Also, 84 per cent of no aliens in Milky Way galaxy is means that they are almost certainly exist in Virgo supercluster with its 2000 galaxies.
No. Or rather, it depends on where the 84% comes from. If it’s an unknown factor that applies to each galaxy independently, then yeah. But if it’s an unknown factor that applies to either all galaxies or none, then adding more galaxies doesn’t help much.
The Drake parameter R* = The rate of star formation (new stars / year). It is set to LogUniform(1,100), meant to be representative of the Milky Way. I can easily replace that in the model with 2000*LogUniform(1,100) to explore your question. The other Drake parameter that might need some thought is f_c = The fraction of intelligent civilizations that are detectable / contactable. For now, let’s not alter this one. The other Drake parameters shouldn’t really change, at least assuming they are similar galaxies.
With that change to R*, P(N<1) -- the probability there isn’t another in the Virgo cluster, becomes 81% (for the 2nd model version with the t V λ decomposition for f_l, which had previously been 84%). The 1st model version that used a LogNormal for f_l changes from 48.5% to 38%.
The versions that explored a less extreme model of f_l (the rate of abiogenesis) see a much bigger change. For example, when f_l is set to 100%, it changes from 10% for Milky Way to 0.05% for Virgo. The Beta distribution version of f_l goes from 23% to 1%.
Your intuition might be that the prob. of being alone would drop by a factor of 2000, which obviously isn’t what happens. What you do see is the distribution for N = # of detectable civilizations (which is a probability dist, not a point prob) shifts right by a factor of 2000. But that doesn’t mean the area under N<1 sees that same change.
No. Or rather, it depends on where the 84% comes from. If it’s an unknown factor that applies to each galaxy independently, then yeah. But if it’s an unknown factor that applies to either all galaxies or none, then adding more galaxies doesn’t help much.
The Drake parameter R* = The rate of star formation (new stars / year). It is set to LogUniform(1,100), meant to be representative of the Milky Way. I can easily replace that in the model with 2000*LogUniform(1,100) to explore your question. The other Drake parameter that might need some thought is f_c = The fraction of intelligent civilizations that are detectable / contactable. For now, let’s not alter this one. The other Drake parameters shouldn’t really change, at least assuming they are similar galaxies.
With that change to R*, P(N<1) -- the probability there isn’t another in the Virgo cluster, becomes 81% (for the 2nd model version with the t V λ decomposition for f_l, which had previously been 84%). The 1st model version that used a LogNormal for f_l changes from 48.5% to 38%.
The versions that explored a less extreme model of f_l (the rate of abiogenesis) see a much bigger change. For example, when f_l is set to 100%, it changes from 10% for Milky Way to 0.05% for Virgo. The Beta distribution version of f_l goes from 23% to 1%.
Your intuition might be that the prob. of being alone would drop by a factor of 2000, which obviously isn’t what happens. What you do see is the distribution for N = # of detectable civilizations (which is a probability dist, not a point prob) shifts right by a factor of 2000. But that doesn’t mean the area under N<1 sees that same change.
Sound reasonable, but we also know that for Earth p=1. So it is not something impossible, which can’t be repeated again. What could be such factor?