Repeat of Hafele-Keating Experiment?

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Main Question or Discussion Point

This famous experiment to test both velocity and gravitational dependent Time Dilation was conducted using commercial jets in 1971.


The experiment was a great success.


However, they only used 4 atomic clocks, which seems too few. Also, atomic clock technology has improved greatly since 1971.


I would like to see a repeat of the experiment being conducted with more clocks and perhaps using supersonic jets. Which organization do you think would be willing to conduct such an experiment?
 

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  • #2
PAllen
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There have been many repetitions.

See the discussion in:

http://en.wikipedia.org/wiki/Hafele–Keating_experiment

The most precise confirmation comes from the GPS system, which continuously verifies both speed and gravitational effects to ever growing precision.

Here is description of separating pure gravity and pure speed effects using super precise clocks that can detect time dilation at speeds of a few meters per second and altitude differences of less than one meter.

http://www.scientificamerican.com/article.cfm?id=time-dilation

Here is a link for the technical article:

http://www.sciencemag.org/content/329/5999/1630.abstract
 
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I wish they would conduct another experiment:

Remove the time correction from GPS and see what happens. :)


But of course they'll never dare to.
 
  • #4
pervect
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I wish they would conduct another experiment:

Remove the time correction from GPS and see what happens. :)


But of course they'll never dare to.
I'm not quite sure what you're proposing, but I"m sure people would be reluctant to muck up the GPS system in the name of science. Especially since there is no need, the existing experiments establish the results to anyone who is open to being swayed by logic.

There is of course a certain fringe element who thinks that there is some vast conspiracy that underlies all the experimental results which confirm relativity . Unfortunately no experiment seems to be able to convince this fringe element, because they'll simply claim that any experiment in accordance with relativity (which is pretty much all of them) is part of this vast, nebulous, conspiracy :-(

Occasionally the fringe element will obsess on some very old and non-replicated result that didnt confirm relativity, and ignore the fact that attempts to replicate the apparently contradictory result failed.
 
  • #5
russ_watters
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Not to mention since the correction was added with math, you could just as easily remove it from collected data with math.
 
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bcrowell
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Not to mention since the correction was added with math, you could just as easily remove it from collected data with math.
They actually do part of the correction in hardware. The clocks on board the GPS satellites are intentionally mistuned so as to eliminate the gravitational time dilation. But that doesn't invalidate your point. Someone who believes in a world-wide conspiracy to cover up the truth is free to use software to eliminate the hardware correction...thereby breaking their GPS.
 
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Unless you guys are all part of the conspiracy derp.
 
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pervect
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Unless you guys are all part of the conspiracy derp.
Well, I"m not part of the conspiracy, but I suppose I could be an ignorant dupe spouting the party line.

On the other hand, GPS seems to be actually working fine as it is, so whoever designed it must have done something right. Now, all the designers could be part of the conspiracy too (and regrettably failed to invite me) - but it's hard to keep a conspiracy that big a secret.

Of course, the conspiracy theorists will tell us that it in fact is not a secret, that "everyone knows" about the big conspiracy to suppress the truth that physics is really all Newton's laws, and that all the apparent later developments are not actually real but just "made up" for - hmmm, I"m not quite sure why they were made up, but I"m sure the reason is sinister!
 
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bcrowell
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  • #10
atyy
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I wish they would conduct another experiment:

Remove the time correction from GPS and see what happens. :)


But of course they'll never dare to.
Unfortunately, most scientists are corrupt. They even got one to write an article saying that the time correction was once removed from GPS - when the first cesium atomic clock was placed in orbit.

"At the time of launch of the NTS-2 satellite (23 June 1977), which contained the first Cesium atomic clock to be placed in orbit, it was recognized that orbiting clocks would require a relativistic correction, but there was uncertainty as to its magnitude as well as its sign. Indeed, there were some who doubted that relativistic effects were truths that would need to be incorporated [5]! A frequency synthesizer was built into the satellite clock system so that after launch, if in fact the rate of the clock in its final orbit was that predicted by general relativity, then the synthesizer could be turned on, bringing the clock to the coordinate rate necessary for operation. After the Cesium clock was turned on in NTS-2, it was operated for about 20 days to measure its clock rate before turning on the synthesizer [11]. The frequency measured during that interval was +442.5 parts in 1012 compared to clocks on the ground, while general relativity predicted +446.5 parts in 1012. The difference was well within the accuracy capabilities of the orbiting clock. This then gave about a 1% verification of the combined second-order Doppler and gravitational frequency shift effects for a clock at 4.2 earth radii." http://relativity.livingreviews.org/Articles/lrr-2003-1/fulltext.html [Broken] (section 5)
 
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