Originally Posted by Lifeshield
Does the whole universe use the same laws for physics (bit impossible to make a statement like that when we cannot even venture outside of our own solar system) or is it a case of us using those laws of physics to understand the universe because we don't know better?
I honestly think it's more a case of the latter.
IF our entire universe didn't use the same fundamental physics, we would have seen so many exceptions by now, that our understanding would be back at square one.
Back on topic: The reason water is important as a precursor for life is the unique angle of the hydrogen atom's bond to oxygen, 109.5 degrees, which gives water it's polarity enabling it to be a weak solvent and not destroy any compounds dissolved in to it. See also expanding when transitioning to a solid.
The next most important element is phosphorus, which is essential because of its vast potential to form different compounds, essential to proteins, DNA, RNA and amino acids.(insert longer discussion about free electrons here. lol)
Arsenic based life was thought to be found on earth, http://www.nature.com/news/arsenic-life-bacterium-prefers-phosphorus-after-all-1.11520
, but was later proven false in that study.
While there is a list of other combinations, http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry
, most require a rather unique set of circumstances that preclude a truly complex life form or even existence at all.