The Mystery Behind a 40-Year-Old Signal From Outer Space May Finally Be Solved

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12. I think that if we will find other technological life

that it will be from observing their engineered structures or observing their propulsion systems. SETI is nice to have - you don't know what may be picked up, but the exoplanet search and characterization is where I think we will see the first signs.

I also think that technological life is exceedingly rare at least at this point in time. In another 2-3 billion years you might find far more (irrespective of space colonization which would totally change the equation if that gets going).

We are early to the party. You need a second or third generation solar system for the heavy metals necessary for technological life (and even life as we know it - think of the importance of heavier elements like Calcium, Potassium, and Iron). These heavy elements are only formed and released in the fire of a end of life star.
1 Billion years for single cell life
2 Billion years for Eukaryotes organisms after that
1 Billion for multicellular after that
500 M for land tetrapods after that