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In Fermi's time, the perception was that an advanced civilization would have large powerful radio stations that could be detected from many light years away. Up
by bewo001 8y ago
In Fermi's time, the perception was that an advanced civilization would have large powerful radio stations that could be detected from many light years away. Up until the 1930s, radio stations did indeed get bigger and bigger. But after WWII it became clear that many smaller stations are preferable over a few big stations. The trend started with FM radio and today we listen to radio using WLAN systems that barely cover the area of an apartment.
An advanced civilization has antennas that don't waste energy by beaming signals into space.
- goatlover 8y agoBut the SETI assumption is that an advanced civilization could beam powerful radio signals into space to let other civilizations know they're around. That's part of the premise for Sagan's Contact, with the aliens listening in and then sending a strong signal upon detecting a new fledgling civilization. From the movie, it's apparent there were various listening posts scattered about the galaxy.
- ars 8y agoYou forgot about radar. Our current radar produces signals that are very very easy to see from incredible distances. But, I'm not sure if the signals will appear to be from intelligence though.