Antropic Principle and Extraterrestrial Life

I was once at a talk my Freeman Dyson. At the end he was asked if he thought there was other intelligent life. He said, though he wanted there to be, no. "Where are they?" was his reason. So you are in good company.However, it is not really "solid" evidence. It does mean that some of the underlying assumptions are possibly (even probably) wrong.Maybe it never becomes possible for desirable for anyone to attempt intersteller travel. Maybe intelligence is not a good survival tactic and if reached causes the extinction of the species. Maybe, maybe, maybe. Too many underlying unknows to say.

You're assuming that they would be enough like us to want the earth. It is possible they would consider it either too hot or too cold or too a lot of other things.The force of gravity here could be greater than they are comfortable with or too low.While life might have to be a lot like us (that is not methane breathing etc.) that doesn't mean they can't be pretty darn different. If we have unicellular life that dies of hypothermia if the water isn't at the boiling point around them then perhaps anything less than 50 or 60 degrees C is too low for these potential visitors.

I see so much power in the evolutionary process that I am willing to give a bit of credance to the idea that it could have been the extremophiles that were the base for the evolution of multicellular life and then SITAPHS.I think I'm also suggesting that there are enough "habitable" worlds that the SITAPHS can pick and choose and ignore those that aren't close enough.It may well be that getting to intersteller travel is still very difficult. It is not at all clear, for example, that we will (in the way we mean here). So if intelligent life is only moderately common (1,000's in a galaxy), spread over perhaps 100 very different types of biosheres and only 1 in ten get to intersteller travel we end up with perhaps a handful in the galaxy who might be interested in Earth and able to get here. If we are lucky enough that all of them can show some restraint and leave other intelligences alone then we are safe.(I'm completely discounting the possibility of successfull intergalactic travel)