Why do light flashes from both ends of a train reach the passenger at the same time?

[Doc Al]

this was posted to show the videos worldline

Once again, you have switched scenarios. This diagram is for the standard scenario in which the lightning strikes are simultaneous in the platform frame.

the strikes are along the X axis both at t = 0

Yes, in the platform frame.

as they occur on the train - they must be simultaneous

The fact that they occur 'on the train' is irrelevant. They are simultaneous in the platform frame, not the train frame.

the light then travels from the sources to the platform observer at t = 4

Sure, it takes time for the light to travel to the platform observer.

the lines also cross the t prime axis but the x prime line is not used to show where they cross on the t prime line

You should be able to draw in the lines to see where and when the events (the lightning strikes) happen in the train frame.

 

[solarflare]

it is not irrelevant when the graph says they occur on the train simultaneously

and again the lines cross t prime from the source on the x-axis

if you want to say that t prime is relevant then the source of the lines that cross t prime must also be relevant

 

[Doc Al]

This thread is obviously going nowhere (and very slowly at that). So it's time to shut it down.

Solarflare: All your questions have been answered several times over. Repeating the same thing isn't going to help. If you're serious, I suggest getting an intro book on relativity. (Or you can read Einstein's own words--see George's link.) Then you can go back and read through this thread again.

Thanks to everyone who contributed their time and effort to this thread.