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Fibre-linked atomic clocks put special relativity to the test

 
 
centrox
 
Reply Thu 8 Jun, 2017 03:48 pm
Atomic clocks in France, Germany and the UK have been used to perform the best-ever confirmation of time dilation as set out in Einstein’s special theory of relativity. The clocks have been connected recently by optical-fibre links, which let the devices be compared to each other to an extremely high degree of statistical resolution. Time dilation predicted by Special Relativity is confirmed to within one part in 100 million.

http://physicsworld.com/cws/article/news/2017/jun/07/fibre-linked-atomic-clocks-put-special-relativity-to-the-test
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Type: Discussion • Score: 3 • Views: 5,979 • Replies: 139

 
layman
 
  -4  
Reply Thu 8 Jun, 2017 04:13 pm
@centrox,
Sorry, but evidence of time dilation does not "test" special relativity. SR is a unique theory, among others which posit time dilation, that is not uniquely "tested" by such experiments.

Such "tests" tend to prove (or disprove) time dilation, that's all. Not SR, per se.
layman
 
  -4  
Reply Thu 8 Jun, 2017 04:22 pm
@layman,
****, after looking at the article, I see that the experiment explicitly employed an alternate theory of relative motion and NOT SR. How misleading can a headline get, I ask ya?

Quote:
The study uses the “Robertson–Mansouri–Sexl” (RMS) framework for violating special relativity. RMS assumes that there is a preferred reference frame in which the average speed of light measured on a return journey (there and back again) between two points is constant in all directions.

RMS contradicts special relativity in all other reference frames by assuming that the average speed of light of a return journey varies according to a formula involving the velocities of those frames relative to the preferred frame.


As a theory, SR specifically rejects and prohibits the existence/use of a "preferred frame."
dalehileman
 
  -1  
Reply Thu 8 Jun, 2017 06:04 pm
@layman,
Quote:
existence/use of a "preferred frame."

Yet Lay doesn't the Twin Paradox almost imply the existence of such a frame
...something that has long puzzled me....
McGentrix
 
  0  
Reply Thu 8 Jun, 2017 06:07 pm
@centrox,
Neat article. Science.
0 Replies
 
layman
 
  -4  
Reply Thu 8 Jun, 2017 06:15 pm
@dalehileman,
dalehileman wrote:

Quote:
existence/use of a "preferred frame."

Yet Lay doesn't the Twin Paradox almost imply the existence of such a frame
...something that has long puzzled me....


Indeed it does, Dale. Or at least the resolution to the so-called "paradox" does, as Feynman, among others, has noted.
0 Replies
 
layman
 
  -3  
Reply Thu 8 Jun, 2017 06:54 pm
@dalehileman,
dalehileman wrote:

...something that has long puzzled me....


We've talked about this several times, Dale, and I've tried before to point out the source of your confusion to you.

You start out by tacitly accepting everything you've "learned" by studying SR as "true." Once you do that, confusion is sure to follow.

What you need to do is start out with the assumption that it is not "true." Once you do that, all appearances of "paradox" disappear.
dalehileman
 
  -2  
Reply Thu 8 Jun, 2017 07:12 pm
@layman,
Thanks Lay, I'll hafta think about that some more. Of course I 'mem' describing my own theory, 'Relative Relativity' which resolves everything
layman
 
  -4  
Reply Thu 8 Jun, 2017 07:21 pm
@dalehileman,
dalehileman wrote:

my own theory, 'Relative Relativity' which resolves everything


Well, it may seem that way to you, Dale, but not to me. Your "theory" best, I can make of it, simply adopts and presupposes the false premise of SR (and thereby the erroneous implications generated by that false premise).

You can start with a false premise and generate a very elaborate and self-consistent theory from it. It can be mathematically beyond challenge. The problems will only become apparent when you go outside your theoretical construction and look at the empirical facts. They (the problems) will never be revealed from within the system.
layman
 
  -4  
Reply Fri 9 Jun, 2017 12:16 am
@layman,
This article also says:

Quote:
Atomic clocks in France, Germany and the UK have been used to perform the best-ever confirmation of time dilation as set out in Einstein’s special theory of relativity.


This too is quite misleading. Time dilation was not "set out" in "Einstein’s special theory of relativity." It was "set out" about 10 years earlier by Henrik Lorentz, who proposed basically the same theory of relative motion (commonly known as "Lorentzian Relativity," which is contradictory to SR) as this article says was used to calculate results in this study.

SR simply co-opted the pre-existing mathematical formulas (known as the "Lorentz transformations") for time dilation from that theory.

Of course the average reader would just read the headline, skim the article, and falsely conclude that "special relativity" has been "tested" and "proven."
0 Replies
 
layman
 
  -2  
Reply Fri 9 Jun, 2017 01:33 am
I normally wouldn't comment on this, but in this case I will:

This is a "scientific" thread with a misleading title. I don't blame the original poster for that--he merely cut and pasted the headline from a misleading article.

My comments about the article are, as far as I know, based on well-known scientific theory/fact. They are merely factual in tone.

Yet these posts are getting at least 4 "downvotes" without any poster disputing a single comment I've made.

What's up with that?
0 Replies
 
fresco
 
  3  
Reply Fri 9 Jun, 2017 01:58 am
At a conference on the Michelson–Morley experiment in 1927 at which Lorentz and Michelson were present, Michelson suggested that Lorentz was the initiator of the theory of relativity. Lorentz then replied:

Quote:
I considered my time transformation only as a heuristic working hypothesis. So the theory of relativity is really solely Einstein's work. And there can be no doubt that he would have conceived it even if the work of all his predecessors in the theory of this field had not been done at all. His work is in this respect independent of the previous theories
layman
 
  -2  
Reply Fri 9 Jun, 2017 02:50 am
@fresco,
Albert Einstein wrote:
The special theory was a more detailed expose of those concepts which are found in Lorentz's research of 1895. Everybody felt his [Lorentz's] superiority, but nobody felt oppressed by it. For me personally he meant more than all the others I have met on my life's journey.


Quote:
Many aspects of Lorentz's theory were incorporated into special relativity (SR) with the works of Albert Einstein and Hermann Minkowski.. The introduction of length contraction and time dilation for all phenomena in a "preferred" frame of reference, which plays the role of Lorentz's immobile aether, leads to the complete Lorentz transformation (see the Robertson–Mansouri–Sexl test theory as an example). Because the same mathematical formalism occurs in both, it is not possible to distinguish between LET and SR by experiment.


https://en.wikipedia.org/wiki/Lorentz_ether_theory
0 Replies
 
layman
 
  -2  
Reply Fri 9 Jun, 2017 03:32 am
@fresco,
Not sure what point you think you're making Fresky, but you seem to completely overlook the point at issue here, to wit:

Time dilation is not SR, and SR is not time dilation. Way too many confuse the two. They think, as the article in question seems to, that if time dilation is involved, then it MUST be SR. Wrong.

Lorentz invented the concept of time dilation. He did not, and would not, try to claim that he invented "special relativity," which, as I said, is it's own unique theory of relative motion that is at odds with Lorentz's theory.

Lorentz always considered the concept of "local time," which he also invented, to be a purely fictitious concept which only served as a useful mathematical shortcut.

Einstein claimed that Lorentz's "local time" was "true time."
fresco
 
  3  
Reply Fri 9 Jun, 2017 04:58 am
@layman,
So according to your 'logic', observation of falling apples is merely verification of Newtons gravitation formula ? Laughing
The fact that Einstein's theories , encompassed and superceded,( being more general than) either Newton or Lorentz etc seems to be beyond your understanding. But keep up the reactionary 'axe grinding' by all means as long as you don't want a credit in Phil Sci 101.
layman
 
  -2  
Reply Fri 9 Jun, 2017 05:19 am
@fresco,
fresco wrote:

The fact that Einstein's theories , encompassed and superceded,( being more general than)


I should have known that, as always, your response would entail your usual sorry display of sneering grandiose pretentiousness designed to hide your ignorance of the topics you purport to pontificate on, eh, Fresky?

More general!? Hahaha. It's called "special" relativity because it only applies in extremely narrow, arguably non-existent, contexts (inertial frames only). This is one (of several) reason why Einstein was never was satisfied with it.

On the other hand, Lorentzian Relativity applies to, and makes accurate predictions with respect to, EVERY state of motion (accelerating or inertial), which SR cannot do. A clear superiority to SR in the aspect of GENERAL applicability.

That is why this particular endeavor, and similar ones such as the Hafele-Keating experiment, could ONLY use LR (not SR) to make predictions which matched the observed, empirical results they generated.

fresco
 
  3  
Reply Fri 9 Jun, 2017 06:52 am
@layman,
Quote:
Because the Hafele–Keating experiment has been reproduced by increasingly accurate methods, there has been a consensus among physicists since at least the 1970s that the relativistic predictions of gravitational and kinematic effects on time have been conclusively verified. Criticisms of the experiment did not address the subsequent verification of the result by more accurate methods, and have been shown to be in error.

Wikipedia : Hafele Keating Experiment.

Note that elementary reactionary 'making a name for oneself' psychology can drive experimental bias. What would the anti-Albertists do if it wasn't for Albert ? (....or anti Freudians.....anti-Marxists...etc, etc)
dalehileman
 
  -1  
Reply Fri 9 Jun, 2017 10:30 am
@layman,
Quote:
Your "theory" best, I can make of it, simply adopts and presupposes the false premise of SR
To the contrary, Lay, it's merely an alternate way of interpreting the effects of relative motion, asserting that the speed of light can also be considered relative; hence, 'Relative Relativity.' Of course everyone else thinks I'm out of my mind, which might truly be the case, but still nobody has countered it

Yet my 'RR' resolves all the q's inferred in the foregoing controversy

For a quick review, my 'RR' asserts that the controversy has a hidden assumption about time-at-a-distance, which I don't deny, but simply explain; that is, it's generally assumed that everywhere in the Universe not in relative motion is at the same 'now.' I merely extend the existing theory to assert that t-a-a-d is also relative

Thus, ignoring any relative motion, if Marty is at a distance of 5 light minutes, the reading of his clock may be supposed five minutes later than here. Thus when I turn on my flashlight he can be said to see it instantly, not 5 minutes later ; so light speed can be thought 'infinite'
layman
 
  -1  
Reply Fri 9 Jun, 2017 02:57 pm
@dalehileman,
dalehileman wrote:

Thus, ignoring any relative motion, if Marty is at a distance of 5 light minutes, the reading of his clock may be supposed five minutes later than here. Thus when I turn on my flashlight he can be said to see it instantly, not 5 minutes later ; so light speed can be thought 'infinite'


Physics is not about subjective perception or supposition, SR claims nothwithstanding, Dale.

I can sit here and "suppose" things until the cows come home, but none of my mental gymnastics with have the slightest effect on the speed of light, the rate at which clocks actually run, etc., in the objective realm of matter in motion.

What I "suppose" is, at best, a matter of psychology, not physics, and I'm interested in physics, not a solipsistic interpretation of "reality.'
0 Replies
 
layman
 
  -1  
Reply Fri 9 Jun, 2017 03:22 pm
@dalehileman,
I'll be fool enough to try this one more time, Dale. Let's take a familiar situation: the twin paradox.

Let's suppose a guy is blasted off of earth in a spaceship and reaches a speed (about .87c, if I recall) where the rate of his clock and the length of his rods are now 50% of what they were on earth. At that point he stops accelerating.

Is there a "paradox" here? No, not at all. So where does this "paradox" enter the picture? What's the problem?

Anybody?
 

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