As you should all realize, that a light year is how far light can travel in a year. A few days ago I was told that in 1995 a supernova 20,000 light years away was seen and the effects of the supernova have just been discovered. Being 20,000 light years away that means the supernova actually exploded 20,000 years ago and that we are seeing it now. The effects of this supernova shot many alpha and beta particles (radiation) into the side of the planet that was facing the explosion. The normal dosage (if you would call it) of radiation recieved normally is about 200 mRem and this number was increased by 80 mRem. Looking at the math if a supernova happened 10,000 years ago, the change would be at 320 mRem. Going to 5000, 2500, 1250, 625 years the effect each time would be muliplied 4X and so if a supernova exploded 312 1/2 years ago then the change would be a significant 327680 mRem or about 33 Rem which is enough to kill a person. If light travels the speed of light (obviously) and nothing is faster than light then how can we detect this? By the time it reaches us we would all be dead. I heard of tachyeon and that it is a radio wave that can travel faster than the speed of light. Does this exist and how does it work? If this does exist can we use it to detect such bursts of radiation before it reaches the earth? Please repond with anything concerning the matter.