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. Tough, eh?
This is a consequence of the clock synch method. 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 has nothing to do with clocks being in synch. This is what the observer observes, not what is measured.
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. 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?
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.
Compared to what? How would you determine if the embankment had a zero velocity or a 1,000 m/s velocity?
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?
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. 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?