If and when we detect evidence of technological life it's not going to be from radio signals of the kind SETI is looking for. It's going to be infra-red. The w

If and when we detect evidence of technological life it's not going to be from radio signals of the kind SETI is looking for. It's going to be infra-red. The window in which humanity releases the kind of radio signals SETI was built to find is fairly narrow. We've largely moved on from broadcast signals to fiber optics, directional beams and lower power. Even the "high" power signals are relatively low power and probably not detectable beyond a few hundred light years. That is a miniscule volume of our galaxy. Combine that with the small window and it's like trying to win the lottery 3 weeks in a row. The limits we have on growing are twofold: 1) living area and 2) energy. These two are actually related. Many (myself included) consider th emost likely path for our species is to build a Dyson Swarm. This is a cloud of orbitals. A so-called O'Neil Cylinder. 20-30 miles long, 2-4 miles wide, spin gravity. Cover it in solar panels for power. This requires a material no more advanced than stainless steel. Such a swarm around our Sun would have access to something like 10"15 times more energy than we have now and a fraction of Mercury's mass would produce trillions of times the land area of Earth. Orbitals would have to dissipate heat somehow. The only way to do this in space is to vent material or to radiate it away. At any likely temperature that means infra-red radiation. That's physics. So a Dyson Swarm around a star would have a huge IR signature that would be entirely obvious from a thousands of light years away. Over enough star systems (eg a galaxy) that distance goes out to millions of light years. So it's a Dyson Swarm we'll see, not radio communications.