CoolP wrote on Aug 3^rd, 2012 at 4:31pm:

701151 wrote on Aug 3rd, 2012 at 3:58pm: Plus, even if there is life outside of our solar system, the question is: Will it be intelligent like us? I hope not since I'd actually like to receive an answer on how to e.g. stop wars about fictional resources (money) or the ones needed for running our 'modern' machines. But I'm afraid the answer could be 'Dear humans, your problem on the wars will, within a short time, solve itself. So long and thanks for all the fish!'  :D :-/ More on the topic. I wonder how you guys define the word life. As said, I'm noticing religious influences in some answers and phrases. Surely being poetic at times. On the scientific view, I personally don't know if the focus on 'needs water, needs the same conditions as on Earth' helps when it comes to all (imaginable) forms. We can surely look for water and then hope for some kind of life form, even former ones, being somehow similar to what we know. This makes sense because you not only have to find it, but you also should be able to detect it. But if you think away from the carbon based life forms, the possibilities are unimaginable big and even the value of intelligence is something being hard to measure. You'll find very intelligent patterns in bacteria, a virus or parasites, not all of them being understood and you certainly wouldn't relate the word intelligence to a single occurrence of those forms. Well, to say it with some greater words. You gotta know what you are looking for in order to find it. Focus on the wrong thing and you may pass by new forms of life without even noticing. Hence the question from above, what is life? As a help, you could look into what projects like SETI define as their 'patterns' since just recording all possible signals ends up with a truckload (or two  ;D) of data and little to no use.

Problem is that carbon happens to be the single most perfect element for creating life forms. Why? Because it has a low mass, and it has four valence electrons, which allow it to be both stable, abundant, and allow for the bonding of more carbons, and as a result, everything else.

Lets look at elements, and atoms (one in the same). An atom can have at most, 8 electrons in its valence ring (the farthest out from the nucleus), with the exception of hydrogen and helium, who only have two (since their valence ring is the first ring, and all first rings have only two). Now an element with one electron in the valence ring is incredibly unstable, because it seeks 7 more to complete the out ring, therefore, it likes bonding with group 17 elements, to form a stable compund, such as NaCl (salt). Now natrually occuring elements in group 1 (except helium) are incredibly unstable, and are explosive, especially in water. That is why they are contained in oil while in their natural state. Although these group 1 elements, called Alkali metals, are metals, they hardly are compared to iron and gold. Group 2 (alkali earth metals) are relatively reactive, at standard temperature, to other metals, and flammible (magnesium). Now lets skip ahead, since all the metals aren't a source for compounds in organisms. Boron, group 13, is a transition metal, and therefore also not suitable for life-compounds. Therefore, our very first non-metal is carbon. His four valence rings (at total of 6 electrons) make him very stable, and allow him to bond to many things, be it hydrogen, iron, more carbon, etc. A carbon atom could bond with for more carbon atoms, and each carbon after that could bond to one, and all the open places in those rings could fill up with hydrogen. Because of this, the possibilites of carbon are endless, because it can bond with more like it, and with other non-metals, and gases like H, or O, or N to make very complex compounds, which can thus form proteins, carbohydrates, nucleic acids, and the other molecules responsible for life. Plus, carbon can have double bonds, peptide bonds, and other types of complex bonds to make rigid structures, which help in teh construction of things such as a cell wall (plants). the only other element.

All other elements in group 14 (the carbon group) are either transition metals, or metals. These are unsuitable for life compounds. It is theorized that silicon could be a base for life, other than carbon, because of its lower weight, less metallic properties, and similarities to carbon (i.e. four valence electrons). However silicon, because it is a transition metal, is unable to form chemical bonds with other atoms, therefore making it unable to be a useful base for metabolic processes, which require chemicals (which exist throughout the universe, since the laws of our universe are essentially universal, pun intended). Because of silicons increased mass, it forms compounds that are bulkier and "monotonous compared with the combinatorial universe of organic macromolecules". Silicon's greater mass and atomic radius makes it very difficult for it to form a double bond with another element.

Carbon is the perfect, and in the eyes of most scientists, the only base for life.