If I emit photons in all directions, their paths in spacetime define what is usually called the "lightcone" whose ‘bottom’ lies at my present moment. Because of the limitation c imposes, the worldlines for anyone moving past me, regardless of their speed, will lie within this lightcone, and so will any and all the events which I can influence. The region of spacetime within my lightcone is called the ‘causal future’; the events which can influence me lie within my ‘causal past.’ Events lying in the region between my causal future and causal past, called my ‘elsewhere’, have no causal relation to me.