Hello,

I am a highschool student doing a project on Special relativity, and have done much research on the subject.

Today, while reading through Albert Einsteins book, relativity: the special and general theory, i had a bit of a thought:

One of the things covered in special relativity is that it is impossible to tell whether something is moving within a point of reference or whether the point of reference is moving.

another thing it covers is time dialation, that the faster something moves, the slower time will progress for that body.

Well, here is my thought: if i have two bodies in space, each one having chronograph identical to the other's chronograph, and the distance between these two bodies is increasing as if the bodies were traveling away from eachother at a significant fraction of the speed of light, and i can say that one of these objects is moving and the other is at rest. As said above, when something is moving, time slows down for it, therefore i can say that for the body in motion, time will slow down relative to the body at rest. So, by comparing the chronographs on these two bodies, i can truly say which body was in motion or which body was at rest...is this correct?

thank you for any input to this matter.

 

HeXeN

 

It's never easy to write without being able to use capital "r's."

HeXeN said in post #1 :

Hello,

I am a highschool student doing a project on Special relativity, and have done much research on the subject.

Today, while reading through Albert Einsteins book, relativity: the special and general theory, i had a bit of a thought:

One of the things covered in special relativity is that it is impossible to tell whether something is moving within a point of reference or whether the point of reference is moving.

another thing it covers is time dialation, that the faster something moves, the slower time will progress for that body.

Well, here is my thought: if i have two bodies in space, each one having chronograph identical to the other's chronograph, and the distance between these two bodies is increasing as if the bodies were traveling away from eachother at a significant fraction of the speed of light, and i can say that one of these objects is moving and the other is at rest . As said above, when something is moving, time slows down for it, therefore i can say that for the body in motion, time will slow down relative to the body at rest. So, by comparing the chronographs on these two bodies, i can truly say which body was in motion or which body was at rest...is this correct?

thank you for any input to this matter.

 

HeXeN

 

nope. you have assumed that one of the bodies is at rest, and there is no way you can do that. all you have done is put yourself in the intertial frame of one of the two bodies. imagine yourself in the inertial frame of the other one, and your results will change.

http://www.scienceforums.net/forums/showthread.php?s=&threadid=1467

 

Should help

There is no way to be at rest. If you are at rest relative to the edge of the universe, what happens if the universe is moving?

that makes no sense.

I mean, if you look at the edge of the universe (if there is one) and see you are not moving relative to it, that doesn't mean you are stopped. The whole universe could be moving, so you wouldn't be at rest!

that makes no sense.

Thank you.

I'm pleased we have cleared that up.

I was sarcastic.

touche.

To simplify, it isn't possible to not be moving.

from what reference frame?

To simplify, it isn't possible to not be moving.

 

To rephrase the double negative:

 

It s possible to be moving.

 

I think this is obvious

VendingMenace said in post #14 :

 

It s possible to be moving.

 

 

heh, well spotted. give this man a nobel. Perhaps a more accurate statement might be "It is possible to be in relative motion" though.

Well, i must say i never expected to recieve 14 replies in the timespan of only a few hours....

 

I also must admit that my original thought was not that one object was at rest, but that both of the bodies were in motion away from eachother. I suppose i should change this around a bit, and say that the point of reference has a chronograph on it and the object who's motion is in question also has one. Well, not exactly, how do i phrase this? Hmm....ok, well, hmm....And to think, i have to write a 6+ page essay on this subject! Maybe i should try using Einsteins example, a train traveling by a railroad embankment. The train is in motion relative to the railway embankment, but the railway embankment is in motion relative to the train. But, if i had a chronograph on the train and one on the embankment, and the train was moving at relativistic speed, then the chronograph on the train would read slower then that on the embankment, but if it were the embankment in motion, then the chronograph in the embankment would read slower then that in the train. Am i just making an ass of myself here?

nope, that is exactly correct. If you are on the platform, then you see the trains clock running slowly, and if you are on the train, you see the platform clock running slowly. This can lead to the so-called "twins paradox" in which a twin leaves earth, travels round the solar system at .99c, and then comes home with the problem that he saw his twin ageing slowly and his twin saw him ageing slowly. Obviously this is completely nonsensical, since A cannot be older than B and at the same time B older than A. I suggest following MrL's link, but the simple answer to this paradox is that one of the twins was doing some accelerating (the one flying round the solar system), and so you have to take General Relativity into account. It is good that you have observed this paradox though. another cool paradox-that-isn't-really is the pole vault paradox (length contractions)

I meant stationary is not possible. Sorry.

of course being stationary is possible.

Depends on relative to what. Relative from outside the universe (if that is possible) then maybe, unless the universe is part of a larger thing, so it is moving, and so on. We cannot find out unless we know that the universe is all there is.

yeah, i knew what you ment Cap'n, but i couldn't resist. SOrry.,

 

Anyways you are correct. Accourding to the special relativity, there is no such thing as a absolute inertial frame. As such, there cannot be any frame wich is absolutely stationary.

I think this might be something that would make an interesting experiment...

What would happen if i were to, say, take a chronograph that measures down to....say....billionths of a second. Actually, i have two of these, and i (somehow) ensure that they are started at exactly the same time, then i put one in some kinda craft that can move at great speeds, at least 10 times the speed of sound, and i let that craft fly around for a few hours with the chronograph on it all the while. When the craft returns to the ground, and i compare the two chronographs.....what would they read?

I recall learning about time dialation in 6th grade and my teacher told us that an experiment similar to this had been conducted....if that is true, does anybody have any information on that?

 

Hmm.....i wonder whether or not i'll do poorly on this project.......or whether the rest of the class just does really well? he he =)

All rest frames are equally valid.

HeXeN said in post #22 :

I think this might be something that would make an interesting experiment...

What would happen if i were to, say, take a chronograph that measures down to....say....billionths of a second. Actually, i have two of these, and i (somehow) ensure that they are started at exactly the same time, then i put one in some kinda craft that can move at great speeds, at least 10 times the speed of sound, and i let that craft fly around for a few hours with the chronograph on it all the while. When the craft returns to the ground, and i compare the two chronographs.....what would they read?

I recall learning about time dialation in 6th grade and my teacher told us that an experiment similar to this had been conducted....if that is true, does anybody have any information on that?

 

Hmm.....i wonder whether or not i'll do poorly on this project.......or whether the rest of the class just does really well? he he =)

 

The one that had been moving (and had undergone ACCELERATION; that bit's critical) would show a smaller amount of time has passed.

 

They've done this, with atomic clocks and 747's (or something similar)

MrL_JaKiri said in post #24 :

 

The one that had been moving (and had undergone ACCELERATION; that bit's critical) would show a smaller amount of time has passed.

 

They've done this, with atomic clocks and 747's (or something similar)

 

And rockets, and they do it all the time now with GPS satellites.