SETI is not how we'll find alien spacefaring civilizations. Within 1000 years, barring some apocalypse, an incredibly conservative prediction is that we will b

SETI is not how we'll find alien spacefaring civilizations. Within 1000 years, barring some apocalypse, an incredibly conservative prediction is that we will be able to build permanent space orbitals. We already have sufficiently strong and readily available materials (ie stainless steel) to build O'Neil Cylinders at 2-4 miles in diameter and 10-20 miles in length that could house as many as a million people. These can be powered with solar collectors. Build enough of these (ie millions) and you have a Dyson Swarm. With our Sun that can give our civilization upwards of 10^26 Watts of power to use (compared to our current estimated 10^11 Watts). This is also known as a Kardashev-2 (or K2) civilization. There are a ton of advantages to this. While it may not be the route that every civilization goes, given it is relatively low tech and has massive advantages in living area and energy availability, it seems like this would happen at least some of the time. These things would stand out from a huge distance because the only way to dissipate heat for a space orbital is to radiate it away into space. That has a wavelength determined entirely by temperature, which for any reasonable termperature range is infrared. So you'd detect a Dyson Swarm from a huge distance away by its IR signature. A galaxy of these (a so-called K3 civilization) would be visible from millions of light years away. A single star would be detectable now from a smaller distance but still a far bigger distance than any form of radio communication as you'd find via SETI. The fact that we haven't seen any evidence of this thus far in our galaxy leads many (including me) to think the most likely scenario is we are the only potential spacefaring civilizatin in our galaxy. The JWST is actually a way better tool for finding spacefaring life than anything SETI has done or proposes.