A forum specifically for the discussion of evolution. All views are welcome by me.
Would ET be an oxygen breather?
I would say yes. That does not mean he would not use an environmental suit. Another concern would be contamination, either way. Him contaminating us or us contaminating him.
Would ET look human?
Again I say yes. The laws and flaws of evolution would likely be the same on any other planet capable of creating life. ET looking like an insect but building a space ship just is not likely.
You are sure being human-centric today, aren't you? If you have a low energy or temperature dependent metabolism, you need not apply to the school of intelligence? Much speculation on alternative metabolisms from Cyanide and Silicon to Arsenates and more, most of which are slow as the main energy sources are seemingly complex and slow in reaction compared to oxygen reduction.
Thank you. I had not found that. Something to consider.
(edited to add ...)
I can only find stuff on microscopic life forms that are non-oxygen. Silicon I can see as a substitute for carbon, but nothing real yet. Would it still breath oxygen?
Does it have to have carbon to be sentient?
Even the theoreticians and speculative writers seem to lean toward slower metabolism for non-oxygen systems. Oxygen seems to be one of the very dangerous and highly reactive materials in the universe so any systems would have to be high conversion engines of heat.