The discussion centers on the perception of velocity in special relativity, specifically how observers in different frames of reference perceive the speed of an object moving close to the speed of light. It is established that speed is inherently relative; an observer will see another object moving fast or slow based on their own relative motion. The relativistic velocity addition rule is highlighted, demonstrating that perceived speed varies depending on the observer's frame of reference. Ultimately, both observers will perceive each other's clocks ticking slowly, illustrating the symmetry of time dilation in special relativity.
PREREQUISITESStudents of physics, educators teaching special relativity, and anyone interested in the nuances of motion and perception at relativistic speeds.
What was it?BadgerBadger92 said:He gave me a one sentence response.
BadgerBadger92 said:My teacher understood my question.
pervect said:If you say so - then it seems he'd be the obvious one to ask. Because nobody else seems to know what you're going on about, certainly not me.
AGAIN, and for the upteenth time in this thread there is no such thing as a "stationary frame of reference". Some of your problem may be a terminology issue, but you have had all this explained to you SO many time already that it's hard to see how to do it again any differently.BadgerBadger92 said:When something is traveling near the speed of light, due to time dilation, would that make it look like it’s going slower according to a stationary frame of reference?
Relative to what? I can assume that you mean relative to what you call a "stationary frame of reference", and I will make that assumption in my answer below, but you would be better served by not making people have to assume such things. Whenever you describe a scenario in relativity, you should always specify speeds, "moving", "stationary", etc., relative to something. If you're not sure what something to use, just adopt the common default of "the observer".BadgerBadger92 said:When something is traveling near the speed of light
If "going slower" refers to velocity or speed, as I defined those terms in post #26, then no.BadgerBadger92 said:due to time dilation, would that make it look like it’s going slower according to a stationary frame of reference?
This helps me. Thank you this is the answer I was looking for.PeterDonis said:Relative to what? I can assume that you mean relative to what you call a "stationary frame of reference", and I will make that assumption in my answer below, but you would be better served by not making people have to assume such things. Whenever you describe a scenario in relativity, you should always specify speeds, "moving", "stationary", etc., relative to something. If you're not sure what something to use, just adopt the common default of "the observer".If "going slower" refers to velocity or speed, as I defined those terms in post #26, then no.
No. When things go faster [relative to a chosen reference] they go faster [relative to that reference].BadgerBadger92 said:I hope this is more clear.
When something is traveling near the speed of light, due to time dilation, would that make it look like it’s going slower according to a stationary frame of reference?
These are the answers I’m looking for. Thank you.jbriggs444 said:No. When things go faster [relative to a chosen reference] they go faster [relative to that reference].
Once you correct for speed of light delays in the observations you make, you may notice that clocks on the moving object are advancing slowly. But that does not mean that the object is moving slowly.
Nor does the fact that you measure the object's clocks to be advancing slowly that the object itself is moving slowly in some hypothetical, unspecified, "stationary" frame.
Just to add to this, @BadgerBadger92, the point is that you use your own clocks and your own rulers to measure the speed of the object. So relativistic effects are irrelevant to your measures because you use clocks and rulers that are stationary relative to you. An observer riding on the object, of course, uses his own clocks and rulers to measure your speed, and comes up with the same speed you measure for him but in the opposite direction.jbriggs444 said:Once you correct for speed of light delays in the observations you make, you may notice that clocks on the moving object are advancing slowly. But that does not mean that the object is moving slowly.
That's a very important difference (at least for extended objects). What you see is the light reflected from the body, and that's different from measuring distances and thus also velocities of the different point of the extended object.malawi_glenn said:what is the difference in seeing how fast it moves than measure how fast it moves?
I know, was wondering if OP had thought about it ;) Socrative methodvanhees71 said:That's a very important difference (at least for extended objects). What you see is the light reflected from the body, and that's different from measuring distances and thus also velocities of the different point of the extended object.
The most important effect is that you don't "see" length contraction but rather a rotated body, when the latter is moving fast relative to you (see "Terrell effect").