Improbability of the Many-Worlds Interpretation?

TheBlackAdder

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"Many-worlds implies that all possible alternate histories and futures are real, each representing an actual "world" (or "universe"). In layman's terms, the hypothesis states there is a very large—perhaps infinite—number of universes, and everything that could possibly have happened in our past, but did not, has occurred in the past of some other universe or universes." –Wikipedia
If the MWI would be true, wouldn't there be at least one reality where human civilization advanced much faster than we did and therefore: contacted all other universes; destroyed all the universes; colonized all other universes; etc.

Since, as far as we know, this has not happened, doesn't this make the MWI improbable?
 
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As far as I know, most and maybe all MWI proposals have the different worlds causally disconnected.
So whatever goes on in world A can never affect events in world B.
No matter how advanced a civilization may be, it simply isn't possible for it do anything to entities in a hypothetical alternate timeline.
 

stevendaryl

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As far as I know, most and maybe all MWI proposals have the different worlds causally disconnected.
So whatever goes on in world A can never affect events in world B.
No matter how advanced a civilization may be, it simply isn't possible for it do anything to entities in a hypothetical alternate timeline.
It's not quite comparable, but it reminds me of a comic about an alien race so technologically advance that they can travel from the comic book to the real world. Now, that would be scary.
 

DrChinese

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If the MWI would be true, wouldn't there be at least one reality where human civilization advanced much faster than we did and therefore: contacted all other universes; destroyed all the universes; colonized all other universes; etc.

Since, as far as we know, this has not happened, doesn't this make the MWI improbable?
As I understand MWI, there is no expectation that all permutations of nature exist. For example, there is no guarantee that there is a world in which I became the US President in 2017. Accordingly, there would be no guarantee that the advanced civilization you imagine exists.
 

Khashishi

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These "other universes" are not other places, but other possibilities. How do you colonize another possibility?
 

TheBlackAdder

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These "other universes" are not other places, but other possibilities. How do you colonize another possibility?
If there is a reasonable possibility some other universe—a place—exists, it might be possible to colonize it. No?

As far as I know, most and maybe all MWI proposals have the different worlds causally disconnected.
So whatever goes on in world A can never affect events in world B.
No matter how advanced a civilization may be, it simply isn't possible for it do anything to entities in a hypothetical alternate timeline.
Has it been proved that traveling to another universe is impossible? I'm just a layman with a question. I'm not defending my theory or anything. It just seems to me, if traveling to another universe hasn't been disproved, it might be possible.
 

entropy1

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Has it been proved that traveling to another universe is impossible? I'm just a layman with a question. I'm not defending my theory or anything. It just seems to me, if traveling to another universe hasn't been disproved, it might be possible.
I think one reason for it to be impossible could be conservation of energy: if one copy of you goes to A and another copy to B, then, if A travels to B, there would be two copies in one universe for instance.
 

DrChinese

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Has it been proved that traveling to another universe is impossible? I'm just a layman with a question. I'm not defending my theory or anything. It just seems to me, if traveling to another universe hasn't been disproved, it might be possible.
Since no one has proved that there are any other universes to travel to yet, it might be difficult to prove it can't be done.

But regardless: you misunderstand scientific theory if you think that it's about imagining something and then doing it. As a general rule, the purpose is not to think up things you can disprove. Rather: Theory is a useful description of some pattern which applies to some scope.
 
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If the MWI would be true, wouldn't there be at least one reality where human civilization advanced much faster than we did and therefore: contacted all other universes; destroyed all the universes; colonized all other universes; etc. Since, as far as we know, this has not happened, doesn't this make the MWI improbable?
You are assuming such is possible. In the MW interpretation its not possible to contact the other worlds.

Thanks
Bill
 
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Has it been proved that traveling to another universe is impossible? I'm just a layman with a question. I'm not defending my theory or anything. It just seems to me, if traveling to another universe hasn't been disproved, it might be possible.
Of course not - but the theory pretty much says they are separate and remain so without delving into the details.

Basically MW is an interpretive thing. After decoherence you have a number of possible outcomes. MW interprets those outcomes as separate worlds - that they cant communicate is pretty much implied by defining what they are. Does it prove it - of course not - the definition doesn't say that - but it would seem at odds with its intent.

Thanks
Bill
 
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As I understand MWI, there is no expectation that all permutations of nature exist. For example, there is no guarantee that there is a world in which I became the US President in 2017. Accordingly, there would be no guarantee that the advanced civilization you imagine exists.
No, many worlds guarantees a very large number of worlds where you are US president. Even in 2017, and even if you're not a US native. It's possible, therefore it exists, according to MWI.
 
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many worlds guarantees a very large number of worlds where you are US president.
Only if such a world is physically possible by unitary evolution from the initial conditions. Discussions of the MWI usually blithely assume that anything that seems "possible" to us based on our ordinary everyday intuitions must be physically possible by unitary evolution from the initial conditions, but I think that assumption is actually way too broad. See my posts and the discussion in this previous thread (and also the other previous thread I linked to in post #4 of that one):

 
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It seems like it's physically possible for Dr. Chinese to become president. To start he could acquire a quantum random number source and use it to bet on the stock market, becoming the richest person on Earth. What could conceivably prevent that from happening?
 
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It seems like it's physically possible for Dr. Chinese to become president. To start he could acquire a quantum random number source and used it to bet on the stock market, becoming the richest person on Earth. What could conceivably prevent that from happening?
Yes. And by possible here, we include stuff that violates the 2nd law, as DeWitt stressed, which pretty much means anything we can classically imagine happens. Dr Chinese becoming President is small potatoes by comparison. Much weirder stuff will occur on other timelines.
 

Mentz114

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Yes. And by possible here, we include stuff that violates the 2nd law, as DeWitt stressed, which pretty much means anything we can classically imagine happens. Dr Chinese becoming President is small potatoes by comparison. Much weirder stuff will occur on other timelines.
My universe is as weird as it gets. There are people who actually believe that MWI is true !
 

Vanadium 50

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Only if such a world is physically possible by unitary evolution from the initial conditions.
That is a key point. None of us (with the exception of Mr. Price) know what is physically possible by unitary evolution from the initial conditions in our universe, which are not known nearly well enough to calculate it.
 

PeroK

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That is a key point. None of us (with the exception of Mr. Price) know what is physically possible by unitary evolution from the initial conditions in our universe, which are not known nearly well enough to calculate it.
It's even possible in some worlds that a deposit account might outperform technology stocks. Or, perhaps that's going too far!
 
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That is a key point. None of us (with the exception of Mr. Price) know what is physically possible by unitary evolution from the initial conditions in our universe, which are not known nearly well enough to calculate it.
I know that Schrödinger's cat will be both dead and alive by unitary evolution, because both outcomes are possible (by design).

The boundary conditions of the universe are only relevant if I wish to know what is going on in Andromeda or beyond.
 
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Vanadium 50

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I know that Schrödinger's cat will be both dead and alive by unitary evolution, because both outcomes are possible (by design).
But that doesn't mean you know that there are universes where Dr. Chinese is President.
 
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But that doesn't mean you know that there are universes where Dr. Chinese is President.
Most classic (in both senses) historical what-ifs are the same as Schrodinger's cat. As I said, since we, following Dewitt, are allowed violate to the 2nd law in MWI, Dr Chinese being President is no big deal. Mutterings about unitary evolution or the boundary conditions of the universe misses the point when it comes to our local part of the cosmos, at the classical level
 

DrChinese

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It seems like it's physically possible for Dr. Chinese to become president. To start he could acquire a quantum random number source and use it to bet on the stock market, becoming the richest person on Earth. What could conceivably prevent that from happening?
I'm liking where this discussion is going. :smile: Not too sure about the president thing though.
 
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It seems like it's physically possible for Dr. Chinese to become president.
That's not the same as saying it's physically possible for him to be president, right now, with nothing else changing. But the latter is what @Michael Price appears to be claiming in post #11.
 
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The boundary conditions of the universe are only relevant if I wish to know what is going on in Andromeda or beyond.
That's not correct. A significant part of the boundary conditions of the universe are in our past light cone, right now, so they are certainly relevant for trying to predict what is possible here and now by unitary evolution.
 
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by possible here, we include stuff that violates the 2nd law, as DeWitt stressed, which pretty much means anything we can classically imagine happens
If things that can violate the 2nd law can happen in some MWI worlds, then the MWI undermines itself, because the possibility of violations of the 2nd law means we can't trust the evidence we have of the past. But if we can't trust the evidence we have of the past, we can't trust the experimental data that led us to adopt QM, and led some people to postulate the MWI, in the first place.
 
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That's not correct. A significant part of the boundary conditions of the universe are in our past light cone, right now, so they are certainly relevant for trying to predict what is possible here and now by unitary evolution.
I meant, to determine what happens in the lab we only need the boundary conditions defined on the lab.
 

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