Mediocrity and Life on Earth
I was amused by this article about mediocrity and life. Apparently, people who think that life is common in the universe tend to use the argument that a given example is more likely to be a common trait than a rare trait, which is mathematically reasonable but will sometimes be the wrong guess.
I do rather the opposite. I look at the fact that life has swarmed all over this planet, including some exceedingly hostile places (solid rock, boiling water, ice, etc.) and conclude based on this hard evidence that life is extremely good at gaining a toehold in harsh conditions. Plus the fact that it managed to survive flipping the whole atmosphere during the Great Farting Oxygen Event. So life is likely to be common, because there are lots of places in the universe. But most of it will resemble the kinds of life found in those harsh conditions: algae, lichens, brine shrimp, ice worms, tardigrades, etc. Not terribly exciting unless you are a xenobiologist or other nerd. A complex ecosystem supporting advanced life needs a more hospitable environment. Still, life is creative, and what it finds hospitable enough to build a biosphere will not always necessarily look like Earth. It is worth seeking Earthlike planets because we know this type can support a biosphere, but that doesn't mean it's the only option. Nature is much, much more creative than most humans with the exception of some of the best worldbuilders.
I do rather the opposite. I look at the fact that life has swarmed all over this planet, including some exceedingly hostile places (solid rock, boiling water, ice, etc.) and conclude based on this hard evidence that life is extremely good at gaining a toehold in harsh conditions. Plus the fact that it managed to survive flipping the whole atmosphere during the Great Farting Oxygen Event. So life is likely to be common, because there are lots of places in the universe. But most of it will resemble the kinds of life found in those harsh conditions: algae, lichens, brine shrimp, ice worms, tardigrades, etc. Not terribly exciting unless you are a xenobiologist or other nerd. A complex ecosystem supporting advanced life needs a more hospitable environment. Still, life is creative, and what it finds hospitable enough to build a biosphere will not always necessarily look like Earth. It is worth seeking Earthlike planets because we know this type can support a biosphere, but that doesn't mean it's the only option. Nature is much, much more creative than most humans with the exception of some of the best worldbuilders.