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Physicists: Tachyons can be reconciled with the special theory of relativity
- skellington 2y agoObviously.
- pavel_lishin 2y agoWhy is it obvious?
- triclops200 2y agoDoes anyone have access to the linked paper? It's not on scihub.
- PaulHoule 2y agoThere is also an arXiv link https://arxiv.org/abs/2308.00450 https://arxiv.org/abs/2308.00450
- triclops200 2y agoThank you!
- magicalhippo 2y agoPreprint here: https://arxiv.org/abs/2308.00450 https://arxiv.org/abs/2308.00450 (was actually linked in the phys.org article)
- triclops200 2y agoThank you!
- pdonis 2y agoThe article title is somewhat of a misnomer: the issue is not finding a classical SR model of tachyons (it has been known for decades that that can be done), but finding a consistent quantum field theory of tachyons.
- magicalhippo 2y ago> To put it simply: in order to calculate the probability of a quantum process involving tachyons, it is necessary to know not only its past initial state but also its future final state. And from the paper[1]: > Therefore, a Lorentz boost can transform a positive-energy tachyon moving forward in time into a negative-energy tachyon moving backward in time. AFAIK, in Feynman diagrams[2], you also specify the initial and final states, and antiparticles are portrayed as moving backwards in time. Is the similarity just superficial or is there more to it? [1]: https://arxiv.org/abs/2308.00450 https://arxiv.org/abs/2308.00450 [2]: https://en.wikipedia.org/wiki/Feynman_diagram https://en.wikipedia.org/wiki/Feynman_diagram
- sigmoid10 2y agoThese are two very different concepts that you are relating here. A Lorentz boost can transform a tachyon into one seemingly moving backward in time because the tachyon already travelled on an (unphysical) space-like trajectory. In special relativity, any space-like trajectory has no causal order of events, so this is more of a statement how much tachyons would screw up the world of physics if they were real. The paper argues that this can be kind of remedied by introducing a dual space, but this is not relevant here. In Feynman diagrams, all particles travel on time-like (i.e. physical) trajectories. Well, technically not, but there is a fundamental mechanism that cancels out any space-like propagator components. But let's not get into that. Back on topic: there is this neat property of quantum field theory (known as CPT symmetry) that says a positron behaves like an electron moving backwards. This is why you usually see arrows denoting anti-particles pointing back in time. But this doesn't mean that anything is actually travelling backward in time. It just makes certain calculations more tractable because of the way field operators are ordered, but there is nothing fundamentally weird about it like for tachyons.
- magicalhippo 2y agoThanks, appreciate the answer. I expected there wasn't much to it, but sometimes these things go deeper.
- pdonis 2y ago