Talk:Tachyon/Archive 1

Untitled
Tachyons arise in many versions of string theory.

Could tachyons be gravitons?

I think it appear only in the bosonic string theory?? no? --Pascal Gauthier 09:22, 14 Mar 2007 (UTC)

Does anyone want to clarify this sentence? It is very confusing with the double negatives.


 * "It is not generally realised that if a tachyon were to exist and were allowed to interact with ordinary (time-like) matter, causality would not be violated" Muaddib131 23:44, 21 November 2006 (UTC)

Tachyons is theorized to exist in universes with extra time dimensions. A universe with 1 space dimension and 3 time dimensions are comprised of only Tachyons.

Could anyone add a link to the name for particles at sub-luminal speeds? I forgot what the name was. -- Redge 11:54, 13 Jun 2004 (UTC)
 * Baryons? Normal matter? Everything? 199.172.246.196 18:37, 6 July 2007 (UTC)
 * Tardon --Michael C. Price talk 22:47, 6 July 2007 (UTC)
 * The uncommon and not-so-well-known term is "tardon". Sounds like it could be the punchline to a joke .... Rotiro (talk) 21:18, 11 February 2008 (UTC)


 * A tachyon might be a magnetic monopole. Many theoretical searches for magnetic monopoles have concluded they may not exist thanks to them breaking multiple physical laws (conservation of energy for one). It seems fashionable to attribute to tachyons anything proven to be impossible.

Can anyone verify this? I removed it as it sounds highly dubious to me; in any case, it is too vague.

We might also need discussion about the wave front effect, virtual particles, and how exactly causality is violated if tachyons exist (which might as well go into the causality link.)

-- CYD

Hmmm... yes, it's a bit like saying "A unicorn might be like a fairy"... one fanciful thing being compared to another. Losing it doesn't hurt the article - good call. - MMGB

You MIGHT have magnetic monopoles which are also tachyons, but it's even closer to say that you might have unicorns which are also infrared. -- CIM --- I think the subject of tachyons is a rather delicate matter, more delicate than perhaps this article presents. That is, I changed "hypothetical" to "theoretical," in an attempt to distinguish between the theory and practice without the ladened hyperbole' (is that a fair description?). It seems to me that tachyons are quite a bit deeper than "fanciful things," where their existence may even end up being necessary in order to explain any number of real phenomena (see entanglement).

http://arxiv.org/abs/hep-ph/9905454

I am considering revamping this page a fair amount.

I look quite favorably upon the existence of magnetic monopoles simply because they lead to quantization of charge. I wasn't aware that they necessarily violated any laws of physics though. 142.161.183.184 06:22, 21 April 2006 (UTC)Matt

Considering that superpartners and even the Higgs are currently hypothetical particles, this adjective implies no opprobrium. If a particle exists "real" or "physical"; if it doesn't it's "fictional" or "unphysical"; if we don't know yet it's "hypothetical". In fact, "theoretical particle" is an oxymoron, because theories are made of ideas, not particles. "Theoretical particle physics" is not the physics of theoretical particles!

It should be said rather strongly that the hypothesis that tachyons exist as particles, and are able to interact with ordinary matter, is very hard to entertain, unless you throw away one of the main principles of particle theory. It would introduce logical paradoxes, that is self-contradictions, unless supplemented by some clever principle which no-one has yet been able to incorporate in a coherent way.

As of now there is no compelling, or even half-compelling, reason to try. Quantum entanglement does not require tachyons, since no energy or information is exchanged faster than c. The paper cited above from the 'arxiv' is on "superbradyons", not strictly tachyons, and is highly speculative. All the references are to the author's own previous work, i.e. no-one else works on this.

Also, the (now removed) link to Florentin Smarandache does not illuminate the topic, as far as I can see, since that page does not mention tachyons. However, see http://scienceworld.wolfram.com/physics/SmarandacheHypothesis.html.

Tdent 19:00, 13 May 2004 (UTC)

George Sudarshan
I nixed the comment in the introductory paragraph about George Sudarshan. I hate to play the card-carrying obnoxious physicist, but any remark like "is considered to be" is weasel terminology. The only reason it could belong in the introduction is if a fuller description followed below, with proper citations to both original journal articles and later retrospectives.

A couple months ago, an anonymous user (82.68.88.6) added a similar comment, "Discovery of tachyons is attributed to Indian scientist George Sudarshan who was nominated for the Nobel Prize six times." IMNSHO, this sounds like gushing from a partisan supporter&mdash;never mind that we shouldn't speak about the discovery of a hypothetical particle. The article on Sudarshan himself seems similarly toned; a good POV shakedown may be in order.

Anville 17:04, 17 Mar 2005 (UTC)


 * Sudarshan is back. This time, it's thanks to anon IP 80.0.191.52.  Please!  Is a single bibliographic citation too much to ask? "Tachyons were first proposed by physicist Arnold Sommerfeld, and named by Gerald Feinberg" .  What did Sudarshan contribute to the theory?  If his name is important enough to be mentioned in the lead, he deserves a paragraph or two down below!  Anville 15:11, 14 October 2005 (UTC)


 * Sudarshan seems to be real:
 * http://scholar.google.com/scholar?q=Sudarshan+tachyon
 * Perhaps the first treatment in quantum field theory.
 * Some followup is required.
 * Of course being nominated for the Nobel prize is such an obscure achievement (because of the large and very inhomogenous group able to nominate), that it never ever should be mentioned in any Wikipedia article.
 * Pjacobi 21:02, 14 October 2005 (UTC)


 * He's definitely real; he even pops up in Surely You're Joking, Mr. Feynman!, thanks to his work on the weak nuclear force. There might be, now that I think about it, a few cases where nominations for the Nobel are actually significant: a person who is nominated several times and eventually wins; a person who is nominated for work shared with others, but because no more than three people can split the award, receives nothing (a bit like Freeman Dyson's role in QED); a person who looks like a shoe-in but dies too soon (e.g., Henry Moseley).  None of these categories apply to the present situation, of course.  Anville 10:52, 15 October 2005 (UTC)


 * It's a little disturbing, as someone from the field, when i read comments about the reality of someone
 * like Sudarshan; a man who has contributed alot to physics. I'm pretty sure he didnt "discover" the
 * physics community. I know he is not known in the general audience (who is except maybe Newton & Einstein)
 * but as people at least knowledgable in physics, its sad to see him not given any credit. by the way, i agree ::::with the removal of sudarshan in the introduction of this topic --Blckavnger 21:56, 15 November 2006 (UTC)

HAHA! This is what I'm talkin' about! This was clearly written with the layman in mind, not like the other incomprehensible mathematical garbage floating around Wikipedia. I salute the author/editor!70.25.138.179

What happened to Feinberg? If he named the tachyon (I've heard he "invented" it...), shouldn't he be mentioned? Trekphiler 12:35, 18 December 2005 (UTC)

Reverted
Yikes! A pre-print from 2005-12. Let's wait for some comments on this, before claiming a revolutionary breakthrough.
 * http://en.wikipedia.org/w/index.php?title=Tachyon&diff=32225280&oldid=32175239

Pjacobi 12:42, 21 December 2005 (UTC)


 * If I don't see an argument brought forward, I'll simply keep reverting. --Pjacobi 19:11, 27 December 2005 (UTC)


 * Reverted back and this removed "Another significant paper appeared recently (December,2005) when Aasis Vinayak.P.G propossed his new paper, 'physics/0511253' , on tachyons with which he is trying to prove that they will have real mass . The paper is a very revolutionary one also." Paper, unrefereed and not peer reviewed, is here; http://www.wbabin.net/science/vinayak.pdf. Probable self-promotion. Alex 15:16, 21 January 2006 (UTC)

This is paper ('physics/0511253’) is basically from the Cornell University Authorized website. www.wbabin.net - might have just lifted the paper. All the submissions here, University Online Library, are up to the university academic standards. The paper is a very revolutionary one itself. Those who are commenting here may first go through the paper. The university will never publish one paper with out the recommendation of an eminent person from the same field. The paper is available at arxiv.org - Dr. Ravi


 * Please see http://en.wikipedia.org/wiki/Wikipedia:Reliable_sources; and I quote; "Cite peer-reviewed scientific journals and check community consensus". Also http://en.wikipedia.org/wiki/Wikipedia:No_original_research under What is excluded?; "An edit counts as original research if it proposes ideas or arguments." http://www.arxiv.org clearly states "appearance of a paper is not intended in any way to convey tacit approval of its assumptions, methods, or conclusions" and that the only criteria for publishing a paper is endorsement; "The endorsement process is not peer review." You may also wish to note the original reverter's comments; the paper is far too new to have met any of these criteria. Alex 15:59, 22 January 2006 (UTC)

Maxwell Planck
Now I was told by a friend, who goes by "The basement man" that the only way to survive the comubstion etc. of a tachyon particle would be throuhg means of black body radiation. Now, is black body radiation truly possible, or is it just another theory? hit me up at, thanks.

http://www.xanga.com/LeUntouchable_xx

suggestions for current revision
I have two points to make about the current revision, particularly the portion that addresses the theoretical scientific framework behind tachyons:


 * The section that discusses tachyons from the point of view of Special Relativity: right now that section more or less starts off with imaginary rest mass and then work from there to v (velocity) being superluminal.  While there's nothing factually wrong per se about it, the presentation seems somewhat backwards; I think it would be more logical to start off with v being superluminal and then show how that implies the rest mass would be imaginary in order for momentum and energy to be real.  I would guess that's how the presentation goes in original papers in physics discussing tachyons, though admittedly I don't have any at hand to properly back myself up. Assuming no objections, maybe if I have more time I will attempt to do a rewrite myself.  Note that this is just purely a matter of the flow of information in the section; I'm not proposing to add or delete any information.
 * The Causality section's first paragraph currently ends with the sentence:   At the very least the principle of special relativity would have to be discarded. I believe that sentence is erroneous.  Indeed it is almost contradictory since one section ago, we just discuss the foundation of tachyons in the framework of Special Relativity itself!  The main issue here is that tachyons can violate the principles of causality.  But if I recall correctly, special relativity doesn't require causality per se; causality is more a principle that physicists generally believe to be true, but is otherwise independent of the framework of special relativity. Thus I marked that sentence with a "citation needed" tag.  If the sentence is fully accurate a citation from a reliable source shouldn't be too hard to find. Otherwise, please remove and/or revise that sentence.24.16.27.166 04:23, 6 June 2006 (UTC)

I think there is a serious deficiency in this section. Tachyons, despite travelling FTL, do not violate causality because they can't be used to transmit information, due to the Gerald Feinberg reinterpretation principle. I'll dig out a reference and rewrite accordingly soon. --Michael C. Price talk 21:27, 28 June 2006 (UTC)


 * Section rewritten with reference to the Feinberg reinterpretation principle. --Michael C. Price talk 19:22, 4 July 2006 (UTC)

I accept the current version. However, if we express all equation in four dimensional form, we do not need to use imaginary numbers. We can start with Lagrangian (§7.2, Gravitation (1973). W. H. Freeman, ISBN 0-7167-0344-0)
 * $$L = \frac{m}{2}\left( \left( \frac{dt}{d\tau }\right)

^{2}-\left( \frac{d\mathbf{x}}{d\tau }\right) ^{2}\right) + e\left( \varphi \frac{dt}{d\tau }-\left( \mathbf{A\cdot }\frac{d\mathbf{x}}{d\tau }\right) \right) +...$$ then we can choose
 * $$\left( \frac{dt}{d\tau }\right) ^{2}-\left( \frac{d\mathbf{x}}{d\tau }

\right) ^{2}=+1$$ for regular particles or tardyons
 * $$\left( \frac{dt}{d\tau }\right) ^{2}-\left( \frac{d\mathbf{x}}{d\tau }

\right) ^{2}=-1$$ for tachyons Since 3D velocity is
 * $$\mathbf{v}=\left( \frac{d\mathbf{x}}{dt}\right) =\left( \frac{d\mathbf{x}

}{d\tau }\right) /\left( \frac{dt}{d\tau }\right) $$ then velocity time component
 * $$v_{0}\equiv \gamma _{tardyon}=\left( \frac{dt}{d\tau }\right) =\frac{1}{\sqrt{1-

\mathbf{v}^{2}}}$$
 * $$v_{0}\equiv \gamma _{tachyon}=\left( \frac{dt}{d\tau }\right) =\frac{1}{

\sqrt{\mathbf{v}^{2}-1}}$$ Energy
 * $$E_{tardyon}=\frac{m}{\sqrt{1-\mathbf{v}^{2}}}$$
 * $$E_{tachyon}=\frac{m}{\sqrt{\mathbf{v}^{2}-1}}$$

And Lorentz transformation for tachyons can be written as
 * $$x^{\prime }=\frac{1}{\sqrt{v^{2}-1}}\left( xv-t\right) =\left(

x\sinh \beta -t\cosh \beta \right)$$
 * $$t^{\prime }=\frac{1}{\sqrt{v^{2}-1}}\left( tv-x\right) =\left(

t\sinh \beta -x\cosh \beta \right)$$ I've used these transformations to make the tachyon image. --TxAlien 02:00, 6 September 2006 (UTC)


 * And a pretty awesome image it is, too! -- Grey Knight  ⊖  20:52, 17 November 2006 (UTC)

bit of nonsense
This sounds like noncense: "Tachyons (if they existed) could be used to transmit energy-momentum, but they can't be used for communication." By shannons law if you transmit energy you transmit information. Think about it: just modulate if and when, or how much energy you send, and you automatically send information. Ariel. 11:39, 8 November 2006 (UTC)
 * I agree it sounds like nonsense, but it isn't. I swear it's taken from Feinberg's article.  Do a goggle on the "Feinberg reinterpretation principle".  --Michael C. Price talk 14:38, 8 November 2006 (UTC)
 * To directly address the communication issue: yes you could modulate a signal and send it back in time, but the receiver would detect both your signal and an undesired background signal, which would drown out the information. I've attempted to explain this in the article -- it probably needs more explanation.  --Michael C. Price talk 10:26, 13 November 2006 (UTC)
 * So, you couldn't tell whether or not a signal was sent or not?--RLent (talk) 15:50, 16 January 2008 (UTC)

Scalar Fermion?
I would like to challenge the bit about tachyons as scalar fermions. I'm not familiar with Feinberg's work(and I can't access those journal articles right now to check it out), but this seems quite incongruous with things that I understand quite well. Consider the Higgs field near the maximum of its potential. This field is tachyonic but the quantization is performed using commutation relations. If it were fermionic, one would quantize by introducing non-trivial anti-commutators. So could someone explain to me what the passage in the text means? Maybe there is confusion with the term ghost field; these are fields which satisfy the wrong spin-statistics relation.
 * I was wondering about the Higgs angle, but don't really know enough to comment more. Re the scalar fermions, that's definitely how Feinberg presents it: he says the Lorentz group has no finite dimensional rep for imaginary mass (something I dimly recall from my college days) hence we are dealing with scalars.  The Lorentz transform may switch the annihilation and creation operators in the commutation relation, which voids it: hence we are forced to use anti-commutation relations, which are preserved by an arbitrary LT.  Hence scalar fermions.  --Michael C. Price talk 00:48, 14 November 2006 (UTC)
 * OK, I looked into the Feinberg paper some and he does in fact make the claim that tachyons are scalar fermions. There is something funny about this however. It may be true from some standpoint, but it certainly does not hold up in field theory(see the Higgs mechanism). My understanding is that it has to do with first quantization in special relativistic quantum mechanics(not QFT). This could easily lead to problems since special relativistic quantum mechanics is sort of an incomplete description anyway. I think it should be made clear in the text that although "tachyons are scalar fermions" may follow in special relativistic quantum mechanics, it in no way holds in quantum field theory. Again, the canonical example is the Higgs mechanism but there are others. Joshua Davis 19:02, 14 November 2006 (UTC)
 * I don't entirely follow this: the scalar fermion conclusion looks like a product of QFT analysis: it appears in Feinberg section 4: Quantum Field Theory of Noninteracting Tachyons. Perhaps the Higgs field operators anti-commutate near the local Higgs maxima (at Higgs = 0), whilst the Higgs-Goldstone boson field operators commutate near the local minima?  --Michael C. Price talk 21:13, 14 November 2006 (UTC)
 * That is certainly not how I understand commutation relations to work. Such relations are constraints on operators and are not functions of the expectation values of those operators. I don't know the resolution of this but I'm strongly skeptical of Feinberg's claims. Besides the comparison with the Higgs, I can give another example of apparent incongruity. Part of the reason why he claims that one must use anti-commutators is that there are unitary transformations which switch creation and annihilation operators. But this is common when one studies Bogolubov transforms, which are used to describe Hawking radiation and cosmological particle production and there is never any mention in those contexts of the need to change statistics. It could be that these issues were worked out after this Feinberg paper. I will need to look into it further before I can make a definite conclusion. Joshua Davis 05:37, 15 November 2006 (UTC)
 * Thanks for the Bogoliubov transformation pointer, but it defines them in terms of preserving the CCRs/CARs, whilst Feinberg shows that we have to drop this requirement. Ergo we would probably have to look beyond Bogoliubov transformations in the Higgs/Goldstone case.  Feinberg's claim of the existence of unitary operators (that correspond to Lorentz transformations that flip the sign of a tachyon's energy) seems pretty well founded. --Michael C. Price talk 10:32, 15 November 2006 (UTC)

Language please
"In special relativity, while it is impossible to accelerate an object to the speed of light, or for a massive object to move at the speed of light, it is not impossible for an object to exist which always moves faster than light."

Not being up on this subject and just skimming through to get a gist of this subject. I'm no expert, but this makes little sense to a reader.

"not impossible" is a double negative. Double negatives don't help understanding. Should be "is possible". Then I have a problem because these are hypothetical particles with imaginary mass and have never been detected (I guess). Shouldn't this then read ...

"In special relativity, while it is impossible to accelerate an object to the speed of light, or for a massive object to move at the speed of light, theroetically it is possible for an object to exist which always moves faster than light."

However, this sentence is vague as well. It leaves the reader confused imho because how can a particle get to this point? The confusion arises because to get to superliminary speeds would seemingly be impossible from a subluminary speed. The particle would have to be created at FTL speeds. Therefore it should say so (or have I assumed too much)?

'''"In special relativity, while it is impossible to accelerate an object to the speed of light, or for a massive object to move at the speed of light, theroetically it is possible for an object to exist which always moves faster than light provided it was created at superliminary speed.""

Candy 08:06, 3 December 2006 (UTC)

Energy-momentum relation
The energy-momentum relation given in this article is incorrect, I have corrected it without changing any of the other mathematics on the page. If there are any inconsistencies that crop up from this I apologise... but really it should have been correct in the first place.

$$E^2 = p^2m^2 + m^2c^4 \;$$

changed to

$$E^2 = p^2c^2 + m^2c^4 \;$$

-- Jheriko (talk • contribs) 11:21, 6 December 2006 (UTC)
 * Thanks -- bit of a typo there on my part. And it shouldn't cause any inconsistencies since that is what I'd meant to say. --Michael C. Price talk 12:32, 6 December 2006 (UTC)

Thanks. I was a little worried that by changing those lines I might have broken some other maths later...

-- Jheriko 17:32, 6 December 2006 (UTC)

Existence: Proven/Disproven vs. Shown?
Some time ago, I added a sentence to the first paragraph

which was later changed to

According to the author, this change was because "it is not up to scientists to disprove the existence of tachyons". I only partially agree with this: if tachyons don't exist, it may be possible to come up with physical/mathematical proof of their nonexistence (i.e., a contradiction in existing laws of physics as yet undiscovered). I think it's important to point out that tachyons have never been shown to exist, but that their existence has never been explicitly ruled out either. How should it be worded? Sloverlord 12:33, 30 December 2006 (UTC)
 * I would say revert to your original statement. If it isn't up to scientists to disprove the existence of tachyons, then whose job is it? Mike Peel 17:35, 30 December 2006 (UTC)
 * Very well. Statement reverted. Sloverlord 21:29, 22 January 2007 (UTC)

Rearranging E-p relation
What is the justification for moving the mass term to the other side of the equation? It seems to be arbitrary, just so you can get a real mass. Why should we expect any particle to obey a different energy-momentum relation? Also, although I don't seem to know as much about tachyons as some people on this page, I'm going to add a sentence about the implication of a theory predicting tachyons and the "physicalness" of tachyons, to the best of my knowledge. Please clarify it if I'm wrong. Rotiro 09:58, 14 March 2007 (UTC)
 * It is rearranged just so that we get a real mass. But it's not a different equation, it's the same equation, just with m'=im, which is why we expect the "new" equation to be obeyed by tachyons.--Michael C. Price talk 10:09, 14 March 2007 (UTC)
 * Okay, so this does not really help the imaginary mass issue. Tachyons still have imaginary mass, as understood by the usual E-p relation. Arbitrarily putting m' = im just hides the imaginariness. Right? In this case, I don't really see the point of such re-arrangement. It seems to me that we are just trying to make ourselves happy by pretending the mass is real, but it doesn't change anything. Rotiro 10:28, 14 March 2007 (UTC)
 * There's no pretence going on, since the underlying dynamics is unaltered by the rearrangement. PS I don't agree with your "physicalness" of tachyons statement.  The whole point of Feinberg and others was that tachyons could exist.  That we don't see them is another issue (we don't see a lot of things that could exist.) --Michael C. Price talk 10:26, 14 March 2007 (UTC)


 * Yes, the dynamics are unchanged. So you're saying that if we interpret tachyons as obeying the usual E-p relation we would view them as having imaginary mass, but if we interpret them as obeying the re-arranged relation, we would not view them as having imaginary mass. Just like how we interpret particles going backward in time (which we can't understand easily) as anti-particles going forward in time. Okay, I think I understand that. If this is correct, maybe it should be in the article - the particle/antiparticle analogy is useful to understand the real/imaginary mass. Re: unphysicalness - If the tachyon mass is imaginary, then that's obviously unphysical. But if it were interpreted as real, as above .... Hmm. Well, I thought the presence of tachyons sounds the death knell for a theory, isn't that right? As mentioned in tachyon condensation. Rotiro 10:40, 14 March 2007 (UTC)
 * Yes, but only because we don't observe them, not because they're impossible. Also tachyons imply there would exist no stable lowest energy state vacuum -- again not impossible, but not observed.  I'll add a few words to the article later today. --Michael C. Price talk 11:28, 14 March 2007 (UTC)

Hi, Rotiro asked me to look at the recent edits and comment on this discussion. Tachyons are kind of a funny subject but if thought of properly do not "doom" a theory or demonstrate inconsistency per se. It is best not to think of them as particles in the classical(or even first quantized) sense; this may in fact be inconsistent, I am not sure. But it is certainly consistent when you consider them as waves, or quanta of a field. Waves often have complex components to the energy; this just means that there is some exponential growth or decay as well as the oscillation. Recall waves propagate like $$e^{i E t}$$ so a complex energy means this isn't just a phase but rather grows or decays in time. In classical electrodynamics, when light propagates through some medium, the signal decays as the medium absorbs energy from the wave. But sometimes a system is unstable and a certain mode will increase with time. In field theory, this occurs with the Higgs mechanism. In that case, the potential is not simply quadratic and actually has a minimum. The field has the standard E-p relation at the top of the potential. This is unstable since the mass is imaginary and this mode will grow exponentially. But as it grows, one must take into account higher-order effects in the field magnitude and the E-p relation is no longer the simple quadratic one. This tames the exponential growth and makes the field settle to the minimum of the potential. There one can use the standard E-p relation again, but it now has real mass.

So the upshot, is that tachyons themselves are not signs of inconsistency, just instability. But if the instability is never tamed(if the field keeps growing exponentially) then it will become singular and then presumably inconsistent. Hope that helps. --Joshua Davis 20:55, 14 March 2007 (UTC)

I see, thanks guys. Rotiro 02:58, 18 March 2007 (UTC)

Deleting a link
I have deleted a link to an unpublished article very different from scientific concensus. Dan Gluck 18:57, 20 July 2007 (UTC)

Adding a section
It would appear that many people believe the Sudarshan particles (imaginary mass particles) might someday be shown to exist. This web page almost implies that they actually do as of today because it spends time writing about a model that has yet to agree with experiment. So I added a note to point it out clearly and in so many words, that even after 45 years, this model (like string theory) has produced absolutely nothing! Period!!! If anyone has any evidence that these things exist, I would like certainly like to know about it. Finally, it was my link that Dan Gluck deleted on the assumption that the article was unpublished. In fact, it has been published. (See my Wikipedia user account with user name Ernstwall.) Ernstwall I have no desire to get into a tourney of urination, but Dan has stated in no uncertain terms in his user account that he doesn't want to argue with "nobodys". I trust after reviewing my summary of my background he will not consider me to be a total nobody (maybe just a partial nobody?). Also, does pointing out the obvious fact, in no uncertain terms, that playing with the Sudarshan particle is at a dead end, violate Dan's "scientific consensus" or is it "scientific consensus" that these things exist? —Preceding unsigned comment added by Ernstwall (talk • contribs)


 * The above is pure synthesis and original research. The Higgs field captures many of the properties of tachyons; so, yes, "(imaginary mass particles) might someday be shown to exist". Statements like "the model was based on the naive assumption that the Lorentz transformation, which is based on subluminal measurements, could be applied to the hyperluminal domain" show your utter detachment from reality.  The Lorentz transform is a property of space-time and thence of all its contents, no matter whether field or particle, sub- or super-luminal. --Michael C. Price talk 01:44, 21 July 2007 (UTC)


 * Michael - why do you claim that tachyons can exist in quantum field theory? What can exist is a field whose quanta at the approximation around some point is tachyonic, such as the Higgs expanded around zero VEV, but no tachyon particle is possible in quantum field theory. Dan Gluck 18:15, 21 July 2007 (UTC)
 * I meant of course that tachyon particles do not exist, while tachyonic fields certainly do. Dan Gluck 20:58, 21 July 2007 (UTC)
 * For every field there is a particle -- except that for the tachyons the particles are non-localisable, as Feinberg showed.--Michael C. Price talk 13:25, 22 July 2007 (UTC)


 * I am delighted by the fact that my intimidating remarks have been successful. Anyway, Ernstwall, what I meant was that your article to which your linked is very non-concensussial. Furthermore, by linking to it you do not follow the WP:NPV guideline. Therefore the deletion is justified. Dan Gluck 18:15, 21 July 2007 (UTC)
 * By the way the deletion of the link is unrelated to the deletion of the paragraph regarding the Sudarshan particle. In my (not so humble as you've noticed) opinion, this particle is totally unnotable today, since the modern view of the subject is that tachyon particles cannot exist, so it does not even deserve a paragraph stating that it has no experimental evidence. The article currently simply states that according to the modern view (i.e. quantum field theory) tachyon particles cannot exist. Tachyonic fields do exist, but no corresponding particle does, as is explained under the relevant section dealing with modern interpretation via quantum field theory. Dan Gluck 20:58, 21 July 2007 (UTC)
 * The new section does not explain why tachyons do not exist, but rather why they are unstable. It is not true that they don't exist because their existence would violate causality -- Feinberg's QFT treatment still maintained the CCRs for QFT and the vanishing of the anticommutator of spacelike-separated field operators.--Michael C. Price talk 13:41, 22 July 2007 (UTC)


 * Hi Michael. The new section explains why the modern concept of particles does not allow tachyon to exist as particles. This is not because their existence would violate causality, but because a particle is defined asymptotically, meaning that it has to exist long enough to be measured. While Feinberg's treatment is legitimate, it does not state that particle tachyons exist, in the modern sense (explained in the reference I have given, for example, - Peskin and Schroeder, which I'm sure you know, chapter 7). Dan Gluck 16:34, 22 July 2007 (UTC)


 * Hi Dan, I don't think we disagree about the physics, just best way of expressing it. I don't buy the "defined asymptotically" argument since that would still permit the existence of virtual tachyons appearing as particles in Feynman diagrams.  Also I thought it was a bit cruel to present the Feinberg work as merely a suggestion, yet the next paragraph was presented with absolute certainty -- so I toned it down.  :-)--Michael C. Price talk 06:14, 25 July 2007 (UTC)
 * Yes it was a bit cruel, but as someone who's used to much worse articles, it wasn't that bad... anyway I can live with the present form of the article. My only fear is that people won't understand that all the science fiction stuff about moving faster than light is totally fictitious (according to our present understanding bla bla), because I'm not sure we emphasize that enough. That's why I made the "do not exist" statement in bold letters. Maybe there's another way to emphasize that, or maybe it's already clear. I don't know. Dan Gluck 07:09, 25 July 2007 (UTC)
 * moving faster than light is totally fictitious -- not so sure about the "moving" part; that's what the Feinberg was all about, but I totally agree that information can't be transmitted FTL and that causality is preserved. That's the part I've been trying to emphasize.  As physicists we have grown used to spacelike propagators in QFT.  Virtual tachyon particles seem like a pretty mild extension of this.--Michael C. Price talk 07:40, 25 July 2007 (UTC)
 * I meant in the layman meaning, i.e. a person moving faster than light. Perhaps you're familiar with Arthur C. Clark's ridiculous statement that spaceships may be able to move faster than light in the future, because we already know that there are particles that do that - the tachyons. Since Wikipedia is meant not only for physicists but also for the lay person, it should be emphasized that such things are not possible.Dan Gluck 11:34, 25 July 2007 (UTC)
 * Just saw your last edit and I'm satisfied with that, except that I'm changing the "FTL" acronym to "faster than light". Dan Gluck 11:37, 25 July 2007 (UTC)

Tachyon condensation
I suggest we delete all but the first paragraph of "Modern interpretation: Quantum field theory" and move any non-duplicated material over to Tachyon condensation.--Michael C. Price talk 21:11, 31 July 2007 (UTC)
 * I object. Tachyon condensation should deal with tachyonic fields as a sign of instabilities (note that its' tachyonic fields, not non-tachyonic!). Tachyon should deal with why the tachyon under modern interpretation should not be considered as a particle in the usual sense. Dan Gluck 07:27, 1 August 2007 (UTC) 07:27, 1 August 2007 (UTC)
 * I accept the distinction, but most of the content of "Modern interpretation: Quantum field theory" is duplicated at Tachyon condensation. Can you please remove it?--Michael C. Price talk 08:21, 1 August 2007 (UTC)
 * I'll look at both articles and see what belongs where. Some stuff may appear twice, if it contributes to both articles. Dan Gluck 13:01, 1 August 2007 (UTC)

I've adapted the title of the causality section to conform with the condensation section. Perhaps the "Modern Interpretation" prefix is superfluous for both sections, or we could make both subsctions of s "quantum field theory" section.. --Michael C. Price talk 15:39, 14 November 2007 (UTC)

Diagrams of tachyons
Can anyone please tell me which way the tachyon is to be perceived as moving in the diagrams ? In the second diagram which is the arriving view and which the departing view ? Many thanks.Oharrez 10:41, 6 August 2007 (UTC)Oharrez


 * I don't understand the diagram. Dan Gluck 12:06, 6 August 2007 (UTC)
 * The grey shape is the where the moving FTL sphere actually is. The coloured object that splits in two is what we see (the colours represent the doppler shift).  The description needs expanding. --Michael C. Price talk 13:05, 6 August 2007 (UTC)

Thanks for coming back. However you haven't answered the question in layman's terms; I am not a scientist so don't understand doppler. I just want to know whether the left-hand side ( or the right-hand side ) is the arriving view. Then I can deduce that the other -hand is the departing view. It's a fascinating diagram, it would be a pity to remove it. Much better to explain it, this is after all a layman's encyclopedia. Many thanks. Oharrez 20:27, 6 August 2007 (UTC)Oharrez


 * I agree, improve don't delete. Anyway I think I "get" the diagram now.  The right hand bluish shape is the image formed by the light arriving at the observer -- who is located at the apex of the black lines -- from the FTL sphere as it approaches.  The left-hand reddish image is formed from light that leaves the sphere after it passes the observer.  Since the object arrives before the light the observer sees nothing until the sphere starts to pass the observer, after which the image-as-seen-by-the-observer slowly splits into two -- one of the arriving sphere (to the right) and one of the departing sphere (to the left). --Michael C. Price talk 23:04, 6 August 2007 (UTC)

Thank you for the explanation and the improved caption to the diagrams. I suppose it's a bit like being overflown by a fighter-jet, you see the back end of the departing aircraft and then hear the roar of its engines as the sound-wave trundles on behind.Oharrez 09:09, 7 August 2007 (UTC)Oharrez
 * By a supersonic jet, yes exactly.--Michael C. Price talk 09:39, 7 August 2007 (UTC)

Thanks again for your comments but it strikes me that if we follow the supersonic jet analogy, instead of having one image that splits into two, both departing in opposite directions from the same point, we have two images or series-of-images/sounds, one arriving ( even if in reverse order ) and one departing. This is not the same as one image breaking into two and both departing from the same point. What do you think ? Oharrez 09:21, 8 August 2007 (UTC)Oharrez


 * I think that the difference is just because when we have a sphere, the images of its upper and lower parts connect with the arriving and departing images to create one connected image. When the back part of the sphere leaves the point where the observer is located, this will no longer be true and we will see two separate images. So the difference from a supersonic jet is because: 1. we have here a 3-dimensional description, and 2. the sphere is moving THROUGH the observer and not passing it by. Dan Gluck 14:41, 8 August 2007 (UTC)
 * 1. I agree. 2. Standing on-axis certainly makes the double image effect more dramatic, but even if you're watching from a distance you'd still see the same effect, namely one image appearing without warning which then splits in two.  I don't know to prove this rigorously but you can probably convince your self of this by drawing trigonometric diagrams; 2a) there has to be one point on the path of an object from which the light first hits you (the observer) and hence at that moment you only see one image and 2b) as time goes to +infinity the distance off-axis become irrelevant (compared with the along axis distance) and you must see two images.  By continuity the one image must separate into two. --Michael C. Price talk 17:59, 8 August 2007 (UTC)
 * Yes, you're right. Dan Gluck 10:44, 9 August 2007 (UTC)

Diagram should be deleted kept
(I changed to "keep" - see below)

I propose to delete the diagram as original research. I don't understand at all what's going on there. I believe the diagram should be understandable at least for the average PhD student in physics... Dan Gluck 12:07, 6 August 2007 (UTC)
 * Diagrams are not subject to the WP:OR. I say keep the diagram; as it says: if a tachyon passed you you would not see it until after it has passed and then you would see two images - both moving away from you. PS I do not have a PhD.--Michael C. Price talk 12:23, 6 August 2007 (UTC)
 * Note there is more detailed analysis associated with the graphic. I don't follow it all yet, but neither have I seen any obvious flaws. --Michael C. Price talk 13:02, 6 August 2007 (UTC)
 * Michael, I believe someone (probably you :-) ) should explain in the diagram what we see there. Dan Gluck 18:17, 6 August 2007 (UTC)
 * Great Michael. Now even I can understand it :). I now think the diagram should indeed be kept. Dan Gluck 13:37, 7 August 2007 (UTC)
 * Diagram rules! Keep forever, this stuff is blowing my mind!! MisplacedFate1313 (talk) 08:52, 5 March 2009 (UTC)

Deleted paragraph
I deleted the following paragraph, due to WP:NOTE, WP:V, WP:OR. This result has no citing (the citing leads to another encyclopeida with no source to support this specific claim), it has not been reproduced, and the model is highly non-mainstream.

''Some modern presentations of tachyon theory have demonstrated the possibility of a tachyon with a real mass. In 1973, Philip Crough and Roger Clay reported a superluminal particle apparently produced in a cosmic ray shower (an observation which has not been confirmed or repeated). This possibility has prompted some to propose that each particle in space has its own relative timeline, allowing particles to travel back in time without violating causality. Under this model, such a particle would be a "tachyon" by virtue of its apparent superluminal velocity, even though its rest mass is a real number.''


 * This paragraph has irritated me for a long time. Thanks for removing it. --Michael C. Price talk 13:06, 6 August 2007 (UTC)

Joke
Because it was already on the other side.

Why did the tachyon cross the road?


 * ) Shnakepup 15:20, 26 August 2007 (UTC)

Tachyons and Special Relativity
Special Relativity, strictly as formulated in the original papers and in most textbooks, does not allow any particle moving faster than light.

Special Relativity theory works with one real time dimension and three real space dimensions. So having v being greater than c (and having imaginary numbers as the contraction/dilatation factor in Lorentz equations) requires extending special relativity to deal with complex numbers.

Once such mathematical extension to complex numbers is accepted, all the rest of the article is OK. However it would be inappropriate to assume such extension without explicitly stating it, especially because this article will be read by people with very different backgrounds, not only physicists.

I suggest the following paragraph, or something similar, to be included in the article:

Rigorously speaking, tachyons are incompatible to special relativity, at least as it is known today. One way to understand such incompatibility is to remark that in special relativity, time and each of the three space dimensions are represented by real numbers. When deducing special relativity equations, like Lorentz space-time transformations, it is unavoidable, at one point, to take the square root of the expression:
 * $${1 - \frac{v^2}{c^2}}$$.

In fact, such square root is explicitly present in most of special relativity equations. If v is greater than c, then the abovementioned expression has a negative value and it has no square root in real numbers. So special relativity equations can not be deduced. Note that this problem is not solved by claiming that tachyons have zero mass or imaginary mass.

Although extending special relativity to deal with complex dimensions is mathematically feasible, currently there is no experimental evidence supporting a four complex dimensional space-time.

The following discussion regarding tachyons and special relativity assumes a somehow “extended” special relativity to deal with complex versions of space-time and mass.

—Preceding unsigned comment added by 189.24.6.58 (talk) 03:31, 5 September 2007 (UTC)

Removal of content
I have removed the following cluase from the article: - "- but they don't exist anyway (by tachyon condensation)." I cannot see how such a preemptive dismissal of content without specific comments in the text itself explicitly identifying why such preemptive judgement is made is even remotely acceptable. It was stated by the editor who inserted the content that the issue was "discussed" on this talk page. "Discussion" and "consensus" are far from being the same thing. I would now ask the editors involved in this page whether they believe the content I removed should be included or not. If they indicate it should not, I would also request some input as to what alternate phrasing, if any, would be acceptable, so that we can determine what the existing consensus regarding this subject is. Thank you. John Carter 19:15, 13 November 2007 (UTC)
 * I presume you neither read tachyon condensation nor checked the past discussions on this? --Michael C. Price talk 00:05, 14 November 2007 (UTC)
 * Actually, you presume incorrectly. I did read the sections of the talk page which had headings which indicated relation to this topic and I did not see what would be qualify as consensus. Content of the other page is basically irrelevant to the content of this article. If you can however demonstrate to me a specific section which clearly indicates that a consensus of the editors agreed to the specific wording used in the now-removed content, I will gladly withdraw my objeciton. However, I do believe that based on what I have read that the content as added was not agreed to in advance. If I am wrong, my apologies. If by whatever chance I am right, I would welcome discussion as to what phrasing should be used. John Carter 00:25, 14 November 2007 (UTC)
 * Sounds like I didn't presume incorrectly. Show me the talk section with the lack of consensus mentioned. --Michael C. Price talk 00:36, 14 November 2007 (UTC)
 * Actually, I didn't see any sections which indicated that there was a consensus. That is why I specifically asked you to indicate where that consensus was achieved, and now repeat that request. John Carter 00:41, 14 November 2007 (UTC)
 * Right, so you accept that there is no evidence for a lack of consensus. For evidence for consensus, see "adding a section" for starters. --Michael C. Price talk 00:45, 14 November 2007 (UTC)
 * Interesting. However, it does not address the specific question I asked regarding the specific content added. Also, please note by policy the obligation rests on you to demonstrate where consensus was reached. I note once again that you have yet to offer any such clear evidence of consensus. Also, I really wish people spelled Arthur C. Clarke's name right, particularly considering that he is a moderately respectable futurist who explicitly disagrees with that statement which I have removed. Also, Dan Gluck's sweeping statement that "such things are not possible" is itself dubious, given the admittedly unlikely but still at least theoretically possible, as indicated in the last paragraph of the Faster-than-light, which explicitly states that such things are at least mathematically possible. I am sure you would agree that we do not yet know enough raw data on the universe outside the planet to be really able to make such sweeping generalizations that "such things are not possible". And, now for the third time, I request a specific indication that the consensus was reached. I note now that there are two parties, Gluck and yourself, who seem to support such phrasing, and at least one party, myself, who has serious reservations that such a sweeping statement denying the very possibility of something is responsible in a field such as this, about which even the experts would acknowledge our knowledge of the subject is basically limited to a very pathetically small segment of the various possibilities. I do acknowledge however that there was to date agreement of one person to that statement. As there is now a disagreement about the sweeping nature of that statement, however, I would request that comments from other parties come in to establish a current, existing, consensus. John Carter 00:56, 14 November 2007 (UTC)
 * The only person to have spoken against the consensus on the talk page is you, who has made the lead and the main body contradictory. --Michael C. Price talk 01:12, 14 November 2007 (UTC)
 * True. However, I do note that the earlier consensus discounted at least one source who might generally be thought as being at least notable. As indicated above, the specific phrasing can be seen as being problematic. There is no particular rush to restoring content which seems to dismiss recognized sources as "unreliable". I also note that at least some other parties, I think Hawking (?), have also indicated that faster-than-light travel is at least theoretically possible. Therefore, dismissing it as impossible could be seen as both explicitly ignoring reliable sources and original research. I would welcome substantive discussion of more acceptable phrasing, and look forward to further input regarding that subject from any and all parties. John Carter 01:19, 14 November 2007 (UTC)
 * "the earlier consensus discounted at least one source who might generally be thought as being at least notable. " eh? Notable or reliable?  They're different things.  And don't be vague, who are you referring to? --Michael C. Price talk 01:54, 14 November 2007 (UTC)
 * Please actually read the earlier discussion. The two of you explicitly denounced Arthur C. Clarke's statements. I would have thought mentioning the name once might have been enough. Evidently I was mistaken. Also, now that I have the opportunity, several recognized scientists over the years have asserted at least the possibility of faster-than-light travel. To write off all of them with a single simple phrase is clearly less than acceptable. John Carter 01:59, 14 November 2007 (UTC)
 * Please calm down. You did not say that you were referring to your earlier mention of SF author ACC, and so I asked for clarity.  Has ACC published a text book about, or in a scientific journal on, tachyons?  I doubt it.  BTW I did not "explicitly denounce" Arthur C. Clarke's statements; never even mentioned the guy (although I like his stories).  You're imagining things and getting a bit hysterical, just as you did before. --Michael C. Price talk 02:17, 14 November 2007 (UTC)
 * And you are continuing to indulge in the accusations and attempts at misdirection which have put you in the situation you are now in. Your attempts to dodge directly responding to fairly clearly made points by once again insulting others is now on record here as well. By the way, I have requested comment from the Physics project. I believe that they will be probably fairer than you. And I sincerely suggest that, considering you are now on probation for your misconduct for a full year, that you perhaps learn something from the experience, like ceasing to indulge in your earlier problematic behavior. John Carter 02:21, 14 November 2007 (UTC)
 * And I suggest you stop misrepresenting me. As I said, I never made any comment about ACC. Although quite how he is relevant to a science subject such as tachyons is beyond me. --Michael C. Price talk 02:25, 14 November 2007 (UTC)
 * Michael, it is not a misrepresentation to state that above you have explicitly violated the policy of WP:NPA, and have once again indulged in a weakness that has been observed by several people regarding your conduct, specifically your tendency to to avoid directly dealing with questions asked of you by attacking and insulting others, as you have explicitly done above. In fact that was the exact nature of my incomplete evidence as reported here. I sincerely hope that you can in time overcome this tendency of yours. John Carter 14:01, 14 November 2007 (UTC)
 * It is not a PA to state that you're imagining things (such as my claimed explicit rubbishing of ACC, which never happened). Yes, I have a tendency to ignore irrelevant questions, such your issues about the arbcom evidence; they are irrelevant to tachyons (take it to my talk page).  As for the hysteria, that is my judgement of your mental state to explain your evidential blunders; less of a PA than your overblown accusations of fraud etc.  Again, take it to my talk page -- no one here is interested. --Michael C. Price talk 15:11, 14 November 2007 (UTC)
 * No one is interested in your insulting personal opinions either. Too bad that hasn't stopped you from deciding to almost start the discussion with one. John Carter 16:46, 14 November 2007 (UTC)
 * I see: so when I point out a factual error on your part that is "almost" a PA. :-) --Michael C. Price talk 21:27, 14 November 2007 (UTC)

Arthur Clarke should not be used as a source for anything scientific. ScienceApologist 16:36, 14 November 2007 (UTC)
 * I don't think he was being used as a source, rather that his theories were being explicity discounted bove and that seems to have been involved in making the decision to change the content. He was I believe respected for some work relevant to oceanography, but that isn't relevant to this article. And the point was only made because of the apparent effort to discount any and all such theories, regardless of who they came from. John Carter 16:46, 14 November 2007 (UTC)
 * If John Carter bothered to read the talk page more carefully he would see that ACC's views were a spur to presenting the scientific position more clearly, and nothing more. Nothing scientific was discounted. --Michael C. Price talk 21:27, 14 November 2007 (UTC)
 * And if Michael Price bothered to read my statements, he'd know I never said anything different. I sincerely hope he learns to actually deal with content at some point, and cease his seemingly never-ending stream of put-downs and obvious attacks, for the sake of both the project and himself. John Carter 21:30, 14 November 2007 (UTC)
 * AFAICS the content issues are consensually settled. --Michael C. Price talk 22:16, 14 November 2007 (UTC)
 * Well, they aren't. What would seem to be required before making any sort of statement to the effect that "it's impossible" or "it doesn't exist" would be a proximate qualifier along the lines of "according to current prevailing opinion", which is still lacking in the final paragraph of the introduction. I think all parties can understand that such sweeping statements should be qualified whenever they are made, and that it should be indicated that it is only according to one extant theory, however highly regarded it is. Also, the last sentence of the introduction seems to be conflating Feinberg's analysis, mentioned twice, with someone else's opinion, referenced at the end. And the section after the hyphen makes reference to something outside the article, without even making a single statement regarding the subject in the article, which is at best extremely poor article construction, particularly in the introduction. Also, the fact that the first "by Feinberg's analysis" could be seen as indicating that the second "also by Feinberg's analysis" is contingent on the first reference to Feinberg seems to be placing all the emphasis on that single source. Unless sources which explicitly stated that such a source were universally accepted, and no such sources are yet indicated, that would seem to be placing too much emphasis on that single theory. Based on all the above, the introduction I believe is still in dire need of grammatical and content work. Basically, all that was done was restoring the content and adding a reference. Consensus is based on a lot more than that, particularly since several of the concerns I first expressed have yet to be addressed at all, so far as I can see. John Carter 22:36, 14 November 2007 (UTC)
 * Science is all about finding universal truths and thereby making sweeping statements. Such universal qualifications you seek are, well, universally valid and thereby redundant.  Do you seek to pepper each and every paragraph in every science article with the same redundant qualifer?  Unless you have a reliable source that makes a specific criticism of the expressed theories about tachyons I see no grounds for inclusion.
 * I don't see the problem with the repetition of "by Feinberg's analysis", since both points are made in the source (and evidently this was not understood by some editors, which was why this is stressed more than previously).
 * I reject your point about conflation since each clause is referenced, again in line with the practice in science articles, but let's see what Dan, Joshua, ScienceApologist et al thinks about this.--Michael C. Price talk 11:03, 15 November 2007 (UTC)
 * I specifically requested only one source on one particular claimant's reliability, which would seem to be reasonable for a party featured as prominently in the lead of the article. The statement about making sweeping generalizations is basically irrelevant and ignored. The attempt to create a smokescreen to obscure that request above is completely irrelevant to the discussion, and unfortunately seemingly in keeping with that editor's tendency toward unfounded statements. Also, it should be noted that wikipedia is specifically intended for the general reader, and that it is not a good idea to assume that the reader is an expert. Such a reference establishing the credibility of the only source cited on a subject of that importance are reasonable. Regarding sources, the entry in Encyclopedia Britannica makes no such statement as "but they don't exist anyway", and the Encyclopedia Americana states at the end of the entry on "Tachyons", "Whether this means that tachyons do not in fact exist, or whether future experiments of a different type will reveal them, remains uncertain," which is an entirely different take than this article's current blanket dismissal. On that basis, I believe it can fairly be stated that this article as it is currently constructed makes what could be called extraordinary claims. Extraordinary claims require extraordinary sourcing. It should also be noted that the existing lead section does not conform to the standards of WP:LEAD, and in particular the following quotation about biographies which probably also applies here:"When writing about controversies... neither suppress notable information nor overwhelm the subject with negative material; always pay scrupulous attention to sources. Write clinically, and let the facts speak for themselves." As it is, this article does seem to be suppressing notable information about contrary viewpoints, and even specifically writing them off. Also, the lead currently contains a single sentence paragraph, which is counterindicated in the style guidelines. Also, the final clause in question violates that style guideline as well, "Do not tease the reader by hinting at startling facts without describing them." The statement that tachyons do not exist is not in fact expanded upon anywhere in the article. As such, the final section of the lead in particular completely fails to adhere to even the most minimal standards of style. John Carter 15:31, 15 November 2007 (UTC)
 * It is hardly teasing the reader since a link is provided to tachyon condensation and a section in this article exists as well which explains why tachyons don't exist. Probably it is could be clearer, although my solution would be just leave a pointer to the condensation article and delete the duplicated material/section content here.


 * BTW claiming that tachyons don't exist is not an extraordinary claim. Claiming they do (or might) is. Please cut-and-paste the entire paragraph from the Encyclopedia Americana so that we can judge context.  In particular I want to see what "this" refers to. --Michael C. Price talk 16:21, 15 November 2007 (UTC)
 * It is a claim which is not made elsewhere, thus it qualifies as an extraordinary claim. And references to other articles are not indicated as being sufficient in the MOS. Creating a separate section of the article to deal with it is what is indicated, or at least further references within the article itself, particularly not for content included in the lead section. Regarding the presumptuous nature of the above request, here is the entry in its entirety User:Warlordjohncarter/Tachyon. Asd it is in print, I assume that it is understood that it cannot be cut and pasted from a different site. As the statement within this article clearly is one which is not made elsewhere, I believe that it does in fact qualify as an extraordinary statement. And please note that the writer of this entry seems to be the same Gerald Feinberg who is the source of the statements in contention, although I presume the entry in this dictionary, copyright 1997, is in fact written later than the 1967 article referenced. Unfortunately, the time the article was written is not included in the article. John Carter 17:13, 15 November 2007 (UTC)
 * Interesting. So the "this" was only in reference to the lack of empirical evidence and in no way a criticism of Feinberg's theoretical work (which would have presented a conflict of interest) or the later work on tachyon condensation by others. --Michael C. Price talk 17:30, 15 November 2007 (UTC)
 * Perhaps. However, as the article was written by Feinberg himself, presumably after the article cited, it would seem to me that the contention of the article is in fact one that the author himself does not any longer make with the same degree of force. And, considering the article was written by Feinberg, whom you take as apparently being the ultimate source, I believe that would be an additional indication that the contested statement ending the lead needs to be elaborated, or better, removed from the lead entirely. Also, I note that you have not addressed any of the other points raised. Considering I have fulfilled your requests, I very much request that you respond in kind. Thank you. John Carter 17:40, 15 November 2007 (UTC)
 * No perhaps about it. The article quite clearly only comments on the lack of empirical evidence.  So my point remains: find me a source that specifically expands upon the Feinberg ref and/or tachyon condensation. --Michael C. Price talk 17:56, 15 November 2007 (UTC)
 * The article is also written by Feinberg himself, presumably after the other source mentioned, as already indicated, which would seem to indicate that even the writer himself has perhaps decided that the statements from 1967 are not such as he would make at the time of the writing of the encyclopedia article. Also, I find myself once again forced to ask you to respond to the other points made, as you have continued to refuse to respond to them. Please do respond to them, rather than continuing to ignore them. Thank you. And, as these concerns have not yet been addressed, I have placed the appropriate tags for improving references and copyediting until they are addressed. John Carter 18:07, 15 November 2007 (UTC)

Dear John Carter. The reference of Peskin and Schroeder, on which the "they don't exist" entry relies, is the most common (and usually considered the best) text book on quantum field theory, making it the best source on the subject. If you find a source of equal quality which contradicts it, please let us know. Otherwise, this whole debate is pointless. Have a good day! Dan Gluck 18:50, 15 November 2007 (UTC)
 * Thank you for the information. It's nice to actually get some. However, the remaining problems which I raised before, which specifically include the fact that at least one recognized source in the field, Feinberg himself, seems to indicate that he believes that tachyons might exist, as per the quote in Americana from him, as well as the fact that as it now stands the article clearly is referring to something in the lead which is not elaborated on at all in the content of the article, indicates that (1) the article may well be a violation of POV (even if it is the most generally accepted POV), as at least one verifiable, reliable source seems to indicate that he believes such particles could at least potentially be proven to exist, and (2) clearly violates MOS, most importantly WP:LEAD. As a suggestion, I think it might make sense to create a summary section regarding the current theory of tachyon condensation, particularly given the comparatively poor condition of the tachyon condensation article itself, which would describe when the theory was developed, how it seems to impact the possibility of tachyons existing, and what if any parties still disagree with the idea that tachyons cannot exist. Such would seem to be required, after all, for the article to not violate NPOV, until and unless the theory is clearly, absolutely, and specifically proven beyond a doubt. And, as we all know in matters of this kind, such absolute proof rarely if ever exists. However, clearly, by including such information only in the lead and not referencing it anywhere else in the article, this article as it is currently constructed almost certainly violates both POV and MOS guidelines. Also, I regret to say that as currently constructed the entire last sentence of the lead might be seen to violate WP:SYNTH, as it seems to be grouping multiple ideas together in a way which does not seem to have apparently done in the sources themselves. I will forego placing the POV tag as well, at least for a while, if I receive clear indications from some party who has responsibly worked with the article, such as the editor who posted the last earlier comment, that there will be an effort to address these concerns in the near future, and actually see efforts to that effect in the near future. John Carter 20:50, 15 November 2007 (UTC)


 * This Encyclopedia Americana article (as read here: User:Warlordjohncarter/Tachyon ) speaks of tachyons hypothetically ("If they were indeed to exist ... ") and more or less concludes that people have looked and never found any evidence. Physicists often look for things that they don't entirely expect to find, just to be sure. I really don't think this article supports the statement "However the debate and scientific speculation over the existence of tachyons is still open". A more accurate interpretation would be "There is no experimental evidence for the existence of physical tachyon particles, but scientists remain open to the possibility." But the second part is redundant, since scientists are (or certainly should be) always open to the prospect of anything, provided that it has enough firm, reproducible scientific evidence. It would be much more appropriate and accurate, so I'll change it to "There is no experimental evidence for the existence of physical tachyon particles". That's really what the encyclopedia article seems to be saying. Rotiro (talk) 21:52, 11 February 2008 (UTC)

New Age Anoyance
Im not certain there is a wiki article about it but it has become a common internet scam to use 'tachyon' as some kind of mysterious holistic energy found in products certain sites sell, evidentally increasing the negative entropy of the human system and spontaniously healing/strengthening. I wonder if there is any way we can mention this? 12.206.61.50 (talk) 21:23, 3 February 2008 (UTC)


 * Perhaps it could be better to give that no credence. Rotiro (talk) 21:36, 11 February 2008 (UTC)


 * I believe this speculation has to do with Nicolas Tesla's research into finding ways for tapping energy directly from the ether. According to rumour, he was apparantly close to some kind of breakthrough, but then he lost all economical support. The corporative supporting him was alledgedly into the electric bulb business. I've heard his laboratory was destroyed. As I reason, the signified element, the ether, objective for Tesla's experimentation has, at least on the level of the signifier, evolved, or merged into the theoretical tachyonic field. Thus it attracts such "New Age" speculation here above referred to. Allthough I would imply that the history of inventions has been followed by all sorts of speculation about beneficial theurapeutic, or medical properties (cf. Galvanotherapy, Cymatic therapy, Radiotherapy, magnetotherapy and so on) with regard to the new "worlds" which is explored. This should be regarded as a rather reasonable redundancy, and not a phenomenon specific to New Age. Often, I believe, that the inventors themselves are the most imaginative of the potential fantastic effects of their discoveries, confer for instant John Logie Baird, inventor of television, who imagined that his invention would make visible the invisible spirits of the ether. It might even be hold that it was his prime motive. What it actually became in our culture he despised. --Xact (talk) 14:52, 31 July 2009 (UTC)

Caption of Image:Tachion04b.jpg too long
The caption of this current image in this article is way too long, it takes up the whole length of the browser! WinterSpw (talk) 02:30, 4 June 2008 (UTC)
 * Don't think of it as a caption. Think of it as a sidebar. Your section title is too tall with the image, by the way. --70.128.112.146 (talk) 16:20, 18 June 2008 (UTC)


 * The caption is also a bit confusing, someone should tidy it up for better comprehension for other readers. WinterSpw (talk) 20:41, 25 July 2008 (UTC)
 * We can try, but tachyons are inherently confusing, IMO. --Michael C. Price talk 20:55, 25 July 2008 (UTC)

QUESTION : Could tachyons be gravitons?
At some point there are many similar charactheristics of both particules in which i find interesting.

1- They are both massless 2- They are both hypothetycal 3- They are both related to strings theory 4- Gravitational energy tends to be weak, so much its hard to be detected, but has unlimited range; tachyons tends to have infinite speed at low or zero energy. Being not a physicist i can hardly explain the correlation but thats somehow why i ask the question ;). —Preceding unsigned comment added by 96.20.61.73 (talk) 09:56, 11 August 2008 (UTC)


 * The short answer is No. Tachyons are by definition faster than light particles. Gravitons do not travel faster than light, they probably travel at the speed of light, in fact. Also Tachyons aren't massless... they have an imaginary mass. There's a big difference between a mass of 0 and a mass of say, 3i, not to mention that physics right now doesn't have a proper explanation for what an "imaginary" mass would be. The fact that they are both hypothetical and related to string theory at this stage doesn't make much difference simply because there are a lot of hypothetical particles that come up in string theory that we have no evidence for yet. And while a tachyon's speed will vary inversely with its energy, that says nothing about the "range" of the particle. We're pretty sure that gravity (and thus, the graviton) being massless, propagates at the speed of light, and would therefore also negate the idea that they are tachyons. Though there are a few superficial correlations, they have very different properties. Drlecter491 (talk) 15:29, 8 September 2008 (UTC)

Casuality
I am quite convinced that if tachyons could be made they could be easily used to send information backwards in time. The Feinberg reinterpretation principle doesn't quite work. If I can create negative energy tachyons, I can construct an Alcubierre_drive, and if not, I can exclude the other solution as nonphysical. Either way, backwards information is within reach. 75.45.10.20 (talk) 20:10, 21 September 2008 (UTC)JH


 * if tachyons could be made they could be easily used to send information backwards in time. Wrong.  Read Feinberg.  --Michael C. Price talk 18:42, 22 September 2008 (UTC)


 * Coule has argued that schemes such as the one proposed by Alcubierre are not feasible because the matter to be placed on the road beforehand has to be placed at superluminal speed. -- Later, by slightly modifying the Van Den Broeck metric, Krasnikov reduced the necessary total amount of negative energy to a few milligrams. Feinberg's reinterpretation principle requires that it be possible to construct negative energy tachyons. Catch on now?


 * So what? You're saying nothing new or interesting. I think you should read his article.--Michael C. Price talk 06:42, 23 September 2008 (UTC)


 * If negative energy tachyons can be created then FTL is already possible under general relativity. If not, then Feinberg's principle doesn't work. Choose your poison. —Preceding unsigned comment added by 75.45.18.99 (talk) 03:17, 24 September 2008 (UTC)

A Remarkably 'Precognitive' Article on some aspects of Tachyon Physics.
[Rewrite, tidy] This article on tachyons is much expanded since I last looked several years ago, however it seems that with expanded detail comes expanded speculation. My central complaint is that the article simply assumes and knows to much, and precognitively tells the us answers to questions that physics hasn't solved yet. As such it makes several quite obvious errors about causality and assumes that current models of Quantum Mechanics and Relativity are correct at all velocities (impossible for obvious reasons). Saying that "A is correct and everything else is wrong inevitably comes before the discovery that A is wrong too. Any real solution has to deal with Relativity, with non-locality, and Minkowski space time and gravitational curvature. - Oh dear that has already broken the Quantum based answer in this article. (Relativity maps gravity one way Quantum Mechanics another, at least one is wrong.)

[snip] ...

- Specifically tachyons can or might break causality. - This seems so obvious to me but then I am developing a model of causality that specifically allows for local causality breaking and copes far better with such things.

- Although Imaginary Mass is pretty much the standard model for the tachyon and can be derived directly from Relativity, it is hardly mentioned. - Maybe because it emerges from the wrong side of the physics.

- The third point is rather uglier, the article states an old saw about tachyon velocities. Well while not directly incorrect this assumes a great deal about the FTL universe (much of it wrong) and its really little more like angels dancing on the head of a pin. (My OR shows that tachyons have a very complicated phase space and different maps and many different behaviors are quite possible, but some are not. [snip - not till published])

Finally on the section on New Age 'nonsense' I'm afraid that I may be partly responsible for some of this since I talked on the subject in several groups five or six years ago, and a lot of what appears now looks a little like my terminology of the time. One of the uncomfortable things about tachyon behaviour is how closely it models parts of 'psychic phenomena', and unfortunately I pointed that out. Where people like the 'New Agers' fall down of course is that no-one actually knows how to generate such things as large scale Quantum Coherence or tachyon transience - otherwise their bracelets and magic totems would already work.

Sorry if I am rather critical of the article but this is an irritation to me - I hate seeing something I know is incorrect. [Finally I have to apologize for the very poor quality of the previous version, written after a night of no sleep.] 22 Sept 2008, Lucien86 (talk) 12:45, 18 April 2009 (UTC)


 * The statement that tachyons would not break causality is referenced, not just asserted as you complain. I suggest you acquaint yourself with G Feinberg's work. --Michael C. Price talk 18:40, 22 September 2008 (UTC)


 * [Rewrite] That's not the problem though, the position stated is at least partly speculative - having a reference is worthless if its wrong, in FTL physics and tachyons we are dealing with the clash of inherently incompatible models of science. My own work is still lacking experimental proof and is probably years from publication, I may never publish - any comments I make beyond a certain point become OR. The central problem is that FTL behaviour almost certainly is causality breaking. Physics as it stands in this area is till very incomplete. Works like Feinbergs are very detailed but he is missing an essential part of Relativity - that GR specifically requires the transfer of information faster than light.


 * Even if all my own work is rubbish such heavy claims about something so speculative are dangerous because they can give a very wrong impression of the truth. - In this case Wikipedia's rule of only quoting referenced work is again a likely potential route to disaster or at least egg on face. (The rule of being like an Encyclopedia is that Encyclopedias are slightly wrong about almost everything.) Sorry for hassling you. 24 Sept 2008, Lucien86 (talk) 11:28, 18 April 2009 (UTC)
 * Please so not rewrite your earlier talk page contributions, especially when they have later responses attached.
 * Specifically tachyons can or might break causality. - This seems so obvious to me  -- it seems obvious to a lot of people, and they're all wrong, as Feinberg's work shows.
 * --Michael C. Price talk 13:25, 18 April 2009 (UTC)

If they exists, where's the difference?
If tachyons really exists, what difference if tachyons don't exists?The main clue for tachyons is to know what things would change if they exists.And if they don't exist, what things are changed? Agre22 (talk) 03:38, 24 May 2009 (UTC)agre22

Assessment comment
Substituted at 22:09, 3 May 2016 (UTC)