The detection probability is rare enough that such a list would be truly pointless.Originally Posted by dgruss23
Agreed. However, this doesn't make a "rare Earth" it only makes a "rare civilization" argument. Earth has been around much longer and life has been on Earth since very early.Yes and no. Yes, our single data point indicates that intelligent life evolved. But no this doesn't translate to a galaxy full of civilizations because we've been here for the tiniest fraction of the Earth's history.
No, I'm saying the parameter space isn't well constrained. I'm not saying it's automatic.So you're saying stick any planet in a habitable zone and it will be habitable? Nothing else matters? If its in the zone ( 8) ) it will automatically be able to hold onto a suitable atmosphere and liquid water?
Then you shouldn't search for habitability because habitability implies biology as being limitted to terrestrial conditions.And as I've said, I don't think biologies are the only limiting factor.
The assumed biology is that a) life must be on the surface and b) it requires a liquid solvent. I might give you b) but I won't give you a).You need to have a planet that can hold a minimum atmosphere. A liquid boils when its vapor pressure reaches the atmospheric pressure exerted on it. So a planet has a large enough mass to be able to hold onto a thick enough atmosphere. Not a lot of biology in that if you're talking about surface ecosystems.
There's actually more to it than mass. For one, we have issues with composition. Heavier atmospheres can stick on smaller bodies.I can't say for sure what that mass is, but I'm sure eventually we'll be able to determine that.
The key here is you underlying assumption is that you are considering only Earth-like biologies. That's the same problem with doing a search for "habitable".Some of the other key RE arguments are not about biology either: Is the Moon important or not? Is the mass and placement of gas giants important or not?