Can Tachyons exist?

  • #1

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Tachyons are hypothetical particles which travel faster than light and some scientists say they have real mass. They violate relativity and causality, are they possible or are they seen as impossible?
 

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  • #2
Vanadium 50
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  • #3
Who?
It is stated on the Wikipedia that modern Tachyon theories use real mass instead of imaginary, and some scientists use real mass, no names are given
 
  • #4
jbriggs444
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It is stated on the Wikipedia that modern Tachyon theories use real mass instead of imaginary, and some scientists use real mass, no names are given
Wikipedia has references. Why not chase the references and give us the names listed there?
 
  • #5
Ibix
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A real-massed object exceeding the speed of light is inconsistent with relativity.

Things travelling faster than the speed of light can allow causal paradoxes in relativity.

Neither of these things mean that real-massed objects exceeding the speed of light are impossible. Relativity would have to be inaccurate in some way, and we haven't seen that yet - but developing competing theories that give the same predictions in domains we've already tested and different ones in domains we could test is one way forwards. How plausible massive tachyon models are, I've no idea - above my pay grade.
 
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  • #9
PAllen
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Reference 7: Is written in French and must be bought to read

Reference 8: https://arxiv.org/abs/1112.4187

Reference 9: http://rspa.royalsocietypublishing.org/content/468/2148/4174

But, I just want to know whether these particles can exist in the first place.
Please look especially at section 10 and later in reference 8. You have to change special relativity to accommodate nonimaginary mass tachyons. Then, no better answer can be given beyond what Ibix provided in #5. Even more briefly:

If conventional SR is true, then real mass tachyons do not exist. Beyond that, we have no evidence for tachyons of any type. Some researchers think there good reason to consider their existence, others do not.
 
  • #10
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Leave causality aside for a moment..any object with mass needs infinite energy to move at speed of light, so the answer is: no it is impossible.
 
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  • #11
jbriggs444
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Leave causality aside for a moment..any object with mass needs infinite energy to move at speed of light, so the answer is: no it is impossible.
That argument forbids a mechanical process that starts with a massive object moving at less than the speed of light and accelerates the object to the speed of light. It does not forbid the creation of particles already moving faster than light.
 
  • #12
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That argument forbids a mechanical process that starts with a massive object moving at less than the speed of light and accelerates the object to the speed of light. It does not forbid the creation of particles already moving faster than light.
I see.. so "creation" of particle with mass at exactly the speed of light is impossible, bypassing the speed of light makes it possible!
But the particle will have negative relativistic mass which makes it non-physical particle, maybe just a mathematical one.
 
  • #13
PAllen
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I see.. so "creation" of particle with mass at exactly the speed of light is impossible, bypassing the speed of light makes it possible!
But the particle will have negative relativistic mass which makes it non-physical particle, maybe just a mathematical one.
Within SR, a tachyon will have imaginary mass, but positive energy. There are SR violating theories of positive mass tachyons, see references earlier in this thread. These theories try to match all known tests of SR. I suspect the number of physicists who think this has anything to do with reality is rather small
 

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