rich1.0LeoWandersleb (npub1gm…78rf6)https://njump.me/npub1gm7tuvr9atc6u7q3gevjfeyfyvmrlul4y67k7u7hcxztz67ceexs078rf6njumphttps://njump.meIn an interview, Elon Musk recently said that Earth has just the right gravity at which space travel [with chemical rockets] is theoretically possible. A bit less gravity and it would be easy. A bit more and it would be impossible. I'm not sure what the limit would be but the fact that we have enough in the tank to do a propelled landing tells me there is still some margin. But not much, as much of the breaking before landing is done by air friction. So while a bit bigger planet would not be able to land as smoothly, a much bigger planet basically needs nuclear propulsion to get off the ground. So what are the actual limits here? Earth invented life and went through snowball times and global extinction events. Bigger planets' intelligent life cannot get off their surface - or might not have a solid surface at all that's not covered by liquid hydrogen. Could intelligent life develop on a gas giant? If so, what would be the hurdles to even communicate out? How would one go about sending a radio signal from Jupiter? Would life on Jupiter even come up with radio technology given it's probably useless on their planet? Or can more complex molecules not develop at all on gas giants? In the other extreme, smaller planets, getting to space is "easy" but getting to life or intelligent life probably not. With less of an atmosphere, comets are more frequent to hit the surface. It needs less rock for "global" events. I don't understand enough about the origins of life to rule out non-carbon based chemistry but I would find it hard to believe life to spring into existence on a planet that has no liquid for chemistry to happen in.