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Is the many worlds interpretation of quantum mechanics correct?

The many worlds interpretation of quantum mechanics says that a quantum event doesn't have a single random outcome, but rather all possible outcomes, meaning that each event splits the universe into multiple divergent universes that exist in parallel.

Implications to Other Questions

Is physical reality a mathematical structure?
Is the many worlds interpretation of quantum mechanics correct?
Do we have an immaterial soul?

Experts and Influencers

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Experts In Science

Steven Weinberg    Nobel Laureate in Physics
The final approach is to take the Schrodinger equation seriously... In this way, a measurement causes the history of the universe for practical purposes to diverge into different non-interfering tracks, one for each possible value of the measured quantity. ... I prefer this last approach.
01 Oct 1994    Source

Eliezer Yudkowsky    Artificial Intelligence Researcher
So let me state then, very clearly, on behalf of any and all physicists out there who dare not say it themselves: Many-worlds wins outright given our current state of evidence. There is no more reason to postulate a single Earth, than there is to postulate that two colliding top quarks would decay in a way that violates conservation of energy. It takes more than an unknown fundamental law; it takes magic. The debate should already be over. It should have been over fifty years ago.
11 May 2008    Source

Experts In Physics

Max Tegmark    Professor of Physics
Everett’s theory is simple to state but has complex consequences, including parallel universes. The theory can be summed up by saying that the Schrödinger equation applies at all times; in other words, that the wavefunction of the Universe never collapses. That's it - no mention of parallel universes or splitting worlds, which are implications of the theory rather than postulates. His brilliant insight was that this collapse-free quantum theory is, in fact, consistent with observation.
05 Jul 2007    Source

Experts In Science

Roger Penrose    Mathematics Professor
You want a physical theory that describes the world that we see around us. ... Many worlds quantum mechanics doesn’t do that. Either you accept it and try to make sense of it, which is what a lot of people do, or, like me, you say no—that’s beyond the limits of what quantum mechanics can tell us. Which is, surprisingly, a very uncommon position to take. My own view is that quantum mechanics is not exactly right, and I think there’s a lot of evidence for that.
06 Oct 2009    Source

Peter Woit    Physicist
My take on Many Worlds is that I’m not very interested in something which is purely an “interpretation” of QM. If it’s fully equivalent operationally to other “interpretations”, arguing about which is better doesn’t seem to be a worthwhile activity. There is an interesting issue about the “interpretation of quantum mechanics”, that of understanding how classical physics emerges from a fundamental quantum mechanical theory, but I don’t see that Many Worlds has anything useful to say about this.
06 Dec 2009    Source

Experts In Physics

John Stewart Bell    Physicist
So I believe that the many‐universes interpretation is a kind of heuristic, simplified theory, which people have done on the backs of envelopes but haven’t really thought through. When you do try to think it through it is not coherent
01 Jan 1986    Source


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0 Points      MTC      23 Feb 2013      Stance on Question: Agree
To the best of my knowledge of quantum mechanics, which is admittedly nowhere near what I’d like it to be, many worlds is the best interpretation we have.

4 Points      JGWeissman      06 Mar 2010      Stance on Question: Agree
I recall studying physics as an undergrad. I had learned how to set up a quantum mechanics problem involving 2 particles, and it is not much of stretch, at least conceptually, to see how to expand this approach to handle n particles. So I considered what happens when I use an instrument to measure some property of a particle in superposition. Well, the device is made of particles, (more than I can keep track of, but this doesn't bother the universe at all), so those particles go into to superposition representing have measured the different values of the property of the measured particles. And then I look at the readout on this device, and I, being made out of particles as well, will go into superpositions of having observed all these different measurement results. Each configuration of me has one of the experiences that collapse theory would predict, even though I never applied the poorly defined concept of a collapse to my analysis. So take Occam's Razor, and cut out that unnecessary complexity. Later, I learned that this result is called Many Worlds.

1 Point      Adam Atlas      08 Apr 2010      Stance on Question: Agree
Indeed. I've never studied physics formally (for more than a semester), but I remember hearing about the idea of particles being in superposition, and then entire experimental apparati being in superposition, until an "observer" interferes with it, and eventually I figured out... "Wait, why can't the observer itself just be in superposition? It would look the same from the inside, and that way the universe doesn't have to have some random number generator making decisions and eliminating most of its information whenever someone learns something about a particle." Seems pretty obvious, in retrospect.

0 Points      Benja      08 Apr 2010      General Comment
If the different interpretations predicted different results, I'd shut up, because I'm not a physicist. But they predict the same results. Given that fact, I can know, from the rules that apply to all scientific theories, that the correct theory is the one that has the least math. Many worlds doesn't need the wave collapse function. That means it has less math. Therefore it's the correct theory.

0 Points      edo      23 Aug 2011      General Comment
so you live with 'the fact' that there are an infinite numbers of you (and not only you the whole fcking universe) spring every day to existence (from cossing a coin, whopsakee, there's another universe with fcking 6 Millard people, what the hell). the holocaust wasn't so terrible if you put in perspective, all those people are still alive somewhere. It seems to me that no-one believes this, or they must be locked away.

0 Points      Benja      23 Aug 2011      General Comment
It's a strange idea - perhaps too strange for us to get our minds around it - but the strangeness of it doesn't make it untrue.

"It seems to me that no-one believes this, or they must be locked away."
Lock away half of theoretical physicists then.

"the holocaust wasn't so terrible if you put in perspective"
You're committing the fallacy of Appealing to Consequences.

"(and not only you the whole fcking universe)"
The fact that your finite brain has difficulty imagining large numbers doesn't make the theory less likely to be true.

"fcking... fucking... what the hell... 'fact'... 'lock 'em away'"
I understand that many questions on this website (e.g. abortion) make people jump up and down and get all emotional. But this question? Seriously?

"infinite numbers of you"
Large finite numbers are not infinite numbers. When hyperbole meets math...

0 Points      edo      24 Aug 2011      General Comment
sorry i am just a really dumb copy, but how can you possibly live with this 'knowledge'??!! And i really don't understand if more then half of the phycisists believe this , why not every book ever written about physics since then is mainly about this? Or in any case a lot,lot,lot, more. It maybe a fallacy, but i'm just expressing my feelings, everything in life seems trivial if this true,and why no-one tries quantum suicide? Or just suicide (because of this). Thinking everytime you take a chance youre generating a universe seems to much to handle. The f*cks seem entirely justified if this is true.

For me then i don't undersand how not to get emotional about this, but maybe that's because i don't understand it. the maths are way beyond me, but is the conclusion that people really split (like the whole universe) or that there are a many many universes exactly a like untill some quantum event happens? I am from holland so the abortion issue doesn't really get me, being cloned every second does.

0 Points      Benja      24 Aug 2011      General Comment
Thanks for your reply.

I confess I've got a little freaked out by some of the conclusions from physics too. The first time I got freaked was when I realized how incredibly small we were in the universe. The second time I got freaked was when I realized that the universe ends in a heat death, where everything every human has ever done gets extinguished. However, after these two insights, I started to realize something. Nothing in my life had changed as a consequence of these insights. I was still concerned with the same shit I was always concerned with. I still cared about whether I could get that cute girl to smile. This desire seems no less important in the wake of this new knowledge. In fact, maybe it seemed more important. But really, I'd just rediscovered a piece of wisdom:

Don't worry about what you can't change; worry about what you can change.

I can't change the nature of the universe. And all those parallel universes are just that - parallel - they don't interact with each other in any way. It makes sense for each of you in each parallel universe to worry about Numero Uno. Worrying about each other - when each of you can do precisely zero to affect each other - doesn't really make sense.

As for worrying about future yous - we've always had to worry about divergent universes. If you buy a lottery ticket, you have to expect two possible universes: the one with you that won vs. the one with you that lost. If you drive a car, you have to expect (as least) two possible universes: the one where you get to your destination safely vs. the one when you crash and die. The discovery of quantum mechanics didn't introduce the need to consider branching possibilities in our lives. And in fact, evolution has nicely equipped your mind to only consider the most common variations in possible future universes! If you did actually consider every quantum possibility - well now you would need to be locked up in an insane asylum ;)

A final note - if I think many-worlds doesn't matter then why do I care? Well, I find it fascinating more than freaky. Well, mostly :)

0 Points      Edo      24 Aug 2011      General Comment
thank you this is kind of reassuring, so, one last question, Dp I in no way 'make' a parallel universe, there already there? I think the word splitting troubles me, i can understand that there is a universe where someone exactly like me choses B when I chose A, and have to chose between A or B, but not that the universe is then being created, there already were 2 universes, but on that moment they differ in tracks. Is that how I should understand it?

because i don't want to be responsible when getting in my 'hypothetical' ( i don't have a license yet, tough most of my almost exact copies do), car, for getting them killed while I arrive safely to my destination

0 Points      Benja      24 Aug 2011      General Comment
Well the "hollywood interpretation of quantum mechanics" would be that the universe splits for each choice you make. But it doesn't work like that. A human choice, in terms of quantum mechanics, is a macro event, that occurs at the neural level, which is a huge aggregate of quantum events where the effects of individual quantum events are statistically ironed out. In any case, it sounds as if you're venturing into the realm of the problems of free will and moral responsibility, where quantum mechanics is arguably a red herring, let alone a particular interpretation of quantum mechanics.

P.S. You'll reduce the chance you'll die by not getting in a car. But you'll increase the chance you'll be fucking bored. Ditto for many yous.

0 Points      Edo      25 Aug 2011      General Comment
ok, remains the question: Are there according to most many-world believers many universes exactly the same until they differentiate (like I found out David Deutch thinks), or are were continuously being split. That's not a small difference. All those Physicists may be smart, but expressing there views clearly in language other then math seems a very hard task.

0 Points      edo      27 Aug 2011      General Comment
i have mailed steven weinberg and he says he hasn't settled his mind about this subject so he can be removed of the agree list

0 Points      e      09 Nov 2011      General Comment
I conducted a poll with eminent theoretical physicists, and astrophysicists,
this where the outcomes
a: I subscribe to the MWI that contains many parallel universes that differentiate during every 'quantum event' (meaning that there are many perhaps an infinite number of copies of everyone that inhibits earth)

b: I subscribe to the MWI that contains many parallel universes that split during every 'quantum event' (meaning that there are many perhaps an infinite number of copies of everyone that inhibits earth constantly being created)

c: I don't subscribe to a or b, because I think they are both false

d: I don't prefer any of the above

C: 18
D: 7
A: 1
b: 2

this is interpreted in favor (I won't explain this here) to mwi,

that being said, isn't it weird that (i'm not a physicist) this theory says it has no extra postulates,
when there still needs to be a selection mechanism that spreads the outcomes in a probabilistic manor,
so it has to 'count' itself or something, which universe has gotten which outcome

0 Points      e      09 Nov 2011      General Comment
I suppose this can maybe be answered with 'infinity', or something,
but that is a freaking huge postulate itself isn't it?
note I am not close to being a physicist, but it seems to me that if we take the physics community seriously
we have to come to the conclusion that the vast majority doesn't agree with it, even in the group that is most
likely to believe it.
it does however surprise me that there are physicists who do actually believe this, because
it really is freaking absurd and mind blowing.
That however itself isn't a reason to say well if some physicists are inclined to believe such
absurd things it must be true. Cause many physicists seem to take absurdity as a pro.
Because they don't like 'boring' like susskind.
Most of the people who say they believe it still wouldn't held a funeral for their beloved mother,
if she came out a life out the schrodinger's cat box. I don't have a proof for this, but it seems
to me that this is the case.

0 Points      e      09 Nov 2011      General Comment
so if you where a judge, and mwi-er when someone put's a cat in the schrodinger box,
and it comes out a life, you don't convict him for an attempt to kill the cat,
but actually the kill itself (if you believe the universes actually increase, you have to give him a
medal for creating all kind of new universes).
I'm sorry but is anyone really wanting to go this far? It seems to me that mwi-ers are
'geeks' who really like to make the theory work at all costs, but when it comes to life
they just live on like it's all bullshit. as most eminent physicists think in the first place.

0 Points      e      24 Nov 2011      General Comment
in fact with the postulate of infinity it still isn't enough to derive the born rule according to move physicists,
even deutsch thinks there is an extra mathematical structure needed to tie all the universes together.
So what we got is an interpretation that wants to replace another interpretation that's a bit ugly (CI)
by an interpretation that's every bit as ugly, or even more ugly, and also postulates an infinity of universes,
And a theory that has proponents willing to tell lies to make it have a good reception.
So I think it's safe to reject it for now (after freaking more then 50 years, trying to make it work)

0 Points      Edo      23 Dec 2011      General Comment
Steven Weinberg:

There is now in my opinion no entirely satisfactory interpretation of quantum mechanics. The Copenhagen interpretation assumes a mysterious division between the microscopic world governed by quantum mechanics and a macroscopic world of apparatus and observers that obeys classical physics. During measurement the state vector of the microscopic system collapses in a probabilistic way to one of a number of classical states, in a way that is unexplained, and cannot be described by the time-dependent Schrodinger equation. The many-worlds interpretation assumes that the state vector of the whole of any isolated system does not collapse, but evolves deterministically according to the time-dependent Schrodinger equation. In such a deterministic theory it is hard to see how probabilities can arise. Also, the branching of the world into vast numbers of histories is disturbing, to say the least. The decoherent histories approach gives up on the idea that it is possible to completely characterize the state of an isolated system at any time by a vector in Hilbert space, or by anything else, and instead provides only a set of rules for calculating the probabilities of certain kinds of history. This avoids inconsistencies, but without any objective characterization of the state of a system, one wonders where the rules come from. Faced with these perplexities, one is led to consider the possibility that quantum mechanics needs correction."

0 Points      Paul W.      14 Dec 2013      General Comment
That is good to know because for a while there i was considering that hell exists.