What if tachyons are detected?

[dendros]

TL;DR Summary

What would happen to current physics if tachyons are proven to be real?

Suppose that tachyons are detected in an experiment and other experiments confirm this discovery so that their physical existence is proven beyond any reasonable doubt.

My question is as per title and I'm asking this because I'm really curious and of course I would be excited if they're discovered because it seems that this would be a very important discovery.
And to be more clear, I'm not only asking about their existence but also the implications of their existence.

At a basic level, I imagine that a new theory, based on further experiments, would be required to be deduced in order to explain their properties and behavior. Would this theory contradict the GR or incorporate it as a special case? How would this affect the current cosmological theories? And so on.

Also, I wonder if they could be used for some technical appplications.

 

[anorlunda]

Summary:: What would happen to current physics if tachyons are proven to be real?

Also, I wonder if they could be used for some technical appplications.

They would be wonderful for sports betting. They could transmit race results back in time to before the race started. Just watch the movie "The Sting," to see the value.

 

[Vanadium 50]

What would happen to current physics if magic is proven to be real?

 

[dendros]

@Vanadium 50: then physicists would become wizards? :)

More seriously, I understand that the existence of tachyons is theoretically possible and from that I was simply asking what would mean for the current physics if they're no longer a theoretical construct but a physical reality - discovered by experiments.

As you know, the Universe does not care about our ideas so if tachyons exist they will exist regardless of what we think about the possibility their existence.

I'm simply curious about the implications of their existence from a theoretical and practical view point.

 

[berkeman]

Also, I wonder if they could be used for some technical appplications.

Since there are no published papers announcing their discovery, there are two possibilities:

1. None of the experiments so far have had positive results
2. At least one of the experiments has had positive results, but for obvious reasons, they have decided not to make the discovery public

I'm not going to be able to make any further comments publicly on this topic. Have a nice day.

 

[.Scott]

More seriously, I understand that the existence of tachyons is theoretically possible and from that I was simply asking what would mean for the current physics if they're no longer a theoretical construct but a physical reality - discovered by experiments.

As you know, the Universe does not care about our ideas so if tachyons exist they will exist regardless of what we think about the possibility their existence.

The problem comes with transmitting information at faster-than-light speeds. If that can be done, a system can be set up to transmit information back in time - hence the allusion to "The Sting" by @anorlunda .

Detecting a tachyon could be problematic. How would you even verify that what you detected was a tachyon? (And @berkeman won't tell - but he says that @Dale will have something to add in less than half an hour.)

 

[Dale]

Since there are no published papers announcing their discovery

But there are plenty of published papers discussing how they would and would not work

 

[sysprog]

They would be wonderful for sports betting. They could transmit race results back in time to before the race started. Just watch the movie "The Sting," to see the value.

That's a well-worth-watching classic movie anyway . . .

 

[Vanadium 50]

My point was that you can't just say "tachyons" and have a fully consistent theory appear out of nowhere. This is a poorly defined question.

 

[dendros]

@Vanadium 50: but where did I say about a "fully consistent theory of tachyons" appearing out of nowhere? All I said was that further experiments would be required in order to elaborate such a theory.

It seems that no one wants to guess what impact would the existence of tachyons have on physics.

 

[Vanadium 50]

but where did I say about a "fully consistent theory of tachyons"

At the very first post. If we had an inconsistent theory of tachyons, how could your question possibly be answered?

You asked a very lazy question. You shouldn't be surprised it is not generating satisfactory answers.

 

[DaveC426913]

Detecting a tachyon could be problematic. How would you even verify that what you detected was a tachyon?

Because you would tell yourself what it was.

"Dear Morning Bob: this is Afternoon Bob. At 3:47EST today, you will discover tachyons."

 

[Dale]

It seems that no one wants to guess what impact would the existence of tachyons have on physics.

Well, that is not exactly true. It isn’t a large body of research, but it is more than “no one”. Here is a paper on tachyons by Feinberg

https://www.relativitycalculator.co..._velocities/possibility_faster_than_light.pdf

 

[PeroK]

Well, that is not exactly true. It isn’t a large body of research, but it is more than “no one”. Here is a paper on tachyons by Feinberg

https://www.relativitycalculator.co..._velocities/possibility_faster_than_light.pdf

Interesting, but hardly a "B" level treatment. That might be the point. At a B level one could say "so what" if tachyons exist. In fact, there was an introductory homework question recently involving tachyons. Perhaps it's only when you get to relativistic QFT that the real questions arise.

 

[Dale]

hardly a "B" level treatment. That might be the point.

True, but the point is that we are being overly dismissive of the question. It is a valid question and has valid answers in the literature. An appropriate answer to the OP would be a B level summary of the issues in such papers, not dismissal and discouragement.

 

[Vanadium 50]

I don't think we are. What changes are necessary depends on the properties of these tachyons. To take an overly simple case, suppose there were tachyons, but they did not couple at all to ordinary matter. No change would be required.

Now suppose they couple only gravitionally to ordinary matter. This is already complicated enough that the possibilities for changes start to branch: it may even be that this requires no changes at all.

If you let tachyons couple to ordinary matter through electromagnetism, you have issues with time travel causality. If you let tachyons couple only through short range forces, you might or might not, depending on which quantum numbers your tachyons carry.

Or, you could dump all of this quantum stuff and declare there to be a preferred frame, not for matter, but for tachyons. That fixes your time travel causality problem.

Or...or...or...

I think the magic analogy is perfectly good (which is why I used it). Are we talking sorcery, or voodoo, or divination, or alchemy, or...

 

[256bits]

I don't think we are. What changes are necessary depends on the properties of these tachyons. To take an overly simple case, suppose there were tachyons, but they did not couple at all to ordinary matter. No change would be required.

Now suppose they couple only gravitionally to ordinary matter. This is already complicated enough that the possibilities for changes start to branch: it may even be that this requires no changes at all.

If you let tachyons couple to ordinary matter through electromagnetism, you have issues with time travel causality. If you let tachyons couple only through short range forces, you might or might not, depending on which quantum numbers your tachyons carry.

Or, you could dump all of this quantum stuff and declare there to be a preferred frame, not for matter, but for tachyons. That fixes your time travel causality problem.

Or...or...or...

I think the magic analogy is perfectly good (which is why I used it). Are we talking sorcery, or voodoo, or divination, or alchemy, or...

That is more than I even knew or thought about tachyons!

 

[Ivan Seeking]

I don't think we are. What changes are necessary depends on the properties of these tachyons. To take an overly simple case, suppose there were tachyons, but they did not couple at all to ordinary matter. No change would be required.

Now suppose they couple only gravitionally to ordinary matter. This is already complicated enough that the possibilities for changes start to branch: it may even be that this requires no changes at all.

If you let tachyons couple to ordinary matter through electromagnetism, you have issues with time travel causality. If you let tachyons couple only through short range forces, you might or might not, depending on which quantum numbers your tachyons carry.

Or, you could dump all of this quantum stuff and declare there to be a preferred frame, not for matter, but for tachyons. That fixes your time travel causality problem.

Or...or...or...

I think the magic analogy is perfectly good (which is why I used it). Are we talking sorcery, or voodoo, or divination, or alchemy, or...

There's a solution of the equations of general relativity called the Aichelburg-Saxl solution, which describes massless black holes moving at the speed of light. There's no experimental evidence that these actually exist, but they're fun to think about nonetheless, since you can use the equations of general relativity to figure out what they would do if they did. – Dr. John Baez

 

[dendros]

@Vanadium 50: I did not ask about the nature of coupling of tachyons to normal matter. I just asked about the implications of their mere existence. That's why this thread is at B level.

But you're right about my first post asking about a fully consistent theory of tachyons out of nowhere. So I apologize for that.

Basically (and at a basic level) I want to know if their mere existence would profoundly change the current physics or not - regardless of how they interact with normal matter or any such details, because this would require a fully consistent theory of tachyons as you say.

 

[Dale]

I posted a paper on tachyons, but I know that there are more and it is not an area of research that I have paid particular attention to. So unfortunately, I cannot summarize or simplify the ideas, because I don't know them well myself.

It might be fruitful for you to search for a few journal papers on tachyons, read the abstracts, and then ask specific questions.

 

[sysprog]

If tachyons become evident (or will have already become evident) that would call for re-evaluation of Prof. Feynman's dismissal of Fatio's - LeSage's collisional theory of gravity . . .

 

[.Scott]

If tachyons become evident (or will have already become evident) that would call for re-evaluation of Prof. Feynman's dismissal of Fatio's - LeSage's collisional theory of gravity . . .

... because there would not be "drag" evident for moving objects.

But tachyons would propagate gravitational waves faster than light.

And you would still need to consider whether the collisions are elastic or inelastic.

If they're elastic, the "gravity" doesn't work because you would get the same number of tachyons scattering out as collided with a planet or star.

If they're inelastic, how do you mix an imaginary mass traveling >c with an ordinary mass at <c?

 

[Curiouser]

If tachyons existed, wouldn't that imply that they have negative mass?

 

[DaveC426913]

If tachyons existed, wouldn't that imply that they have negative mass?

Imaginary mass.

https://en.wikipedia.org/wiki/Tachyon#Mass

 

[elcaro]

What would happen to current physics if magic is proven to be real?

Current physics is - for the undereducated minds - already indistinguishable from magic...

 

[DaveC426913]

Current physics is - for the undereducated minds - already indistinguishable from magic...

What a great quotable turn-of-phrase!

 

[Ivan Seeking]

Current physics is - for the undereducated minds - already indistinguishable from magic...

So we have a complete Theory of Everything? I hadn't heard.

 

[Ivan Seeking]

If you think you understand quantum mechanics, you don't understand quantum mechanics - Feynman

 

[Cooky Monstr]

The answer makes up the plot of the book TIMESCAPE by Gregory Benford. The author is a serious scientist, but this book is sci-fi.