Relativity of simultaneity

In summary: Sorry,but you again messed up with X and Y.The two events are never simultaneous in Y frame!They are simultaneous in X frame.My question is just, will Y predicts that events will be simultaneous in X frame or...Yes, Y would predict that the events would be simultaneous in X frame.
  • #1
Inhsdehkc
19
0
Suppose two spaceships A (at rest) and B(moving right with velocity v relative to A) one above the other with observer X in A and Y in B,both at the middle of the their spaceship.Let two events event RED and event BLUE strike at the edges(RED at left edge) of the both spaceship when Y is just above X.Then with respect to X the two events will be simultaneous whereas for Y event Blue will occur first than event red.My question if i was Y then what would i predict for X whether X will see two events simultaneously or not??(Does my question make sense?)
p.s. my english so poor sorry for ur inconvenince.Thanks in advance.
 
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  • #2
Yes, Y would agree that X does see the events as happening simultaneously, because he also see the light signals from the red and blue events arrive at X's central position at the same time.

Both Y and X agree that the events were not simultaneous in the Y frame but were simultaneous in the X frame.<Edited yet again. Hope I have X and Y the right way round now>
 
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  • #3
Inhsdehkc said:
Suppose two spaceships A (at rest) and B(moving right with velocity v relative to A) one above the other with observer X in A and Y in B,both at the middle of the their spaceship.Let two events event RED and event BLUE strike at the two edges(RED at left edge) of the spaceship when Y is just above X.Then with respect to X the two events will be simultaneous whereas for Y event Blue will occur first than event red.My question if i was Y then what would i predict for X whether X will see two events simultaneously or not??(Does my question make sense?)
p.s. my english so poor sorry for ur inconvenince.Thanks in advance.
If you mean the two events occurred simultaneously in X's rest frame at the two ends of his spaceship A, then, yes, Y will see that the light from those two events will propagate toward X and meet him simultaneously, even though, to Y, those two events are not simultaneous in his rest frame. Whether or not you could predict this, is another question as you would have to have prior knowledge of everything that was going to happen in order to make such a prediction.
 
  • #4
ghwellsjr said:
If you mean the two events occurred simultaneously in X's rest frame at the two ends of his spaceship A, then, yes, Y will see that the light from those two events will propagate toward X and meet him simultaneously, even though, to Y, those two events are not simultaneous in his rest frame. Whether or not you could predict this, is another question as you would have to have prior knowledge of everything that was going to happen in order to make such a prediction.

But relative to Y ,X is moving towards event red with same velocity 'v'(comparable to c),then won't Y see that Event red reached X before blue??( as before X can perdict that Y will see event blue before event red as Y is moving towards event blue with velocity v relative to X,cannot Y say that X will meet event red at first??)
 
  • #5
yuiop said:
Yes, Y would agree that X sees the the events as happening simultaneously because he also see the light signals from the red and blue events arrive simultaneously at X's central position.

Both Y and X agree that the events were not simultaneous in the Y frame but were simultaneous in the X frame.

Sorry.but i am not getting this.how could Y agree that X would see both events simultaneously as Y will see that X is moving towards event red with same velocity v??
 
  • #6
Inhsdehkc said:
Sorry.but i am not getting this.how could Y agree that X would see both events simultaneously as Y will see that X is moving towards event red with same velocity v??
Sorry, I accidentally switched X and Y around. I will edit my post to correct that.
 
  • #7
yuiop said:
Yes, Y would agree that X does not see the events as happening simultaneously, because he also see the light signals from the red and blue events arrive at X's central position at different times.

Both Y and X agree that the events were not simultaneous in the X frame but were simultaneous in the Y frame.<Edited. Hope I have X and Y the right way round now>

Sorry,but you again messed up with X and Y.The two events are never simultaneous in Y frame!They are simultaneous in X frame.My question is just, will Y predicts that events to be simultaneous in X frame or not?
 
  • #8
Inhsdehkc said:
ghwellsjr said:
If you mean the two events occurred simultaneously in X's rest frame at the two ends of his spaceship A, then, yes, Y will see that the light from those two events will propagate toward X and meet him simultaneously, even though, to Y, those two events are not simultaneous in his rest frame. Whether or not you could predict this, is another question as you would have to have prior knowledge of everything that was going to happen in order to make such a prediction.
But relative to Y ,X is moving towards event red with same velocity 'v'(comparable to c),then won't Y see that Event red reached X before blue??( as before X can perdict that Y will see event blue before event red as Y is moving towards event blue with velocity v relative to X,cannot Y say that X will meet event red at first??)
That's why I started my post with "If". You have to define which frame the events are simultaneous in which you did not do. If they are simultaneous in frame A (which is what I assumed you meant), then X sees the light from them arrive at his location simultaneously and so does Y. That's the definition of simultaneity in Special Relativity. If you instead meant that they were simultaneous in frame B, then Y will see the light from the events arrive at his location simultaneously. What happens depends on what you say happens but you can't have it be both ways or be ambiguous.
 
  • #9
ghwellsjr said:
That's why I started my post with "If". You have to define which frame the events are simultaneous in which you did not do. If they are simultaneous in frame A (which is what I assumed you meant), then X sees the light from them arrive at his location simultaneously and so does Y. That's the definition of simultaneity in Special Relativity. If you instead meant that they were simultaneous in frame B, then Y will see the light from the events arrive at his location simultaneously. What happens depends on what you say happens but you can't have it be both ways or be ambiguous.

I have already mentioned that the events are simultaneous in X frame(sorry if it wasn't clear).
But how will Y predicts that both events are simultaneous in X frame as he will see that X is moving towards event red with same velocity v relative to him??
 
  • #10
Inhsdehkc said:
I have already mentioned that the events are simultaneous in X frame(sorry if it wasn't clear).
But how will Y predicts that both events are simultaneous in X frame as he will see that X is moving towards event red with same velocity v relative to him??
Y can use the A frame to analyze the situation just like we can. But as far as what Y sees from his rest frame B, he will determine that the events occurred at different times and that's why the light from them reach X simultaneously.
 
  • #11
ghwellsjr said:
Y can use the A frame to analyze the situation just like we can. But as far as what Y sees from his rest frame B, he will determine that the events occurred at different times and that's why the light from them reach X simultaneously.

yoU mean Y viewing from his rest frame B to X (throug a telescope or by any other) will see events occurring simultaneously or at different times in X??
 
  • #12
Inhsdehkc said:
Sorry,but you again messed up with X and Y.The two events are never simultaneous in Y frame!They are simultaneous in X frame.My question is just, will Y predicts that events to be simultaneous in X frame or not?
It appears I had it right the first time before you threw me off course. I have edited my original post back to how it was.

Further to your questions here. Y does not see the red and blue events as simultaneous in his own reference frame, but he does agree that from X's point of view the events would appear to be simultaneous to X in X's reference frame. Both X and Y agree that the light from red and blue events arrive at X's location simultaneously.
 
  • #13
Inhsdehkc said:
yoU mean Y viewing from his rest frame B to X (throug a telescope or by any other) will see events occurring simultaneously or at different times in X??
When an observer is actually watching what previously happened through a telescope or just with his bare eyes, he has to wait for the images of those remote events to propagate to him. Then he can use any frame, in which light is defined to propagate at c, to assign co-ordinates for when and where those remote events occurred. Different frames will assign different co-ordinates to events but they will all agree on what each observer actually sees.
 

1. What is the concept of relativity of simultaneity?

The relativity of simultaneity is a fundamental principle in Einstein's theory of special relativity. It states that the concept of "simultaneity" is relative and depends on the observer's frame of reference. In other words, events that appear simultaneous to one observer may not appear simultaneous to another observer who is in relative motion.

2. How does the relativity of simultaneity affect our perception of time?

The relativity of simultaneity challenges the traditional notion of a universal time frame. According to this principle, time is not absolute and can vary depending on the observer's frame of reference. This means that two events that are simultaneous for one observer may occur at different times for another observer, leading to the concept of time dilation.

3. Can the relativity of simultaneity be observed in everyday life?

Yes, the effects of relativity of simultaneity can be observed in everyday life. For example, the GPS system depends on the precise synchronization of clocks on satellites and on the ground. Because of the relative motion between the satellites and the Earth, the clocks on the satellites appear to run slower from the perspective of the Earth, leading to the need for adjustments in order for the GPS system to function accurately.

4. How does the relativity of simultaneity relate to the famous "twin paradox"?

The twin paradox is a thought experiment that illustrates the effects of time dilation and the relativity of simultaneity. In this scenario, one twin stays on Earth while the other travels in a high-speed spacecraft. When the traveling twin returns, they would have aged less than the twin who stayed on Earth due to the effects of time dilation. This is because the traveling twin experienced a different frame of reference and perceived time differently.

5. Does the relativity of simultaneity apply to all reference frames?

Yes, the relativity of simultaneity applies to all frames of reference, whether they are in uniform motion or at rest. This is one of the fundamental principles of special relativity, which states that the laws of physics are the same for all observers in uniform motion. This means that the relativity of simultaneity is a universal concept that applies to all frames of reference in the universe.

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