- #1
GearsofWar
- 26
- 0
Does a photon age?
Yes, everyone agrees on local physical facts like this.GearsofWar said:a related question:
Suppose a battery-operated clock flew at 99.999999999999999999999999999999999999% the speed of light.
When we decelerated the clock to rest relative to the lab frame, and took the batteries out so the hands would stop, would we all agree on the time read on the clock?
It's not really valid to apply the time dilation equation to the photon, but I don't think there's any meaningful sense in which it could be said to age, so I'd say no.GearsofWar said:Does a photon age?
Sure. Why not? Since its meaningless to speak of time as measured in the photons rest frame we are left speaking only in terms of (coordinate) time and as such a photon can exists for any given amount of time. I suppose you can call that "aging."GearsofWar said:Does a photon age?
peter0302 said:The only meaningful definition of "age" in the context of a subatomic particle would be decay, since subatomic particles have no "moving parts" by which to measure their age, and photons do not decay.
Your other question about the clock - yes, we'd all agree on the time read on the clock. Not sure what your point is.
One of the clearest experimental verifications of time dilation is the decay of muons in the atmosphere. Muons last only a short time in a lab, but those coming from space, traveling at relativistic speeds, actually last long enough to be detected on the surface. That wouldn't be possible unless they slowed down their "aging." A photon, traveling at 'c', would have its "aging" slowed down to zero, so we could never know what would happen to the photon if it ever did "age."
It's actually unknown whether they decay, there are some theories which say they should. But in any case, a larger clock moving alongside a proton would still tick as seen in any frame, so even if they don't decay, it's not a consequence of time dilation.GearsofWar said:Protons don't decay either.
Does that mean that time stops at the speed of protons?
A clock which is approaching the speed of light relative to us will tick slower, approaching a rate of zero, in our frame (in the clock's own rest frame at any given moment, it is our clocks which are ticking slower). But it's impossible to accelerate a clock to exactly the speed of light (it would require infinite energy), and the Lorentz transformation gives meaningless answers if you try to plug in v=c to calculate the "frame" of a photon.GearsofWar said:So does a photon age?
Does a clock which approaches the speed of light tick faster or slower?
Do you understand that there is no objective truth about the rate a clock is ticking in relativity, that the answer will be different in different reference frames, and no frame is physically preferred over any other? The details of how fast the clock is ticking at different points depend on what frame you choose. Regardless of what frame you choose, if the clock's speed is v at a given moment in that frame, then its rate of ticking at that moment will be slowed down by a factor of [tex]\sqrt{1 - v^2/c^2}[/tex] in that frame. But of course, different frames will disagree about the clock's speed at any moment along its journey.GearsofWar said:How about a clock which is approachingthe speed of light not relative to us?
Would it tick slower or faster?
There is also no objective truth about speed in relativity, except for light which has the same speed in every frame. In our rest frame, we may have a speed of zero while the clock is moving at 99.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999% the speed of light and is ticking extremely slowly in our frame, but in the clock's own rest frame it has a speed of zero and we have a speed of 99.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999% the speed of light, and it is our clocks which are ticking extremely slowly in this frame.GearsofWar said:Also, if a clock is going
99.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999% the speed of light, would time pass slower or faster for it?
JesseM said:Do you understand that there is no objective truth about the rate a clock is ticking in relativity, that the answer will be different in different reference frames, and no frame is physically preferred over any other? The details of how fast the clock is ticking at different points depend on what frame you choose. Regardless of what frame you choose, if the clock's speed is v at a given moment in that frame, then its rate of ticking at that moment will be slowed down by a factor of [tex]\sqrt{1 - v^2/c^2}[/tex] in that frame. But of course, different frames will disagree about the clock's speed at any moment along its journey.
There is also no objective truth about speed in relativity, except for light which has the same speed in every frame. In our rest frame, we may have a speed of zero while the clock is moving at 99.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999% the speed of light and is ticking extremely slowly in our frame, but in the clock's own rest frame it has a speed of zero and we have a speed of 99.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999% the speed of light, and it is our clocks which are ticking extremely slowly in this frame.
No, I'm not. The time dilation equation only works equally well in different inertial frames, i.e. the frames of observers with constant speed and direction. You can't use the time dilation equation in the frame of an observer moving in a circle (not to mention that when moving around the Earth, you have to go beyond special relativity where the time dilation applies, and take into account the curvature of spacetime predicted in the neighborhood of the Earth by general relativity).GearsofWar said:so what you're saying is that after an atomic clock is flown about the world, and the plane lands, they will see that our clock has ticked slower and we will see that their clock has ticked slower.
No, I don't. Perhaps you should ask questions and try to understand what I'm saying before jumping to conclusions that I'm contradicting established physics and trying to "taunt" me about it. The idea that all inertial reference frames are equally valid physically, and that they differ on questions of who is moving faster or whose clock is ticking slower, is one of the most basic ideas of special relativity, any introductory text on the subject will explain this.GearsofWar said:I think you need to update this wikipedia entry and tell them that their experiments were false:
JesseM said:No, I'm not. The time dilation equation only works equally well in different inertial frames, i.e. the frames of observers with constant speed and direction. You can't use the time dilation equation in the frame of an observer moving in a circle (not to mention that when moving around the Earth, you have to go beyond special relativity where the time dilation applies, and take into account the curvature of spacetime predicted in the neighborhood of the Earth by general relativity).
JesseM said:No, I don't. Perhaps you should ask questions and try to understand what I'm saying before jumping to conclusions that I'm contradicting established physics and trying to "taunt" me about it. The idea that all inertial reference frames are equally valid physically, and that they differ on questions of who is moving faster or whose clock is ticking slower, is one of the most basic ideas of special relativity, any introductory text on the subject will explain this.
Please ease up on the attitude. What experimental results do you think JesseM is "denying"?GearsofWar said:Yes, but the experimentalists took both the time dilation due to gravity, acceleration, and velcoity into account.
The experiment showed that relativistic time dilation is a physical effect.
Why are you denying the experimental results?
The experiment showed that relativistic time dilation is a physical effect.
Why are you denying the experimental results?
JesseM said:No, I don't. Perhaps you should ask questions and try to understand what I'm saying before jumping to conclusions that I'm contradicting established physics and trying to "taunt" me about it. The idea that all inertial reference frames are equally valid physically, and that they differ on questions of who is moving faster or whose clock is ticking slower, is one of the most basic ideas of special relativity, any introductory text on the subject will explain this.
Doc Al said:Please ease up on the attitude. What experimental results do you think JesseM is "denying"?
Of course it is. Even if you do an experiment like this in flat spacetime with no gravity, it's still true that all frames will agree that a clock moving in a circle around a center which is moving inertially will age less than a clock which is at a fixed position on that circle. They will disagree about the circular clock's speed as a function of time v(t) as it moves around the circle, and also disagree about its rate of ticking as a function of time [tex]\sqrt{1 - v^2/c^2}[/tex], but when they integrate [tex]\int \sqrt{1 - v(t)/c^2} \, dt[/tex] for one complete circle to find the total time elapsed on the circular clock between two meetings with the clock at a fixed position on the circle, they will all end up with exactly the same answer for the elapsed time, and all agree it is less than the elapsed time on the other clock. In general, when different frames calculate how much time elapses on two clocks between two successive meetings of these clocks, they will always get the same answers regardless of the motion of the clocks--that's just a nice feature of the mathematics of special relativity.GearsofWar said:Yes, but the experimentalists took both the time dilation due to gravity, acceleration, and velcoity into account.
The experiment showed that relativistic time dilation is a physical effect.
Sigh. The fact that all inertial frames are on equal footing is relativity 101, GoW, I think physicists would have noticed if it conflicted with the Hafele-Keating experiment. All you're doing here is boldly displaying your own ignorance of the basics of the subject.GearsofWar said:Why are you denying the experimental results?
Yes, you are taunting. You are implying that JesseM does not understand relativity and that he is "denying" the results of experiment. You're obviously new here. If you want to stay, try to be civil.GearsofWar said:I'm not taunting you.
I'm just asking you why you're denying the physical results of the physical experiment that demonstarted the physical reality of relativistic time dilation for moving clocks, which have been physically shown, by physical experiment, to physically tick slower when they're physically moving:
age is diffrent for all forms of matter. mainly for a photon it can't see or precive age like we do. so a photon age's in a way that it would move from one stat to another stat that we could know the diffrence or even observe the change from one start point within time to another -.- I'm sure there are meany ways to test, to see any changes from one point to another. so the answer for now would have to be yes or no till proven with data or an obeservation test I'm sure that someone that has a the funding or lab to do such will do such or has done such allready -.-GearsofWar said:Does a photon age?
JesseM said:Of course it is. Even if you do an experiment like this in flat spacetime with no gravity, it's still true that all frames will agree that a clock moving in a circle around a center which is moving inertially will age less than a clock which is at a fixed position on that circle. They will disagree about the circular clock's speed as a function of time v(t) as it moves around the circle, and also disagree about its rate of ticking as a function of time [tex]\sqrt{1 - v^2/c^2}[/tex], but when they integrate [tex]\int \sqrt{1 - v(t)/c^2} \, dt[/tex] for one complete circle to find the total time elapsed on the circular clock between two meetings with the clock at a fixed position on the circle, they will all end up with exactly the same answer for the elapsed time, and all agree it is less than the elapsed time on the other clock. In general, when different frames calculate how much time elapses on two clocks between two successive meetings of these clocks, they will always get the same answers regardless of the motion of the clocks--that's just a nice feature of the mathematics of special relativity.
Sigh. The fact that all inertial frames are on equal footing is relativity 101, GoW, I think physicists would have noticed if it conflicted with the Hafele-Keating experiment. All you're doing here is boldly displaying your own ignorance of the basics of the subject.
Doc Al said:Yes, you are taunting. You are implying that JesseM does not understand relativity and that he is "denying" the results of experiment. You're obviously new here. If you want to stay, try to be civil.
But do you understand them?GearsofWar said:I agree with Einstein's euqations of relativity.
I agree with the experimental results.
What do you mean by "physical"?Relativistic time dilation is a physical effect. Right?
1. If you pick out two events on a clock's worldline (like two successive meetings with another clock) and ask for the time elapsed on the clock between those two events, all frames will predict exactly the same answer. If you have two clocks whose worldlines cross twice, one moving inertially and the other accelerating at some point in its journey, all frames will agree that the clock that accelerated will have elapsed less time. This is time dilation as a real physical effect.GearsofWar said:I agree with Einstein's euqations of relativity.
I agree with the experimental results.
Relativistic time dilation is a physical effect. Right?
JesseM said:1. If you pick out two events on a clock's worldline (like two successive meetings with another clock) and ask for the time elapsed on the clock between those two events, all frames will predict exactly the same answer. If you have two clocks whose worldlines cross twice, one moving inertially and the other accelerating at some point in its journey, all frames will agree that the clock that accelerated will have elapsed less time. This is time dilation as a real physical effect.
2. If you ask how fast a clock is ticking at any given moment on its worldline, or ask which of two clocks is ticking faster at a given moment, different frames can disagree on the answers to these questions. This is time dilation as a frame-dependent quantity.
Again you imply that you are pointing some error in JesseM's understanding of relativity. Enough already.GearsofWar said:There you go again...
Please reveiw the experiment--the clocks read differently when they are compared in the lab--note the part I emboldened--please do not ignore it again:
Doc Al said:Again you imply that you are pointing some error in JesseM's understanding of relativity. Enough already.
So... I take it you don't understand that clock rates, in general, are frame dependent?GearsofWar said:All I'm saying is that relativistic time dilation is a physical effect and that moving clocks run slow.
Doc Al said:So... I take it you don't understand that clock rates, in general, are frame dependent?