Slashdot Mirror
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.
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...
Well, we don't really have any reason to expect alternate universes to exist at all, except that the theories don't preclude them.
The real problem is that we have some really huge gaping holes in established theory*, places that we *know* our understanding is flawed, and all the "patches" we've dreamed up are so outlandish that we need even more outlandish experiments to test them, where we've even managed to dream up potential experiments at all.
* for example - General Relativity requires that the base energy of empty space be exactly zero, while Quantum Mechanics requires that it have a definite non-zero value. (the so-called vacuum energy field) Both cannot be the case, so clearly one or both theories must be flawed.
--- Most topics have many sides worth arguing, allow me to take one opposite you.