- #1
stovepipe
- 17
- 0
Hi again,
So I'm still relatively new to working with Relativity (no pun intended) and to these forums and I have a question about simultaneity. I have read that simultaneity is broken when events are viewed from different frames. I wasn't quite sure what this meant until I worked out an example for myself today, and it puzzles me.
I set up a theoretical experiment in which two clocks were synchronized and placed equidistant (L/2) from a flash bulb. Obviously, to anyone in the same frame as the apparatus the time shown on both the clocks would be (L/2)c + tflash , if the flash went off.
An observer now travels at .6c parallel to the apparatus. At the instant this observer passes the bulb, it triggers the flash. Observer A then records the time shown on each clock when the reflected light reaches him. He records the clocks to display (L/5)c and (4L/5)c!
How can this be?!? Of course the answer is that the simultaneity of events was broken. But it doesn't make sense that the same sets of photons could hit the same sets of clocks at 2 different times, or in fact at an infinite number of times! (One could imagine an infinite number of reference frames all with different speeds less than c all passing the origin at the same time.)
I took the time to fully work through the example with the 2 frames I set up, and found that both frames can be used to predict what was seen by the other frame. Just that the two frames disagree on what actually happened. No wonder refs make bad calls!
While mathematically this seems feasible, it didn't really make physical sense. I mean what if instead of a flash bulb it was a lethal dose of gamma radiation, and my cats were standing in front of the clocks. The cats wander off of the target platforms just before the clocks strike (L/2)c. But according to other frames the radiation has already hit. It's like Schrodinger's cat all over again! But instead of whether or not it was observed, it's who observed it. So do my cats live?
Thanks,
-Steve
So I'm still relatively new to working with Relativity (no pun intended) and to these forums and I have a question about simultaneity. I have read that simultaneity is broken when events are viewed from different frames. I wasn't quite sure what this meant until I worked out an example for myself today, and it puzzles me.
I set up a theoretical experiment in which two clocks were synchronized and placed equidistant (L/2) from a flash bulb. Obviously, to anyone in the same frame as the apparatus the time shown on both the clocks would be (L/2)c + tflash , if the flash went off.
An observer now travels at .6c parallel to the apparatus. At the instant this observer passes the bulb, it triggers the flash. Observer A then records the time shown on each clock when the reflected light reaches him. He records the clocks to display (L/5)c and (4L/5)c!
How can this be?!? Of course the answer is that the simultaneity of events was broken. But it doesn't make sense that the same sets of photons could hit the same sets of clocks at 2 different times, or in fact at an infinite number of times! (One could imagine an infinite number of reference frames all with different speeds less than c all passing the origin at the same time.)
I took the time to fully work through the example with the 2 frames I set up, and found that both frames can be used to predict what was seen by the other frame. Just that the two frames disagree on what actually happened. No wonder refs make bad calls!
While mathematically this seems feasible, it didn't really make physical sense. I mean what if instead of a flash bulb it was a lethal dose of gamma radiation, and my cats were standing in front of the clocks. The cats wander off of the target platforms just before the clocks strike (L/2)c. But according to other frames the radiation has already hit. It's like Schrodinger's cat all over again! But instead of whether or not it was observed, it's who observed it. So do my cats live?
Thanks,
-Steve