We've had EM comms for 100 years. Let's assume life, and civilisations capable of sending comms beyond their solar system have emerged multiple times during the

We've had EM comms for 100 years. Let's assume life, and civilisations capable of sending comms beyond their solar system have emerged multiple times during the history of the universe. If civilisations have a shelf life (for whatever reason) and don't exist indefinitely, it's extremely unlikely the timespan of someone transmitting and us receiving would overlap during those 100 years. Chances of existence/comms overlap are tiny even for the next 1 or 10 million years - even if Earth origin civilisation is still around then.