Aliens could already be dead.
Aliens might be extinct
Expert Dr. Frederick Walter has proposed the theory that extraterrestrials might not have made contact with Earth because they have been wiped out.
The astronomy professor thinks that "supernova" radiation could have killed off other lifeforms in the galaxy as the frequent collapse of giant stars may have released enough to destroy any signs of life.
Dr. Walter, from Stony Brook University in New York, believes that a giant gamma ray beam could be responsible for the alien extinction.
He said: "It's just one of many possible explanations. Sort of morbid, I suppose."
However, the academic has reassured humans that they shouldn't fear getting blasted to death by the gamma rays.
Dr. Walter said: "They're rare, and they're directed. It's not something you can prepare for."