Recent content by LBoy

Not a doubt here, eventually it can be preciselly defined locally in a tangent space at a point, but physically I think this has no sense (although there is a local "similarity" between a tangent space and a R4 "space-time" with cartesian coordinates, but this makes less and less physical sense...

I would like to think that simultaneity is something that is independent of a clock synchronization procedure, like a real and physical measure (or maybe rather a feature of a space time for a choosen observer) with a precise definition (mathematical), regardless of the clock-synchronization...

It is obvious that they are conventions, my bad that I didn't specify that I was thinking about obvious conventions, not about general things being obvious, I will be more precise from now. :) In the simplest 2-D case of SR, inertial observers, simultaneity of two events for an observer is...

Oh yes, 1 and 2 are pretty obvious, using non-inertial observers is beyond my question, the question concerns only the third point: defining simultaneity for a choosen observer is not a convention, it is a precise term (mathematical and physical too - imho) for this chosen observer. PAllen's...

I think this definition is not fundamentally different from mine. Before PAllen answers I would like to know your view on the issue of simultaneity: convention or physical reality? Because I admit I don't understand this argument.

The Minkowski diagram (Italicus post 30) shows that the two signal reception events by OT and OE are not "colocated at the same event", we are dealing with two different events: OE receives a lightning strike signal, and OT receives two signals. These events are separated both temporally and...

From the diagram we clearly see that light lines from A and B intersect blue skewed t' line in two separate points Q and P respectively. Thus for the OT both events are not simultaneous. It means that pulse from B arrives first and from A second. OT really sees B first and A as the second pulse...

Thank you for your answer. Lots to think about :) 1. First comment about simultaneity of flashes. Original idea,the starting thought-experiment describes situation in and out of the train. For the observer in the train flashes at the front (B) and at the back (A) are not simultaneous so in his...

No, because that would mean that for both of them A and B occurred simultaneously. We explained this many times before. The rest of explanation below is wrong. For example - the OT will not see flash B (front) as bigger and A smaller, velocity doesn't change the intensity (I assume that you...

I would like to see it if you wouldn't mind, train experiment works for me, however I see the whole environment, a galaxy of possibilities of making an error due to a lot of irrelevant effects present. I can filter it out I suppose however I see that Hans might have a problem with this, he...

As I see I cannot edit my previous post,OK, so I'm doing it here.

Thank you, my bad! There should be OT (observer in the train) instead of OE of course, I will change it immediately.

I think there may be a cosmic equivalent to this idea. Take two stars (or two particles), of roughly equal mass and different velocities towards us (as measured by blueshift/redshift for example). Let them move around some massive object that affects their trajectories. If relativistic mass...

As far as I remember from history of physics this postulate appeared after an attempt to explain the results of experiments of Michelson and Morley, without it the results didn't make sense. For me it is a direct result of the diferent sign in space-time metrics, for example (-, +, +, +) -...

1. Yes you can, from the same diagram. Assuming there is no motion on the y-z surface. If there is a complicated motion (example - rotation on y-z) then this simple two dimensional diagram with t and x only is not suitable as a model for this problem. 2. Yes you can, if you have a point in...