Are Tachyons Just a Science Fiction Dream?

[wolram]

http://www.physics.gmu.edu/~e-physics/bob/n.htm

Ask most physicists about tachyons, however, and you'll be told that they belong strictly in the realm of science fiction. That skepticism is understandable, since nearly all experiments searching for tachyons have so far turned up negative. Even worse, according to some physicists, if tachyons exist, they could be used to send messages back in time. Nevertheless, over the years a few physicists have held out hope that tachyons might actually exist --possibly disguised as some other known particle.
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im not sure if this is the correct place for this post, but as
the tachyon crops up in many documents with wide implications
why not?
anyway if the above is correct, why are so many documents
published about or including tachyons, when it seems very
few physicists think they exist?

 

[selfAdjoint]

Your source is just incorrect, or maybe behind the times. String physics has lots of tachyons. I just did a search on the high energy physics preprint arxiv for the years 2000 to present, for any paper that mentioned tachyon in its abstract. There were 626 papers that did.

The use of tachyons to violate causality is just one shortcoming they have. Within string physics they cause the vacuum to collapse, a very undesirable, as in fatal for the universe, thing.

 

[wolram]

From Wikipedia, the free encyclopedia.


A tachyon is a hypothetical particle that travels at superluminal velocities. Many strange properties have been attributed to tachyons, mainly by science fiction authors.

In the language of Einstein's theory of special relativity, a tachyon (were it to exist) is a particle with space-like four-momentum. If its energy and momentum are real, its rest mass is imaginary. It is doubtful if an imaginary mass is physically meaningful.
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yes i agree there are lots of papers on the tachyon, but they
mostly involve string theories, outside string theory there
seems to be a lot of skeptisism about ther existence.

 

[NateTG]

I don't know how valid this is, but it has been suggested that tachyons would generate Cherenkov radiation. Since this radiation has not been observed, poeple generally think that tachyons do not exist.

A problem is that the notion of tachyon refers to anything traveling faster than the speed of light, so there may be tachyons that do not generate cherenkov radiation, and thus may exist.

 

[suyver]

Originally posted by NateTG
I don't know how valid this is, but it has been suggested that tachyons would generate Cherenkov radiation. Since this radiation has not been observed, poeple generally think that tachyons do not exist.

I'm sorry, but I think that this is wrong: Cherenkov radiation has been observed many many times and is (to my knowledge) not related to tachyons at all. It is simply emitted when a (charged) particle travels faster than the speed of light in the medium. For example: the blue light emitted from the uranium-core in the water-bath of a nuclear powerplant is Cherenkov radiation.

Also, this radiation is used in high-energy physics detectors: http://cosray2.wustl.edu/tiger/science/instrument/cherenkov/.

 

[wolram]

http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/tachyons.html

You can now deduce many interesting properties of tachyons. For example, they accelerate (p goes up) if they lose energy (E goes down). Furthermore, a zero-energy tachyon is "transcendent," or infinitely fast. This has profound consequences. For example, let's say that there were electrically charged tachyons. Since they would move faster than the speed of light in the vacuum, they should produce Cherenkov radiation. This would lower their energy, causing them to accelerate more! In other words, charged tachyons would probably lead to a runaway reaction releasing an arbitrarily large amount of energy. This suggests that coming up with a sensible theory of anything except free (noninteracting) tachyons is likely to be difficult. Heuristically, the problem is that we can get spontaneous creation of tachyon-antitachyon pairs, then do a runaway reaction, making the vacuum unstable. To treat this precisely requires quantum field theory, which gets complicated. It is not easy to summarize results here. However, one reasonably modern reference is Tachyons, Monopoles, and Related Topics, E. Recami, ed. (North-Holland, Amsterdam, 1978).
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i think it is correct to say that tachyons have been searched
for by looking for cherenkov radiation.

 

[suyver]

Originally posted by wolram
i think it is correct to say that tachyons have been searched
for by looking for cherenkov radiation. [/B]

OK, now I understand: they search for Cherenkov-radiation in vacuum, which would be a proof / hint of tachyons. Any results on that yet? I misread NateTG's post as suggesting that tachyons are the particles that 'make up' Cherenkov radiation. My mistake. me =

 

[wolram]

tachyons are one of a host of ghostly particles that
theorists enjoy fantasising about, as far as i know
no evidence has been found to support there existence.