Conversation is impractical unless we’re very close. To understand why, imagine that the Milky Way is stuffed with a million alien societies. The nearest to us will be about 100 light years away. If we detect a signal from these cosmic neighbours and grab a microphone to ask a penetrating question, it will take at least 200 years before we can expect an answer – so don’t count on conversation.
Below:
Is anyone out there? SETI hopes the Allen Telescope Array will pick up signs of alien life
© Seth Shostak