I think this is the proper forum. And I am fascinated by physics, though I am a dunce (comparatively speaking). So, any physics mavens who deign to respond, please do so as if you’re explaining calculus to a kindergartner.
And apologies if I’m just completely misunderstanding the whole concept.
Anyway, as I understand it, the multiverse theories (there are a few) assert that the quantum wave that collapses in classic physics, where one of the possible states in the superposition “wins,” gets it all wrong. There is no collapse. All the possibilities that exist manifest themselves in different universes, all of them real and all of them beyond our ability to detect.
I’m sure that’s a shitty way to summarize it, but my question is more basic: Where does all the matter come from as these new universes burst into being? That’s a lot of matter—a whole universe’s worth. As I understand it, every superposition does not collapse, it simply creates alternates where all the possibilities are realized.
I know this is all unprovable, but my question (and why I put it in this forum) is, how do proponents of these theories explain this?
Sorry if my explanation and question is so muddled that your expert response is, “huh?”
That’s an interesting question. I’ve also wondered where all these new universes are, and why doesn’t our universe experience gravitational pull from them. I’m sure that’s probably not an accurate question to ask. I look forward to reading comments on your question.
Same place as all the matter from the universe we’re in. It has no prior cause. (There weren’t no “prior”, after all). If you can do a universe as a vacuum fluctuation, it shouldn’t be any real biggie to do a multiverse as a variation on nothingness as well.
I’ll have to read more on vacuum fluctuations; thanks for the reference. But I’m still befuddled (my default state). Didn’t all matter in our universe exist in the Big Bang’s singularity? Who knows where that came from, but our universe was “built” with the matter in the singularity. An alternate universe that creates itself with every superposition, producing a reality that at that moment is virtually identical to our own (except for the resolution of the superposition) needs to have matter. How did that materialize, from what?
The answer may well be the same as for the singularity’s matter—who knows? But that’s not very satisfying. Our universe has a source, albeit one whose precursor we can’t determine. What is the alternate universe’s predicate?
Perhaps superpositions are constantly being created and destroyed. So we’re not birthing “new” universes made of “new” matter with each superposition collapse. We’re just rearranging the deck chairs of the universes we have.
Said another way, and this is highly metaphorical, the thing we call “The Universe” is not a “the”, and it’s not “universal”.
It’s a momentary arrangement of some fraction of all the stuff in existence. A moment later the fraction is in a different arrangement. We don’t think of that as creating or destroying anything. And as our fraction changes conformation over time, so do the other fractions we can’t see, but that we think under the multiple worlds interpretation, are really out there “somewhere” in different configurations that are subtly connected to the history of our configuration.
All this is massive arm-waving by somebody (me) who does not really know what he’s talking about.
I thought we had observed the effects of dark matter and dark energy, but that so far we haven’t had any direct observations of the dark matter or dark energy itself.
I believe that’s the correct interpretation of Hugh Everett’s “Many Worlds” hypothesis. There are a number of different notions of a multiverse, but Everett’s “many worlds” is the formulation usually used to account for quantum superposition. AIUI, the error in the OP is assuming that collapse of the Schrodinger wave function somehow “creates” alternate universes. It doesn’t; instead, what we see as wave function “collapse” is every possible quantum state settling into its own pre-existing universe. Or, IOW, what @LSLGuy said.
I’m certainly no expert, but there was a good set of articles in the 5 July 2007 issue of Nature (Vol 448, Issue 7149) on the 50th anniversary of the publication of Everett’s “many worlds”. hypothesis. To quote David Deutsch from one of those articles, “our Universe is only a tiny facet of a larger multiverse, a highly structured object that contains many universes. Everything in our Universe — including you and me, every atom and every galaxy — has counterparts in these other universes.”
Deutsch has long been a firm believer in “many worlds”. Famously but controversially, he was one of the first to propose quantum computers, not so much as computing engines per se, but in his view as an empirical demonstration of the ability to harness massive amounts of computing power from not just one universe, but from many. Here’s an interesting quote from his book The Fabric of Reality:
To those who still cling to a single-universe world-view, I issue this challenge: explain how Shor’s algorithm works. I do not merely mean predict that it will work, which is merely a matter of solving a few uncontroversial equations. I mean provide an explanation. When Shor’s algorithm has factorized a number, using 10500 or so times the computational resources than can be seen to be present, where was the number factorized? There are only about 1080 atoms in the entire visible universe, an utterly minuscule number compared with 10500. So if the visible universe were the extent of physical reality, physical reality would not even remotely contain the resources required to factorize such a large number. Who did factorize it, then? How, and where, was the computation performed?
I do not find buzzwords, like “multiverse” and “many worlds”, useful for visualizing quantum-mechanical phenomena, including in this case. The question, “why is there matter?” is related to questions like why was there a Big Bang in the first place, then why is there more matter than antimatter (otherwise everything would just annihilate), which is also not completely straightforwardly obvious.
Those are not “buzzwords”, they’re serious theories. After being dismissed for many years, Everett’s “many worlds” has found renewed acceptance and respect in theoretical physics. The OP’s question is not “why is there matter?”. It was formulated as “Where does all the matter come from as these new universes burst into being?”. The answer that several of us tried to give in the context of a multiverse is that new universes don’t “burst into being”, but were there all along.
That’s probably a better way to think about it; I was referring to “dark energy” as the phenomenon as a whole, rather than as one of the possible explanations which involves actual energy of an unknown source.
Buzzwords rarely are, but the problem is that there is no way to visualize quantum-mechanical phenomena. It doesn’t exist in the same conceptual space that our brains comprehend. You can’t visualize 4 dimensions (and really, you can’t even visualize 3), but so why would you be able to visualize QM?
And that’s why a substantial portion of those in QM fields are in the “shut up and do the math” category. If you want to know the result of an experiment, you do the math, and it works. If you want to understand what is going on, you are going to have to rely on analogies to the math, and those will never be complete and can often be misleading if taken too literally.
Now, as to where the matter and energy of the “new” universe came from, it needs to be remembered that conservation of energy laws only apply to a closed system, and an infinitely expanding multiverse is not a closed system.
I am not dismissing anything. I mean that, for example, in various introductions to basic quantum mechanics for non-experts we are told things like, consider a particle moving along a single line. Its wave function is a map \psi\colon \mathbb{R}^1 \to \mathbb{C}, and the probability that the position of the particle belongs to some set E is \int_E \bigl|\psi(x)\bigr|^2\,dx… The state of a quantum system is described by a density matrix on an appropriate Hilbert space… if \psi_1 and \psi_2 are two pure states then we can take a coherent superposition c_1\psi_1+c_2\psi_2… Nowhere are the words “many worlds” or “multiverse” used to explain anything.
OK, but this is unclear to me. (I guess “bursting into being” = Big Bang?) Could you explain this bursting process in slightly more detail?
I do kinda lean towards Mathematical realism, and then there is no need to ask where anything comes from. It exists because the math says it does. In this case, it’s less of a “split” and more that there were two universes that were absolutely identical until a particular point where they diverge. There are as many universes as there are real numbers, and you can find an infinite number of real numbers that match eachother to any arbitrary decimal point that then diverge.
There is a function that describes our universe, and an infinite number of functions that almost describe our universe, many of which described our universe up until that atom decayed or didn’t decay, after which they started to diverge.
Right, because words aren’t usually used in math. The simplest answer is that both outcomes are real, and that they describe the outcomes in different universes. It’s the collapse of wavefunction that requires buzzwords to explain, as it complicates things and needs a whole new layer to exist.