# Horizon of the events

The horizon of the events is consisted the area of the Espace-temps in which an event perhaps perceived by an observer.

Let us suppose that an event occurs in a point of space at a given moment. So that an observer located at a distance $d$ can detect this event, it must wait until information concerning this event comes from to him. As information cannot travel more quickly than the speed of the Lumière $c$, that is to say approximately 300.000 km/s, it will be able to measure this event later only $d/c$ seconds. Same manner, for a time $t$ given, only the observers located at a distance lower than $ct$ will be able to detect the event. It is this limit between the area of the space in which an event could be observed and that where it cannot any more the being which is called the horizon of the events.

## See too

 Random links: Glossary of archeology/Fortifications | Jean Béliveau | The Darkroom | Épaphos | Casaletto Lodigiano | Rouge_de_plan_de_guerre