In the article here a theory is discussed that particles, including specifically a hypothetical type of neutrino, could travel through time, as well as through space. The article mentions that the Large Hadron Collider could begin detecting such particles before they are created in subsequent experimental events.
Very interesting, but my question is: Why would one expect a neutrino generated by an event in the future, in the Large Hadron Collider at it’s location in the future, to be detectable in the current location of the Large Hadron Collider? Even if current motion is conserved across temporal travel by some bizarre characteristic of spacetime, we know for a certain fact that the current LHC has a rapidly changing motion due to dozens of forces acting on it in the current frame of reference.
So, it seems to me that the LHC is the one place you could be fairly certain would not show the creation of particles created by the LHC. Is the proposed temporal displacement some quantum quantity, Like one planck interval? In that case, I suppose it might be indetectably altered in its location and vector. Indetectable seems to have drawbacks as well.
Right off the bat, I can say that they’re not avoiding any paradoxes. The Grandfather Paradox doesn’t require full-grown humans to travel in time; anything which sends information back could do it. I didn’t read all the way through, but if they can’t even get the science fiction right, then I don’t trust them to get the science right, either. Assuming there’s any actual grounding to what they’re saying at all, I’m guessing that they’re using a metric with a funky signature (multiple timelike dimensions), which causes all sorts of weirdness (including but not limited to time travel).
The neutrinos mentioned are not what they are expected to see in the LHC. Some years ago they introduced so-called sterile neutrinos (in addition to the electron-, muon-, and tau-neutrinos) to explain some other observed anomaly. Even then, they weren’t observed, only inferred to explain the anomaly.
The sterile neutrinos were able to travel back in time (in their theory) because they didn’t interact except through gravity, and that allows them (somehow) to move through a dimension (or dimensions) outside the three usual space dimensions. I’ve read elsewhere of gravity being so weak for the same reason (higher dimensions), so that part, at least, is being explored by others.
The particles they are expecting to possibly observe are Higgs singlets, which also don’t interact except through gravity, and so also could travel backwards in time. Presumably, these travel between 0 and -c (that is, if you filmed them and ran the film backwards, they’d travel less than c, like normal particles), but I don’t know. If they do, that means that they’d behave like normal collision products in that they wouldn’t travel very far before decaying into other particles. The decay products are what they will detect in the LHC, but if the theory is correct, they will detect these shortly before (nanoseconds; the speed of light is roughly 1 foot per nanosecond) the collision occurs, rather than shortly after.
I don’t know if the protons and anti-protons are so tightly bunched up, to where they’d know exactly (to less than a nanosecond) when they’d collide. If not, I’d guess they’d see these decay products coupled with decay products from the normal forward-time-traveling particles, and be able to determine that they had to come from the same collision.
Sterile neutrinos were postulated to explain some oddities with neutrino oscillation: Neutrino oscillation experiments can tell you something about the masses of the neutrinos involved (specifically, the quantity m[sub]2[/sub][sup]2[/sup] - m[sub]1[/sub][sup]2[/sup]), and three different experiments were giving three wildly different values for that quantity. Now, two experiments giving different mass splittings is fine, if they’re looking at different pairs of neutrino types in their oscillations, but three different splittings can’t be explained that way, unless there’s a fourth type of neutrino. Such a fourth neutrino would, by definition, have at least some weak interactions, since the neutrino oscillation itself is a weak phenomenon, so it’s not correct to say that they interact only gravitationally. And even if they did interact gravitationally, and the extra dimensions were such that this enabled them to leave the brane, you’d need a spacetime with rather peculiar properties (which ours does not appear to have) for that to enable time travel.
So, what justification do these guys have for deciding that “leaving the brane, and then re-entering it” is going to be bound by such four dimensional limits as light speed? Or freakin light years, for that matter? Seems to me you start time traveling, and stop time traveling distance and sequence of events is a bit much to expect to predict.
I am more willing to go along with Chronos with the “there ain’t no setch animal” in this case, than I am willing to accept that a foot per nanosecond has meaning when the concept of nanosecond itself has just been set aside.
You are assuming the physics in the other dimension/brane are unpredictable/unknowable. I think. The only difference the theory may predict is you can go -c or some such over in them there parts. I think.
OK, I’ve skimmed over the paper. It’s not the kind of weirdness I was expecting: Their extra dimension is spacelike, not timelike. What they don’t show, though (at least, I think-- I haven’t read the whole thing), and which I might get around to double-checking myself, is that their metric allows for a particle to remain at a constant coordinate position: They seem to be assuming that it can (their argument for closing the closed timelike curves depends on it), but that’s not always a given for metrics with off-diagonal time terms.
As an aside, it really bugs me when a paper neglects to mention which sign conventions it’s using. Their equations were really confusing me until I remembered that particle physicists generally use the opposite sign on their metrics from what relativists use.
Oh, one other point: This isn’t a theory; it’s at most a category of hypotheses. This result does depend on spacetime having certain properties, and there’s no reason to believe it actually does have those properties, nor do they claim that it does. Really, all they’re saying is that we can’t yet rule out the possibility that it might have those properties, and if it does, we might be able to detect them at the LHC or other particle accelerators.
So, if we observe a decay product which has the appropriate conservation of momentum, but occurs before the event which will cause it, that would be consistant with the multi-dimensional description of space time which they present.
I am not sure how you demonstrate that the decay event is the related. It does seem a bit less convienient given that the conservation of momentum must be exact, if that is the case. It makes it a tad less unreasonable that it happens “near” the collision, if not after. I must admit to a huge pile of ignorance on how frequent unexplained decay events are outside of the LHC, or how much variability there is in momentum characteristics of such events.
Thanks for the enlightened help.
I hope I didn’t just make a fool of myself, but, hell, I do that fairly often.