Time dilation - a global hoax?

[Mowgli]

You' date=' on the other hand, haven't posted any evidence to the contrary (unless I missed something). It's all about burden of proof.

[/quote']

The problem with a religious attitude is that "evidence" is a moving target, much like some people choosing to believe in creationism.

 

I once posted a link to the discussion of an algebraic error (http://www.RelativityChallenge.com) in AE's derivation. The response from this forum was, why bother with an "archaic" derivation when I could derive it more modern ways. Here is another challenge by Cameron Y. Rebigsol, which offers you money, if some of you would like to make money out of your faith in SR!

 

Short of a complete new theory, what would you consider proof? Challenging dominant physics paradigms is so difficult that there was journal paper about it, citing prominant dissenters and their fate.

Einstein came up with SR without academic funding. And the Keplerian view did' date=' in fact, explain all that the Copernican view did, in a simpler way. Kepler didn't just rant that Copernicus was wrong. Again, burden of proof. [/quote']

I think kkris1 was referring to pre-Kepler era, to a model where the earth was at the center of the universe, which could still predict eclipses accurately. The accuracy of the predictions is not proof enough for the rightness or the completeness of the theory.

[Mowgli]

You can measure the lifetimes of particles in different frames of reference and observe exactly the correct time dilation effect.

You would consider that model independent?

What happens is that you measure a deay time in the lab frame, boost it back to the rest frame, and make a distribution. You take the time constant of this exponential distribution as the measured lifetime. The trouble is that you don't know what the "real" lifetime to begin with.

[[Tycho?]]

A model independent, SR time dilation has been measured? Impossible to measure by definition.

 

...how the hell is this impossible to measure? One clock says one thing, another is slower. Time dilation, as simple as that. How is this impossible to measure?

[CPL.Luke]

mowgli the gps sattelites run their clocks something like 39 nanoseconds/ day faster than normal in order to have their clocks be in aggreement with earth clocks. if they didn't do this the gps reading would shift by several kilometers each day.

 

^note they run faster do to the combined effects of SR and GR (they experience less gravity)

 

experiments have also been done where one plane flys an atomic clock at high speed for a few days and then compares their clock reading to a stationary clock (they measure a discrepancy that is exactly what SR predicts it should be)

 

also if you refuse time dilation then things like gravitational lensing wouldn't occur anymore (these effects have been observed)

 

do some research into the subject before you denounce it mowgli

[blike]

Severian kindly took the time to explain the flaws in the ideas you presented. Either address what he said and substantiate your claim or this thread will be closed.

[Mowgli]

mowgli the gps sattelites run their clocks something like 39 nanoseconds/ day faster than normal in order to have their clocks be in aggreement with earth clocks. if they didn't do this the gps reading would shift by several kilometers each day.

^note they run faster do to the combined effects of SR and GR (they experience less gravity)

You are right' date=' the GPS atomic clocks should run slower than similar clocks at ground level by 7.2 microseconds a day. However, they are also subject to the effect predicted in the general theory of relativity, and they should run faster by 45.9 microseconds a day. The clocks are actually corrected by 38.7 microseconds (not nanoseconds) a day, and they stay synchronized to the clocks on the ground. It is hard to call this correction a verification of special relativity because it is the result of two competing effects, the general relativistic effect being six times larger than the one we are trying to verify. It may be possible to incorporate the whole effect in general relativity. In fact, it may also be possible to incorporate the covariance of Maxwell’s equations in general relativity. I have no idea how to do it, so please don't challenge me on that. May be after I retire

experiments have also been done where one plane flys an atomic clock at high speed for a few days and then compares their clock reading to a stationary clock (they measure a discrepancy that is exactly what SR predicts it should be)

After correcting for GR effects and effects due to acceleration, right? Not quite model independent, is it? Once you know what it is that you are looking for in an experiment, it is hard not to find it. All experimentalists struggle with this bias problem. The greater ones recognize it and bend over backwards to maintain the highest levels of scientific integrity, but even they are not immune to it.

also if you refuse time dilation then things like gravitational lensing wouldn't occur anymore (these effects have been observed)

Again' date=' more of a GR effect.

do some research into the subject before you denounce it mowgli

Wonder why you didn't mention cosmic rays being able reach the earth despite their short lifetime? Or, more generally, the null results of MMX type experiments? Our inability to accerleate particles beyond the speed of light?

[kkris1]

The issue here is the definition of time dilation. Time dilation is:

 

[math]t=\gamma \tau[/math]

 

where t is the time between two events in a particular frame of reference and [math]\tau[/math] is the proper time between the events. The proper time is the time in the frame in which the two events happen at the same spatial point.

 

 

In the first diagram' date=' the event where the light is sent out and the event where the light is redetected are both at the same space point for an observer in the ship. Therefore the time it takes on the straigh path is the proper time, and the time on the angled path is greater (as per the above forumla). This is time dilation..[/quote']

 

I would like to advise you to check how the idea of time dilation was conceived. The straight vertical path in one inertial frame (inside spaceship) becomes slanted line in second inertial frame (one of the stationary observer).

Because speed of light was said to be constant, the "patch"of time dilation was applied to save invariance of speed of light regardless of inertial frame.

 

 

As you should know, there is no "priviledged" inertial frame, they are all equal and therefore you can't say in this particular inertial frame time is "proper" or ïmproper". you can legitimatelly say the spaceship is stationary and the observer is moving in oposite direction.

[Mowgli]

'']...how the hell is this impossible to measure? One clock says one thing, another is slower. Time dilation, as simple as that. How is this impossible to measure?

Because, in order to compare two clocks, you have to put them at the same space point at two different times. Which means, you either have to move the "stationary" clock or slow down the moving clock, either of which will violate the conditions to apply SR. Or, necessitate model-dependent corrections. Note to mention that GR corrections always apply because we are always in a gravitational field.

[kkris1]

I don't understand why this thread is still alive. Didn't I explain the confusion in the OP? What else exactly are people not understanding about time dilation?

I think you do not understand it. Time dilation doesn't apply to two events observed in one inertial frame, it supposedly applies to one event viewed from two different inertial frames

[Severian]

You would consider that model independent?

 

Yes' date=' it is model independent. It only requires quantum mechanics which has nothing to do with gravity or relativity.

 

As you should know, there is no "priviledged" inertial frame, they are all equal and therefore you can't say in this particular inertial frame time is "proper" or ïmproper". you can legitimatelly say the spaceship is stationary and the observer is moving in oposite direction.

 

Time dilation is a conequence of the Lorentz transformation. The equation I wrote down is actually a simplified version of the Lorentz transformation in the special case where the initial frame is has no spatial displacement between the two events. (This makes the time a proper time, which is just a definition of course.) The Lorentz transformation between the frames does not change, but if you change the set-up then the time tilation equation will change because you have a different simplification (the spatial displacement between the events in the other frame becomes zero). You would find that you get exactly the same time dilation equation, but with the two times reserved.

 

What is your problem with that? This is the application of a completely frame independent set-up showing that relativity predicts time dilation in an entirely consistant way.

[Severian]

I think you do not understand it. Time dilation doesn't apply to two events observed in one inertial frame, it supposedly applies to one event viewed from two different inertial frames

 

And how does one have a time interval between one event?

[kkris1]

I would suggest read about this famous Einstein's "thought' experiment and you will know what we are talking about. I'm not trying to be rude, but i can see you completely misunderstood it

[Severian]

I would suggest read about this famous Einstein's "thought' experiment and you will know what we are talking about. I'm not trying to be rude, but i can see you completely misunderstood it

 

Do I really need to point you towards the big blue star to the left? I have explained your initial problem, and I am correct. Explain in detail where you object (so that I can facilitate your learning) or get the hell out of these fora.

[Tannin]

Instead of trying to understand the ¨thought experiment¨ proposed by kkris1, this thread is going to overturn the SR and all the ¨conventional science¨

Making verbal statements (however appealing they may seem) is not enough for physics. Fortunately, we have our language of diagrams and formulas.

I´ll try to explain what I´ve meant in my first post in this thread and I´ll be happy to hear your comments and corrections.

Here is the diagram:

Moving observer shoots simultaneously two rays: one is vertical and makes an angle [math]\theta=90^\circ[/math] with the floor (broken line) and the other slanted by the angle [math]\alpha=-45^\circ[/math] with regard to the ¨vertical¨ ray. The vertical ray hits the ceiling, while the slanted ray obviously reaches the point [math]\left(-\frac{h}{\sqrt{2}}, \frac{h}{\sqrt{2}}\right) [/math](assuming shooter to be the coordinate origin and h the ceiling height).

Now, moving with the speed of [math]V=\frac{c}{\sqrt{2}}[/math] in the positive x-direction will rotate both velocity vectors by [math]45^\circ[/math] - light aberration (Landau, Lifshitz - formula 5.6).

[math]\sin{\theta}=\frac{\sqrt{1-\frac{V²}{c²}}}{1+\frac{V}{c}\cos{\theta^\prime}} \sin{\theta^\prime}[/math]

Definitely, the paths travelled by the rays cannot change - velocity of light is constant in every inertial frame and thus there is no time dilation for the light rays.

So all we have - rotation of the velocity vectors with the angle [math]\alpha[/math] being conserved and equal to [math]45^\circ[/math], while the aberration angle [math]\theta´[/math] depends on the velocity of the moving observer.

I don´t see any reason why the two-segment paths of rays (before and after reflection) shouldn´t behave the same way - rotation only (red lines in the diagram). Moreover, if we are taking the snapshot after [math]\frac{2h\sqrt{2}}{c}[/math] the second ray will hit the ground. The distances 0C and 0C´ will be equal in both frames of reference and the distance C0C´ will be equal to [math]\frac{2h\sqrt{2}}{c} \times \frac{c}{\sqrt{2}} =2h [/math], the distance travelled by the moving observer in this interval of time.

So, I guess the origin of the kkris1 paradox was the assumption of time dilation for the light rays - ¨shorter distance in the longer time¨. In the above picture, everything is fixed ¨equal distances in equal time¨.

[kkris1]

Well, if you know you are correct that's great, you do not need to learn anything . I'm not so sure if I'm correct as well. But I still would strongly suggest read some more info. E.g on the website:

http://www.phys.unsw.edu.au/einsteinlight/jw/module4_time_dilation.htm

[swansont]

I think kkris1 was referring to pre-Kepler era, to a model where the earth was at the center of the universe, which could still predict eclipses accurately. The accuracy of the predictions is not proof enough for the rightness or the completeness of the theory.

 

OK, so look at Ptolemy vs Copernicus. Same answer.

 

The geocentric model isn't invalid. It is equivalent; all you have to do is transform your coordinate systems. The heliocentric model is used and accepted as truth because it's simpler and consistent with other observations (gravity) that have no direct connection with orbital mechanics. But geocentrism was only discarded when the more complete heliocentric model was there to replace it. If you are going to lean on geo vs helio models as examples, you should know that it is not enough to rail on about some perceived problem with SR; to discard it requires some theory that explains what SR explains, and something more, be it extra explanations or simplicity.

[swansont]

You are right' date=' the GPS atomic clocks should run slower than similar clocks at ground level by 7.2 microseconds a day. However, they are also subject to the effect predicted in the general theory of relativity, and they should run faster by 45.9 microseconds a day. The clocks are actually corrected by 38.7 microseconds (not nanoseconds) a day, and they stay synchronized to the clocks on the ground. It is hard to call this correction a verification of special relativity because it is the result of two competing effects, the general relativistic effect being six times larger than the one we are trying to verify. It may be possible to incorporate the whole effect in general relativity. In fact, it may also be possible to incorporate the covariance of Maxwell’s equations in general relativity. I have no idea how to do it, so please don't challenge me on that. May be after I retire

 

After correcting for GR effects and effects due to acceleration, right? Not quite model independent, is it? Once you know what it is that you are looking for in an experiment, it is hard not to find it. All experimentalists struggle with this bias problem. The greater ones recognize it and bend over backwards to maintain the highest levels of scientific integrity, but even they are not immune to it.

 

[/quote']

 

But independent measurements of GR effects confirm those effects; they are independent and you can calculate them separately. GPS satellites are not the only vehicles that carry atomic clocks, yet the kinematic and gravitational corrections combine to give the right answer for any combination of the two, as far as has been measured. (And you don't have to have moving clocks to have them at different points in the gravitational potential.)

[swansont]

Well' date=' if you know you are correct that's great, you do not need to learn anything . I'm not so sure if I'm correct as well. But I still would strongly suggest read some more info. E.g on the website:

http://www.phys.unsw.edu.au/einsteinlight/jw/module4_time_dilation.htm[/quote']

 

You really need to consider that you are still not understanding the material on that page, and that Severian does.

[Mowgli]

If you are going to lean on geo vs helio models as examples, you should know that it is not enough to rail on about some perceived problem with SR; to discard it requires some theory that explains what SR explains, and something more, be it extra explanations or simplicity.

In other words, a complete new theory that explains everything that SR explains and then some. Clearly not one PRL article

Seriously, the trouble with the current orthodoxy in phyiscs is that even if you find simpler explanation for certain phenomena, you will find it impossible to find any decent avenue to make it public, or even discuss it (this forum included). The reason is that some of the assumptions in the current theories (SR in particular) are accepted with such fervor that even a reinterpretation of the theories is met with contempt and (sorry) assumptions of ignorance. This is a sad state not only for the dissenter, but for physics in general. Let me sum it up with a long quotation:

"Science alone of all the subjects contains within itself the lesson of the danger of belief in the infallibility of the greatest teachers of the preceding generation. We are only at the beginning of the development of the human race, of the development of the human mind, of intelligent life—we have years and years in the future. It is our responsibility not to give the answer today as to what it is all about, to drive everybody down in that direction and to say: ‘This is a solution to it all.’ because we will be chained then to the limits of our present imagination."

— Richard Feynman

[Mowgli]

GPS satellites are not the only vehicles that carry atomic clocks, yet the kinematic and gravitational corrections combine to give the right answer for any combination of the two, as far as has been measured.

These are the other combinations of GR and SR I have seen so far:

• Around the world atomic clock (J.C. Hafele and R.E. Keating (1971)), where GR effect was about 150 ns and SR about 50. Sagnac was +/-150 ns depending on the direction of flight, giving a prediction of about 40+/-20 ns in one direction and about 300+/-20 in the other direction. The experimental verification was of the order of one sigma in both cases (which is not that impressive given the huge error in the first prediction where GR and Sagnac more or less cancelled off).
  
• TWTT flight tests (2003), where the GR effect was about -20ns and SR was about 5ns (both linearly increase from zero to the stated values as a function of the flight time). The Sagnac effect was a wavy function of time. Again, GR/SR is about 4 throughout the time range.
  

Not really all possible combinations of gravitational and kinematic effects, but I do get your point. But don't you get the feeling that there should be bigger structure in which all the three effects can be neatly accommodated? Wouldn't you at least want to think along that line? If your answer is no, then that's what I mean by orthodoxy or religiousness in physics.

[Mowgli]

Yes' date=' it is model independent. It only requires quantum mechanics which has nothing to do with gravity or relativity.

[/quote']

Hmmm... the lifetime of a particle as calculated in the Standard Model is not model dependent?

[CPL.Luke]

Mowgli GR simplifies to SR in flat space.

 

you just said that an earth observer's time is dilated with respewct to the sattelite observer, how can you possibly say that time dilation doesn't exist?

 

not to mention all the oher results that you supplied on your own, which all say the same thing

[swansont]

These are the other combinations of GR and SR I have seen so far:

• Around the world atomic clock (J.C. Hafele and R.E. Keating (1971))' date=' where GR effect was about 150 ns and SR about 50. Sagnac was +/-150 ns depending on the direction of flight, giving a prediction of about 40+/-20 ns in one direction and about 300+/-20 in the other direction. The experimental verification was of the order of one sigma in both cases (which is not that impressive given the huge error in the first prediction where GR and Sagnac more or less cancelled off).
  [*']TWTT flight tests (2003), where the GR effect was about -20ns and SR was about 5ns (both linearly increase from zero to the stated values as a function of the flight time). The Sagnac effect was a wavy function of time. Again, GR/SR is about 4 throughout the time range.
  

Not really all possible combinations of gravitational and kinematic effects, but I do get your point. But don't you get the feeling that there should be bigger structure in which all the three effects can be neatly accommodated? Wouldn't you at least want to think along that line? If your answer is no, then that's what I mean by orthodoxy or religiousness in physics.

 

Well, there's also the Vessot experiment with a Hydrogen maser in a rocket, and the Pound-Rebka experiment, which was gravitational redshift. Just off the top of my head. Satellites exist in geosynchronous orbit, too (not sure if the Japanese Quasi-Zenith system is in operation yet, but I imagine telecom satellites all have clocks aboard these days), Galileo will be at a different altitude than GPS, and they've already tested a few satellites, and then there are LEO objects, too. Clocks were to have gone on the ISS via NASA (funding was cut), and the ESA program to do so is still in place AFAIK. So there's plenty of corroboration and further opportunity to measure all this. I predict it will work, relativity-wise, and that almost nobody will be surprised about that.

 

There are reams of time-transfer data from standards labs that nobody bothers to write up because relativity is so well-established that it's simply not worthwhile to do a "relativity confirmed yet again" paper that nobody will publish because it's so blinking far from the cutting edge of physics.

 

You seem to be upset because I don't wish to tilt at your windmills. Sorry, but that's not how it works. You don't get to define the problems I work on, and that I have a choice does not make it a religion. "Relativity doesn't give me a warm, fuzzy feeling" simply isn't a motivation for me, and all you're doing is trying to engage in rhetorical games in order to discredit a scientific theory. Only contradictory evidence can do that.

[swansont]

In other words' date=' a complete new theory that explains everything that SR explains and then some. Clearly not one PRL article

Seriously, the trouble with the current orthodoxy in phyiscs is that even if you find simpler explanation for certain phenomena, you will find it impossible to find any decent avenue to make it public, or even discuss it (this forum included). The reason is that some of the assumptions in the current theories (SR in particular) are accepted with such fervor that even a reinterpretation of the theories is met with contempt and (sorry) assumptions of ignorance. This is a sad state not only for the dissenter, but for physics in general. Let me sum it up with a long quotation:[/quote']

 

 

There are only two assumptions that go into SR. One is that the laws of physics are valid in inertial frames, and the other is that c is a constant. The latter basically falls out of Maxwell's equations. Since relativity and E&M seem to work pretty well, I'd say that a high degree of confidence is justified.

 

Is belief that gravity will pull you down if you jump off a cliff a religion, too?

 

Here's a quote that I like: "It is not enough to wear the mantle of Galileo: that you be persecuted by an unkind establishment. You must also be right." Bob Park

 

Being unorthodox is not, in and of itself, sufficient justification. But you have spent all of your time complaining about how SR is religious orthodoxy, but you haven't presented an alternative. So, until you do so, stop accusing people of actions and attitudes that they haven't demonstrated.

[Severian]

Hmmm... the lifetime of a particle as calculated in the Standard Model[/u'] is not model dependent?

 

The change in the lifetime from one frame to another is not model dependent.