I found in my text book it's only define by [math]ds^2[/math]

 

but I want to know its physical meaning

 

thanks

Slower than lightspeed, lightspeed, faster than lightspeed.

Can you explain those word?

What is a consequence of faster than lightspeed ?

> What is a consequence of faster than lightspeed ?

 

Space-like separated spacetime events, can't be connected by a signal slower or equal that of light speed, only by faster than lightspeed. And according to SR postulates, there are no such signals in nature, which means there can according to SR be no causal relation between space-like separated events.

 

Time-like and light-like events are those than can possibly be causaly related.

 

Of course there could still be correlations, which is not the same as causality. Of course, one might argue howto prove a causality without resting on correlations for evidence, or how to make a foolproof definition of physical causation in terms of measurements only

 

/Fredrik