birdman

Ok so they'd see it after what they perceived as one second, but how is the "will be judged by the traveller to have occurred 3/4 of a second ago" calculated? And who is it relative to?

Thanks for the reply. In that case, if light adjusts it doesn't matter how fast the train is going, the observer on the train and the stationary observer should see the event at the same time if the event happens as they pass? I'm quoting verbatim from the book, so unfortunately I'm not sure whose seconds they relate to..

Hello all, Posted this in the 'Relativity' section but no takers..may be a little elementary for that folder, perhaps someone could help here..: 'ABC of Relativity by Bertrand Russell - A layman strikes..' Hope someone can help with my understanding of a part of this book. Train is travelling at 3/5 the speed of light and passes a stationary observer at a point which an event in the direction of the train occurs - "An event which happens in the forward direction along the railway, and which the stationary observer judges to be now (or rather will judge to have been now when he comes to know of it) if it occurs at a distance along the line which light could travel in a second, will be judged by the traveller to have occurred 3/4 of a second ago" From what I understand of this, the observer on the train will receive the light from the event before the stationary observer because it is travelling towards it and therefore will see it before the stationary observer (this may be incorrect) but I cannot see why it will be 3/4 of a second ago - can someone run me through this algebraically in order to put my mind at ease? Many thanks for help in advance!

Got it! Y = 2X / (1-4X) Y * (1-4X) = 2X Y-4YX = 2X Y = 2X+4YX Y = X(2+4Y) Y/(2+4Y) = X Can't believe I didn't see that earlier, thanks for your help guys..

Hello Klaynos, Thanks for the swift reply, but I'm a little confused by "multiply by any x terms which are divisions"?

Hello all, Hope someone can help with this simple problem I'm having rearranging this equation to put X in terms of Y: Y = 2X / (1-4X) Answer given is X = Y / (2+4Y) but I can't see why, can anyone help me out with the intermediate steps? Many thanks!!

Hello all, Hope someone can help with my understanding of a part of this book. Train is travelling at 3/5 the speed of light and passes a stationary observer at a point which an event in the direction of the train occurs - "An event which happens in the forward direction along the railway, and which the stationary observer judges to be now (or rather will judge to have been now when he comes to know of it) if it occurs at a distance along the line which light could travel in a second, will be judged by the traveller to have occurred 3/4 of a second ago" From what I understand of this, the observer on the train will receive the light from the event before the stationary observer because it is travelling towards it and therefore will see it before the stationary observer (this may be incorrect) but I cannot see why it will be 3/4 of a second ago - can someone run me through this algebraically in order to put my mind at ease? Many thanks for help in advance!