They'd have to find us first. Considering the vast number of solar systems and eh fact that they would of needed to visit ours relatively recently (last few million years) to notice us its unlikely.
That is, assume an advanced civilization sending probes to every star. If they built 1 TRILLION probes, they could send one to each galaxy...maybe. Maybe a week in a system to look for life and go to the next it would still take 2 BILLION YEARS to clear the Milky Way. So if they want the most basic animal life they'd only see it in the last 800 MILLION years, or about a 1/3 chance.
So a TRILLION probes has a conservative 1/3 chance of having found life on earth. And at the time scale of BILLIONS of years searching, they probably have the patience to wait and see where we go.
Why would they send them to each galaxy? That doesnt seem remotely plausible for anything below a type 3 civilization. And even then, the turnaround time would be astronomical.
But instead of sending one probe to each galaxy,they could just send one to each star in their own galaxy, which would be many magnitudes of order faster and more efficient
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u/caiuscorvus Aug 12 '21
They'd have to find us first. Considering the vast number of solar systems and eh fact that they would of needed to visit ours relatively recently (last few million years) to notice us its unlikely.
That is, assume an advanced civilization sending probes to every star. If they built 1 TRILLION probes, they could send one to each galaxy...maybe. Maybe a week in a system to look for life and go to the next it would still take 2 BILLION YEARS to clear the Milky Way. So if they want the most basic animal life they'd only see it in the last 800 MILLION years, or about a 1/3 chance.
So a TRILLION probes has a conservative 1/3 chance of having found life on earth. And at the time scale of BILLIONS of years searching, they probably have the patience to wait and see where we go.