Silicon-based life?

Question

My question may not be suitable here, because it's more of astrobiology. Life as we know it is carbon based. 1. Is life based on silicon possible?2. What would the conditions for habitability for silicon based life be?3. Can both carbon- and silicon-based life co-exist?4. Is any silicon-based life found on Earth? Can any be grown in the laboratory?

Answer 1

This is a very interesting question and a fun one to ponder. I will try to answer your questions as best I can given what is known about this and to the extent of my knowledge.

1. Is life based on silicon possible? That's the million dollar question, and one scientists have been pondering for a long time. The easy answer is we don't know. We haven't seen it yet, and when we do we will know it's possible.
2. As you know the exciting thing about silicon is that it can form an expanded octet, meaning it can form more than the 4 bonds that carbon can. This means that silicon-based life may have infinitely more diversity on the molecular level. Silicon bonds are also more heat resistant, so environmental conditions such as heat or other stress may favor silicon based life.
3. It is unlikely that carbon and silicon based lifeforms would coexist, but not impossible. It is strongly believe that life an earth stems from a single source. That does not mean that other life did not arise, only that one branch dominated and survived. If life arises similarly elsewhere, even if both evolved, one would probably grow to dominate.
4. There are no silicon based lifeforms on earth, but many shelled animals incorporate silica in their shells. At some point it may be possible to create silicon life in a lab, but at the current state we haven't even mastered creating carbon based life, so it will be a long time if at all before we can begin examining silicon based life.

I hope that helped, this is a really fun topic!