I find this persuasive – 3. Extraterrestrials have not had time to establish large spacefaring civilizations. (Let’s not forget that the universe is extremely young, at merely 13.8 billion years old; that the farther afield we look, the further back in time we’re seeing; lastly, that it’s looking like galaxies shall remain able to support life for trillions of years into the future. All of this may imply that we’re living in an ancestor simulation, which is something I find very highly plausible.)

1. Interstellar travel is unfeasible, at any level of achievable technological development. (This may imply that advanced extraterrestrials would retreat into simulations rather than colonize the stars. Possibly similar to how, in Peter Watts’ Blindsight, humans blithely retreated into a self-indulgent sim called “Heaven”. This looks increasingly probable for humanity — of all possible futures, the Cyberpunk version might be the one we’re stuck with.)

2. Our observations are being deliberately manipulated or confused by extraterrestrial intelligences so as to frustrate SETI efforts. (The more ubiquitous and common extraterrestrial life is, the more plausible this theory may be.)

3. Extraterrestrials have not had time to establish large spacefaring civilizations. (Let’s not forget that the universe is extremely young, at merely 13.8 billion years old; that the farther afield we look, the further back in time we’re seeing; lastly, that it’s looking like galaxies shall remain able to support life for trillions of years into the future. All of this may imply that we’re living in an ancestor simulation, which is something I find very highly plausible.)

4. That extraterrestrial intelligence exists, and may even have visited or does visit Earth, but that we simply have not noticed it.
4.1. Spacefaring civilizations are sufficiently rare that they are not in our search volume.
4.2. They exist, but their total energy supplies are universally below the search’s detection threshold.
4.3. ETI’s with large energy supplies universally expel waste heat at low temperatures (i.e. wavelengths longer than the capabilities of the search).
4.4. Spacefaring ETI’s inevitably discover and universally employ physics that makes their civilizations effectively invisible in the MIR despite having large energy supplies (for example, expelling their waste heat as neutrinos, efficiently using their energy supply to emit low-entropy radiation, employing energy-to-mass conversion on a massive scale, or by violating conservation of energy).

…I’d add that it is possible to mask IR radiation, to some degree, even today. It’s far from impossible that spacefaring, advanced civilizations are, for one reason or another, intentionally masking their radiation signature.

I’d also add that the inverse square law makes it impossible that we’ll accidentally pick up meaningful signals from anywhere, and it ensured that SETI’s early chances of success were always very low.

So, with all that said, it’s essentially a non sequitur to say “we don’t see anything, therefore something out there must be killing everything.”

http://www.amazon.com/Rare-Earth-Complex-Uncommon-Universe/dp/0387952896/

Plate tectonics is important. You not only have to have an environment that’s just right, it has to stay just right for billions of years. Mars used to be a much friendlier place.

But current circumstances are aberrant.

In fact current circumstances are extremely aberrant.