Spacelike-separated event

Mathematically, we can decide if two events are timelike-separated or spacelike-separated by just looking at the sign of the spacetime interval between them.

On the light cone, these are events on the left/right part of the cone.

Different observers might not agree on the order of two spacelike-separated events.

Further discussion at Section "Light cone".

The opposite of those events are timelike-separated events.