bystander wrote:Jim Leff wrote:...
I understand it's difficult to imagine non-carbon, non earth-like life. But it's in no way "VERY REASONABLE" to assume it will be carbon-based or otherwise similar to what we see on earth. There is absolutely no reason whatsoever for such an assumption. ...
Three of the four most abundant elements in the universe are hydrogen, oxygen, and carbon. Why is not "VERY REASONABLE" to assume life is based upon those elements? (The fourth is helium which is not reactive.)
Another essential element to life as we know it, nitrogen, is also among the top seven, joined by iron and neon (another non-reactive element). The other elements each contribute less than 0.1%.
rstevenson wrote:And it's not just the abundance of those few elements that make life based on them very reasonable. It's also the amount of energy required in their various reactions.
If life exists elsewhere, which is likely, it is only reasonable to expect it to require both water and cabon. This is because both are abundant, because water is such a good solvent, and because carbon chain molecules can have unlimited combinations of configurations, shapes, etc. No other element can match carbon in its versatility.
I agree with Jim Leff's comments here:
, but I wouldn't use the word "ghost".Jim Leff wrote:We don't know how aliveness happens. Once kindled, we certainly know a lot about what helps life thrive, and what makes it decline and extinguish. But animation itself is still a complete mystery. If I give you a pile of chemical materials and energy sources, you will not be able to animate it. Even if I give you a nearly optimized arrangement of those materials (i.e. a corpse), you still will only flounder. We know a lot about the machine, but nothing about the ghost.
It spite of Chris' assurances that life must arise fairly easily given the right set of conditions, this remains an unproven assumption. Even so called simple life is extremely complex.