Munim Posted 7 hours ago Share Posted 7 hours ago What is the nature of the motion of light with respect to itself? Does it experience time and displacement? Link to comment Share on other sites More sharing options...
swansont Posted 7 hours ago Share Posted 7 hours ago Relativity doesn’t afford us the ability to say; light is not in an accessible frame of reference, so the transforms do not work. Link to comment Share on other sites More sharing options...
MigL Posted 6 hours ago Share Posted 6 hours ago 50 minutes ago, Munim said: What is the nature of the motion of light with respect to itself Without any reference, like air resistance, ir points passed, such as empty space, would you feel motion or displacement ? I assume it feels a little stressed from the stress-energy-momentum tensor forcing it to change its path through curved space-time around massive bodies. Bad pun ?? Link to comment Share on other sites More sharing options...
exchemist Posted 6 hours ago Share Posted 6 hours ago (edited) 1 hour ago, Munim said: What is the nature of the motion of light with respect to itself? Does it experience time and displacement? In theory it does not experience time (time dilation -> ∞ as v -> c). Absent any sense of time, it seems to me that "experience" has no meaning. Edited 6 hours ago by exchemist Link to comment Share on other sites More sharing options...
swansont Posted 5 hours ago Share Posted 5 hours ago 1 hour ago, exchemist said: In theory it does not experience time (time dilation -> ∞ as v -> c). Absent any sense of time, it seems to me that "experience" has no meaning. It’s undefined. You can’t use the Lorentz transform to shift between an inertial frame and that of a photon, and back. Link to comment Share on other sites More sharing options...
geordief Posted 4 hours ago Share Posted 4 hours ago 1 hour ago, MigL said: Without any reference, like air resistance, ir points passed, such as empty space, would you feel motion or displacement ? I assume it feels a little stressed from the stress-energy-momentum tensor forcing it to change its path through curved space-time around massive bodies. Bad pun ?? Would it rather see the world moving (jiggling) and itself just traveling in a "straight line"? Would it experience the alternating magnetic/electric fields or do they disappear in its "own frame"? Link to comment Share on other sites More sharing options...
swansont Posted 2 hours ago Share Posted 2 hours ago 2 hours ago, geordief said: Would it rather see the world moving (jiggling) and itself just traveling in a "straight line"? Why jiggling? (The sinusoidal depictions of E & M fields are the field strength, not their trajectory, if that’s what this is a reference to) Link to comment Share on other sites More sharing options...
geordief Posted 1 hour ago Share Posted 1 hour ago 43 minutes ago, swansont said: Why jiggling? (The sinusoidal depictions of E & M fields are the field strength, not their trajectory, if that’s what this is a reference to) No it wasn't (but I am under no illusion as to how nonsensical my notion is) The jiggling was me imagining the whole universe moving left/right /up/down as the light was the only actor moving in a straight line .(is that a bit reminiscent of the world spinning around the famous ,presumably stationary bucket of water?) The e/m fields observation was an afterthought -or a second thought as to how they would seeem to the photon itself (wouldn't exist?) ps yes I think I understood that they were field strengths and not trajectories but would they exist for the photon? If there is no valid frame of reference for the photon does that mean we can't ask any questions as to what is going on there even if they seem ridiculous? Link to comment Share on other sites More sharing options...
MigL Posted 1 hour ago Share Posted 1 hour ago In empty space, a photon would not know it is moving, as it is moving at constant velocity, and there are no reference points for it to discern its velocity or distance travelled. Further, it would need to interact with any reference point, so it needn't be totally empty space Link to comment Share on other sites More sharing options...
swansont Posted 1 hour ago Share Posted 1 hour ago 5 minutes ago, geordief said: ps yes I think I understood that they were field strengths and not trajectories but would they exist for the photon? Yes. It’s still EM radiation. 5 minutes ago, geordief said: If there is no valid frame of reference for the photon does that mean we can't ask any questions as to what is going on there even if they seem ridiculous? We can answer questions based on observations from valid reference frames, i.e. ones an observer (with mass) can be in. Link to comment Share on other sites More sharing options...
Mordred Posted 59 minutes ago Share Posted 59 minutes ago It gets worse than that as ds^2=0 for null geodesics which is another reason for a photon frame being invalid as a reference frame. Its nonsensical answers such as time stopping or the photon existing everywhere at once that makes it obvious on the photon frames invalidity. Link to comment Share on other sites More sharing options...
MigL Posted 39 minutes ago Share Posted 39 minutes ago True. But we can attempt to 'see' what happens to the frames around the photon. As Einstein did when he imagined travelling along with one, to arrive at SR. Link to comment Share on other sites More sharing options...
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