Talk:Hafele–Keating experiment

Broken link
Link number 5 in the Link section is broken. One should either remove it or change it, right? what would be the correct link to the repeated experiment? —Preceding unsigned comment added by 194.169.250.90 (talk) 13:50, 7 April 2008 (UTC)

Time dilation
Link number 5 in the Link section is broken. One should either remove it or change it, right? what would be the correct link to the repeated experiment? —Preceding unsigned comment added by 194.169.250.90 (talk) 13:51, 7 April 2008 (UTC)

This is an obvious case of two extreme POV's. If someone has a reference ready about a more modern repeat experiment (I'm sure that there was at least one!), it would be good to add that and to rephrase (soften) some sentences. Harald88 21:29, 17 October 2005 (UTC)

An engineering discussion of the functioning of the GPS satellite system pins down all of the relevant facts and measurable values. Velocity time dilation, the sagnac effect and general relativity are all engineered into the operation of that system. Sort of a 24/7 experiment, if you will. Jok2000 22:41, 17 October 2005 (UTC)

That's right, and there are papers about that as well as, if I remember well, a special test done by the military. What is lacking now is a precise reference and referral to it with a summary here in this article. Harald88 20:10, 18 October 2005 (UTC)

BTW:, thanks Jok, your addition of GPS details is already a good improvement. Harald88 12:16, 20 October 2005 (UTC)

The UK's NPL re-did the experiment for the 25th anniversary of the original H&K version.

http://www.npl.co.uk/publications/metromnia/issue18/

It wasn't a round-the-world affair, but it was done with more precise equipment. The results are (quoting from the above website):

''On return to NPL the travelling clock was predicted to have gained 39.8 ns, including an additional geometric factor. This compared remarkably well with a measured gain of 39.0 ns. We estimated the uncertainty due to clock instabilities and noise to be around ±2 ns. This short flying clock experiment therefore provided a clear demonstration of relativistic effects.''

A USENET reference notes a report of this report in the 2005 Feb 26 issue of New Scientist. mdf 21:21, 20 October 2005 (UTC)


 * Thanks! Still, I remember that I downloaded, maybe one year ago, an original recent PDF report about such a test - likely directly from a reliable source (New Scientist, I'm sorry to say, I don't find very qualified, nor news summaries (I searched NPL's publications, but didn't find it). But if I don't find "mine" back soon, then we can cite the one you found, at least temporary. Harald88 22:17, 20 October 2005 (UTC)


 * I searched on the New Scientist web site and couldn't find any such article. The experiment was done as part of a BBC program commemorating the original experiment's 25th anniversary, and the program was then sold to Nova. There is a transcript of the program on Nova's web site.--24.52.254.62 01:31, 19 June 2006 (UTC)

http://www.npl.co.uk/publications/metromnia/issue18/ is a dead link. Is there another citation or reference for this experiment? --68.53.221.14 (talk) 01:46, 20 January 2008 (UTC)


 * Here is the NPL pub 18http://resource.npl.co.uk/docs/publications/newsletters/metromnia/issue18_einstein.pdf 71.120.142.163 (talk) 15:06, 12 March 2024 (UTC)

GPS reference
More sources need to be cited to back up the claim that the GPS system has anything to do with time dilation effects vs redshift effects. Jeff Carr 13:33, 21 January 2006 (UTC)


 * How do you mean? Time dilation of a distant EM source is measured as redshift... Harald88 15:55, 21 January 2006 (UTC)

special relativity explanation
I thought that in special relativity no inertial frame is preferred. However, the explanation for why the westward clock ran fast compared to the ground(gained nanoseconds) whereas the eastward clock ran slow seems to appeal to the frame of 'the universe as a whole'. Am I misreading something? -Intangir 01:29, 8 April 2006 (UTC)


 * What you may have missed: the used calculations can be done for any inertial frame - in this case the earth centered inertail frame was used for convenience, and not that of "the universe". Should this be clarified perhaps? Harald88 15:58, 8 April 2006 (UTC)


 * Done.--24.52.254.62 01:27, 19 June 2006 (UTC)

I am confused with the explanation that the clock in the eastward going plane would have a higher velocity than the clock on the ground, and the clock in the westward going plane would have a lower velocity than the clock on the ground: first, the clock on the ground is not at the center of the earth (was it perhaps at a pole so at the center of rotation? Otherwise the clock on the ground would also be moving), and two- I would imagine the relative ground speed of the plane would be the same in either direction. Is it the fact that due to the elevation, and therefore larger radius, that this change in velocity exists? — Preceding unsigned comment added by 75.144.165.5 (talk) 21:03, 29 August 2016 (UTC)


 * Please sign all your talk page messages with four tildes ( ~ ). Thanks.
 * With respect to the "Earth centered inertial reference frame" (ECIF), a clock on the ground (for instance at the equator) "goes East" by the Earth's rotation, so a clock on an eastbound plane "goes East faster" (w.r.t. the ECIF) than the ground clock, whereas a clock on an westbound plane "goes East slower" than the ground clock. Anyway, per wp:Talk page guidelines, such questions should go to the wp:Reference desk/Science, as here we should discuss the article, not the subject. - DVdm (talk) 07:25, 30 August 2016 (UTC)

POV war - please end it
Please don't delete published expert opinions that disagree with your POV - Wikipedia demands that significant contrary opinions are all included. In this case such a behaviour even makes no sense at all, as the results of more recent experiments are beyond doubt anyway.

Thus I'll reinsert the deleted published POV's, and harmonize the text accordingly. Harald88 19:15, 20 June 2006 (UTC)

PS I'm not sure if Kelly's research has been published other than by his university (his papers were kindly sent to me by them); and I don't know if university papers are accepted as "source" for Wikipedia. Harald88 19:45, 20 June 2006 (UTC)


 * Hi -- The current version, with your latest edit, seems fine to me. I suppose the issue is what would count as a "significant contrary opinions." I don't think there are any significant opinions that are against the validity of special relativity, but I suppose my definition of "significant" might differ from yours. The current version accurately explains that although there some people tried to challenge the validity of the experiment, they were later proved wrong. NPOV doesn't mean that we have to give equal credence to people who say the Earth is flat, or that the periodic table is a hoax.--24.52.254.62 00:09, 21 June 2006 (UTC)


 * Hi we seem to agree, except perhaps about the validity of experiments: an experiment's validity doesn't depend on the correctness of the theory that is tested, instead it depends on the quality of the equipment and the skills of the experimenter. But perhaps it was a slip of the pen, and you meant that some people continued to doubt the validity of the theory. Note also that at that time relativity theory was by far not as established as for example the spherical Earth today. Hafele-Keating was really a milestone as it was the first realisation of Einstein's 1905 proposal for a time dilation experiment. Harald88 21:57, 21 June 2006 (UTC)

the Kelly paper
Kelly's paper is "notable" because it created a flurry of interest when it was published, and because AFAIK, nobody has been able to fault his analysis. I no longer have my files, but as far as I recall, Kelly's paper essentially said that the large degree of intermittent error in the HK test meant that the results should probably have been discarded as worthless regardless of whether they happened to support SR or not. The clock with the largest error was also the clock that contributed most of the desired result: if that clock had been taken out of the experiment (as later USNO guidelines would suggest), then most of the reported effect disappeared.

This isn't to say that the prediction itself is wrong ... only that the experiment that set out to verify it, judged according to more modern quality criteria, was arguably too unreliable to be counted as a proper verification of the effect.

The apparent shortcomings of the H-K experiment don't amount to a criticism of special relativity (if the experiment is invalid it doesn't count one way or the other), but some people may take the SR community's enthusiasm for this experiment (without subjecting it to the proper sceptical scientific analysis) as an indication of "cultural problems" in this part of the physics community that seem to be preventing proper scientific standards from being maintained. We should have been told about these problems immediately by the mainstream community itself, we shouldn't have had to wait 25 years for an "outsider" to do their job for them, and that outsider shouldn't have been subjected to the character assassination that happened, for apparently just telling the truth. When an experiment is done for the very first time, sometimes it isn't quite as good as the experimenters think ... the equipment is often being used in unusual ways, and in extreme conditions, and potential problems may not emerge until some time later, by which time everyone's become more familiar with the techniques involved. This is just something that happens from time to time.

IMO we shouldn't be especially critical of H&K either -- they had a cool idea for a relatively inexpensive experiment, they went out and did it, and they tried to report the results that they obtained. Good for them. It perhaps wasn't their fault if the technology wasn't quite good enough at the time for their results to be quite as significant as some SR proponents made them out to be. That's the thing about famous experiments ... they are/were experimental, and the more famous an experiment, the more "experimental" it's likely to have been. Sometimes they work well, sometimes they don't. The most famous ones often turn out with hindsight to be a bit dodgy, because they tend to be pushing the experimental "envelope" further than anyone's been able to go before. The thing is to be honest about it. ErkDemon 14:04, 7 May 2007 (UTC)

GPS section needs citations
An anonymous user whose IP address keeps changing keeps removing fact tags and not citing any sources. The whole section is heavily biased too. This week I'll try to do some research and get to the bottom of this, but in the meantime, qualifying everything with "seems to" is not an improvement. —Keenan Pepper 05:50, 22 August 2006 (UTC)

Just google for GPS and time dilation. You will be able to find the equations. Jok2000 20:24, 22 August 2006 (UTC)


 * The equations aren't the issue, because everyone agrees on them. The issue is whether the effects they represent are negligible. Are Our job is to present the different views from a neutral point of view and with appropriate citations so readers know who's whose views they are. —Keenan Pepper 01:38, 23 August 2006 (UTC)

This is the "anonymous user whose IP address keeps changing" (whew, you caught yourself a real Internet bandit, Mister! Try google for 'dynamic IP'). Now, let’s cut to the chase: besides watching too many episodes of Star Track (you are a teen, aren't you), what exactly qualifies you in this subject matter, to insist on the ridiculous notion that GPS could not survive without GR or SR?

One thing is to learn how to read and then be proud of it, like in your case of a Star Trackie boy scout. It’s a totally different ballgame to be able to actually read scientific papers in an area of interest. Now, go tell your science advisor you are unable to do this. Perhaps you will, in a few decades from now, but just not yet. OK? So kid, do us a favour and go have a cup of milk. Oh, and please try hard to not pollute the Internet with Dart Wader wormhole misfit realities. Hope you really are going to do "more research on this", although, in all honesty, I am not certain how you plan on accomplishing that in such a brief time. Oh, don't tell us, you own a paper-copy of the Hawking's "Brief..." too! —The preceding unsigned comment was added by 80.65.175.63 (talk • contribs).


 * I'm trying to ignore your personal attacks, so there's not much left to reply to. I'm not insting that "GPS could not survive without GR or SR", in fact personally I believe your point of view is closer to the truth. But it doesn't matter what I believe, because, as you put it, I'm just a "Star Trackie boy scout". People don't care what you or I think, they care what experts think and what's published in reputable journals. That's why WP:V and WP:CITE are so important. —Keenan Pepper 01:38, 23 August 2006 (UTC)

Message to 80.65.175.*
I'm not going to put this on 256 talk pages so I'll put it here. Stop vandalizing this talk page or I'll ask permission to do a range block. It's not funny anymore, so just quit it. —Keenan Pepper 04:14, 25 August 2006 (UTC)

- When you post a GPS ownership title in your name for all to see, you will be most welcome to start "turning us in". Until then, besides teenagers like you, Wikipedia remains open to all, I believe? —The preceding unsigned comment was added by 80.65.175.42 (talk • contribs).


 * I don't understand what you mean by "post a GPS ownership title in your name". Wikipedia has always been open to everyone, regardless of age. Why do you keep adding links to Sign your posts on talk pages with the text "...signatures on Wikipedia are not intended to indicate ownership or authorship of any Wikipedia article"? I never put my signature on the article itself, and I never implied that my signature indicated ownership of the article, so I don't know what your point is. Please spell it out for me so that my feeble teenage mind can understand, rather than using cryptic vandalism. —Keenan Pepper 21:43, 25 August 2006 (UTC)

Stop policing me while polluting Wikipedia with your Star Track fantasies about GPS being a proof of relativity theories. I have contributed to Wiki in several areas over the years, always as an anonymous user, and I intend to do just that in the years to come. 99% of my posts stood the test of time, but I have never encountered such a ridiculous figure like you. —The preceding unsigned comment was added by 213.249.155.239 (talk • contribs).

Civility
A general comment to all users. Do not modify other users' talk page comment and remain WP:CIVIL. Also please do not use personal attacks. JoshuaZ 16:36, 26 August 2006 (UTC)

GPS continued
First of all, how many people think the GPS section even belongs in this article? It doesn't seem to have much to do with the experiment performed by Hafele and Keating.

Second of all, doesn't even mention relativity. It's mostly about the combination of inertial navigation systems with GPS. The only other source is the book GPS satellite surveying, which I'm going to check out from my university's library right now. I doubt it really says all this stuff the article currently implies it says, but I could be wrong. We'll see. —Keenan Pepper 16:00, 8 September 2006 (UTC)

Let's start with: "Why do you believe that the functioning GPS's system time dilation is unrelated to the time dilation expected by Haefel & Keating, which they also seem to have measured?". After that, we can then argue as to why the theory (that is to say, the equations) behind both cannot be used in the article. Then when we're done that, we may ask the question, why are some users so dedicated in to making Wikipedia worse? (i.e. that insulting dude continually deleting the equations?). Then after that, we can ponder why there are so many cranks trying to mess up "time dilation", "twin paradox" and "Haefele Keating" all at the same time. Hm, and now I notice, also "GPS" with that innaccurate quote about GR&SR being unimportant (thus the importance of the equations). Jok2000 20:51, 8 September 2006 (UTC)


 * I have Leick's book right here and on page 68 it says: Relativistic effects are important in GPS surveying, but fortunately can be accurately computed. The atomic frequency standards in the satellites are affected by both special relativity (the satellite's velocity) and general relativity (the difference in the gravitational potential at the satellite's position relative to the potential at the earth's surface. That's very satisying to me. —Keenan Pepper 23:35, 8 September 2006 (UTC)


 * Good - then that is settled. Harald88 13:28, 9 September 2006 (UTC)


 * Not even close to being settled: since when are 'important' and 'critical' synonyms? What a lack of focus! Where does it say in the Leick's book that GR/SR are critical to GPS, so much to claim the GPS as a proof of the two theories as the present style of your writing implies (avoiding conditionals)?  Can you show it, please?  I didn't think so... — Preceding unsigned comment added by Unknewthat (talk • contribs) 01:51, 10 September 2006


 * I had the impression that the disagreement was about if "GPS section even belongs in this article", based on the erroneous argument that GPS experiments had nothing to do with the Hafele-Keating experiment. Phrasing is a different issue altogether. Harald88 08:27, 10 September 2006 (UTC)


 * Uknewthat: I have rv'd for the following reasons: 1) I think the equations for the various effects are an important part of this article and should not be deleted. Physics does involve the use of mathematics.  2) The section on GPS seems argumentative to me.  That is, it appears to be pushing a point of view.  3) I suspect that the point of view being pushed lies outside the scientific mainstream.  Cardamon 12:57, 16 September 2006 (UTC)


 * No. Keenan is an Einstein's teenage groupie who takes equations and quotes by researchers out of context and uses them to impose his own (a teenager's, mind you) view of what complex notions mean. Leick clearly stated in the same book (see the GPS section) that relativity corrections are not needed to achieve even the mm accuracy with GPS. Likewise, Einstein's equations taken out of context and placed next to a phoney experiment claims is nothing else but a hoax meant to impress the uninitiated. —The preceding unsigned comment was added by Uknewthat (talk • contribs).

I am starting an RFC on User:Uknewthat: Requests for comment/Uknewthat. If you have anything to say about this user, please say it there. —Keenan Pepper 19:41, 16 September 2006 (UTC)


 * This person(s) now goes 'inquisition style'. A note to the serious readers/users of Wiki: I do not intend to discuss anything with an 18 year old Einstein's groupie, let alone sophisticated science. Have your milk Keenan, and then go to bed. You'll do the world a big favour. —The preceding unsigned comment was added by Uknewthat (talk • contribs).

3RR
I have filed a report about this page at WP:AN/3RR. Dual Freq 15:14, 17 September 2006 (UTC)

References format
I notice that Mpatel chose  without discussion to move 2 of the 4 references to footnotes. Actually, moving to that format is not such a bad idea. What do people say to the idea of putting all the references in this article into that format? Cardamon 10:58, 4 October 2006 (UTC)


 * Yes. Pfalstad 11:46, 4 October 2006 (UTC)
 * Agree, general refs are hard for the reader to follow unless it's done like Harvard refs. --Dual Freq 23:24, 4 October 2006 (UTC)

If the A. G. Kelly ref recently added applies to the fact tag that was removed I believe it should be used with a citation tag so that future readers will know that that item is referenced. --Dual Freq 23:24, 4 October 2006 (UTC)

Page protection
I've protected the page because Uknewthat seems to be engaged in a slow revert war against consensus. Please try to reach some kind of agreement here, or if you're unable to, let me know. SlimVirgin (talk) 01:07, 5 October 2006 (UTC)


 * Why did you revert the last change? That seemed like a good compromise -- leave the stuff what this chap writes about his grandfather's experiment, but ADD what I put about the GPS not being a definitive proof of GR/SR theories. What is the problem with that?  Why revert that? Why lock without including what the other side has to say? — Preceding unsigned comment added by Uknewthat (talk • contribs) 12:54, 5 October 2006


 * This page is about "his grandfather's experiment", but doesn't really have anything to do with the GPS. So we discuss the first, and not the second. Ben Standeven 14:41, 5 October 2006 (UTC)


 * There may be a misapprehension here.  It is true that Buddhist Monk Wannabe left messages   on Uknewthat's talk page indicating that "Joe Hafele" was his or her grandfather.  However,  User:Buddhist Monk Wannabe seems to have never edited the Hafele-Keating experiment article.  (In his first message to Unknewthat, Buddhist Monk Wannabe apparently thought that Unkewthat had written the material on the experiment.)   So, to "leave the stuff what this chap writes about his grandfather's experiment" would be to leave nothing. Cardamon 21:37, 5 October 2006 (UTC)


 * What are you talking about? The H-K experiment page implies H-K has major GPS relevance by the concluding sentence. Besides, the last link is to "GPS Time Dilation". Very sneaky indeed! As for the whose-grandpa-did-what and all that: good thing my grandpas had only fought Hitler so they never had a chance to do any foul science; sorry if I didn't recognize the grandboy as the author of the sneaky page. Einstein troll puppets all look the same to me, as indeed they should. — Preceding unsigned comment added by Unknewthat (talk • contribs) 23:53, 7 October 2006


 * Hi, Uknewthat. I'd like to repeat that there is no evidence that any part of the H-K experiment page was ever even edited by User:Buddhist Monk Wannabe.  I would like to ask you to consider that people may disagree with you without being either puppet or trolls.  In other words, please assume good faith.  Also, repeatedly calling someone a puppet or a troll can be considered a  personal attack.  Finally, could you please start signing and dating your comments?.  Doing this makes it clear who said what, and when.  This helps a lot in keeping a talk page easy to understand.  It isn't hard.  Just put four tilde's (~'s) in a row at the end of your statement, and Wikipedia will do the rest. Cardamon 06:56, 10 October 2006 (UTC)


 * Actually, I don't think that sentence and link belong either; but in any event it is better to have one sentence and a link than a whole section of the article on something only tangentially related. Ben Standeven 16:27, 10 October 2006 (UTC)

I'd like to add that User:Jok2000 added the See also GPS item here. I believe it was added to placate certain anonymous users repeatedly adding POV GPS related non-sense to this article. It appears to me that it was a (failed) attempt to compromise with the anonymous users. Funny thing is, the anons kept adding the very same GPS POV section that Uknewthat keeps adding. (and also was unable or unwilling to sign posts.) --Dual Freq 23:49, 10 October 2006 (UTC)


 * I'm wondering whether it would be okay to unprotect the page now. Let me know, please. Cheers, SlimVirgin (talk) 20:01, 12 October 2006 (UTC)

EVERYONE: Please note that, in an agreement with SlimVirgin, I have only added a paragraph to the H-K page, without doing any edits to the rest of the page. The added paragraph is based in part on the discussion that can be found on the GPS page. Uknewthat 01:25, 15 October 2006 (UTC)

Why is GPS mentioned
Does anyone know why GPS is relevant here at all? Relativity is related to GPS, but why this experiment? It seems that an earlier version of this article claimed that the equations shown were used in the GPS system. Is there a source for this? Unless this experiment has some specific relevance to GPS, we should remove the references.. Hopefully that will help keep the cranks away too. Pfalstad 15:25, 15 October 2006 (UTC)


 * Only inderectly relevant. The atomic clocks in the GPS satellites are corrected for SR/GR relativistic effects, using the same equations as teh HK-experiment. But I think it is enough to mention GPS time delation as a "see also", as it is done right now.Mossig 16:53, 15 October 2006 (UTC)


 * I agree with Pfalstad. HK seems to be here only as a distraction. The author can always start his or her own Web site to expand on an experiment as obscure as this one. 1freerider 20:32, 3 November 2006 (UTC)


 * ? I wasn't saying that the HK experiment had no relevance..  I just wondered why the GPS material was present in this article.  Pfalstad 21:47, 3 November 2006 (UTC)
 * Easy: the GPS was brought up as alternative verification of the same laws as HK tested for--similar as set forth in GPS-- but that part was edited out by someone. Consequently the line of logic got lost. Harald88 21:52, 3 November 2006 (UTC)

photo
In Hartle's Gravity: An Introduction to Einstein's General Relativity, there's a nice photo of Hafele and Keating getting on the plane with the clock. The photo credit is to the US Naval Observatory, which makes me think that it might be PD. Anyone know anything about this? A Google Images search doesn't turn it up.--76.81.164.27 05:31, 10 April 2007 (UTC)
 * Another interesting image: http://www.usno.navy.mil/library/photo/clk6c.html . This would appear to be from the same type of experiment, but the date is from the year before. Maybe the Lloyd-Percival experiment failed, and then Hafele-Keating got it to work the next year? Googling on Lloyd and Percival yields nothing of interest that I can find.--76.81.164.27 03:40, 11 April 2007 (UTC)

I have made some historical photos available here http://www.lightandmatter.com/article/hafele_keating.html, along with some info on their copyright status. I think they qualify for use in this article under WP's policy on non-free content http://en.wikipedia.org/wiki/Wikipedia:Non-free_content, so I'm going to go ahead and put one in.--Fashionslide (talk) 04:22, 23 August 2012 (UTC)

Hafele-Keating Experiment Disproves Rather Than Confirms Special Relativity
It is apparent that the claim that this experiment confirms relativity is false. Special relativity demands symmetrical time dilation. This means that each clock runs slow relative to the other clock. Since the experiment does not verify this result, but shows that one distinct clock, the airplane clock, runs slower than the ground clock, then the symmetric prediction of special relativity is refuted by observation. Hence the claim that this experiment verifies special relativity is false. 71.251.176.71 13:10, 12 September 2007 (UTC)


 * Which reliable source are you citing here? Harald88 19:38, 12 September 2007 (UTC)


 * The anonymous writer is technically correct: the experiment confirms the general relativity theory. (Special relativity does not include accelerated frames of reference.) Mossig 21:07, 12 September 2007 (UTC)


 * You mean SRT does not include gravitation effects on time dilation - indeed.
 * However, the term "Relativity" usually includes gravitation. Harald88 20:46, 15 September 2007 (UTC)

I agree that HK disproves special relativity. An observer at the Naval Observatory (the reference clock) would see both planes moving at the same velocity (one east, one west). According to the Naval Observatory Observer, both plane clocks should run slower and at the same rate. There's no need for any calculations involving the center of earth reference point. Did anyone ask what time the pilot saw?! The pilot should have seen a different time than ground observers because he/she was moving at the same velocity (at all times) as the plane clock. this is the essense of the twin-paradox (which has not been fully resolved for me). HK seems to indicate that there is a universal frame of reference and that things are not "relative".--Leeapted (talk) 22:17, 25 June 2008 (UTC)

Because of the rotation of the earth, wouldn't an object moving east need to do so at a higher velocity or for a longer time before returning to the origin, as compared to an object moving west? 64.131.244.219 (talk) 14:33, 8 December 2008 (UTC)

Glad to see that someone cares! due to the fact that our atmosphere is rotating along with earth, flight times (and speeds) from new york to london and back are about the same (actually i believe that london to ny is longer due to prevailing winds). the simple point is this, for an observer in new york, the plane from london to new york is moving at a higher velocity than the observer and the clock should slow down (for that observer). hafele-keating found that the clock ran faster. they seem to think that using a center-of-earth frame of reference clears everything up! it doesn't! hafele-keating seems to indicate that there is a preferred frame of reference (and i'm not so sure it's the center of the earth). --Leeapted (talk) 20:50, 11 December 2008 (UTC)

I'm so glad to have found a place where this idea is being floated. I've been racking my head for awhile until I finally stumbled across this experiment. Perhaps someone can clear this up for me too. It makes sense that the two clocks are different because of the rotational velocity of the earth. But wouldn't this mean you could apply this to bigger idea. What if I was in space without being able to see any reference points(stars, planets). Let's say I was moving 1m/s in a direction. If I had one clock go ahead of me 5m/s and one clock go behind me 5m/s, relativity tells me I should be getting back the same variances from both clocks since I have every right to say I am the one that is still and everything else is the thing that's moving, but the H-K experiments seems to tell me that I should get a different variance from the clocks because I am moving too(just like the Naval Observatory was rotating with the Earth). If that's the case...doesn't that mean I can use this experiment with enough sensitivity to figure out "absolute stillness" which kinda could mean I could figure out the "center" of the universe, or at least prove it's existence? --Demon380 (talk) 08:26, 24 June 2009 (UTC)

Has this experiment anything to do with special relativity at all? Can you even apply special relativity to this case, since it does not involve movement at constant velocity? Akvilas (talk) 21:35, 31 January 2010 (UTC)
 * Special relativity is not limited to motion with constant velocity. However, the experiment cannot be explained simply by special relativity, because the airplanes experienced both kinematic and gravitational time dilation.--75.83.69.196 (talk) 01:55, 15 November 2010 (UTC)

I can slow my mechanical watch with a magnet. Does this prove that I managed to slow down time? What I want to say is that H&K experiment has nothing to do with relativity claims. In our reality space and time are concept and cannot bend, twist, slow down or speed up. 80.237.46.17 (talk) 22:41, 31 October 2012 (UTC)

Exactly, the clock only measures itself, not time. Atomic clock can be influenced by Lorentz contraction (length of the resonator matters). Hence Einstein could have been wrong, the time is constant and speed of light is variable (if the speed of our observing is variable with the changing speed of light, then we wouldn't notice the speed of light is not constant). 178.40.24.137 (talk) 18:47, 2 November 2014 (UTC)

Equations section
I'm confused by the equations section in this article. What is k? Vectro (talk) 14:34, 8 December 2008 (UTC)

Tushey webpage
I have moved this link to what seems to be a personal webpage from the article to here:

 http://www.tushey.fw.hu/en/hk_eng.htm 
 * Tom Tushey:Theoretical fundamentals for the H-K experiment

Why is this supposed to be a reliable source?? Cardamon (talk) 20:01, 30 January 2009 (UTC)

Bang Goes The Theory
An experiment along similar lines was shown on the BBC's Bang Goes The Theory programme. More info is available at http://www3.open.ac.uk/media/fullstory.aspx?id=19636. Adambro (talk) 12:52, 10 September 2010 (UTC)

Curved Space
How does this Experiment justify its results knowing that gravity just bends space/time? If we are on a curved path through gravity, and that gravity is detectable by moving clocks, wouldn't that tend to show that the MM experiment results were due to the "ether" and not necessarily space dilation? After all, the atoms in the atomic clock would only be effected by the curvature of space/time, not what the earth was doing; unless there was sufficient frame dragging for them to be effected by it - and that means the MM results were due to the "ether"/frame dragging. All in all this experiment seems to produce contradictory results and cannot be used to differentiate between "ether" and relativity. And when considered as a whole based on the comments made throughout this discussion, it would tend to show that there is something else besides relativity causing the clocks to vary their timing. And as far as the "doesn't work for non-inertial frames" group, please show how the rotating frame causes the clocks to detect the motion.

BWilliams2010 (talk) 20:36, 25 September 2010 (UTC)


 * This article talk page is not really the place for this. This is where we duscuss the article, not the subject or part of it -- see wp:TPG. You might try to put this question at wp:reference desk/science. Good luck. DVdm (talk) 20:58, 25 September 2010 (UTC)

Undue weight given to kooks
The article spends almost as much time debunking anti-relativity kooks as it does discussing the experiment itself. This clearly violates WP's rule about not giving undue weight: http://en.wikipedia.org/wiki/Wikipedia:Reliable_sources_and_undue_weight I am going to greatly shorten all the text starting from "A few authors..." down to the end of the Overview section.--75.83.69.196 (talk) 01:44, 15 November 2010 (UTC) Done. I've also changed to better references on the higher-precision follow-up experiment by Alley et al.--75.83.69.196 (talk) 14:44, 15 November 2010 (UTC)

Undefined notation
Some of the notation in the Equations section is never defined. I'm guessing that R is the radius of the earth (but then why the subscript i?), phi is the latitude, and lambda is the longitude.--75.83.69.196 (talk) 03:48, 16 November 2010 (UTC)

Repetitions
I'v included a description and a link to the 2010 repetition of the experiment (see here), and the original link to the 1996 repetition (see here). --D.H (talk) 16:25, 19 June 2011 (UTC)

Revert of GPS related paragraph removal
dvDM deleted a paragraph discussing the experiment's historical link to GPS and the military, complaining "Undid revision 467435338 by 75.83.69.196 (talk) wp:UNSOURCED addition, and not related to article subject — they had clocks on airplanes, not on satellites." I have restored the paragraph and added several sources. The complaint about airplanes versus satellites doesn't make sense; as explained in the text and the references, the whole thing was part of an interlinked research program involving both airplanes and satellites. dvDM, please assume good faith, please don't act in a confrontational and heedless manner, and please discuss things constructively on the talk page. Considering that I'd just added a total of 10 references to the article, it hardly seems reasonable or productive to delete text without discussion while complaining of a lack of references. There is a { { Citation needed } } tag that can be used to complain in cases like this. --75.83.69.196 (talk) 17:07, 24 December 2011 (UTC)


 * Trust me, I assume good faith. I just think that the addition was highly off-topic, and it was unsourced, so I . You restored it with sources. Good, although not compliant with wp:BRD—you should have waited untill after a wp:consensus per this discussion. Now, i.m.o. is still highly off-topic, so I propose we remove it. Any seconds? - DVdm (talk) 12:56, 25 December 2011 (UTC)


 * Why do you consider it off topic? The article is about an experiment. The paragraph explains *why* the experiment was funded: because specific practical applications were anticipated. You'd have to have an extreme ivory-tower view of science to imagine that applications are irrelevant in any discussion of an experiment.--75.83.69.196 (talk)


 * I.m.o. it is off-topic, because the paragraph about GPS is an anachronism w.r.t. the specifiic subject of the article. But I asked for seconds, and you are a first. That doesn't count. Cheers - DVdm (talk) 21:31, 28 December 2011 (UTC)


 * GPS is not an anachronism with respect to the article. The paragraph clearly explains that there was an ongoing program that led to GPS, and the Hafele-Keating experiment was part of that ongoing program. The program began before Hafele-Keating, it continued after Hafele-Keating, and Hafele-Keating was funded as part of it. Have you read the history section of the GPS article?--75.83.69.196 (talk) 00:00, 29 December 2011 (UTC)


 * The Hafele-Keating experiment is not explicitly mentioned anywhere in the GPS article. Do you have a source that backs the fact that HK was indeed funded as part of the GPS-program? If such a source exists, it should be easy to find, and it could be used to back a good addition to this article (and to the GPS article as well). Otherwise, without such a source, we'll have to remove the section as wp:original research. Please read that part of the Wikipedia policy. - DVdm (talk) 10:53, 29 December 2011 (UTC)


 * I didn't claim that HK was mentioned in the GPS article. I didn't claim that HK was "funded as part of the GPS-program." I didn't claim either of those things on the talk page, and the paragraph in the article didn't claim that.--75.83.69.196 (talk) 20:45, 29 December 2011 (UTC)


 * Indeed, you said "...ongoing program that led to GPS.... The program began before Hafele-Keating, it continued after Hafele-Keating, and Hafele-Keating was funded as part of it." to justify mentioning GPS in this article. Without a source for this, there is no room to mention this "ongoing program that led to GPS" in this article, and actually even less the GPS program itself. That would even be second-order original research. Have you read the policy at wp:NOR? - DVdm (talk) 21:38, 29 December 2011 (UTC)


 * By the way, I have neutralised the section header per wp:TALKNEW: "Do not mention other editors by name in article talk page headings." - DVdm (talk) 23:03, 29 December 2011 (UTC)

The reliable sources don't seem to make the connection to the HK experiment so it seems like a WP:Synthesis (unless some quotes that I may have overlooked could be shown). IRWolfie- (talk) 22:02, 31 December 2011 (UTC)


 * I have removed the closing paragraph per wp:NOR and wp:SYNT. Although interesting, its relevance to this article is not supported by the given sources. I looked for supporting sources but didn't find any. If anyone can find some, feel free to present them here, so we can discuss reintroduction. - DVdm (talk) 12:48, 2 January 2012 (UTC)

AJP reference
I came across the following reference, which describes the proposed experiment in future tense: Hafele, American Journal of Physics 40 (1972) 81, http://ajp.aapt.org/resource/1/ajpias/v40/i1/p81_s1 --75.83.64.6 (talk) 00:18, 16 September 2012 (UTC)

source of info for mountain-valley experiments?
D.H. put in some good numerical data from the Italian and Japanese mountain-valley experiments. Very cool! I assume the Italian data came from the Nuovo Cimento paper, but what about the Japanese data? The only reference we have is to what looks like an internal report, which I assume can no longer be obtained...were the results ever published in a journal somewhere?--75.83.64.6 (talk) 00:18, 16 September 2012 (UTC)


 * I directly took it from "Iijima, S.; Fujiwara, K. (1978). "An experiment for the potential blue shift at the Norikura Corona Station. Annals of the Tokyo Astronomical Observatory 17: 68-78". It is scanned in snipped format in Google books, see here and here. For instance, the abstract reads:
 * An experiment to detect the potential blue shift resulting form the general relativistic theory has been conducted by carrying a commercial cesium beam clock between the Tokyo Astronomical Observatory (Mitaka, 58 m above the sea level) and the Norikura Corona Station (2876m above the sea level) in turn. The cesium clock was kept in operation during about one week respectively and alternatively at Mitaka, Norikura, Mitaka, Norikura, and Mitaka. After correcting the effects of the environmental conditions which were different between these two places, the detected net rate change due to the potential blue shift corresponding to the altitude difference, 2818m, became (+29.0 ± 1.5) × 10-14. As the amount of the blue shift expected from the theory is +30.7 × 10-14, the ratio of the amounts detected to expected is 0.94 ± 0.05.
 * Regards, --D.H (talk) 08:32, 16 September 2012 (UTC)
 * Thanks very much, D.H., for both the further info and the transcription of the abstract. If I correct "form" to "from" and search in google books for the first sentence, I get a view of almost all of the abstract.--75.83.64.6 (talk) 18:57, 16 September 2012 (UTC)
 * Ben - I've just sent an email to the National Astronomical Observatory of Japan (successor to the Tokyo Astronomical Observatory) asking if it would be possible for me to get a scanned copy of the paper. I usually don't have too much luck with this sort of request, unfortunately. In addition, Shigetaka Iijima appears to be a currently active member of the IAU, so I'm currently trying to locate an email address for him. If I do manage to find one, I usually have a decent success rate with direct email contact with an author. Wish me luck! Stigmatella aurantiaca (talk) 19:28, 16 September 2012 (UTC)
 * Ben - check your lightandmatter.com inbox. Stigmatella aurantiaca (talk) 10:44, 19 September 2012 (UTC)
 * The webmaster of NAOJ very kindly sent me a copy of the Iijima and Fujiwara paper, which I forwarded on to Ben. I specifically identified you and Ben as people with whom I would share this paper. I don't see a Wiki email account for you, though. If you set one up, I can email you download information for my Google docs account. Stigmatella aurantiaca (talk) 10:44, 19 September 2012 (UTC)
 * Very cool, thanks! The environmental effects were quite large, and there were several of them to be corrected for. It's clear that this was really pushing the state of the art with atomic clocks in 1978. I haven't seen the Briatore paper, but I wonder if it's actually cleaner.-Ben --75.83.64.6 (talk) 23:50, 19 September 2012 (UTC)
 * A fortiori, one could state that Hafele and Keating's experiment in 1971 was at the bleeding edge of what was possible. A naive analysis of their published data in Fig. 1 only enables one to establish, to an 0.05 level of statistical significance, that the eastward and westward moving clock ensembles experienced relative clock discrepancies of the correct sign and of magnitude consistent with the predictions of general relativity. Their Fig. 1 gives the totally false impression that no timing comparisons were performed during the eastward and westward trips themselves, that the only timing comparisons that took place, took place on the ground when the traveling clocks and the USNO clocks were united.
 * In actuality, clock intercomparisons among the four traveling clocks were performed every few minutes throughout the entire duration of the experiment. With this timing intercomparison data, Hafele and Keating could perform correlated rate change analysis. It is important to note that "...the relative rates for cesium beam beam clocks do not remain precisely constant. In addition to short term fluctuations in rate caused mainly by shot noise in the beam tubes, cesium beam clocks exhibit small but more or less well defined quasi-permanent changes in rate." With continuous intercomparisons among the four clocks, it was possible for Hafele and Keating to identify precisely when these jumps in rate occurred. Correlated rate change analysis enables a vastly greater improvement in accuracy than the two-fold improvement that one would expect from a simple averaging of the outputs of the four clocks, and is used by all standards organizations in analyzing clock data.
 * This is the point that crackpots like Kelly, or even defenders of the H-K experiment like ErkDemon above did not understand.
 * Current portable cesium and rubidium atomic clocks are, of course, several orders of magnitude more stable than the portable clocks of forty years ago. Stigmatella aurantiaca (talk) 10:01, 21 September 2012 (UTC)
 * I wasn't criticizing the validity of the Iijima experiment. It's just that for pedagogical purposes it's unfortunate that one cannot, for example, show the graph from the paper and connect it directly to the predictions of GR, without taking into account all of these very large corrections. I wasn't commenting on Hafele-Keating at all.-Ben --75.83.64.6 (talk) 18:32, 21 September 2012 (UTC)
 * Whoops, sorry if my tone was a bit overbearing! I didn't think you were being critical of the Iijima experiment. It's just that I've spent a good deal of time studying the Hafele-Keating experiment, and under a different name, I used to discuss this and related topics on various science newsgroups. So it's the first time in maybe ten years that I've discussed the subject, and my thoughts just gushed out. :-) Stigmatella aurantiaca (talk) 19:25, 21 September 2012 (UTC)
 * No worries. I know it gets tiresome dealing with anti-relativity kooks.--75.83.64.6 (talk) 21:10, 21 September 2012 (UTC)

I obtained a copy of the Briatore paper. They did do a cleaner job of eliminating environmental effects that Iijima. They kept the sea-level clock in a barometric chamber, at the same pressure as the one on the mountain.-Ben, --75.83.64.6 (talk) 21:10, 21 September 2012 (UTC)
 * I'd be interested in seeing the paper. Can you send me a scan? Stigmatella aurantiaca (talk) 22:30, 21 September 2012 (UTC)
 * http://www.scribd.com/doc/106593804/briatore-1977 - Ben, --75.83.64.6 (talk) 02:02, 22 September 2012 (UTC)

Equation section It would be better to split the effect into its kinematic and its gravitational part. Further spliting into "velocity" and "Sagnac" effect would need at least a simple derivation, or better a physical explanation. Is there really any good reason to intoduce the "Sagnac effect" here, as the usual formula for kinematic time dilation from SR is self-suficient? Talking about the "Sagnac effect" make sense only if it is related to the use of this term in interferometry and if it is explained why this term in the HF experiment has this relation with the Sagnac effect highlighted in interferometry. — Preceding unsigned comment added by 80.200.0.103 (talk) 10:26, 27 April 2013 (UTC)

About Mendel Sachs
Why does the Hafele Keating experiment article mention Herbert Dingle and Mendel Sachs at all? Their opinion is not notable. The dissent of Herbert Dingle and Mendel Sachs is not indicative of any doubt in the scientific community.

It is well known that Herbert Dingle never understood the first thing about relativistic physics. His objections came from deep misunderstanding.

In august 2011 Mendel Sachs wrote on his website about the Twin paradox: I have recently been asked if I still believe what I said in my 1971 paper, "Resolution of the Clock paradox" (Physics today, 24, 23 (1971)), [...] my main claim: that the letter 't' in the formulas from special relativity, [...] is not a physical process, such as the physical aging of a human being or the unwinding of the spring of a clock! Rather, 't' represents an abstract measure of time, such as the reading of the hands of a clock, not the physical unwinding of the spring behind the face of the clock. [...]

Please read the entire blog entry to make sure you understand what he is saying.

It's unclear whether Mendel Sachs ever took notice of the results of the Hafele Keating experiment. (Unfortunately it's no longer possible to ask him, he died may 5th, 2012)

Whatever the case, the evidence is clear that Mendel Sachs disagreed with the scientific community on a fundamental point, and that his point of view was incompatible with many different experimental results.

I suggest that the mention of Herbert Dingle and Mendel Sachs is removed from the article. --Cleonis | Talk 11:12, 28 April 2013 (UTC)
 * I removed the phrase. --D.H (talk) 11:27, 29 April 2013 (UTC)

Equation variables not all labelled
Not all the variables in the equations (section) are labelled - without them, the equations are useless, unless you happen to be already familiar with the equations - which defeats the purpose of Wikipedia, surely. Missing are i, R, h0 and phi. Also, the variables should appear in the same font and italic style in the labels as they do in the equations, to remove any possibility of confusion. A worked example using the results/predictions from the one of the described experiments would also remove doubt.--Quitequick (talk) 08:13, 29 October 2013 (UTC)


 * Indeed. It would also be nice to have a direct reference to the book or article from which these equations were pulled. I tagged the section. - DVdm (talk) 08:19, 29 October 2013 (UTC)

Tom van Baak's replication
You're very welcome. I figured that with the Wired article, the PTTI presentation (establishing professional respect; he's not WP:FRINGE) and the TV show, we've established WP:Notability. And, although self-published, his own web site is a good source for the practical details of carrying out the experiment. 71.41.210.146 (talk) 16:16, 31 March 2017 (UTC)

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Removed badly sourced challenge section
Per lack of wp:reliable sources, wp:FRINGE and wp:UNDUE I have removed the fringy, badly sourced section about the challenge of the test results. Cited sources were this (as a subpage of this) which is someone's personal opinion on their private website, and this which is just an obituary of Kelly, a mechanical engineer, not even a physicist. Comments welcome. - DVdm (talk) 11:49, 1 November 2020 (UTC)