That is called "not happened yet" in our lightcone.
It's an easy concept to grasp, but many people resist considering an event to have not yet happened when it has not yet crossed our lightcone. If you are really interested, then I suggest Stephen Hawking's book A Brief History of Time.
It's an easy concept to grasp, but many people resist considering an event to have not yet happened when it has not yet crossed our lightcone. If you are really interested, then I suggest Stephen Hawking's book A Brief History of Time.