May 4, 2008

How we always see the past ...

This very idea freaked me out when I realized for the first time that we always see the past !
Like when I am looking at a star in the sky, it is totally possible that this star no longer exists.. the sky is displaying a snapshot taken in th past. If it's a star five lightyears away from earth, then I certainly am looking at a picture taken five years ago. Light travels at the rate of 30 million metres per second, so even if I am talking to the person sitting right before me, it takes more or less three nanoseconds for light to reach my eyes from that I cannot see his instant reaction untill I wait for more 3 nanosecs :)