Search for extraterrestrial life
At first glance, it may seem that the biological question of “What is life?” has been answered without any doubt or hesitation. The fundamental axiom claiming that all living things are made up of cells is considered a simple and sufficient answer to understand this topic. For most known living entities on Earth, this claim holds true. However, when it comes to viruses, the matter gets complicated. Although a virus exhibits typical characteristics of a living organism, it cannot behave as an independent unit with cytoplasm, enzymes, and its own replication mechanism.
On Earth, there are even stranger life forms than viruses: prions. A prion generally does not resemble any cellular structure. This ordinary and extremely small entity that is the causative agent of mad cow disease is, in fact, a protein (a polypeptide) that normally functions in the brain. When the disease-causing form of this protein emerges through some mechanism, other normal proteins begin to resemble each other in a chain reaction and convert into prions. That is, a prion thus reproduces itself, replicates.
When trying to expand the biological understanding of living organisms beyond Earth to astronomical scales, the thread generally slips out of the hands of biologists, falling into the hands of physicists and mathematicians.
The most important thing that a cell passes on to the next generation is information.
A universal definition of life must rest upon the understanding of information. The informational micro-containers we call cells on Earth pass on the experiences they have gathered while adapting to their environment and surviving to the next generation primarily through genetic material DNA (deoxyribonucleic acid) . However, just as not every monkey species will evolve into humans (statistically speaking, the probability of such is negligible), the likelihood of any primitive informational genetic material evolving (through chemical evolution) into highly complex DNA elsewhere in the solar system is also very low.
Situated on the mountain “Pic de Bure” (2550 m) in the French Alps, the 6-antenna interferometer - “Plateau de Bure Interferometer (PdBI)”
NASA is in search of life on Mars today, but in reality, it does not fully know what it is looking for.
Outside Earth, the criteria that should be applied to decide whether what we find in space is alive is not well understood by science. Because Mars is Earth's neighboring planet, any living organisms found there may resemble those found here. In fact, according to one theory/hypothesis, the origins of life on Earth might trace back to Mars. It is presumed that ancient bacteria could have arrived here from places like Mars, broken off from meteorites. However, the situation on Jupiter's moons could be entirely different. Furthermore, I do not even mention the living beings born on other stars, in other galaxies, outside the solar system.
So, currently, at its most fundamental level, what does our astronomical concept of life consist of?
It should be noted that living structure is generally contrary to the universe, or rather, contrary to the course of the universe.
According to one of the fundamental laws of thermodynamics in physics, the evolution of living cells operates as a force in the opposite direction in an ever-disintegrating universe, that is, a universe that is increasing in disorder (which must increase), or in other words, an increasing entropy. Evolution has developed from a primitive proton, ion distinction to a complexity of living organisms such as cells, tissues, organs, systems, organisms, humans, and even communities from those organisms, from communities to civilizations, consciousness, capable of writing these sentences about themselves. These contradict the general course of the universe, which is a decrease in complexity, as stated by the law of entropy.
According to the science of physics, life, in the overall landscape of the universe, amidst infinite vastness, is an extraordinary exception at an extremely microscale. I liken this to the waves hitting rocks at the shore; sometimes, a single droplet suddenly “splashes” 5 meters high.
Because that exception in space is extremely rare, the information (complexity) that arises by chance must not revert back every time to prevent being lost, but must be handed down step by step for development to the next generation. For this, a carrier is necessary. On Earth, that is DNA. In other places in space, this will likely be a system with a remarkably different structure or could be. When the field of astrobiology in biology discovers this strange new molecule, the volume of fundamental biology textbooks such as Campbell Biology will at least increase by 25%.
Author of the article: Araz Zeyniyev, molecular microbiologist, Habitat project leader