Timeline for Can a particle with non-zero rest mass "tunnel" into the tachyon world without having to cross the $m=\infty$ barrier?
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| Aug 18, 2021 at 3:01 | history | tweeted | twitter.com/StackPhysics/status/1427827903966892037 | ||
| Aug 18, 2021 at 0:57 | answer | added | Eric Smith | timeline score: -1 | |
| Aug 17, 2021 at 16:35 | comment | added | A.V.S. | There is quite a lot of mainstream literature about “instantaneous quantum tunneling”, including experimental observations such as this paper (see also popular account), though discussions do not usually use the word “tachyon”. So I think this question does have a positive answer (in a sense). | |
| Aug 17, 2021 at 0:40 | comment | added | The_Sympathizer | That said, if we assume Lorentz symmetry of hypothetical tachyonic dynamics, then we can use ordinary(!) Lorentz transformations to transform between tachyonic frames that we define using some suitably tachyonic processes, just not bradyonic to tachyonic or vice versa. Namely, the time axis of an "inertially"-moving, i.e. straight and steady, tachyon must lie long a spacelike line, and a Lorentz transformation can transform one such line into another. But the precise form of such tachyonic frames depends on what the tachyonic dynamics would be. | |
| Aug 17, 2021 at 0:36 | comment | added | The_Sympathizer | the physics in a tachyonic reference frame - however you want to construct that - is necessarily different than that in a bradyonic one, because for one, logic would say that bradyonic particles would have to be regarded by the tachyonic observer as moving faster than light. The point is you can make sense of the imaginary, but the imaginary Lorentz transformations are not necessarily symmetries of physical dynamics. | |
| Aug 17, 2021 at 0:35 | comment | added | The_Sympathizer | @PM 2Ring : Yes regarding the gamma factor in the Lorentz transformation. Keep in mind though that "reference frames" in general are coordinate systems, just with a difference in semantic content; so there's no reason to limit "tachyonic reference frames" to only the Lorentz transformations of bradyonic ones. Moreover, one can argue the idea of Lorentz-transforming a bradyonic situation to a tachyonic one is kind of "against the spirit" of those transformations because what they are "really" about is they are symmetries which preserve the physics, and | |
| Aug 16, 2021 at 23:51 | comment | added | PM 2Ring | @The_Sympathizer Ok. It's related to what happens in Schwarzschild coordinates when a particle crosses the event horizon of a black hole. However, in that scenario, the outside universe is causally disconnected from events inside the event horizon. And we can switch to other coordinates that don't have a coordinate singularity at the event horizon. | |
| Aug 16, 2021 at 23:03 | comment | added | The_Sympathizer | Also, regarding the question, I'd suggest the answer is no because we have not observed such tunnelling. However, it would be very interesting to elaborate on the reasons for why that is. I suspect - but am not knowledgeable enough to say for sure - that it has to do with the same as why an electron can't suddenly "tunnel" into having a mass of 1000 keV, for example, if put in an environment with suitable energy. The mass is a fixed parameter of the quantum field that those particles inhabit. | |
| Aug 16, 2021 at 23:02 | comment | added | The_Sympathizer | @PM2Ring : Imaginary gamma can be understood at least in 1+1 dimensions as exchanging the spatial and temporal axes of the reference frame, i.e. "space becomes time and time becomes space". However, this doesn't work as nice in 3+1 dimensions, so I'm not sure. That said, it only matters if we want to define a "reference frame" for tachyons, versus considering observing them from our own. | |
| S Aug 16, 2021 at 18:47 | history | bounty started | nav | ||
| S Aug 16, 2021 at 18:47 | history | notice added | nav | Canonical answer required | |
| Aug 16, 2021 at 18:46 | history | edited | nav | CC BY-SA 4.0 |
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| Aug 14, 2021 at 16:31 | comment | added | nav | @PM2Ring Thanks for the link. | |
| Aug 14, 2021 at 16:30 | comment | added | nav | @PM2Ring Well, to be honest, I don't have an answer to how such a transition can happen. I can't visualize how an object with imaginary mass would look like or behave; nor guess what would happen to the "real" part of the mass after the transition. What I'm trying to understand here is whether any factor(s) outside relativity (such as QM effects) can play a role on the process and allow anomalous behavior (particularly for very low masses, as I hinted in the question). | |
| Aug 14, 2021 at 16:28 | history | edited | Qmechanic♦ | CC BY-SA 4.0 |
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| Aug 14, 2021 at 16:06 | comment | added | PM 2Ring | But anyway, the problem isn't just that $\gamma\to\infty$ as the particle approaches lightspeed. As your question alludes to, $\gamma$ becomes imaginary for $v>c$. How do you tunnel to such a state? | |
| Aug 14, 2021 at 16:02 | comment | added | PM 2Ring | We prefer to avoid the old concept of relativistic mass on this site. Please see physics.stackexchange.com/q/133376/123208 | |
| Aug 14, 2021 at 15:53 | history | asked | nav | CC BY-SA 4.0 |