- #51
Joanna Dark
- 40
- 0
I wanted to see what would happen if the platform observers recorded L1 on the train's clock and wondered if they would agree it is traveling at c. Someone in my class asked the question why the speed of light is constant but we use two clocks operating at different speeds to measure it? That made me curious.
In the end I worked out that the trains clock is running slower but for the train observers they had traveled an equally less distance. The platform observers agree on the time L1 left TN and when it hit TS's sensor. But the train observers disagree.
TN thinks that PS saw the light arrive in double the time he claims. TS saw TN flash his light earlier than PN claims he did. Or another way to look at it, TN and PN agree that they were perpendicular when TN flashed his light. TS doesn't agree they were perpendicular, he believes that PN is much closer and therefore PN's clock is slow. The same in reverse if I conducted the experiment regarding L2.
How could I observe the speed of L1 using the train's clock? In my first experiment I set up 3 observers to record the "time elapsed" between two points (F and S) from the trains perspective (T) and the tracks perspective (F,S). The string of sensors I set up parallel to the tracks between F and S, I didn't use, because in the process I realized it would achieve the same result as T on the train, but the only difference is that it records each second of the T's clock from multiple stationary positions. In theory, using a computer and a string of sensors, I could watch a moving clock next to a stationary clock and therefore time the speed of light on the moving clock.
What I expected would occur didn't (that for the platform observers both clocks would see light travel at c) but in SR that is to be expected.
So to answer the original question: If light is constant why do we use 2 clocks speeds to time it?
We don't. The light travels only one distance between two points and the clocks are operating at the same speed in their own frames. The only reason there is a difference of opinion is because from the platforms perspective, meters and seconds are smaller and out of sync. But otherwise both agree that L1 traveled between point A and Point B at v=c.
The way I have explained the situation sounds really simple though, when it's not. If a person snaps their fingers on both hands, did they do it simultaneously? For some, traveling at a certain velocity and direction, they did, for some the right one snapped first and others still saw the left one snap first. Those who saw the right hand snap first will not all agree on the delay before the left hand snaps. If you are to accept SR then you need to understand that all answers are simultaneously correct and there is no way to know when each hand snapped, unless you are basing this on a single set of frames.
I would still like to know how aceleration and deceleration and total time dilation affect my understanding as per my last post.
In the end I worked out that the trains clock is running slower but for the train observers they had traveled an equally less distance. The platform observers agree on the time L1 left TN and when it hit TS's sensor. But the train observers disagree.
TN thinks that PS saw the light arrive in double the time he claims. TS saw TN flash his light earlier than PN claims he did. Or another way to look at it, TN and PN agree that they were perpendicular when TN flashed his light. TS doesn't agree they were perpendicular, he believes that PN is much closer and therefore PN's clock is slow. The same in reverse if I conducted the experiment regarding L2.
How could I observe the speed of L1 using the train's clock? In my first experiment I set up 3 observers to record the "time elapsed" between two points (F and S) from the trains perspective (T) and the tracks perspective (F,S). The string of sensors I set up parallel to the tracks between F and S, I didn't use, because in the process I realized it would achieve the same result as T on the train, but the only difference is that it records each second of the T's clock from multiple stationary positions. In theory, using a computer and a string of sensors, I could watch a moving clock next to a stationary clock and therefore time the speed of light on the moving clock.
What I expected would occur didn't (that for the platform observers both clocks would see light travel at c) but in SR that is to be expected.
So to answer the original question: If light is constant why do we use 2 clocks speeds to time it?
We don't. The light travels only one distance between two points and the clocks are operating at the same speed in their own frames. The only reason there is a difference of opinion is because from the platforms perspective, meters and seconds are smaller and out of sync. But otherwise both agree that L1 traveled between point A and Point B at v=c.
The way I have explained the situation sounds really simple though, when it's not. If a person snaps their fingers on both hands, did they do it simultaneously? For some, traveling at a certain velocity and direction, they did, for some the right one snapped first and others still saw the left one snap first. Those who saw the right hand snap first will not all agree on the delay before the left hand snaps. If you are to accept SR then you need to understand that all answers are simultaneously correct and there is no way to know when each hand snapped, unless you are basing this on a single set of frames.
I would still like to know how aceleration and deceleration and total time dilation affect my understanding as per my last post.
