The question of whether aliens exist or where they are has always been around. The facts are that there are billions of planets out in the universe with the potential to support life. So perhaps one of the reasons why we have not seen any aliens yet is because they are not what we think they are. In other words, they might be completely different from us and follow other biological rules. For example, their life could be silicon-based and thrive in other environments. These include acidic environments, extreme temperatures, lack of substances like oxygen.
Life on Earth is carbon-based. This element is abundant in the universe and a great primary building block. The reason for this is because it has 4 valence electrons and can readily bond with many elements like oxygen. If you look at the periodic table, below carbon, you can see silicon. This element can also form 4 covalent bonds and has similar chemical properties to carbon. On top of that, it can also be considered abundant in the universe. Perhaps on other planets it is silicon, and not carbon, that forms the building blocks of life.
For the purposes of discussion, we can look at Titan for the possibility of silicon-based life. Titan is one of the many moons Saturn has. It could be considered to have too harsh an environment to sustain human life. Their atmosphere is 94% nitrogen and 6% methane meaning that there is no oxygen and the water it has is frozen as they receive extremely little sunlight. However, silicon-based life may only need methane as the agent for energy sources and not require oxygen. In fact, due to the lack of oxygen, silicon dioxide, a solid is not capable of forming. Thus, giving organic silicon life a pathway to form. Titan’s surface is very cold, so the silicon-based life would be found near the core of the planet where it is hot. Metabolic processes, other chemical interactions would be entirely different from ours.
On another note, these are all hypothesis of the possibility of another life form. There are many barriers imposed by our understanding of science. Also, there is still many grey areas that we cannot explain- would silicon-based life have their genetic code for example? More research on planetary science and astrobiology need to be done to shed more light on the topic of aliens, but what a fascinating topic it is.
Laura L, Year 12