It makes sense to me why they’d look at stuff that indicates life on earth though, because we don’t yet know what causes life to form, all we have is Earth life. We know life can form on planets like Earth because, well, it has.
Even then, evolution is historically contingent. If you rewound and replayed the tape of life on earth and changed a few early conditions, you’d end up with a very different story. Evolutionary biology teaches us that life on other planets should be different from us more than similar. This also applies at the biochemical level.
It’s understandable that people take your logic and run with it, but it rapidly clashes with evolution. In addition, we don’t actually know what conditions are necessary for abiogenesis (probably not just one kind). Even on our own planet! We know there wasn’t much atmospheric oxygen at the time. And possibly not that much water. Yet exobiologists look for oceanic planets with atmospheric oxygen because that’s what we have. Sure, oxygen is a good electron receptor and can be produced from water (in our case, chlorophyllic photosynthesis), but there is mo reason to think photosynthesis would evolve the same way independently. Exactly the opposite, actually. It should be different. No reason to think there would even be proteins. The chemistry would be very different. And it took over a billion years for chlorophyllic photosynthesis to evolve on earth!
It makes sense to me why they’d look at stuff that indicates life on earth though, because we don’t yet know what causes life to form, all we have is Earth life. We know life can form on planets like Earth because, well, it has.
Even then, evolution is historically contingent. If you rewound and replayed the tape of life on earth and changed a few early conditions, you’d end up with a very different story. Evolutionary biology teaches us that life on other planets should be different from us more than similar. This also applies at the biochemical level.
It’s understandable that people take your logic and run with it, but it rapidly clashes with evolution. In addition, we don’t actually know what conditions are necessary for abiogenesis (probably not just one kind). Even on our own planet! We know there wasn’t much atmospheric oxygen at the time. And possibly not that much water. Yet exobiologists look for oceanic planets with atmospheric oxygen because that’s what we have. Sure, oxygen is a good electron receptor and can be produced from water (in our case, chlorophyllic photosynthesis), but there is mo reason to think photosynthesis would evolve the same way independently. Exactly the opposite, actually. It should be different. No reason to think there would even be proteins. The chemistry would be very different. And it took over a billion years for chlorophyllic photosynthesis to evolve on earth!