In the summer of 1950, physicist Enrico Fermi posed a simple question to his colleagues at lunch: "Where is everyone?"
Fermi meant extraterrestrial life in the universe.
Probably, according to him, in the 4.4 billion years required for the development of intelligent life on our planet, the rest of our galaxy should have been flooded with similarly intelligent, technologically advanced aliens. But despite decades of searching the Milky Way for signs of aliens, we have found nothing or no one.
This puzzle became known as the Fermi Paradox.
Scientists have offered countless potential answers to the question, including that aliens overwhelm or intentionally hide from us. Some researchers also suggest that highly advanced technological civilizations are being destroyed before they are able to come into contact with other intelligent life in the universe.
Read more: Alien civilizations may have explored the galaxy and already visited Earth, a new study says. We just haven't seen them lately.
In his new book, End Times, author Brian Walsh discusses 1