safe.This all has relevance to MWI multiverse hype. The big problem - if you believe in the reality of principles like the conservation of energy, or causal closure, at all - is that MWI violates energy conservation in the most fundamental fashion. That is at the guts of an instinctive objection.
Now if you are not used to taking the materiality of the Universe seriously, then perhaps it is easy just to imagine the free creation of endless worlds, or endless world branches. — apokrisis
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