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Missing Matter, Parallel Universes?
Phoghat writes "Could mirror universes or parallel worlds account for dark matter — the 'missing' matter in the Universe? In what seems to be mixing of science and science fiction, a new paper by a team of theoretical physicists hypothesizes the existence of mirror particles as a possible candidate for dark matter. An anomaly observed in the behavior of ordinary particles that appear to oscillate in and out of existence could be from a 'hypothetical parallel world consisting of mirror particles,' says a press release from Springer. 'Each neutron would have the ability to transition into its invisible mirror twin, and back, oscillating from one world to the other.'"
And in this parallel universe, everyone has a goatee.
The missing matter is all in the form of single unmatched socks.
Luckily we have more than one cosmologist, so it's not really a problem if some try new explanations (and maybe get to test them), because we have other cosmologists doing other things. Or are you going to suggest that there's only one cosmologist, going backwards and forwards through time and across the whole universe?
You mostly have that backwards. "Normal people" invent outlandish untestable explanations -- often with reference to supernatural intelligences -- for unexplained phenomena all the time, whereas the "mirror particle" hypothesis makes quite specific, testable predictions (and specific tests are recommended in the paper.)
Dismissive assumptions are so much more scientific than actual testing.
We read all this stuff trying to understand anything and all, and then the next paper they release will just say "Bazinga!"
I'm guessing the people who thought relativity and quantuam mechanics were bupkis probably used similar lines of reasoning.
You might want to try reading Brian Greene's "The Elegant Universe". It a fairly approachable book on superstring theory and hidden dimensions for laymen.
The theories are very elegant and well thought out but are inherently difficult to prove since the sizes of the things that need to be seen are so small that they are currently unseeable, or energies required are so huge we can't produce them, so there is currently no way to experimentally prove the theories. The main superstring theories suggest 10, 11 or 26 dimensions of which we can actually see only four.
No one is advocating embracing superstring theory, hidden dimensions or multiverses as fact, since even their advocates know they are only theories, but neither should they be discarded as "bupkis" until they are disproved since they may be a way forward in understanding and resolving unresolved conflicts in quantum mechanics in particular. They are regrettably as difficult to disprove as they are to prove.
I'm of the opinion if smart people want to keep thinking about these things they probably should. Just because they are very hard problems doesn't mean they should be given up on. If smart people like the people that wrote this paper can figure out novel ways to test these hard problems, more power to them.
@de_machina
Yes and no. Your link refers to mirror matter based only on parity symmetry while I believe the paper at hand is more general. The arXiv preprint discusses this at the start:
Concerns about parity are irrelevant for our following discussions: they extend to a parallel sector (or sectors) of any chirality. Nevertheless, in the following we shall name the twin particles from the `primed' parallel sector as mirror particles.
To set things up, imagine stepping through a mirror and doing some physics experiments. You would expect everything to work out the same as before so long as "left" and "right" were reversed (...along the axis normal to the mirror...). That turns out not to be the case, which was surprising--some decades ago a few experiments with relatively exotic particles didn't work out as expected (brief history here). Thus matter "through the mirror" and "before the mirror" are distinguishable. It's possible that matter through the mirror exists in our before-the-mirror universe, though it shouldn't interact much with the matter we're used to because the force-carrying particles need to be mirrored as well which ends up leaving only gravitational interactions. As you may have guessed, this is a potential candidate for dark matter. The lack of electromagnetic interactions would prevent distant mirror matter from being seen, and the lack of strong or weak interactions would nix many lab tests (like those that detect neutrinos, which are detected by their weak interactions).
My (poor) understanding of the paper is that they consider an essentially arbitrary parallel universe with wimpy interactions with our own universe (except gravitationally), not necessarily just one created by parity changes. In particular they focus on transitions of neutrons from our universe to the parallel one and use such transitions to explain an anomalous dependence on magnetic field direction in a previous experiment.
As usual, caution is the best plan. The authors call for more experiments, and I'm sure there are numerous explanations for their results that don't require (IMO) spooky transitions between parallel universes.
Just a minor note: Einstein won his Nobel for his work on the photoelectric effect (which ironically helped launch the quantum theory he distrusted the rest of his life), not for relativity. I'm not sure if you meant to imply that or not.