|Life After People|
The SETI institute and NASA through its Kepler Mission are looking for planets that are, or can be, inhabited. Which means that they are looking near stars.
Some of which will go nova, or destroy the planets near them in another way.
Under current scientific models the stars which have planets near them will destroy those planets at some time. Our star, the Sun, will do so by expanding in size to a point out near the orbit of Mars.
Since we know that, it seems obvious that we will try to leave this planet to find another star with habitable planets. It seems obvious because if we do not do that, we cease to exist as a species.
We can assume that any other intelligent life species that wanted to continue to exist would do the same. They would try to find another home world.
I offer a search technique for consideration, which could fine tune the search Kepler and SETI are doing.
Look for signals from solar systems where the star has gone catastrophic, that is, has gone nova, super-nova, or has expanded out to destroy the planets near it like the Sun is going to to us. If there was any life on any planets there, the looming catastrophe may have caused signal transmission from any intelligent life there, well before the solar destruction.
But when we do the looking, we should look at the record of events before the catastrophe, we should also look back as many years before the catastrophe as possible, in cases where we have those astronomical records in our grasp.
For those systems where there were species who could not develop a way to do space travel to another planet, we might detect a signal for help.
And in those cases where the species could and did develop space travel, did find another star with a habitable planet, then did thereafter travel to it, we would expect a different signal to find its way toward us.
But remember that, in any search of this type, any signal will in most cases be older than our species, since great distances of space are involved.
Which involves great spans of time for signals to travel through, even at the speed of light.
Any signals received will be very, very old.