Talk:Quark–gluon plasma

For relativistic matter, pressure and temperature are not independent variables

Actually, what matters here is not whether the theory is relativistic or nonrelativistic, but whether the theory has conserved charges allowing us to have chemical potentials. The QGP states depend upon the temperature AND baryon number density. The pressure depends upon both the temperature and baryon number density.

Your last sentence is absolutely correct, but I'd wanted to avoid a discussion of μ_B here, in order to avoid the full QCD phase diagram. (That now finds its place in the QCD matter article). As for non-rel vs rel: it is relevant, since particle number is conserved in the non-rel case (text book stuff). I added a para in the chemical potential article to clarify (in any case, this para was needed there). Thank you for a very useful comment. Bambaiah 10:47, May 21, 2005 (UTC)

Unless there is some reason why this article is mostly arranged in a Q&A format, wouldn't it be better to write it normally? Dilbert 22:02, 17 March 2006 (UTC)

Dilbert, you are probably a professional in the field. It's worth remembering that for general readers, the QA format is FANTASTIC! Reading the article, I found myself thinking, finally a simple easy to read wiki article that is not trying to pretentiously link together long paragraphs. Bravo to whoever did this —Preceding unsigned comment added by 83.196.101.199 (talk) 14:05, 13 January 2010 (UTC)

Broken Links

There are several broken links in this page. Someone should fix them. scienceman 19:02, 29 March 2006 (UTC)

Good stuff

I find the general introduction in Q and A very clear. Hail to the author! I even believe there should be more articles with the Q&A format.

Info D 12:03, 7 October 2006 (UTC)

Reference [1]

What is the meaning of the reference [1] ("may have been partially successful[1]. Currently,") ? Currently, it points to one of the SPS experiments, CERES, suggesting it was the one who was successful ? I'm not sure that physicists in this field will agree with that.

I suggest : the list of the final heavy ions experiments at CERN : http://newstate-matter.web.cern.ch/newstate-matter/Experiments.html

with the press release that the CERN issued at this time

(sorry for my bad english)

83.202.115.126 23:40, 17 January 2007 (UTC)

while lorentz contracted??

I found this extremely odd when reading, it striked me as not fitting in.

"The particles are then accelerated to ultrarelativistic speeds & slammed into each other while lorentz contracted."

If the "lorentz contracted" bit is correct, it should be wikified IMO, if not is should be removed.

(Remember to sign your posts). I agree. As written it does appear to be a superfluous statement, along the lines of saying 'accelerated to ultrarelativistic speeds & slammed into each other under relativistic condition', or, 'the green grass was green'. I think it is symptomatic of the whole article, which looks like it has been written in great haste. I do seem to remember that Lorentz contraction is of considerable importance to theoretical calculations regarding the statistical mechanical behaviour of QGP. Pehaps that is why it is there, as a phrase in need of expansion/clarification. 1812ahill (talk) 19:59, 23 October 2009 (UTC)

I edited that bit, i kept the mention of it being Lorentz contracted, simply because people might not realize that, but it implied you could collide them at that speed without Lorentz contracting it, which i found sloppy.(And the nucleii don't pass through each other.(I think there is a distinction between the wavefunctions passing through each other and the nucleii themselves passing through each other.) 88.159.69.195 (talk) 15:40, 9 June 2011 (UTC)

Safety Concerns section

The new "safety concerns" section seems out of place here. The QGP itself is not a safety concern, it is a state of matter. If there are safety concerns about one possible mechanism for making QGP (namely the LHC) then they belong on the LHC page. The QGP does not consist of strangelets, and in fact has very little to do with them. Strangelets have net strangeness, while QGP (at least as made at heavy-ion colliders) has zero net strangeness. QGP is hot and strangelets are cold. They are different phases of matter. I think this section should be removed from this article. Dark Formal (talk) 02:46, 13 January 2008 (UTC)

Does the charge of a quark-gluon plasma need to be integral?

Or in other words, can you split a quark-gluon plasma into two pieces that cannot fully decay back into familiar particles without ending up with a free quark left over, i.e. requiring that these pieces represent one or more stable particles with very high mass and fractional charge?

Also, if the plasma must have a net integral charge, how would it "decide" where to break if, hypothetically, you had a large enough clump of it that you could split it in half before light could travel back and forth to each end? Wnt (talk) 23:04, 16 May 2008 (UTC)

For an infinite volume of QGP, the charge density must be zero, or else there would be infinite electrostatic energy costs. For a finite-sized volume, the charge must be an integer. Ultimately this is because the state as a whole must have zero color charge (like a big nucleus) to avoid infinite energy costs (a color-electric flux tube). That's a technical summary---feel free to ask for clarification. Dark Formal (talk) 03:05, 17 May 2008 (UTC)

Thanks for your answer! If you would, could you put a mention of the integer charge in the article (for a finite volume; the lay reader isn't expecting to encounter an infinite volume ;) ). It would also be nice to work in a wikilink for flux tube somewhere. Since this isn't my field and I don't have a source handy I'm leaving this to you, though. ;)

I'm still a bit confused about splitting the plasma in half, though. As the article says, it is not just a simple collection of free quarks, so I'm inferring that if you had a long rod-shaped mass of the plasma and found some "bullet" dense enough to blast it in half in a very short time, what happens is that the flux tubes are actually stretched out and eventually produce new quarks at the cut ends to maintain the required charge and color properties. But what confuses me about this is that in order for that to happen, this pattern of flux tubes needs to contain all of this information at the site where the break would occur. I suppose in the minimal-energy case you could have a "plasma" made up of some neutrons lying next to one another, and the tubes exist only to prevent a neutron from being chopped in half. But what happens in the high energy case when no distinct subentities exist - do you have one of these tubes running between every possible subset of two or three suitable quarks in the entire plasma? It seems like in order to cut such a plasma you might need to produce many times more particles than it contains, but I could be so wrong. Wnt (talk) 14:17, 17 May 2008 (UTC)

Sorry, I can't answer this in a simple way. The full answer involves the group-representation properties of large numbers of quarks. Analogy: you know that a group of electrons gives one combined electric field which is then "eaten up" by the appropriate number of positive charges. Simialrly, the quarks in one half of the QGP give one combined color flux which is just exactly eaten up by the rest of the quarks. Dark Formal (talk) 03:23, 18 May 2008 (UTC)

It's been a long time since I was involved in this field, but this question reminds me of Young's slit experiment where the question is how does one photon passing though one slit 'know' how to interfere with a photon passing through another slit spatially seperated from it to produce the overall resulting interference pattern. The answer must surely lie in abandoning (for this question at least) the idea of the quarks as distinct particles (statistical mechanics) and instead of looking at them as being represented by Wavefunctions, i.e. there is fuzzyness present at this microscopic scale, discrete (billiard ball type) particles don't exist and 'information' is transferred as a consequence of the interactions/interference between each 'particle's' wavefunction, subject to the usual laws of the speed of light, Heisenbergs uncertainty priciple, mass-energy conservation, etc.

This question also reminds me of the concept of Hawking radiation, where virtual particle-anti-particle pairs can result in the emergence of a real particle by its virtual other half falling into the black hole. So long as the various conservation laws are obeyed these things can (so it seems) be done. As is usual in the world of quantum mechanics, it is very difficult because we are stuck with the words of our every day macroscopic world to discuss the counter intuitive microscopic environment, where a 'tube' is not really a tube and a 'bullet' not any kind of bullet in any normal conceivable manner. (Btw. Dark Formal and Wnt I'm not trying to sound patronizing as I bet you probably know more than I do about this subject - I'm just trying to propose an answer Wnt's question, assuming I've understood it, and the subject in general (I too could be so wrong):)) 1812ahill (talk) 20:55, 23 October 2009 (UTC)

Color current?

I was wondering about "color current" in these plasmas. If you have a ring-shaped plasma of up and down quarks, and apply a strongly varying magnetic field, there should be some tendency to generate currents of up quarks and down quarks going in opposite directions - I think. (Since the up quark has twice the charge and half the weight I assume it would carry most of the current... figuring out the resistance of a ring of QCD plasma is another matter!)

Now, as I [(don't)] understand the QCD theory, the neutrons used to make up the plasma will each have had an up quark of any color at random, and by transferring gluons they could swap color with down quarks at any time. But even so a quark-gluon plasma made out of neutrons could have any number of up quarks with twice the number of down quarks... so there is a very good chance that not all quarks moving one way will have the same color. I've seen mention of color currents in reference to the "whitening" of the QCD plasma,[1] but having one running constantly sounds more (hypothetically) manipulable. At that point, well, I note that there is such a thing as chromomagnetism,[2] that papers about it seem to talk about quasiparticles, flavour symmetry breaking, S-wave tetraquarks and all kinds of groovy things, but the waters of my insight are rapidly sinking into the sands by this point. So I'll just ask: can you induce a color current in these plasmas and can you use it to apply a chromomagnetic force to things? Wnt (talk) 19:23, 1 June 2008 (UTC)

Rewrite

This article reads like a FAQ. I'd rewrite it myself to comply with standards, but I am not familiar with the topic at all. Momo Hemo (talk) 10:32, 8 August 2008 (UTC)

Move protection

Why is this article protected from moves? I would expect to see an en dash, rather than a hyphen, in the title; see MOS:DASH, "En dashes in page names". If there is a reason why an en dash would be inappropriate here, I think it should be explained somewhere (either in an HTML comment in the article after the bolded title, or on the talk page). -- Army1987 (t — c) 15:08, 12 October 2008 (UTC)

Done, finally. False vacuum (talk) 20:27, 10 April 2009 (UTC)

Fix 'abelian' link

The current link for 'abelian' leads to a disambiguation page. Could someone who knows what they're doing fix this to link directly to the right definition?

169.229.109.115 (talk) 01:25, 2 December 2008 (UTC)

None of them fit so I have removed the link. Thanks, SqueakBox 16:17, 6 December 2008 (UTC)

I propose removing the {{rewrite}} tag

since I'm guessing it was prompted mainly by the fact that several of the section headings were questions. This is no longer the case, and I think the article is reasonably well-constructed (except for that last section; I'll have to take a look at that). False vacuum (talk) 20:28, 10 April 2009 (UTC)

To clarify, I'm not saying there isn't immense room for improvement; just that I don't see the need for that particular tag. False vacuum (talk) 21:05, 10 April 2009 (UTC)

New information

I just read an article that seems to provide relevant information on this. Any ideas? [[[3]]] —Preceding unsigned comment added by 75.53.161.143 (talk) 22:04, 21 April 2009 (UTC)

Mean free time?

In the section Flow, there is the statement: "These indicate that the mean free time of quarks and gluons in the QGP may be comparable to the average interparticle spacing". It does not seem obvious to me that a time is comparable to a spacing (distance). Is 'mean free path' intended here? --RexxS (talk) 05:24, 6 October 2010 (UTC)

Updated info?

The opening paragraph describes things "as of February 2010", and uses language that describes November 2010 as being in the future. Has independent verification of the experiment described occurred? Did CERN perform those tests as planned? If so, have any results been released? 124.149.82.73 (talk) 14:00, 26 February 2011 (UTC)

The last few lines at the opening paragraph does not make so much sence, did they desover this or not? Or does the data need to be processed? (I dont know how to leave my signature)

Indeed. The article on the LHC says that the QGP was confirmed there. Is this correct? I have no expertise in the subject. Ashmoo (talk) 18:16, 30 December 2013 (UTC)

The QGP is indeed confirmed. --35.13.167.205 (talk) 14:49, 17 October 2014 (UTC)

Quark-gluon plasma

At 25C? Really? 188.221.120.67 (talk) 19:02, 4 September 2011 (UTC)

Interesting Boiler Plate at Start of ARticle: This article's factual accuracy may be compromised due to out-of-date information. (June 2011)

Does the boiler plate imply that all "scientific claims" are destined to be deemed factually inaccurate after the passage of time? If so, then all scientific claims are in fact factually inaccurate, requiring a disclaimer at the start of all such articles, like: "Note that this is a scientific article (science being human knowledge) and it is surely factually inaccurate and destined for rebuttal and/or revision. (EnochBethany (talk) 17:42, 25 December 2014 (UTC))

Should Passive Voice Weasel Words be deleted from the article?

One reads: "This phase is thought to consist of asymptotically free quarks and gluons, which are several of the basic building blocks of matter.[citation needed]. It is believed that . . . " Note the passive voice weasel words: "is thought to" . . . It is believed that . . . ." Who are thinkers who think thus? Who are the believers who believe that? Is there a reliable 2ndary source which lists the thinkers and believers? One could put, "As of December, 2014, there are 26 professors of science in accredited universities who believe that . . . (with various degrees of certitude, some being dogmatically certain while others only think this theory is the best model which has occurred to them as a tentative explanation), and here are their names: A, B, C, . . . . However, less than 5 percent of such physics professors have been polled." (EnochBethany (talk) 17:56, 25 December 2014 (UTC))

Any information on electron disintegration?

To my understanding quark type matter is produced when a proton or neutron disintegrates. Is there any information about what happens when an electron disintegrates? — Preceding unsigned comment added by 108.46.17.166 (talk) 14:46, 9 November 2015 (UTC)

Electrons (and other leptons) are fundamental and don't disintegrate, unlike hadrons (protons and neutrons) which are composed of quarks. Vaughan Pratt (talk) 02:53, 11 November 2020 (UTC)

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Quark–gluon plasma as a Big Bang phase

1. old diffused universe explodes due to maximum quantum decoherence - the Planck constant doesn't allow more decoherence, thus space enters a big bang phase transition
2. a single particle - a universal scalar Boson is created (no homogeneity explanation needed inside that particle) - [as a matter of fact a googolplex number of universal scalar Bosons are created, each being the initial state of different offspring universes]
3. that universal scalar Boson explodes becoming a degenerately compressed Quark–gluon plasma of universal proportions, which was homogenous and isotropic not because of some "cooking time of inert spatial expansion", instead simply because it was descended from a single universal scalar Boson
4. that Quark–gluon plasma expands universally and standard Big Bang model begins
5. loop from the start

---

some people simply don't accept the looping, but maximum quantum decoherence Planck brickwall theory seems logical, the "eternal empty universe theory" doesn't accept any future "Big Bang phase transition due to the future maximum universal diffusion", but it doesn't work mathematically, because due to the Planck constant, we aren't allowed to expand the universal wavefunction to infinity, the only solution is the fragmentation of that mother wavefunction to offspring wavefunctions but violently, Big Bang style.

Add theory: black holes as a different state of quark–gluon mixed phase (study phase transitions in Chennai University India - at extreme conditions we cannot separate the nomenclature of phases) without a singularity (the black hole core is surrounded by the less dense known quark–gluon plasma

Different phases of gluon matter. (we need a Great Indian Physicist of Madras, who is a little bit insane - I repeat a little bit, otherwise we will lose the notional point) — Preceding unsigned comment added by 2A02:2149:8860:A000:8401:A651:E8D2:E10A (talk) 23:47, 5 February 2018 (UTC)

Big bang timing

Someone should add to the article when during the Big Bang do we expect to have found QGP, before the first protons and neutrons formed? Nutster (talk) 06:02, 21 February 2018 (UTC)

æther?

Any wistful mention of æther takes away from a very technical topic in physics. Is this a physics term? — Preceding unsigned comment added by 2600:6C50:A7F:6D4C:3C29:5BD5:65FB:9ED8 (talk) 05:57, 17 November 2021 (UTC)

the term æther is actually used in the citation for that passage doi:10.1140/epja/i2015-15114-0

"What we call quantum vacuum, they called æther." So I removed æther from the article to avoid potential confusion with the outdated usage of that term. Pmokeefe (talk) 05:59, 28 May 2024 (UTC)

splat

The article says:

> In short, a quark–gluon plasma flows like a splat of liquid,

What's a "splat"? Is this really the clearest way to say whatever is intended here?

John Baez (talk) 18:00, 4 March 2022 (UTC)