Talk:Cherenkov radiation

Glow

This article states that "even very radioactive substances do not glow in air"; on the other hand. polonium claims, supported by LANL [1], that polonium does glow blue in air "by excitation of the surrounding air". Is this a different glow, or is this article wrong? --Andrew 18:07, Dec 16, 2004 (UTC)

Upon further research, a number of radioactive substances definitely glow (see the CRC handbook; eg. polonium, promethium, and radium). So I took out the claim:

The Cherenkov effect is used as a visual cue in Hollywood movies to announce radioactive materials. However, it should be noted that even very radioactive materials do not glow in air - the particles are simply too slow - and that even in water a source may be producing a dose of radiation lethal in seconds without easily visible Cherenkov radiation. A source itself would only glow if it was very strong, transparent, and an insulator.

I wrote that working from the basis that a particle would only produce a Cherenkov effect in air if it was faster than the speed of light in air (meaning it'd have to be at a highly relatavistic speed). This may be a misunderstanding of the physics involved on my part, however. In any case, we should probably note that the glow cannot be counted on to identify a (perhaps dangerously) radioactive object. I'd also note that "excitation of the surrounding air" could refer to excitation of electrons in air, by passing particles, which then produces light when the electrons return to the ground state. This is different from Cherenkov radiation. Pakaran 00:18, 29 Apr 2005 (UTC)

I suspect that the ionization of air is what causes the blue glow of highly radioactive materials (see criticality accident). A beta particle would have to have about 6 MeV of kinetic energy to produce Cerenkov glow in air (rest mass is 0.511 MeV, refractive index of air is about 1.003); radium gives about 0.046 MeV. --Andrew 03:30, Apr 29, 2005 (UTC)

Heaviside's prediction

Should we mention that Cherenkov radiation was predicted by Oliver Heaviside in 1888-1889?

Absolutely: in standard practice (calling an effect after the one who predicted it, starting with Halley) it would even be called Heaviside radiation. Thus it should be mentioned in the leading paragraph. Harald88 17:02, 22 March 2006 (UTC)

Except that Heaviside's "prediction" concerned an hypothetical charged particle moving faster than light in the VACUUM. 79.32.63.99 (talk) 13:18, 14 October 2011 (UTC)

If I am not mistaken, he only considered this (in vacuum) as a hypothetical possibility. What would happen if...? There was nothing wrong with this. My very best wishes (talk) 14:47, 24 August 2013 (UTC)

I've referenced Paul J Nahin's book on Oliver Heaviside for this.

I also referenced a similar predictive work by Arnold Sommerfeld - it seems that due to the newly found restriction of Einsteins relativity in the early 1900s, any intellectual games with super-c particles were also quickly forgotten. --Gunnar (talk) 20:07, 16 January 2019 (UTC)

Explicit definition

This may seem like an obvious question to those who are technically acquainted...

You say that the absence of Cherenkov radiation is not a sure sign of the absence of dangerous levels of radioactivity, but could it be said that the presence of Cherenkov radiation is a sure sign of the presence of dangerous radioactivity? --68.107.141.30 00:52, 25 December 2005 (UTC)

Yes, it's true that the presence of the Cherenkov's Radiation means that -to put things simply- you're in big trouble. But only if you are in the same medium as the one in which the radiation occurrs or and similiar and close to the source. If you're in a medium which stops the radiation then it's, of course, stopped. For example: imagine Cherenkov's Radiation occurring in a place fully isolated from the outside -- you're safe outside as long as the isolation is not destroyed. Isolation can anyting that doesn't meet the requirements for the radiation to take place. Another example: It's much harder to produce the radiation in the air than it is in water. If you produce weak radiation in water then you can make it powerful enough for it to visible in water, but at the same time weak enough for it to be harmful in air. Then, you'll be able to actually watch it, standing next to the water pool. —Preceding unsigned comment added by 83.142.107.30 (talk) 23:14, 6 April 2008 (UTC)

Tscherenkov / Cherenkov

In the Science and technology in the Soviet Union article, the name is spelled as Tscherenkov (assuming it's the same person). Should there be a redirect from Tscherenkov radiation to Cherenkov radiation? Googling suggests this is the german spelling of the name. --129.240.122.183 22:35, 26 January 2006 (UTC)

Sure, why not? Done. -- Xerxes 04:17, 27 January 2006 (UTC)

This is a small point but it's noteworthy: while the man's name is Cherenkov, the phenomenon is called Cerenkov Radiation (without the 'h'). I've never seen it spelled with an 'h' in any physics text. But this is a small point. Astrobayes 22:23, 29 June 2006 (UTC)

The spelling Cerenkov was frequently used in scientific papers in the past. (I have no idea why). According to Google ngrams, since about 1995 the majority of English-language works use "Cherenkov". --ABehrens (talk) 06:11, 12 January 2018 (UTC)

See Pavel Alekseyevich Cherenkov for further discussion. The guy's name was "Черенков", not any of the above. The current standard transliteration would seem to be "Cherenkov", but transliterations have been known to change over the years. "Čerenkov" does appear to dominate in science, but what that indicates is questionable. Probably it means that it was the favored spelling of someone who wrote a notable book. If someone is interested and has a lot more free time than I do, it would be a nice thing to track down. :) Andrew Rodland 22:28, 17 July 2007 (UTC)

There are at least a dozen standards for the Romanization of Russian. The Scholarly/Scientific system, which uses single characters to represent single Russian letters, would write "Čerenkov". So does the ISO-9 standard, and the Russian GOST 7.79(System A). Other standards would use "Cherenkov". --ABehrens (talk) 06:11, 12 January 2018 (UTC)

See V.P. Zrelov,Cherenkov Radiation in High Energy Physics, 1970, widely referred to physics text... —The preceding unsigned comment was added by Stuart Ponder 63.199.162.164 (talk) 08:54, 5 December 2006 (UTC).

In Russian Language does not exist letter -Č-, there it is -ч-. This way of writing -ch- comes from Czechoslovakia, and a couple of other balkan states. Probably the original article that this name was taken from was written by a Czech person. The sound that you are looking for (-ch- in English) is written the same way you write it in English language, namely -ch- (if you translate from Cyrillic alphabet into Latin, that is). The reason why, sometimes, you come across a -TCH- variation of it, is because in Russian language the sound -ch- is a shorter(!) AND "tougher"/stronger sounding -ch-. I.E. think of the Chicagoans (in the States) pronouncing the name of their city (Chicago), well, now make it, (the -ch-), sound "shorter" and sharper. That would be the difference in pronunciation. It is NOT a German way of spelling it. You see, there is no set standard in Russia how to write some of their sounds, that is why you get to see so many variations of spelling of the same sound. Eg.: Russian name Сергей, can be written as Sergei, Sergey, and Serguei, but in each variant it sounds the same. English language has 26 letters, Russian has 33. The sound -sh- is -ш-, however, you can come across -sh- way of spelling it almost as much as -sch-. Sound -я- can be written as -ya-, -ja-, and -ia-. Russian name Ваня, can be written as -Vanya- and -Vania-. Яблоня as -jablonya- (apple tree), and so on and so forth... So, you can send that link from Tcherenkov to Cherenkov with an easy heart. (And for the love of god, folks, remove this -Č- from his name in this one. This is the very reason I even got here in this discussion to let you know. It almost lookes like... blasphemy(?) the more I look at it). :) I'm sure the dude who created it meant well, it's probably that he used a Czech source for reference, or something. - Regards. :) —Preceding unsigned comment added by 128.205.115.91 (talk) 02:03, 6 March 2008 (UTC)

There are several official Russian standards for transcribing Cyrillic using the Roman alphabet. (You can see them at ru:Транслитерация русского_алфавита латиницей). In one of those systems, "Ч" is transcribed as "Č". "Tch" is the French way of representing the "ch" sound. Since French was the international language of diplomacy, the "tch" Romanization was formerly (until about 20 years ago) used on Russian passports. --ABehrens (talk) 06:11, 12 January 2018 (UTC)

Superluminal?

Could someone explain in the article what's meant by "faster than the speed of light in the medium"? I thought the speed of light was a constant, and nothing could go faster than it?

Nothing can go fater than Light in vacuum, however, you can go faster than light in a medium (like water or glass) because light is slowed down. --Falcorian ^(talk) 03:42, 25 March 2006 (UTC)

If you want a straightforward answer, consider this: The speed of any electromagnetic wave is, to first order, v = c/n, where n is the medium's index of refraction, c = 3*10^8 meters/sec.squared. For vacuum, n=1 so the speed of light (which is an electromagnetic wave) is v=c. Nothing can exceed that speed. But, for many material media n>1 so then v<c and light in that medium travels slower than light in vacuum. It is therefore possible for something traveling faster than this speed to exceed the speed of light in that medium. Astrobayes 22:27, 29 June 2006 (UTC)

That, sir, is a terrible redefinition of "straight-forward" and you should be ashamed of yourself.--Healyhatman (talk) 02:10, 25 June 2008 (UTC)

That struck me as a very straight-forward explanation and I also consider the analogy of 'why' (in the article itself) to be a great one.96.52.176.113 (talk) 03:52, 17 September 2008 (UTC)

Yes. Einstein's famous theorem states that no object can travel faster than the speed of light in a vacuum (or free space if you prefer) The omission of those all-important three words in most quotes is what causes the confusion. --Anteaus (talk) 23:19, 6 November 2008 (UTC)

Luminal boom

Should I add "sometimes this is refered to as a "luminal boom" - because I've heard that before. 68.6.112.70 08:16, 17 April 2006 (UTC)

Generally, made-up words and phrases should not be added to articles. The analogy to sonic booms is already in the article. -- Xerxes 15:54, 17 April 2006 (UTC)

Where have you "heard that before?" If you cite a verifiable source, then what you're saying would carry some weight behind an edit or addition. If not, then it's probably best to leave this phrase out as it would be more likely to garner a revert. Astrobayes 22:30, 29 June 2006 (UTC)

What we're dealing with here is an accumulation of emitted energy from a source which piles (adds) up slightly ahead of the source because the source is moving so fast that the radiated energy can't get away from it. which is analogous to the accumulated emitted sound energy of an airplane moving at the speed of sound.WFPM (talk) 00:52, 2 November 2010 (UTC)

Definition

The definition mentions that this effect is when a "charged particle" goes through an "insulator". However, I would think that this effect should occur when ANY particle (charged or not) passes through ANY medium (inulator or not) at faster than the propogation speed of photons in that medium. 68.6.112.70 08:18, 17 April 2006 (UTC)

You're wrong about charged particles; a neutral particle has no impact on the electromagnetic fields inside the medium, so it cannot produce radiation. The bit about conductors is already explained in the article: no light is produced. -- Xerxes 15:54, 17 April 2006 (UTC)

In that case something else must be used to detect neutrinos since they do not carry a charge. I read that Cherenkov Radiation was used in the IceCube neutrino detector. Something must be contradicting. — Preceding unsigned comment added by 138.226.68.10 (talk) 15:05, 19 April 2012 (UTC)

IceCube and other Cherenkov-based neutrino telescopes measure the reaction products of a neutrino interaction, such as electrons, muons, and tau's, which are charged particles and emit Cherenkov radiation. -- Questgame (talk) 10:35, 2 July 2019 (UTC)

Accelerating 'matter' beyond speed of light.

"Colloquially and in chemistry, matter is easy to define because it is directly associated with mass." [[2]]

I think the use of the term 'matter' in the following sentence in this article on Cherenkov radiation is misleading: "Matter can be accelerated beyond this speed [the speed of light] during nuclear reactions and in particle accelerators."

The problem is that 'real', 'physical' matter can NOT be accelerated beyond the speed of light. Only theoretical particles like Tachyons (which do not have any mass) can go beyond the speed of light. 'Matter' suggests real particles with real mass, hence it is misleading. The problem of course is the loose definition of matter, but in this instance i think it pays to be pedantic since not going beyond the speed of light is a fundamental rule we all learn in physics class!

Instead i would suggest something like the following: "Certain special particles can be accelerated beyond this speed during nuclear reactions and in particle accelerators."

--Kavrod 14:46, 8 January 2007 (UTC)

I disagree. It says: "For example, the speed of light in water is only 0.75c. Matter can be accelerated beyond this speed during nuclear reactions and in particle accelerators." which is true. Matter can be accelerated to faster then 0.75c in water. Further, it says right after that "Cherenkov radiation results when a charged particle, most commonly an electron, exceeds the speed of light in a dielectric (electrically insulating) medium through which it passes." Matter can't break 1c, but it can certainly go faster than the speed of light in certain mediums. --Falcorian ^(talk) 18:05, 8 January 2007 (UTC)

As far as I have read here it has not been mentioned that while the index of refraction for visible light is approx 1.5 in water it may be close to one and even below one for high energy photons (X-rays/gamma) or short wavelength (de Broigl)/high energy particles. To be clear; I am referring to the real part of the index of refraction that is related to phase-shift, not the imaginary part that is related to absorption. Also, it is the average speed of light that is below c in a medium with n>1, between hand shakes/interactions the re-emitted photon always propagate at c. While Im at it, the closer to resonance the longer it takes before re-emitting the photon.

85.230.24.89 (talk) 20:34, 23 April 2009 (UTC)

When you say that "the re-emitted photon always propagates at c", you' re beginning to talk my language! So the propagation away from each atom is at c, yes? And that explains how the light can "speed back up" after being "slowed down" in the medium. But now consider the "first atom" transition. If it exits at c, then when does it ever travel at c/n? Maybe we're dealing with crossed light pathways rather than faster than medium speed pathways?WFPM (talk) 14:39, 1 November 2010 (UTC)

the angle is not 90 degrees.

The figure shows an 90 degree angle between wavefront and emission angle. Note that the pysical light front of photons are not in 90 degree angle with the emitted light. This is due to the difference between group and phase velocity. Read for example http://arxiv.org/abs/hep-ex/0008001 —Preceding unsigned comment added by 130.237.208.86 (talk) 13:28, 4 November 2007 (UTC)

Correct for the usual case of a dispersive medium. Maybe one should note that right angle the image is true for the ideal case of a non-dispersive medium (where phase and group velocity are the same). Maybe I come round to do this at some point. -- KlausFoehl (talk) 11:58, 23 July 2009 (UTC)

Image change?

Just being proper and asking first, but I think we should change the current image with this one to the right. I feel it illustrates the phenomenon more obviously (for lack of a larger vocabulary). Any thoughts? --RA dialogue observe 06:14, 14 December 2007 (UTC)

There has been no answer for a few days, so I'm just going to assume no one cares and change the image already. --RA dialogue observe 07:06, 19 December 2007 (UTC)

I missed it the first time, but no, no problem at all. New one looks good! --Falcorian ^(talk) 16:26, 19 December 2007 (UTC)

the overall blue image looks more impressive but I think this one is more explaining http://de.wikipedia.org/w/index.php?title=Bild:TrigaReactorCore.jpeg&filetimestamp=20050823070124 perhabs we can use both or combine them? (87.162.72.43 (talk) 09:00, 14 July 2008 (UTC))

I've placed it in the section about reactors, so now they're both in use! I think it fits better there since it shows a little Cerenkov and a lot of reactor. --Falcorian ^(talk) 18:32, 14 July 2008 (UTC)

Speaking of images, do these images have a really slow shutter speed, or does it really look that bright to the naked eye? If it's a slow shutter speed, that should probably be mentioned in the captions or article.

I don't know, so I went to flickr and found some to compare. It seems like they are that bright. --Falcorian ^(talk) 17:37, 25 June 2009 (UTC)

It depends on circumstances, how "hot" the environment is, but yes, the light can easily be that bright. -- KlausFoehl (talk) 12:03, 23 July 2009 (UTC)

Energy loss

It is not mentioned, but I presume that particle loses energy during this radiation. If it is so, it should be mentioned in article. Is there relationship between deceleration X-ray radiation and Cherenkov-radiation? Thanks, V —Preceding unsigned comment added by 84.0.210.214 (talk) 16:46, 9 August 2008 (UTC)

Yes, this issue should be more stated explicitly. As stated in Frank–Tamm formula, the electron does not lose energy or momentum.

Uh, this isn't really true. The Frank-Tamm formula explicitly states how much energy the electron is losing, unless that energy is being pulled from somewhere else (such as the medium). But as far as I know, cherenkov radiation doesn't locally cool down the medium. Conservation of energy says that the energy emitted must come from somewhere, my bet is that the particle slows down. Spott (talk) 01:24, 2 December 2010 (UTC)

As the charge travels at a constant speed, according to the Larmor formula it should not be radiating at all. Hermann Haus has explained the phenomena by pure classical Maxwellian electrodynamics using the nonradiation condition of a moving charge. I do not know whether the text in section Physical origin is supposed to describe some alternative quantum explanation, or whether it is just some physics mumbo jumbo. -- Petri Krohn (talk) 13:39, 29 May 2009 (UTC)

Maxwell's equations in medium, and if one computes the Poynting vector one acually sees that energy is transported. But other energy loss mechanisms for a moving charge in medium are much larger, hence one tends to neglect the Cherenkov radiation contribution. -- KlausFoehl (talk) 12:16, 23 July 2009 (UTC)

Čerenkov / Cherenkov

Copied from Wikipedia talk:WikiProject Physics/Archive May 2009. -- Crowsnest (talk) 09:41, 8 July 2009 (UTC)

Why is it spelled Čerenkov radiation? I've only ever seen it spelled as Cherenkov radiation. 70.29.208.129 (talk) 07:49, 25 May 2009 (UTC)

A Google Scholar and Google Books search gives that "Cerenkov radiation" and "Cherenkov radiation" are far more common than "Čerenkov radiation". I will change it to "Cherenkov radiation", in agreement with Pavel Alekseyevich Cherenkov. See also WP:COMMONNAME. -- Crowsnest (talk) 09:13, 25 May 2009 (UTC)

While Cherenkov is most frequent, I say that Čerenkov as per Scientific transliteration of Cyrillic should remain being mentioned. -- KlausFoehl (talk) 14:08, 19 April 2013 (UTC)

Cherenkov is a Russian name and therefore russian romanization rules apply. They do not contain transliteration to european special symbols for obvious reasons. — Preceding unsigned comment added by 46.42.45.137 (talk) 08:51, 30 July 2017 (UTC)

As there are many languages using the Roman alphabet and with different pronounciation, there are different romanization rules for the Russian language / Cyrillic alphabet. For instance:

• pt: Tcherenkov
• es: Cherenkov
• fr: Tcherenkov
• it: Čerenkov
• ro: Cerenkov
• nl: Tsjerenkov
• dk: Tjerenkov
• no: Tsjerenkov
• se: Tjerenkov
• de: Tscherenkow
• fi: Tšerenkov
• hu: Cserenkov
• po: Czerenkow
• cs: Čerenkov
• sk: Čerenkov
• sl: Čerenkov
• hr: Čerenkov
• tr: Çerenkov
• et: Tšerenkov
• lv: Čerenkovs
• lt: Čerenkovas

The Ч-sound and the v/w ending is different. In some languages there are some special accents and other signs, in other not - eg. we Germans have the ä/ö/ü-Umlaute which are also written as ae/oe/ue if you don't have a suitable keyboard. Often it is seen polite to use the original letters, e.g. to use the é/è/ê accents for French names. But for this case this does not apply, as the original Russian name written in the Cyrillic script has no háček. The question is: does the English language use a háček as standard feature? Answer: no. Therefore I see no use in using "Čerenkov" here in the English part of wikipedia. It would be different, if Paul had been born in Tallinn and and a birth certificate with "Tšerenkov". Then it would be polite to use his name in the original version with háček. But for the English transcription of Черенков, I agree that only one version should be presented here on this English page - the English romanization of the Russian language (not the French, not the German and also not the Turkish). BTW: Cherenkov seems to be fine when applying GOST 7.79 System B. --Gunnar (talk) 22:53, 16 January 2019 (UTC)

File:Advanced Test Reactor.jpg Nominated for Deletion

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Gravitational Cherenkov Radiation

As there isn't an article on gravitational cherenkov radiation as far as I can tell I thought I should propose the creation of a section on it in this article. BarryFFFFFF (talk) 20:08, 4 January 2012 (UTC)

Id really like a more comprehensive description of the actual source of the light it says The charged particles "polarize" the molecules of that medium

Thinking water, so basically the rapid particle effects the electromagnetic field of the h2o molecule as it travels near it, is there a distance from the atom effect on frequency as the nearness of the moving particle to the atom would effect the amount of excitation, that is how high up the waters electron goes, so water compared with ice would have different cherenkov radiation emission frequencies (colors) because the atom spacing is different between crystal n fluids.

Uses of Cherenkov radiation I have heard neutrinos are neutral, so that seems to suggest more could be written as to the way their presence produces cherenkov radiation when they pass near an atom or is it that neutrinos have a particularism where they have to actually meet the nucleus (which goes with their specialized detectors) to "polarize" an atom the move near Could a person measure the velocity of a chemical reaction like CH(twenty) -> 5CH4 live from the amount of larger amount of cherenkov radiation it produces

also it looks like a person could make a sort of amusing "what radiation is that" thing if materials engineers used something like CVD to create hundreds of particularly spaced micro refractors (kind of like a GRIN lens) the little |||||||||| side areas with the matching refractive ndex to the velocity of the particle would glow describing precisely the kind of radiation — Preceding unsigned comment added by 68.185.2.34 (talk) 01:30, 5 April 2013 (UTC)

articles Cherenkov detector and Cherenkov radiation

There are articles Cherenkov detector and Cherenkov radiation. I think that an overlap in contents is unavoidable, but I wonder: should some content in Cherenkov radiation be better placed in the Cherenkov detector article?

I do not think that the two articles should be merged.

Waiting for other opinions. And I suggest Talk:Cherenkov detector for discussion. -- KlausFoehl (talk) 16:05, 19 April 2013 (UTC)

Vacuum Cherenkov radiation - Proposed Deletion

I propose the deletion of this section, "Vacuum Cherenkov Radiation," because it describes an unobserved phenomenon supported by various unobserved phenomenon. Currently, "Vacuum Cherenkov radiation" is a pseudo-scientific supposition describing a yet unobserved phenomenon with no supporting empirical or solid theoretical evidence.

"Vacuum Cherenkov radiation is the conjectured phenomenon which refers to the Cherenkov radiation of a charged particle propagating in the physical vacuum."

This wouldn't be Cherenkov radiation, as Cherenkov radiation is caused by emission from the medium itself. The proposed "vacuum Cherenkov" radiation would be a different phenomenon entirely, one that has not been observed and according to special relativity and the Standard Model should not be observed in the foreseeable future, at least not by the mechanisms describing Cherenkov radiation in the main article.

The section goes on to explain the possible mechanics of the proposed effect. These explanations rely on altering fundamental physical constants, ignoring various rules of the Standard Model, ignoring special relativity, modifying the topology of space-time itself, discovered non-existent (thus far) superliminal particles, or discovering energy dependent velocities of those particles (again no evidence of that so far) ... it describes an unobserved phenomenon backed by unobserved phenomenon and unsupported theoretical models.

In short, this section is not science. Interesting perhaps, but not science and because of this I do not feel it belongs in this article. If there are no major objections, I would like to delete this section but thought I would discuss it first.

Vcfahrenbruck (talk) 22:00, 29 September 2013 (UTC)

Gamma rays

I can't find any mention here of gamma rays inducing Cherenkov radiation, even though that was how the original discovery was made. The original research paper of 1934 was entitled, "Visible Emission of Clean Liquids by Action of γ Radiation." http://web.ihep.su/owa/dbserv/hw.part2?s_c=CERENKOV+1934 http://web.ihep.su/dbserv/compas/src/cerenkov37/eng.pdf Zyxwv99 (talk) 00:31, 12 September 2014 (UTC)

"In Popular Culture" section

I'm dubious about some of these claims, and the cited sources don't back them up:

In popular culture[edit]The typical association of Cherenkov radiation with accelerated particles from radioactive materials and processes, as well as its perceived other-worldly glow, have made it a common popular-culture hallmark of radioactivity. It determined the colour of Doctor Manhattan in Watchmen,[10][11] as well as the radioactive glow of products from the nuclear power plant in The Simpsons (where it was inaccurately portrayed as green[12]). The classic blue glow that is usually given off by Godzilla's spines before he fires his Atomic Breath, and the normally-blue colour of the beam itself, can also be attributed to Cherenkov radiation.

Source [10] talks about Cherenkov radiation, but doesn't say anything about doesn't say any thing about Dr Manhatten, or pop-culture depictions of radiation in general. ([11] does say that his colour was inspired by Cherenkov radiation). [12] says that the typical depiction of radioactive materials as glowing green (e.g. in the Simpsons) is based on the commonest colour of radium paint. I'll have a go at rewriting the section to better reflect the sources. Iapetus (talk) 09:37, 21 August 2015 (UTC)

Cherenkov Big Bang Cycles (Cherenkov Big Bang)

older essay

We detect netrinos via emitted "Cherenkov radiation" produced when they collide with atoms in the water. Photons are the particles that travel inside the void faster than any other particle. This is the case only in the pure void. In water other particles travel faster than photons, for example electrons. Our Universe is expanding - if we compare relativistically afar galaxies - faster than the speed of light in the void. The universal expansion is an accelerative one, thus in the future each single point, will ubiquitously diverge (rip apart) faster than light - a non relativistic - therefore absolute, ubuquitous and scalar (adiabatic "scalar field" expansion - thus homogeneity is not an issue/conondrum) (expansion)-explosion due to humongous speed. During the "Cherenkov Big Bangs" (plural because "cosmic inflation" predicts infinite ones), not electrons, but the "chromodynamic noise of the void" the "fabric of space-time" itself, will explode faster than light, and that event will produce (if we solve the maths) the observable energy levels, if we extrapolate backwards in time. Hence the Universe never dies, it only experiences infinite "Cherenkov Big Bang" consecutive events (we don't know if the "Cherenkov Big Bang Cycles" are totally ubiquitous - because our "visible horizon" is negligible if compared to the Megaverse). read also: /Wilczekian Noise/ Empty space is not empty. It's full of chromodynamic noise or quantum noise or the Wilczekian field. Empty parts of the Universe are filled with normal noise or normally arranged noise or normally distributed noise (there are no forced patterns-no directivity). Matter is looping noise. Gravity is elongated chromodynamic noise, that seeks a lower energy overall arrangement, in order the gravitational group consumes less space and thus less energy. Dark matter is like the ripples of a pool. Some chromodynamic noise patches become elongated and others compressed, not only the observed surfaces cause the gravitational effect, but the overall dark matter regions. Dark matter is NOT something different from the rest of space. All the pool we call Universe is full of water/Wilczekian noise, simply only some parts of the Universal pond are wavy, that doesn't mean water exists only in the wave. "Wavy chromodynamic noise" or "dark matter", means that the noise of the void at the specific regions (we observe the phenomenon) has become non-omnidirectional thus exhibits three-dimensional (3D) directionality (not totally polarized directionality, because the "wilczekian grid" of the dark matter - chromodynamic noise has to be parallel to the shape of the "dark matter" region). Dark energy is way more fundamental. Dark enegy is one with space-time itself. If you let alone space with no galaxies at all, it (space-time) instantaneously explodes faster than the speed of light in the void. (I use the term "lightspeed" or "light-speed", it is acceptable in dictionaries, it means many things, I mean "faster than the speed of light in the void") Dark energy in a huge volume of space with nothing inside causes Big Bangs. But, Big Bangs after that Big Rip, generate a huge amount of matter. Nowadays many afar galaxies are relativistically diverging faster than the speed of light in the void. In the future, when "dark energy" will prevail, each single point of the Universe will diverge from itself (it will rip apart it's viscera). That will not be a "relativistic light-speed divergion" but an "absolute/fundamental/ubiquitous light-speed divergion" phenomenon of each Universal point. That explosion (Big Bang) will transform energy into matter, thus the acceleration will be reduced after a while. Note 1: Huge amounts of energy, generate new particles. Note 2. Particles are non-omnidirectional phenomena of the chromodynamic noise (wilczekian grid), and decelerate the affects of "dark energy" Dark energy due to entropy always prevails at last, and a new circle of creation begins.

Cherenkov: add pronunciation

Cherenkov: add phonetic characters please! — Preceding unsigned comment added by 2A02:587:4109:3E00:1CA5:C59E:60BC:4528 (talk) 07:35, 23 October 2016 (UTC)

Black hole's Cherenkov radiation

note that the whole "black hole system" is not only the core, but
(noted from the extrerior to the interior)

1. the black hole disk and the polar geysers
2. the "range of the event horizon" which isn't absolute, but relativistic according to the relative speed and position of the observer
3. normal matter after the event horizon (it exists in huge black holes)
4. neutron plasma (80% neutrons, 10% protons, 10% electrons)
5. the quark-gluon plasma before the core
6. the "feresingularity particle" the almost-point-like indivisible core particle

Where the Cherenkov radiation occurs in a black hole? (because there, particles of its non central layers, travel faster than light)

• a theoretical black hole has a neutral charge (actual ones usually consume something by decaying it and that generates charge, if they're alone they still vomit an astronomically negligible amount of matter)
• in a huge black hole, the "normal matter layer region" inside the black hole, doesn't generate Cherenkov radiation, but "observed Cherenkov radiation" to an observer who is less deep inside the black hole, but sees things, because he/she travels fast enough towards the object of observation

Cherenkov radiation occurs to all layers of the "black hole system", except the core (feresingularity particle = it is a fundamental particle, it isn't a point, it reaches the maximum degeneracy level of the universe, with more pressure we either have a bigger particle [the pressure fails to compact more energy], or some energy escapes as radiation [again, a failure of compression] [the feresingularity's maths offer explaination why the Big Bang blasted, using parts of the Roger Penrose's looping universe mechanism])

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Speed at which light propagates

Hello all

I have made a recent change to the article by editing one of the sections to explain the speed at which light propagates and why it is slower than the actual speed of light. Please comment on my changes

Shadowstone1 (talk) 09:05, 22 August 2019 (UTC)

Misconceptions

The article says "There are some misconceptions about Cherenkov radiation. For example, it is believed that the medium becomes electrically polarized by the particle's electric field. If the particle travels slowly, then the disturbance elastically relaxes back to mechanical equilibrium as the particle passes. But when the particle travels, the limited response speed of the medium means that a disturbance is left in the wake of the particle, and the energy contained in this disturbance radiates as a coherent shock-wave. Such conceptions do not have any analytical foundation, as electromagnetic radiation is emitted when charged particles move in a dielectric medium at subluminal velocities which are not considered Cherenkov radiation."

I've had three or four shots of vodka, so I could be wrong, but as far as I can tell, the third and fourth sentences combined with the last sentence don't seem to connect to the first two? If they do, I suspect there needs to be more explanation. — Preceding unsigned comment added by Dstar3k (talk • contribs) 23:08, 21 August 2020 (UTC)

I double that even without vodka. What is the actual misconception? What is described in the text below or is that the explanation how things actually work? Especially the last sentence does not make any sense to me at all as I was taught in my physics studies that this is exactly how Cherenkov light works. Looking online for physic lectures, this is also what is taught(i.e. ). So is the misconceptoion that non coherent light might also be called Cherenkov light? I do not get it, please add some explanation or remove the section outright.P91 (talk) 13:15, 11 September 2020 (UTC)

References

Curie, Heaviside, Sommerfield

From Quora:

The first person to see it was Marie Curie in 1910. Since she didn’t pursue the observation, so she clearly didn’t think much about it. Heaviside and Sommerfeld predicted it independently in 1888 and 1904 respectively

This is not any of it in our current article and should be. I have asked there for sources. Or can someone here provide them? Andrewa (talk) 00:17, 7 July 2021 (UTC)

Forget the above, it's there and I missed it somehow. Andrewa (talk) 06:42, 8 July 2021 (UTC)

Don't forget gravity...

The text blurb: "While the speed of light in vacuum is a universal constant (c = 299,792,458 m/s)"

... is misleading. The speed of light in vacua is only constant in a space without a gravitational field (which doesn't exist anywhere in the universe because gravity is a long-range force) or a constant gravitational field (which doesn't exist anywhere in the universe because gravity obeys the Inverse-Square Law).

Einstein reiterated this fact many times, a few examples of which are below:

1913: “I arrived at the result that the velocity of light is not to be regarded as independent of the gravitational potential. Thus the principle of the constancy of the velocity of light is incompatible with the equivalence hypothesis.”

The Equivalence Principle states that there is no functional difference between actual translational acceleration and gravitational acceleration.

1916: “In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity.”

1920: “Second, this consequence shows that the law of the constancy of the speed of light no longer holds, according to the general theory of relativity, in spaces that have gravitational fields. As a simple geometric consideration shows, the curvature of light rays occurs only in spaces where the speed of light is spatially variable.”

This is how gravitational lensing (ie: the curvature of light rays around a gravitating body) occurs, which was what originally corroborated Einstein’s theory.

76.30.103.137 (talk) 06:21, 8 November 2024 (UTC)