If intergalactic travel is easy then the model of the first intelligent species in each galaxy taking over that galaxy fails to explain why we don’t encounter other species. We should still expect species to spread far out.
I don’t think his idea actually relies on intergalactic travel being difficult, just the way he stated it. If, say, intergalactic travel is easy, but not intercluster, then the idea could still apply, just at the galactic cluster level rather than at the galaxy level.
Either they would have arrived already (and taken over the galaxy, suppressing us in the process) - or they have yet to arrive. The chances of them initially showing up around about now are going to be pretty small.
They apparently haven’t arrived here already—unless they seeded us originally—else where are they? So, if they are out there, they have yet to arrive.
I don’t really see how all this makes much difference to the original argument.
The point of that argument was that seeing yourself alone in the galaxy with no aliens around is only to be expected—if the first intelligences rapidly expand and suppress the subsequent development of other intelligent life. So, being first is not so much of a miracle.
Hmm—I can’t see where I was assuming that.
If intergalactic travel is easy then the model of the first intelligent species in each galaxy taking over that galaxy fails to explain why we don’t encounter other species. We should still expect species to spread far out.
I don’t think his idea actually relies on intergalactic travel being difficult, just the way he stated it. If, say, intergalactic travel is easy, but not intercluster, then the idea could still apply, just at the galactic cluster level rather than at the galaxy level.
Either they would have arrived already (and taken over the galaxy, suppressing us in the process) - or they have yet to arrive. The chances of them initially showing up around about now are going to be pretty small.
They apparently haven’t arrived here already—unless they seeded us originally—else where are they? So, if they are out there, they have yet to arrive.
I don’t really see how all this makes much difference to the original argument.
The point of that argument was that seeing yourself alone in the galaxy with no aliens around is only to be expected—if the first intelligences rapidly expand and suppress the subsequent development of other intelligent life. So, being first is not so much of a miracle.