"Radical New Quantum Theory Says Other Universes Affect Our Own"

[The Intransigent Faction]

Parallel universes (http://en.wikipedia.org/wiki/Parallel_universe_(fiction)) have long been a staple of science fiction. But according to a radical new theory of quantum mechanics (https://journals.aps.org/prx/abstract/10.1103/PhysRevX.4.041013#abstract) published Oct. 23 in the journal Physical Review X, other universes are real--and they exist in vast numbers. What's more, the scientists behind the theory say the other universes exert a subtle repulsive force on our own universe--and that this force is what makes the quantum realm so mind-bendingly bizarre (http://www.physics.org/toplistdetail.asp?id=17).
"Any explanation of quantum phenomena is going to be weird, and standard quantum mechanics does not really offer any explanation at all--it just makes predictions for laboratory experiments," Prof. Howard Wiseman, a physicist at Griffith University in Brisbane, Australia, and one of the creators of the new "many interacting worlds" theory (http://phys.org/news/2014-10-interacting-worlds-theory-scientists-interaction.html), told The Huffington Post in an email. "Our new explanation...is that there are ordinary (non-quantum) parallel worlds which interact in a particular and subtle way."


The theory is a new twist on the so-called "many worlds interpretation" of quantum mechanics, which dates back to the 1950s. As Wiseman explained (https://app.griffith.edu.au/news/2014/10/27/new-quantum-theory-is-out-of-this-parallel-world/) in a written statement issued by the university:

"In the well-known 'many worlds interpretation,' each universe branches into a bunch of new universes each time a quantum measurement is made. All possibilities are therefore realized--in some universes the dinosaur-killing asteroid missed Earth. In others, Australia was colonised by the Portuguese. But critics question the reality of these other universes, since they do not influence our universe at all. On this score, our 'many interacting worlds' approach is completely different, as the name implies."
Wiseman and his collaborators--Dr. Michael Hall, also of Griffith University, and University of California, Davis mathematician Dr. Dirk-Andre Deckert--say that their theory may have important implications in the field of molecular dynamics, which is critical to understanding chemical reactions.
Does it also suggest that humans might someday be able to interact with other universes?
"It's not part of our theory...," Wiseman told Motherboard. "But the idea of interactions with other universes (http://motherboard.vice.com/read/parallel-universes-colliding-could-explain-quantum-weirdness) is no longer pure fantasy."
What do other experts make of the new theory?
Dr. Lawrence Krauss, a theoretical physicist at Arizona State University in Tempe, told The Huffington Post in an email that he was "skeptical." And a popular Czech Republic physicist wrote on his blog (http://motls.blogspot.com.au/2014/10/many-interacting-worlds-approach-is.html?m=1) that while Wiseman and his collaborators had "managed to present some ideas that are at least slightly original," their paper was "another example of the fact that such efforts are a hopeless enterprise and a huge waste of time."
But Charles Sebens, a philosopher of physics at the University of Michigan in Ann Arbor, told Nature that he was excited by the approach (http://www.nature.com/news/a-quantum-world-arising-from-many-ordinary-ones-1.16213) taken by Wiseman and his collaborators.

“They give very nice analyses of particular phenomena like ground-state energy and quantum tunneling," he told the journal. “I think that together they do a nice job presenting this exciting new idea.”
Dr. L. William Poirer, professor of chemistry at Texas Tech University in Lubbock, also expressed support for the "many interacting worlds" theory. He told HuffPost Science in an email that Wiseman and his collaborators had made "an important contribution...There is no experimental evidence to support this yet, but if true, it means that their theory will make different experimental predictions than standard quantum mechanics does."

Clearly, there's no consensus. But if Wiseman is dismayed by the uneven reaction to the theory, he's not letting on.
"There are some who are completely happy with their own interpretations of QM, and we are unlikely to change their minds," he said in the email. "But I think there are many who are not happy with any of the current interpretations, and it is those who will probably be most interested in ours. I hope some will be interested enough to start working on it soon, because there are so many questions to answer."
In the meantime, the last word should probably belong to Nobel Prize-winning theoretical physicist Richard Feynman (1918-1988), who once said, "I believe I can safely say that nobody understands quantum mechanics (http://bouman.chem.georgetown.edu/general/feynman.html)."


I'm no expert on this stuff, but I've seen people taking an interest in it.
It's interesting that "There's no experimental evidence to support this yet", [so let's speculate about all the crazy shit that could happen in conceivable alternate universes which is untestable, apparently].


Any thoughts from someone more knowledgeable about quantum mechanics? Is this "radical new theory" plausible, or just taking a probabilistic shot in the dark at what "could be", or what?

[Rafiq]

I am absolutely no expert with regard to quantum physics - I really don't know anything about it. But I have always been generally more sympathetic toward the relational interpretation of quantum mechanics. T

[BIXX]

There is something to it IMO given a lot of the shit I've read in the past. But I also don't know as much as I would have to to be positive.

[Anglo-Saxon Philistine]

First a small reminder about the credibility of much of science journalism today, courtesy of Z. Weinersmith:

http://www.smbc-comics.com/comics/20090830.gif

Now that that's out of the way, a few words about the "many worlds interpretation" of quantum mechanics. First of all, why do we need to interpret quantum mechanics in the first place? After all, the phrase "interpretation of classical mechanics" is rarely heard, even though classical mechanics also includes complex mathematical structures (phase spaces, Lie Brackets, the Hamilton-Jacobi principal function etc.). The difference is that the interpretation of classical mechanics is straightforward. No matter how we approach the problem, we can cast the solution in terms of trajectories of material particles (or infinitesimal parts of bodies). The problem with quantum mechanics is that what we calculate is not what we end up measuring.

To clarify: quantum mechanics describes the continuous, deterministic evolution of the quantum state of the system (often called the wave function although strictly speaking this should be reserved for the state written down in the basis of position or impulse eigenstates). What we measure are discontinuous, apparently stochastic states of definite position or momentum or whatever variable we have chosen to focus on. If the Schroedinger equation has as a solution a spherical wave expanding from some point, and we place a position detector at some distance from that point, we will not detect a spherical wave (which has a high uncertainty when it comes to position), but a blip corresponding to a particle entering the detector at some definite point.

So, we need an interpretation in order to make sense of this (today, of course, we can also "see" obviously non-classical effects such as superposition etc. in experimental situations). How do the states given by quantum mechanics become the experimental results that we actually measure? One interpretation is the Copenhagen one: in its mature form (given by Bohr and Fok, among other people - including a really lovely article in Pod Znameniem Marksizma) it states that the quantum state of a system represents the various possibilities for the system to appear when placed in an experimental situation. (This is quite different from Bohr's earlier agnosticism and instrumentalism.)

H. Everett had a different answer. To him, there was no point when the quantum state "collapsed" into the states representing experimental results. Instead, he treated the measuring apparatus as a quantum system in itself (this of course includes humans, which are really low-grade position detectors for electromagnetic radiation with some highly faulty wiring). So the measurement apparatus will itself be in some quantum state.

Assume for example the particle we wanted to detect was in the state:

a*|spin up> + b*|spin down>

Then after the particle has been detected by the measurement apparatus, that apparatus will be in a state:

A*|spin up detected> + B*|spin down detected>

A and B have some relation with a and b, which is not important at this stage. But it is interesting to note that even if b is 0, B does not have to be.

Everett then extended this sort of thinking to the universe in general. He assumed that the universe was in a single quantum state, which he described as the "universal wave function". This universal quantum state includes all the measuring apparatus with their various possible states. I am part of that state, for example, and when I watch a particle hitting a fluorescent screen my brain will be in some superposition of states:

a1*|particle has hit the screen at point x1> + a2*|particle has hit the screen at point x2> + a3*|particle has hit the screen at point x3> + ... + s1|THE PARTICLE HAS NOT HIT THE SCREEN THE UNIVERSE IS A LIE> + ...

So this accounts for the apparent "collapse" of quantum states into classical results. They don't collapse, they just get entangled with the quantum states of our apparatus and our brains, which generally speaking do not "talk" to each other.

Now, you may have noticed, this all sounds a bit "abstract" (if you haven't noticed, please marry me). Enter one B. DeWitt, Everett's more successful colleague. How he imagined this is that there are multiple "worlds" corresponding to the branches of the universal wave function, with a new world splitting off whenever a quantum system can be in one of many states.

This is, then, the "many worlds interpretation", the popular version many people hear. But it's just an image, a picture to make the original Everett formulation more intuitive. You aren't supposed to take it too seriously - notably, if you do, the original unintuitive "collapse" that Everett wanted to avoid is replaced by the equally unintuitive "splitting". So nothing has been gained. And it's not as if the various branches of the wave function (which depend on the choice of variables anyway) are strictly speaking forbidden from interacting.

Now, the article that has been posted is talking about something else. It's not an interpretation of quantum mechanics, but a, for lack of a better term, a classical model of quantum mechanics, where they take a classical universe, or rather many such universes, add a few mysterious rules about interaction, and try to reproduce the results of quantum mechanics. They aren't really successful, and their one selling point (that the approach does not include a wave function) doesn't hold in the only realistic scenario (infinite "universes"). So it's all a bit hit-and-miss, really.

[The Cleaner]

all those theories are amzing but i am afraid that no one will ever be able to prove them somehow.

[BIXX]

Very helpful post, 870.

That was actually insanely interesting.

Have you read anything by Brian Greene?

[Anglo-Saxon Philistine]

Very helpful post, 870.

That was actually insanely interesting.

Have you read anything by Brian Greene?

I read his "The Elegant Universe" when I was a bit younger - good grief, has it already been 15 years? That's horrifying. His professional work is well outside my area.

[RedMaterialist]

It was only about 100 yrs ago that they figured out the Milky Way was only one galaxy rather than the entire universe. Why not billions of universes?

[Dodo]

Now that that's out of the way, a few words about the "many worlds interpretation" of quantum mechanics. First of all, why do we need to interpret quantum mechanics in the first place?

I am not an expert on quantum physics beyond popular culture really but this bit interests me. Why do we have to interpret quantum mechanics? If I understand this question in the right context, my answer is this:

For legitimizing any theory of knowledge(obviously including Marxism), we cannot ignore the discoveries in physics(philosophy's connection to physics is quiet big after all). From classical physics to quantum, matter, motion, time, space are all concepts we have to attempt to understand to put up any legitimate propositions.
Quantum physics especially relates to dialectics, and materialist outlooks means we have to familiarized ourselves with what we know so far of "reality" without falling into the trap that we got it all sorted out.