A new solution to the Fermi Paradox is presented: probes or visits from putative alien civilizations have a very low probability until a civilization reaches a certain age (called the Contact Era) after the onset of radio communications.
If biotic planets are common, putative advanced civilizations may preferentially send probes to planets with technosignatures, such as radio broadcastings. The contact probability is defined as the chance to find a nearby civilization located close enough so that it could have detected the earliest radio emissions (the radiosphere) and sent a probe that would reach the Solar System at present.
It is found that the current contact probability for Earth is very low unless civilizations are extremely abundant. Since the radiosphere expands with time, so does the contact probability.
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