The Relativity of Simultaneity

Motor Daddy said:
. Maybe it's easier to use, and it does have some benefits such as GPS etc, but it is wrong for one main reason, he has total disregard for the inertial object's velocity.
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So ignore real world observation, experimentation and technology in order to maintain your delusion.
 
Motor Daddy said:
Einstein uses a totally fabricated system not in keeping with the concept of elapsed time and simultaneity.
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Einstein has been dead for 65 years. Yet, his science has survived the most stringent testing. The fact you don't understand it doesn't falsify it.


Maybe it's easier to use, and it does have some benefits such as GPS etc, but it is wrong for one main reason, he has total disregard for the inertial object's velocity.
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Tough, eh?
 
arfa brane said:
The observer on the train sees light take the same time to traverse the train in either direction, which is a consequence of light having a constant speed. He assumes the latter is true.
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This is a consequence of the clock synch method.

What this is about is forming a rigorous definition of time and more importantly, distance (as traveled by light), in fact identical distances if the A and B have zero relative velocity.
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We know he's defining a standard for time and simultaneity so moving observers descriptions relate to the same events. The point to be made was, it's a convention/definition, not a fact about a physical process.

An official could issue a decree that the moon is only half as far away, but the moon would not comply.

In par. 3, he uses closing speeds in defining the transformation equations,so he knows the outbound and inbound times are different for light transit times, but ignores it to preserve constant light speed.
 
This is a consequence of the clock synch method.
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This has nothing to do with clocks being in synch. This is what the observer observes, not what is measured.
 
AlexG said:
This has nothing to do with clocks being in synch. This is what the observer observes, not what is measured.
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It is seldom the case that simultaneous perception of light signals means simultaneous occurrences of the events that produce them. Viewing the night sky, no one would conclude that the light left all sources at the same time.
If the rear flash ocurred before the front flash, they could arrive simultaneously at the midpoint of the train. The person at the midpoint would resolve this by polling the clocks at both ends with a light signal. The clocks would read the same, but only because they were previously synchronized using the SR method.
This could easily be proved by not synchronizing the train clocks after attaining speed. The clocks would still have earth synched time, but a different rate. When the flashes ocurr, a clock at each flash would indicate different times.
 
The topic of this thread was brought up in another ([post=2749116]Light at Light speed[/post]), and I'm bringing it back here to avoid a major sidetrack in that thread.

Pete said:
Here's a deal for you:
We're considering two mathematical worlds: Newton's world and Einstein's world.
You think that Newton's world is a better match for the real world than Einstein's.
I think that Einstein's world is a better match.

If you agree that only actual measurements of the real world (ie experiments) can decide who is right, then I'll show you the numbers in Einstein's world, one small step at a time, so you can point out any problems.

Deal?
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Motor Daddy said:
How about this. We have a deal, but first you prove to me a relativity of simultaneity exists before you start using it in your method of calculations. Show me your numbers of Chapter 9 and prove to me that a relativity of simultaneity actually exists as Einstein claims it does. Prove it! Show me the numbers!
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I'll start from the assumptions that:
  • the embankment is at rest
  • light travels at c with respect to the embankment
then show that in the mathematical world of time dilation and length contraction:
  • The train observer can't tell how fast he's going. His best measurements tell him he's at rest.
  • He can't synchronize his clocks with the embankment clocks. His best synchronization methods make his clocks out of sync with the embankment clocks
  • The clocks he synchronized as well as he possibly could tell him that the lightning strike at the front of the train happened before the lightning strike at the back of the train.

I'll go one step at a time, and wait for your questions and corrections before proceeding.

In return, I expect that if I am able to do this to your satisfaction, then you will agree:
  • that Einstein's world is a logically consistent world, and
  • that if actual measurements in the real world match Einstein's world better than your own conceptual model, then your own conceptual model is wrong at relativistic speeds.

Agreed?
 
Pete said:
I'll start from the assumptions that:
  • the embankment is at rest
  • light travels at c with respect to the embankment
then show that in the mathematical world of time dilation and length contraction:
  • The train observer can't tell how fast he's going. His best measurements tell him he's at rest.
  • He can't synchronize his clocks with the embankment clocks. His best synchronization methods make his clocks out of sync with the embankment clocks
  • The clocks he synchronized as well as he possibly could tell him that the lightning strike at the front of the train happened before the lightning strike at the back of the train.

I'll go one step at a time, and wait for your questions and corrections before proceeding.

In return, I expect that if I am able to do this to your satisfaction, then you will agree:
  • that Einstein's world is a logically consistent world, and
  • that if actual measurements in the real world match Einstein's world better than your own conceptual model, then your own conceptual model is wrong at relativistic speeds.

Agreed?
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How did you come to the conclusion the embankment was at rest? "At rest" compared to what?
 
It's an assumption, a premise. Not a conclusion.

Every calculation I make will be based on the premises that the embankment is actually at rest, and that light actually travels at c relative to the embankment.

To recap and add clarification:

Assumptions:
  • The embankment is at rest
  • Light travels at c with respect to the embankment
  • Clocks on the embankment are synchronized with each other
  • The train observer knows that light travels at c with respect to something at rest
  • The train observer doesn't know that the embankment is at rest
  • The train observer doesn't know that the embankment clocks are synchronized
  • The train observer has precise clocks, but he doesn't know if they're synchronized
  • Moving clocks run slowly by the Lorentz factor
  • Moving rulers are shorter in the direction of motion by the Lorentz factor

Are these premises acceptable to you?
All my calculations must be perfectly consistent with these premises.


From these premises, I believe I can prove that:
  • The train observer can't tell how fast he's going.
  • His best measurements tell him he's at rest.
  • His best measurements tell him that the speed of light is c with respect to the train.
  • He can't synchronize his clocks. His best synchronization methods make his clocks out of sync with the embankment clocks
  • The clocks he synchronized as well as he possibly could tell him that the lightning strike at the front of the train happened before the lightning strike at the back of the train.
 
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Pete said:
It's an assumption, not a conclusion.
Every calculation I make will be based on the assumption that the embankment is actually at rest, and that light actually travels at c relative to the embankment.
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At rest compared to what? You say it's at rest. What do you mean by that?
 
I don't know how to be any clearer.
What is ambiguous about "the embankment is absolutely at rest"?
 
That's a problem that the train observer will indeed have to address in order to determine the velocity of the train.

I'm starting the with assumption that the embankment is at rest. I'm taking it as given.

But perhaps you would you like to suggest a method of determining the embankment's velocity?
 
Pete said:
That's a problem that the train observer will indeed have to address in order to determine the velocity of the train.
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The train observer has the same problem as you have. You say the embankment has a zero velocity, and the train observer says the train has a zero velocity? So before you or an observer on the train (or any observer in the universe) can make any statements about motion they first need to know their own motion. I've noted and you've made it clear you have no way of actually knowing whether the embankment has a zero velocity or not, you are simply guessing, and there is only 1 chance out of an infinite amount of possibilities that you are correct.

Pete said:
I'm starting the with assumption that the embankment is at rest. I'm taking it as given.
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You have no way of knowing or testing, you just start from a random assumption and work from there, is that correct?

What is your concept of the embankment's velocity? What is that zero velocity relative to, in your mind?
 
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