WE KNOW THAT THE SPEED OF THE LIGHT IS 360000 KM PER SEC.IT TAKES 4 MINUTES TO TRAVEL TO THE SUN IF YOU TRAVEL AT A SPEED OF LIGHT.LIGHT FROM DISTANCE STARS HAS NOT REACHED US YET.
THE STARS WE SEE IN EARTH IS THE STARS WHICH ARE MILLIONS OF YEARS AGO.
IF YOU ARE ABLE TO GO TO THE STARS INSTANTLY.AND LOOK AT OUR EARTH THE EARTH WOULD BE THE ONE WHICH EXIST MILLION YEARS AGO.SO IF YOU ARE ABLE TO ANALYSE THE LIGHT COMING FROM THE EARTH YOU CAN SEE .THIS WAY IF YOU GO FURTHER AND ANALYSE THE LIGHT COMING FROM A PARTICULAR LOCALITY YOU KNOW WHAT YOU WERE 5 YEARS BACK ,10 YEARS BACK ETC.ALSO IF YOU ANALYSE THE LIGHT IN THE SCENE OF CRIME YOU CAN BURST THE CRIMINAL GANG.