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The Search For Neutrons That Leak Into Our World From Other Universes
KentuckyFC writes: One of the more exciting predictions from "braneworld" theories of high energy physics is that matter can leak out of other universes into our own, and vice versa. The basic idea is that our three-dimensional universe or brane is embedded in a much larger multi-dimensional cosmos. These branes can become coupled so that a quantum particle such as a neutron can exist in a superposition of states in both universes at the same time. When the neutron collides with something, the superposition collapses and the particle must suddenly exist in one brane or the other. That means neutrons from our universe can leak into other branes and then back again. Now physicists are devising an experiment to look for this neutron leakage. They plan to put a well shielded neutron detector next to a shielded nuclear reactor that produces neutrons at a research facility in France. All this shielding means the detector should not see any neutrons from inside the reactor. However, if the neutrons are leaking into another brane and then back into our world, they can bypass this shielding and trigger the detector. The team has not yet set a date for the experiment but the discovery of neutrons (or anything else) leaking into our universe would be huge.
So that's where my car keys go.
What if the other brane also has a reactor shield in the same spot?
We need to build a fence to keep these undocumented neutrons out of our Universe and from taking jobs from our neutrons. # IAmNotAScientist
It must have been something you assimilated. . . .
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The idea is to create so many they couldn't help to jump back and forth. To (hopefully) leak into another brane and (hopefully) leak back.
If they just sit in the middle of nowhere, it's a hope that an abnormally large source from another brane just happens to emit in that particular spot at the right time. In other words, beyond improbable.
XML is like violence. If it doesn't solve the problem, use more.
I think the idea is to have a huge source of neutrons in physical proximity to increase the chances of one leaking into the other universe first so it can leak back on the other side of the shielding.
The idea would be to look for neutron counts higher than they should be getting given the amount of shielding. So if it should be blocking 99% but they are seeing 2%, then they would have a possible positive result. So they would be looking for statistically significant differences that could only be explained by neutrons skipping between universes.
Except that the baseline expectation is derived from experience with previous, presumably brane-leaky, shielding.
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The guy who said the election was rigged won the presidency with the second-most votes.
I guess you haven't been keeping up with physics lately, but this kind of thing has been seriously discussed for decades, and has gained a lot of momentum in the last 10 years or so. The only thing slowing down the development of the science of alternate universes is inability to make falsifiable predictions. While not finding neutrons we can't account for wouldn't disprove anything, finding them could be the biggest science news since the prediction of and then discovery of the Cosmic Microwave Background.
It's a weird world out there and the possibilities of what reality really consists of are getting weirder and weirder and yet more plausible at the same time.
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OK, so we have multiple cosmi (space-time continua) embedded in a higher dimensional universe. I'm totally down with that and have written an entire SF novel based on the premise. Those cosmi (as the plural of cosmos) have a coupling. I'm good with that. But that means that "neighboring" cosmi will exist in a coherent bundle, and one will have to get quite distant from "this" brane to find a brane with substantial drift in its general mass distribution.
This is simple statistical mechanics, by the way -- if most brane-to-brane transitions occur in places where there is chuck of mass in one cosmos and none in another cosmos, there will be steady diffusion from the high mass concentration to the low one. This would lead to egregious and painful violation of mass-energy conservation as my foot in this cosmos diffuses into a vacuum in many, many others, because after all, the mass density of any cosmos at all is nearly zero with a hard, hard vacuum nearly everywhere.
This is overwhelming evidence that this sort of brane to brane, cosmos to cosmos transition does NOT happen in a universe in which the cosmi are equidistant and randomly organized. The only way that those transitions are possible at all is if there is a metric in the higher dimensional universe and if neighboring cosmi have ALMOST identical mass distributions and if transitions are only likely as pair exchanges between neighboring cosmi (note the requirement for pair exchanges is also a rather hard one or else one would observe a cumulative violation of conservation of mass in random-walk style that would be impossible to miss and that people have looked for, unless the transitions were VERY unlikely, or became very unlikely as a function of the intercosmos metric separation to increasingly different cosmi.
Note well that these constraints mean that no matter what, they aren't going to "bypass" a shield with a neutron flux, because there are going to be no nearby cosmi/branes in which the shield does not exist.
Note well in addition the response to those who suggest that this might be a way of viewing tunnelling. It is indeed -- the alternative cosmi are one of the POSSIBLE (I don't say plausible) interpretations of path integral formulations of quantum mechanics, integrated out. But in this case you STILL won't get tunneling through a barrier centimeters thick.
So this is a pointless experiment. One might as well just look for egregious violations of mass-energy conservation in everyday experiments, because if there is any substantive probability of mass energy departing our own spacetime cosmos and appearing in another "nearby" one, it would happen all the time and all mass concentrations would diffuse out into a multicosmo heat death.
Gravitation is an excellent possibility as the coupling between branes/cosmi -- one would guess that the "dimpling" of one spacetime dimples all of the neighboring ones on all sides (however many "sides" there are:-). The dimples probably don't have to precisely correspond, but they are likely to have to approximately correspond to minimize almost any sort of coupling across the sheets that permits a transition to occur in the first place.
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Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
I think the idea is to have a huge source of neutrons in physical proximity to increase the chances of one leaking into the other universe first so it can leak back on the other side of the shielding.
I have a big problem with that.
From TFA: "...the number of neutrons that leak back into our universe from another brane will depend on the distance of the detector from the reactor, where they are created in the first place. This rate should fall with the square of the distance from the reactor. So any distance dependence will be good evidence of brane leakage."
What? Why should the creation rate fall with the square of the distance? I can understand the inverse square law from the standpoint of neutron emissions from our own universe, but wouldn't entanglement across branes be, by definition, independent of distance?
"A little misunderstanding? Galileo and the Pope had a little misunderstanding."
It's not entanglement. There's only one neutron. It sounds like a kind of quantum tunnelling, except across "universes." There are types of tunnelling where distance doesn't have the same effect you might expect, but there are other types where it does.
I have a big problem with that.
What? Why should the creation rate fall with the square of the distance? I can understand the inverse square law from the standpoint of neutron emissions from our own universe, but wouldn't entanglement across branes be, by definition, independent of distance?
Reading TFA, it seems that the neutrons are coming from reactor and they are bouncing between the branes due to collisions and the affect of our gravitational field. It's long been suspected that gravity reaches across the branes which is why it is so weak compared to the the forces. This is probably an assumption of their experiment if not of the brane theory they are working with. Gravity is the key as what they are really looking for is a change in the rate they detect neutrons with the difference of the gravitational field that goes with the Earths change in distance from the sun due to its orbit. So, they are next to the reactor probably because it will drown out the other source such as neutrons from cosmic rays, but are hoping to see a change in the number of neutrons that related to the distance from the sun while other variables remain the same.
Correct me if I'm wrong, but does this mean that the neutrons literally flow across a fourth dimensional axis, and then somehow bounce back after they've moved some distance on one of the other axes, landing in the trap while within our plane of the fourth dimension?
Not exactly, the quirk they are testing is effectively the neutron travelling through both "branes" in a superposition state (well, it's actually a bit more subtle than that, but that's the easiest way to explain it).
If so, how are they supposed to spot the neutrons the moment they cross into our brane but before they move into another one?
They aren't tracking specific neutrons, they are making a statistical assumption about a collection of neutrons.
More specifically, by running the experiment multiple times with the neutron source a different distance away from their shielded measurement chamber and at different times of year (to account for different magnetic vector contribution from the sun), they can potentially statistically isolate neutrons detection events that are expected to spontaneously appear (e.g., as a result of cosmic rays originating outside of experimental parameters) from those neutrons that supposedly move in and out of our "brane" as a result of superposition which are sourced locally (whose flux depends on the distance from the source).
We'll see how it goes. They haven't done the experiment yet...
No. Basically brane theories posit that our universe is a 4-dimensional "membrane" in a higher-order metaverse (usually with at least 11 dimensions, or was it twelve? The minimum number at which the various QM constants emerge naturally), and that there are probably other 4-dimensional branes in the metaverse as well. They're one of the four main scientifically recognized classes of possible "parallel universes". Picture if you will many sheets of paper floating in a room, each sheet a universe, and if two sheets were close enough together particles could potentially jump back and forth between them.
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Good. I like when things are questioned. I read both Brian Greene and Lee Smolin.
Nonetheless, there are predictions that can be made based on current research, and it makes sense to try them out if there's a reasonable way to do it.
You are in a maze of twisty little passages, all alike.