Why the Many Worlds Interpretation only applies to a mathematical universe.
I had a phase of liking the MWI in terms of a mathematical universe. By, which I mean the branching of a collapse of a wavefunction can transpire without violating any conservation of energy laws.
However, if one assumes in physics, as do many physicists, that the world is not mathematical, then doesn't it mean that conservation of energy laws would become violated for every branching of wavefunction collapses?
However, if one assumes in physics, as do many physicists, that the world is not mathematical, then doesn't it mean that conservation of energy laws would become violated for every branching of wavefunction collapses?
Comments (31)
Sean Carroll explains this by saying that the energy splits too. Each world takes with it half the energy of the parent world, so that conservation of energy is preserved. Of course that means that if the total energy of the universe is finite, at some point there's not enough energy to split into any more worlds. I'd like to ask Sean Carroll that. I'm sure he's thought about it.
This confronts a pretty pernicious issue as to what or which kind of wavefunction collapses cause this to occur along with the extent of the parent universe splitting to what localized or even global effect(s)?
I'm already in way over my head and know nothing of this other than a couple of Sean Carroll videos on Youtube. My understanding is that MWI avoids wavefunction collapse. The wavefunction doesn't collapse; rather, everything happens. The cat is awake and asleep, as Carroll says. No reason to kill a cat. He mentions that Schrödinger's daughter said, "My father just didn't like cats."
But, there are certain thermodynamic laws that govern probability distributions even for observers.
If you might mean that entropy is limited in certain branches where less entropy progresses summum bonum, then that might be an interesting way these branches evolve. Yet, there's no grand observer, observing this so it doesn't seem to make sense in general.
So, if branching occurs, then it happens with regard to theoretical constants along with conservation of energy and thermodynamic laws, and then you still end up with the base universe just with branching occurring to maintain the least amount of entropy arising, hence some sort of tautology.
What baffles me is how these worlds occur when a QM observation that is made on a probability distribution that has a local effect such as statistical distributions for low entropic and high ordered states. In other words does a minute variation in a probability distribution cause a branching or how large does the magnitude of the effect is required to be to cause branching?
Informed comment.
From the article:
Quoting Philip Ball
This kind of hap hazardous growth of the entire universe would be in only some mathematical abstraction, no? Otherwise some physicist with an axe to grind would claim something about Occam's Razor.
You know that Everett was drinking when he first had his brainwave, while busy thinking up “ridiculous things about the implications of quantum mechanics” ? That at first his thesis was totally ignored until another physicist, Bryce DeWitt, popularised it years later? That he met with Neils Bohr, who refused to even consider the 'many worlds' idea? That Everett left academic research, disillusioned, and became a highly-paid analyst for the Defense Department designing ICBM re-entry paths during the Cold War? That he might have been a character in Dr Strangelove? That he died an alcoholic age 51, with instructions that his ashes be put out in the household waste? See The Many Worlds of Hugh Everett, Scientific American. Note also the telling remark at the end of the first edition of his thesis:
[quote=Hugh Everett]Once we have granted that any physical theory is essentially only a model for the world of experience we must renounce all hope of finding anything like the correct theory ... simply because the totality of experience is never accessible to us.[/quote]
You have to ask whether the whole thing is kind of a joke.
I found Max Tegmark interesting in his mathematical universe and multiverse theory. Then again, it seems remarkable for physicists to think it true that MW's exist when you can simply ask them where do the measurements end and where do they begin. To make the entire universe less intelligible by stating a mathematical notion of determinism with no clear adherence to why I experience this time evolution rather than the other where I won the lottery or Russian roulette game is odd.
I actually posted the following question to stackexchange:
How do time evolutions occur in the Many Worlds Interpretation?
For example, if I assume that I played the lottery today and will probably not win it tomorrow, then what governs the time evolution of the other world where I won the lottery rather than the one where I didn't win it?
Well, I'm extremely sympathetic to Platonism in mathematics, but i see no reason whatever to beleive that justifies the 'many worlds' intepretation. Like I asked in another thread - what problem does it solve? If the many worlds intepretation is the solution, what is the problem?
I think, and it's not only my opinion, that the problem it solves is the so-called collapse of the wave function. That, prior to being measured, 'the object' doesn't actually exist anywhere. All you have is a distribution of probabilities, but it's not as if the electron is hiding in a thicket, awaiting discovery. It's not anywhere, it doesn't actually exist, in an unequivocal way. So this introduces the whole problem of why does observing it cause it to exist? Avoiding that problem is the rationale.
Another solution is given in this paper, which draws on Heisenberg's philosophy of physics.
Hear ye the imminent cries of 'woo-woo'? This is because, in modern thinking, there's no room for any 'degrees of reality' - something either exists, or it doesn't. Whereas what this is saying is that
So, the wave function actually transcends space and time. I put that view on Physics Forum where it was dismissed as 'gobledygook' by one of the residents, but I find the same view in a textbook I'm currently reading, Nature Loves to Hide, by Shimon Malin (a physicist, not a pop science writer.)
From listening to several of Sean Carol's podcasts, it seems he and other physicists of his persuasion take the wavefunction as being descriptive of reality, and it's simpler to go that route than try and come up with some means for there being a wavefunction collapse. You take the math at face value.
But then you can go really overboard with that and end up with Tegmark's multiverse where all mathematical forms exist.
Could well be. But for purposes of this discussion, please note that multiverse theory and the many-worlds interpretation are two entirely different speculative theories.
Seems to me that if we buy the many worlds interpretation, violation of the conservation of energy and matter is the least of our problems.
Mind explaining how? As far as the specifics go, my understanding of many worlds interpretation is that all quantum states exist in some type of branching world or universe. This is just a multiverse theory. All multiverse theories fail at their core, because they are pure speculation without evidence.
Put a horn on a horse, and that sounds plausible. Spin the idea that measurement of quantum objects prevents us from knowing another aspect about that quantum object, and say that all possible quantum entities could exist, and it sounds plausible. But at the end of the day, its all speculation if you can't prove one shred of evidence that such a thing can actually exist.
I understand you might be interested in the higher levels of MWI speculations, but at the end of the day its like speculating whether a unicorn is able to magically heal wounds, or cast spells so it can fly. Its all moot until you can prove a unicorn exists.
MWI is as you explain it, branching due to QM, as an alternative to wave function collapse.
The multiverse theory says that the universe consists of "bubble universes" that branch off and are causally independent of each other. Entirely different theory. Nothing to do with quantum branching. It's a cosmological theory.
https://en.wikipedia.org/wiki/Multiverse
How do we compare our technology today with whatever ideas (concepts - if any) of them that existed 200, 500, 1000, 2000 years ago?
A 'purely' mathematical dimension/perspective mostly refers to the conceptual. Actual phenomena can be worked out even without adequate mathematical knowledge provided there's adequate experiential knowledge.
Could be that there's actually zero energy in the universe.
Way above my pay grade. If Sean Carroll didn't make a video about it, I have no idea :-)
If you read the wiki article you linked, you'll see that MWI is a level 3 classification scheme of multiverse theory. I was correct then.
You seem to have side stepped the larger issue I made however. In the end, MWI is a unicorn theory. Do you have an answer for this?
...according to Max Tegmark's classificatory scheme, which is shared by practically nobody.
Quoting Philosophim
I think it's all nonsense on stilts, but who am I?
MWI is a level 3 classification scheme of multiverse theory....
— Philosophim
...according to Max Tegmark's classificatory scheme, which is shared by practically nobody.
I was replying to fishfry's link. He linked me that, so I assume he found that to be a valid source. If you would like to enter the conversation, feel free. If Max Tegmark's scheme is wrong, who's scheme is right?
Quoting Wayfarer
So one in agreement with unicorn theory then! But I want to give fishfry a chance to refute it.
My personal view, which of course I don’t have any credentials to support. Is that a lot of this kind of theorisation is sign of a kind of decadence. It provides this kind of unlimited conceptual elbow space which can be used to rationalise all kinds of mathematical conjecture, but which will be forever outside any kind of validation even in principle. So It has all the worst features of metaphysics, which scientific types routinely vilify, without even the association with an ethical code which traditional metaphysics at least has. I think science ought to be practiced without any reference to this kind of speculative foam, which I think would provide a kind of bracing austerity, and some needed humility.
Check out this article.
They seem to be using multiverse in a more general way, so in that sense you're right. My understanding of multiverse is as in eternal inflation, which is not a QM theory. I'd agree that there's a considerable confusion between the multiverse and the MWI.
Quoting Philosophim
I didn't sidestep it, I didn't address it at all.
Quoting Philosophim
I have no answer for that. Multiverses as in bubble universes are plausible, in the sense that there are parts of the universe that are causally unreachable from the observable universe. We can't know what's out there. MWI I don't find very plausible, but I don't know enough QM to have an informed opinion.
That's what I see as the principal issue. Evidence is derived from "our" universe, and we generally do not allow conflicting evidence as this is contradictory. If there are multiple universes with conflicting evidence, then we need some principles whereby we could distinguish our universe from others, allowing that conflicting evidence could be acceptable. This is not simply a matter of distinguishing one possible world from others, but what distinguishes our world from all the other possible worlds. At present, there are no principles which would allow us to distinguish one universe from the rest, as "our" universe, except that it's the one we have evidence of.
This is the age-old old ontological question, which is yet to be answered, what distinguishes our world from the many logically possible worlds, as the real world. The simple answer is "evidence", But the many different ways in which evidence may be interpreted produces ambiguity in that distinction. If the ambiguity leads us to believe that every logically possible world is just as real as every other, then we lose the standard by which our world is distinguished from other logically possible worlds, as the real world.. In other words, evidence no longer helps us.