All known forms of life consist of carbon, nitrogen, oxygen and hydrogen. But even assuming that life on Earth and in our solar system is purely organic, does that mean that life is the same throughout the Universe? More than a generation of scientists and theoreticians argue on this topic. However, most of them believe that life can take on the most unexpected forms.
Little green men
Nowadays, finding someone who has never seen a single series of X-Files is difficult. Of course, we have no doubt that there are such. However, the cult series of the nineties strengthened the image of small green men in cultural mass consciousness and made them an integral part of every conversation about life outside the earth.
Meanwhile, scientists smile condescendingly when they mention little green men. Life on Earth, and therefore all life we know in the universe, has several basic characteristics. Most of the compounds we can find contain carbon. Scientists call these compounds organic.
This does not mean, however, that organic life is the only one in the universe. In fact, we can easily imagine the most diverse conditions in which we will find unusual life forms. If you've seen at least a few episodes of Rick and Morty, you know what our imagination is capable of. But let's still listen to the scientists.
Most of the chemical reactions that life is based on take place in the water. Water dissolves many different molecules. A good solvent is what you need for complex chemical processes that create life as such.
Physics of Extraterrestrial Life: Aliens should be like earthlings
No matter how strange it may seem, ammonia is common in the galaxy. It is also capable of dissolving organic compounds such as water, but unlike the latter it solves some metallic compounds. This opens up the possibility of using more interesting chemicals in living organisms.
Ammonia-based life can exist outside of the so-called Goldilocks Zone (the area where liquid water and optimal temperatures can exist on the planet). Astrobiologists often refer to the Saturn satellite Titan. The fact is that it can keep both oceans of water and oceans of ammonia under its surface.
So you can certainly try, for example, to imagine something like an ammonia octopus or a smart ammonia fish. We do not even know, you're probably better off than we are to accomplish this task. If possible, write about it in our telegram chat – we will discuss it.
Silicon based life
Silicon is an excellent ingredient for life anywhere in the universe. Carbon is able to bond with four atoms simultaneously, bind to oxygen, and form polymer chains that make it an ideal component for the complex chemistry of life.
At the same time, silicon as a livelihood is rather limited. Silicon forms stable bonds with a limited number of chemical elements. Silicon chemical processes themselves are unstable in an aqueous medium.
And yet, silicon-based chemistry can turn out to be life-friendly under certain conditions. Such life forms can exist in an environment rich in methane and even liquid nitrogen, and such places exist in the universe. Why not?
And what do you think aliens look like?