In the final episode of Cosmos, Carl Sagan describes a nightmare in which he is traveling the universe and decides to return to earth. As he gets closer, his spaceship intercepts broadcasts that have been traversing space since the invention of radio, from the earliest radio messages to television signals and then eventually...the signals stop.
Microbial life perhaps, but as far as complex life is concerned, I claim habitability on those timescales will indeed be suppressed. Complex life needs plate tectonics, which depends on a planet's internal heat. A red dwarf star may shine for ten trillion years, but terrestrial planets will be stone cold dead long before then.
Also, talk about correlation does not equal causation at your link:
> The basic structure of the Earth, aided by plate tectonics, makes possible the Earth's magnetic field. Neither Venus nor Mars has such a magnetic field. Venus has core and molten regions like the Earth, but a very slow rate of rotation. It produces neither plate tectonics or a magnetic field. Mars has volcanism, but limited to a small number of spectacularly large volcanoes like Olympus Mons. It's magnetic field is weak despite a rotation period similar to that of the Earth. This suggests that the molten nature of the Earth's mantle that facilitates plate tectonics is also essential for the operation of the dynamo that produces the magnetic field.
I mean, N=3 !
1. We don't have enough data about other solar systems, so we don't know where complex life might exist.
2. We don't have enough data about other solar systems, so complex life probably exists all over the place.
If you're arguing for the first position, fair enough; I might not entirely agree, but it is at least reasonable.
But I see too many people arguing for the second position, taking scarcity of data as a license to believe what they want to believe.
Though this paper does provide some needed formalism around the Drake Equation, I don't understand how its results can be meaningful if it "cancels out" one of the largest sources of uncertainty.
Fine, but that same argument says that most life in the universe will be coming along in trillions of years and a fat lot of good that will do for us.