Room-temperature superconductivity?

[sparkyy0007]

If clocks in different frames actually keep times differently (in their FOR), how could one ever measure c to be constant in any frame?
A clock is required to measure c. If the clock runs slow, how could c be measured constant ?

[tomclarke]

If clocks in different frames actually keep times differently (in their FOR), how could one ever measure c to be constant in any frame?
A clock is required to measure c. If the clock runs slow, how could c be measured constant ?

You are now doing it too.

Unless you can think of an experiment that will determine whether "clocks in different reference frames keep time differently" it is a meaningless statement.

But in circumstances where it can be measured (maybe what you mean) note that the time dilation & length contraction effects cancel each other keeping observed c the same.

Time dilation is subtle. It is thought of as a property of velocity, but it is actually a property of bendiness, and can only be truly measured when a moving clock returns.

In inertial FOR you can always claim that time dilation exists, or that this is a measurment artifact. In truth neither has validity because there is no frame-independent way to compare elapsed times, hence no way to answer the question.

I'm spending some time on this thread because this fact about time dilation is so interesting, and most accounts do not make it clear. Most accounts use frame-dependent comparisons to get a specific (correct, but not unique) answer.

[johanfprins]

Consider the cosmic ray muons on their way to earth: Within their OWN FOR they are stationary. AT WHAT RATE DO THEY DECAY WITHIN THEIR OWN INERTIAL REFRENCE FRAME?

Consider muons being generated within a laboratory on earth so that they are effectively stationary relative to earth. AT WHAT RATE DO THEY DECAY RELATIVE TO EARTH'S REFERENCE FRAME?

Are these two decay rates the same or not the same?. If they are not the same then please explain why muons which are stationary within an inertial reference frame will decay at a different rate WITHIN THIS REFERENCE FRAME WITHIN WHICH THEY ARE STATIONARY, than muons that are stationary within another inertial reference frame will decay WITHIN THE LATTER REFERENCE FRAME WITHIN WHICH THE LATTER MUONS ARE STATIONARY.

[sparkyy0007]

Unless you can think of an experiment that will determine whether "clocks in different reference frames keep time differently" it is a meaningless statement.

In the above, the experiment is using light speed c to see if my clock is actually running true.C is c unless it isn't, for all FOR.
The experiment is in my FOR (no transformations necessary) and I know my clock is running slow, cuz they told me so in skool,
but, when I measure c from a distant star normal to my travel vector, in my frame, c is still c (only a little bluer). When I get home,
my clock is a day behind, so at some point the clocks must have physically run at different rates, no?

But in circumstances where it can be measured (maybe what you mean) note that the time dilation & length contraction effects cancel each other keeping observed c the same.

Are you saying the measurement arms of my experiment physically got shorter, in my FOR on the ship and that's why I measured c ?

most accounts do not make it clear. Most accounts use frame-dependent comparisons to get a specific (correct, but not unique) answer.

I have several books on the subject, all with different and conflicting information.

You are now doing it too.

keep forgetting to put some tape over that lens.

[Teemu]

If clocks in different frames actually keep times differently (in their FOR), how could one ever measure c to be constant in any frame?
A clock is required to measure c. If the clock runs slow, how could c be measured constant ?

Michelson-Morley experiment and other animations here show it pretty well.
http://www.phy.syr.edu/courses/modules/ ... ightClock/

[sparkyy0007]

Michelson-Morley experiment and other animations here show it pretty well.
http://www.phy.syr.edu/courses/modules/ ... ightClock/

In my FOR, this amounts to physical length contraction, if I am not mistaken.
I don't buy this, contraction IMO is only an illusion between different FOR's.

The postulate of length contraction was based on aether compression postulated by Lorentz-Fitzgerald.

Length contraction was postulated by George Francis FitzGerald (1889) and Hendrik Antoon Lorentz (1892) to explain the negative outcome of the Michelson-Morley experiment and to rescue the hypothesis of the stationary aether (Lorentz–FitzGerald contraction hypothesis).

Einstein later realized no actual compression was taking place, but the contraction formula was identical
to the needed FOR transformation formula. If Lorentz-Fitzgerald had not published, the Lorentz contraction
would now likely be known as the Einstein transformation.

in 1905, Henri Poincaré was the first to recognize that the transformation has the properties of a mathematical group, and named it after Lorentz.[8] Later in the same year Einstein derived the Lorentz transformation under the assumptions of the principle of relativity and the constancy of the speed of light in any inertial reference frame,[9] obtaining results that were algebraically equivalent to Larmor's (1897) and Lorentz's (1899, 1904), but with a different interpretation.

[tomclarke]

Michelson-Morley experiment and other animations here show it pretty well.
http://www.phy.syr.edu/courses/modules/ ... ightClock/

In my FOR, this amounts to physical length contraction, if I am not mistaken.
I don't buy this, contraction IMO is only an illusion between different FOR's.

The postulate of length contraction was based on aether compression postulated by Lorentz-Fitzgerald.

Length contraction was postulated by George Francis FitzGerald (1889) and Hendrik Antoon Lorentz (1892) to explain the negative outcome of the Michelson-Morley experiment and to rescue the hypothesis of the stationary aether (Lorentz–FitzGerald contraction hypothesis).

Einstein later realized no actual compression was taking place, but the contraction formula was identical
to the needed FOR transformation formula. If Lorentz-Fitzgerald had not published, the Lorentz contraction
would now likely be known as the Einstein transformation.

in 1905, Henri Poincaré was the first to recognize that the transformation has the properties of a mathematical group, and named it after Lorentz.[8] Later in the same year Einstein derived the Lorentz transformation under the assumptions of the principle of relativity and the constancy of the speed of light in any inertial reference frame,[9] obtaining results that were algebraically equivalent to Larmor's (1897) and Lorentz's (1899, 1904), but with a different interpretation.

I have the same problem here. How do you measure "actual length contraction"? Relative to what? And how?

All this stuff is relative.

[MSimon]

that it provides MUCH better accuracy, that it is a technique used as standard to increase accuracy by metrologists.

http://www.lorentzcenter.nl/lc/web/2009 ... al%20I.pdf

Page 17 of the above discusses Allan Variance

http://www.lorentzcenter.nl/lc/web/2009 ... l%20II.pdf

[tomclarke]

that it provides MUCH better accuracy, that it is a technique used as standard to increase accuracy by metrologists.

http://www.lorentzcenter.nl/lc/web/2009 ... al%20I.pdf

Page 17 of the above discusses Allan Variance

http://www.lorentzcenter.nl/lc/web/2009 ... l%20II.pdf

http://www.mahag.com/download/hafele_keating_orig.pdf
This describes the "correlated rate change" algorithm that H&F used. It is an old well-known technique, and obviously increases clock stability by a large factor because by comparing 3 or more clocks one can compensate for random uncorrelated jump type frequency changes. These are the main type of atomic clock instability.

Kelly does not take this into account.

Since 1970 clocks have got more accurate by a factor of 1000 or more. And GPS satellites move faster than aeroplanes. That makes the same effects measurable now with accuracy well over 1000 X what HF could get.

[johanfprins]

Two inertial reference frames Kp and K with clocks at their origins. The clocks are synchronized and the two reference frames move away from one another at a relative speed v.

The Lorentz transformation from Kp to K is given by:

x=gamma*(xp+v*tp) and t=gamma*(tp+(v/c^2)*xp)

The Lorentz transformation from K to Kp is given by:

xp=gamma*(x-v*t) and tp=gamma*(t-(v/c^2)*x)

Clock in Kp remains at position xp=0. When time on this clock is tp, the transformed position x(0) and time t of this clock within K are thus given by:

x(0)=gamma*(v*tp) and t=gamma*(tp): from which it follows that:

x(0)=v*t

Clock in K remains at position x=0. When time on this clock is t, the transformed position xp(0) and time tp of this clock within Kp are thus given by:

xp(0)=gamma*(-v*t) and tp=gamma*(t) from which it follows that:

xp(0)=-v*tp

Now if one of the two clocks are taken on a journey with varying speed v so that it eventually returns to meet up and stop within the other clock's reference frame, the distance between the clocks can only have a single value at any instant in time on either clock during this whole journey. This means that for the time tp on the clock in Kp which gives xp(0) =-v*tp, there must be a time t on the clock within K that gives a distance x(0)=v*t so that x(0)=-xp(0). This demands that after the clocks meet up again, they MUST have that t=tp. If not, it means that the Lorentz transformation is violated and the Special Theory of Relativity is wrong.

Thus IF the flying clock experiments are correct, as claimed on this thread, then it means that Einstein’s Special theory of Relativity must be wrong. Either Hafele and Keating and those that followed them made a stupendous physics breakthrough, or they obtained what they wanted to obtain: I suspect that the latter is the case; but am open to an alternative theory to Einstein's Theory of Relativity.

[GIThruster]

Thus IF the flying clock experiments are correct, as claimed on this thread, then it means that Einstein’s Special theory of Relativity must be wrong.

Not at all. It means your understanding of relativity is wrong, but since you have no education in field theory, that's not much a stretch, is it?

Again, Einstein predicted the result of the flying clock experiments, BASED upon Special Relativity. If you come to the opposite conclusion of what Einstein did, pretty good reason to suppose you don't understand the theory.

[johanfprins]

Thus IF the flying clock experiments are correct, as claimed on this thread, then it means that Einstein’s Special theory of Relativity must be wrong.

Not at all. It means your understanding of relativity is wrong,

My conclusion above has been directly derived from the Lorentz transformation and the Lorentz transformation IS Einstein's Special Theory of Relativity.

Again, Einstein predicted the result of the flying clock experiments, BASED upon Special Relativity.

He thought he did so but did not check whether it violates the Lorentz transformation. He also did this for the length contraction which also violates the Lorentz transformation. Einstein was spot on when he concluded that the speed of light can never be anything else but c relative to any other body. And he was spot-on when he deduced that this defines the Lorentz transformation. But he was wrong in deducing the twin paradox and length contraction; since these scenarios both violate the Lorentz transformation, and thus also his Special Theory of Relativity.

[nogo]

A new paper claiming the wavefunction cannot be a probabilistic interpretation of something else but an actual physical entity (Nature URL for an article containing a link to the actual paper):

http://www.nature.com/news/quantum-theo ... ons-1.9392

Paper itself:
http://xxx.lanl.gov/pdf/1111.3328v1

[GIThruster]

Again, Einstein predicted the result of the flying clock experiments, BASED upon Special Relativity.

He thought he did so but did not check whether it violates the Lorentz transformation..

Einstein didn't check basic math involved in his theory, nor did ANYONE INVOLVED FOR DECADES?

Are you using drugs, Johan?

[johanfprins]

Einstein didn't check basic math involved in his theory, nor did ANYONE INVOLVED FOR DECADES?

Are you using drugs, Johan?

No! I am just stating facts that anybody who knows High School algebra can check for him/herself:

(1) that Einstein assumed that the front and end of a rod that is stationary within one inertial reference farme can also manifest simultaneously within a passing refrence frame. And he did this just after he argued that two simultaneous events (and thus positions) a distance L apart cannot be simultaneous within such a passing inertial reference frame. It is thus impossible to measure (OR see) the length of such a rod at a single instant in time within the passing reference frame: Therefore it is nonsensical to derive a shortened length. I agree that the fact that nobody picked this up for 100 years sounds insane: But this is the factual situation.

(2) Einstein DID not DERIVE the twin paradox: Somebody else was responsible for arguing this scenario (I cannot remember who: Poincare perhaps?). Einstein did derive that the transformed time of a passing clock is slower than in its own reference frame. In fact he accentuated the fact that this is NOT happenning relative to the reference frame in which the clock is stationary but within the reference frame into which the time has been transformed. That this derivation is correct is proved by the muon lifetimes of cosmic-ray muons. Why Einstein did not point out that this does not mean that the clocks carried by two twins who are moving relative to one another are keeping different times, remains another mystery. Maybe he was just not willing to engage in frivolous arguments.