>You can play games with early steam engines burning lignite or peat and it won't matter terribly much at the time or in the long run, but it seems there's only

>You can play games with early steam engines burning lignite or peat and it won't matter terribly much at the time or in the long run, but it seems there's only one way, using metal catalysts, to "invent" your first organic chemistry hydrogenation process, for example. You can make steel in a low tech medieval blacksmiths shop, but transistors have tighter constraints. But, what if these aliens are say chromium or silicone based life from a planet with a chlorine or fluorine based atmosphere. I imagine the dependency chain would look totally different for a species like that. The chemical reactions we rely on for many of our sciences on earth would not work at all in an evironment like that. Combustion based technology would likely not be at the forefront of such a species. I think a lot of anthropomorphization goes on when it comes to aliens. Just on earth we've got billions of different forms of life, all of which is specifically adapted for earth's conditions. Change any of those conditions even a little and life on earth would look totally different, as it has for most of earth's history. I see no reason why any kind of aliens, interstellar travellers or not, would need to resemble us or any of the technological dependency chains we've created. It assumes everywhere else works mostly the same as it has here for the short window as humans have existed and that the chains of technological dependencies humans have created based on the resources available on earth are a universal technological progression all intelligent life must goes through, which just seems arrogant and all knowing to me.