Is spacetime just a mathematical trick or is it the actual physical reality?

[alw34]

No, I meant. What is space? What is time?

Space is what keeps everything from happening to you.

Time is what keeps everything from happening all at once.

 

[Dale]

Experiments confirm SR, they do not confirm our world is a Minkowski spacetime where time is just like space. I distinguish those two things, SR and Minkowski spacetime.

Nature does not distinguish those two things. All interpretations are experimentally indistinguishable.

 

[PeterDonis]

a Minkowski spacetime where time is just like space

Time is not "just like space" in SR/Minkowski spacetime (which are the same thing, as DaleSpam says). There is a fundamental difference between timelike intervals and spacelike intervals (and there is also a third type, null intervals, which is fundamentally different from the other two). Physically, the difference shows up as, for example, the fact that you can't measure timelike intervals and spacelike intervals the same way; you use a clock for the former and a ruler for the latter. Mathematically, the difference shows up as a difference in signs in the metric.

 

[DoobleD]

Thanks for the answers !

 

[industry7]

Nature does not distinguish those two things. All interpretations are experimentally indistinguishable.

How do you measure spacetime?

 

[HallsofIvy]

How do you measure spacetime?

$s^2= t^2- x^2- y^2- z^2$

 

[Dale]

This thread is closed