BILLINGS If the average longevity of an advanced technological society is a few hundred years and two are situated 1,000 light years apart, then even if one discovered the other and sent a message, when the message was received, the society that sent it might no longer exist.”

If the average longevity of an advanced technological society is a few hundred years and two are situated 1,000 light years apart, then even if one discovered the other and sent a message, when the message was received, the society that sent it might no longer exist.”