Time dilation - a global hoax?

[kkris1]

Could anyone explain this?

See attachement

Time dilation.doc

[Severian]

There is no way any sane person is going to open that word document. If you reproduce the argument(?) here, then maybe someone will respond.

[BhavinB]

There is no way any sane person is going to open that word document. If you reproduce the argument(?) here, then maybe someone will respond.

 

........Running virus scan now.....

[Dr. Dalek]

I know it's kinda foolish to open that word doctument, but I'm a risk taker!

 

I was reading about Einstein’s “thought experiment” regarding time dilation. In his explanation the light was reflected from the mirror on the ceiling inside spaceship travelling in horizontal direction in regard to stationary observer. It was concluded that even if the light was emitted perpendicular to the mirror, for external observer it would appear to be travelling on angle . Because speed of light is constant, therefore time would have to be longer . But what if there are two light rays emitted simultaneously as shown on the diagram below?

 

 

For stationary observer the light would appear to travel shorter distance in longer time!

 

 

Can anyone explain it?

 

Cheers

Kris

I couldn't copy over his diagrams.

[Tannin]

Hi, Kris!

Thanks for the wonderful question - I have enjoyed to think about it.

The whole discussion about the time dilation and velocity direction change (light aberration) refers to the case of the uniform motion in the constant direction (inertial frames).

Indeed, the frames of the stationary and the moving observer are inertial: moving observer travels with the constant velocity along the x-axis. But, the frame connected with the light ray is not inertial: light ray changes its direction after the reflection in the mirror. Thus your intuition regarding time dilation and length contraction is not applicable here.

Now let`s analyze light ray travelling one-way: from floor to ceiling. One moving observer shoots simultaneously two light rays: one vertically, the other - by the angle of 45 degrees. Clearly, for the time that the vertical ray hits the ceiling at the height h meters - point (0,h), the second ray wouldn`t reach the ceiling - it would reach only the point (-0.7h, 0.7h). Now for the stationary observer, the roles of the rays are changed: originally vertical ray would seem at 45 degrees (and reach the point (0.7,0.7) - not hitting the ceiling), and the originally slanted ray would seem vertical and hitting the ceiling. What has to be conserved is the ration between the paths of two rays (1:1) and the transition between the stationary and moving observers only rotates the velocity direction.

We are reaching the conclusion, that the decision which ray hits the ceiling and which goes halfway, is up to the observer (stationary or moving).

I hope that I´m not writing nonsense - these paradoxes are sometimes tricky to catch.

Further reference is available in

Landau, Lifshitz - Course of Theoretical Physics - Theory of Fields - par. 5

[kkris1]

But the change in direction of light is not neccesary for our discussion; so for stationary observer it would appear the slanted light would reach the ceiling when vertically travelling ray would cover,let's say 0.7 of the distance to the ceiling.Since velocity is in horizontal direction only, we can exclude any height contraction. The distance travelled vertically by both rays in relation to the spaceship should be the same in both inertial frames.

[Mowgli]

Could anyone explain this?

See attachement

The trouble with your second diagram is that it ignores the length contraction.

 

Trying to find a mathematical inconsistency with the coordinate transformation in SR is like trying to find faults with the matrix multiplication representing a 3-D rotation. It cannot be done. You best bet would be to find arguments, thought experiments or inconsistencies proving (or at least implying) that the logic leading to the SR coordinate transformation is in error.

 

People have found algebraic errors in the derivation of the SR coordinate transformation. They went unnoticed mainly because the logic behind SR is accepted rather blindly. So it is assumed that it doesn't matter Einstein made a silly error, he still got the answer right.

[kkris1]

The length contraction is irrelevant. If time dilation is explained as straight (vertical) ray in one inertial frame becomes slanted in second "stationary" inertial frame, so slanting backwards ray in first inertial frame will become straight (vertical) in second frame. And it is not a matter of "silly" mistakes which you can choose to ignore because the result is right. Before Copernicus discovered the Earth was not centre of universe people could calculate and predict events like solar eclipses with great accuracy, even if their theories were wrong. Physics is not a religion where you have to believe established truths with no rights to question them.

[5614]

Physics is not a religion where you have to believe established truths with no rights to question them.

Oh gosh. Me thinks that is a good summary of this thread!

[Mowgli]

Before Copernicus discovered the Earth was not centre of universe people could calculate and predict events like solar eclipses with great accuracy' date=' even if their theories were wrong.

[/quote']

Interesting, I never thought of it that way!

 

Don't get me wrong, I wasn't defending SR. I was just pointing out that your attack wasn't going to get anywhere the way you planned it. The reason is that SR can be stated like this: space-time has a metric, which is the Lorentz metric. The algebra of the SR coordinate transformation is virtually identical to that of the 3-D rotation. Time dilation is a consequence of the metric. There is no way one is going to find an inconsistency with the consequences of the metric.

 

OTOH, you may be able to find a hole in the assumptions behind the metric. I can think of a few - why should the transformation be linear? If it is not linear, then the question of a metric doesn't arise. Why should the transformation be symmetric? This, BTW, is related to your paradox and the linearity assumption (or its interpretation) as well.

 

One might think that if one found an obvious mathematical error in the derivation of the metric, one would be able to prove SR to be wrong, but that hasn't worked out either.

Physics is not a religion where you have to believe established truths with no rights to question them.

Unfortunately' date=' physics [i']is[/i] a religion. And, for that reason, neither obvious arguments against the underlying assumptions nor demostrable algebraic errors in the derivation will shake the followers' faith! Sorry

[Severian]

OK - I finally downloaded the doc (since everyone else had with no problem)

 

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, 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.

 

In the second case, you are confusing which is the proper time. The events of emission and absoption are no longer at the same place in the in the ship's frame so this is not a proper time. In fact the proper time is in the frame in which the path is not angled and the time in the ship's frame is in fact 't' in the equation above, not [math]\tau[/math].

 

Therefore, as your intuition told you, the angled path still takes longer, but this is still time dilation.

[Klaynos]

There is no way any sane person is going to open that word document. If you reproduce the argument(?) here, then maybe someone will respond.

 

When I get to a linux machine (quite likely not before late tonight or tomorrow) I shall download, and save it as a pdf for all our enjoyment...

[the tree]

Unfortunately, physics is a religion. And, for that reason, neither obvious arguments against the underlying assumptions nor demostrable algebraic errors in the derivation will shake the followers' faith!

Say what now? Physics is getting scrapped and redone all the time!

I shall download' date=' and save it as a pdf for all our enjoyment...[/quote']Done. Who needs Linux anyways...

Time dilation.pdf

[Mowgli]

Say what now? Physics is getting scrapped and redone all the time!

The way modern physics is taught shows a religious reverence to mystic knowledge and a deep rooted intolerance toward criticism. This attitude is neatly reflected in most major religions in the world with their believers showing absolute faith in their doctrines. However, unlike religions where you have competing faiths, there is only one physics, so the religiousness of its attitude is not immediately obvious.

 

To be fair, a large part of the impatience with dissent in physics is well-meaning. Physicists cannot keep listening to every crazy half-baked idea that occurs to any bozo. But their absolute faith in the basic hypotheses and assumptions as facts of nature is a little troubling at times.

[swansont]

The way modern physics is taught shows a religious reverence to mystic knowledge and a deep rooted intolerance toward criticism. This attitude is neatly reflected in most major religions in the world with their believers showing absolute faith in their doctrines. However' date=' unlike religions where you have competing faiths, there is only one physics, so the religiousness of its attitude is not immediately obvious.

[/quote']

 

Utter crap. Unless you have been in a large number of classrooms, you can't say how modern physics is taught. Presenting the postulates of SR and deriving the formulae, and backing it up with some of the experimental evidence (which is what I see in the classes and textbooks with which I am familiar) is not religion.

 

The intolerance I see is not towards criticism, it's toward the individuals who criticize without understanding what they are criticizing, who lack a basic foundation in math and logic, and yet whine that SR must be wrong because they don't understand it. Witness the many people on SFN who have presented thought-experiment criticisms of SR purporting to show an inconsistency, but not understanding that the only way for that to happen is to make a mathematical or logical error in the analysis. It's boring and time-consuming to find the mistakes. Criticize away, but you'd better bring something to the table.

 

SR works. That's really all there is to it.

[[Tycho?]]

The way modern physics is taught shows a religious reverence to mystic knowledge and a deep rooted intolerance toward criticism. This attitude is neatly reflected in most major religions in the world with their believers showing absolute faith in their doctrines. However' date=' unlike religions where you have competing faiths, there is only one physics, so the religiousness of its attitude is not immediately obvious.

 

To be fair, a large part of the impatience with dissent in physics is well-meaning. Physicists cannot keep listening to every crazy half-baked idea that occurs to any bozo. But their absolute faith in the basic hypotheses and assumptions as facts of nature is a little troubling at times.[/quote']

 

Hahahah, no.

 

Take some university physics classes before saying things like that.

[Mowgli]

']Hahahah' date=' no.

 

Take some university physics classes before saying things like that.[/quote']

Why would you assume that I haven't?

[the tree]

Why would you assume that I haven't?

Exactly what you said is a pretty good clue. There are examples to the contary in everyday copies of New Scientist.

[Mowgli]

Utter crap.

Such remarks and a general assumption of ignorance on the part of the dissenter are the typical responses to criticism. Not like religious intolerance? I should probably rest my case here.

 

SR works. That's really all there is to it.

As kkris1 pointed out,

Before Copernicus discovered the Earth was not centre of universe people could calculate and predict events like solar eclipses with great accuracy' date=' even if their theories were wrong.[/quote']

A theory can work without being "right." Of course, the typical response to this observation would be a cynical invitation to develop a new theory that would explain every phenomena explained in the current theory. And this has to be done with no academic or funding support.

[CPL.Luke]

^its actually done all the time, take QM, QFT, the standard model etc.

 

Mowgli kkris1 made a mistake somewhere, like the others on this forum I know that because we've seen people come on here with these long drawn out though experiments involving 10 different things in ten different ways. THey essentially are constructing a problem thats very very tedious and easy to mess up. After debunking your first 5 or so you get tired of reading the examples and finding the mistakes, and then having to convince someone thatt they made a mistake and getting yelled at for being a physics drone.

 

although I must admit I started two threads like this once upon a time

 

One in which I was arguing that potential energy didn't exist

 

and anouther in which I was arguing that a photon had mass.

 

I eventually learned I was wrong.

 

 

PS We should start a pseudoscientists anonymous

[[Tycho?]]

Such remarks and a general assumption of ignorance on the part of the dissenter are the typical responses to criticism. Not like religious intolerance? I should probably rest my case here.

 

 

As kkris1 pointed out' date='

 

A theory can work without being "right." Of course, the typical response to this observation would be a cynical invitation to develop a new theory that would explain every phenomena explained in the current theory. And this has to be done with no academic or funding support.[/quote']

 

 

What the hell are you even talking about? We arn't even discussing the theory behind time dilation. Time dilation itself has been measured many many times, and knowledge of this phenomenon is being used as we speak.

 

All your argument boils down to is "SR might be wrong", of course without giving us any reason to think so. SR is an incedible successful theory, and has stood up to a great deal of cristism over the years.

 

We get a lot of people who dont know anything about physics coming in and trying to poke holes in theories like this. If you feel like doing so then do it, using physics, and be sure to show your work. If you dont want to do this, then too bad.

[swansont]

Such remarks and a general assumption of ignorance on the part of the dissenter are the typical responses to criticism. Not like religious intolerance? I should probably rest my case here.

 

But I explained why it's utter crap, rather than stop with a dogmatic statement. You, on the other hand, haven't posted any evidence to the contrary (unless I missed something). It's all about burden of proof.

 

 

As kkris1 pointed out' date='

 

A theory can work without being "right." Of course, the typical response to this observation would be a cynical invitation to develop a new theory that would explain every phenomena explained in the current theory. And this has to be done with no academic or funding support.[/quote']

 

Einstein came up with SR without academic funding. And the Keplerian view did, 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.

[Severian]

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?

[Mowgli]

']Time dilation itself has been measured many many times' date=' and knowledge of this phenomenon is being used as we speak.

[/quote']

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

[Severian]

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

 

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