Scientists Explain How to Find Them

Alien life may not be like life on Earth, so trying to find evidence of their existence requires some creativity.

Scientists know of only one example of life in the universe, and it exists on Earth. But what if life can form in other ways? How do you search for aliens when you don’t know what they might look like?

It’s thought that microbes are likely the most common form of extraterrestrial life, since they can arise more easily than larger organisms.

But it’s possible that an advanced alien civilization exists somewhere in space. In either case, these alien species may not resemble anything scientists know about life, Live Science reports.

Since the discovery of the first planet outside our solar system in 1995, scientists have discovered more than 5,000 planets orbiting other stars. Many of these planets are small and rocky, like Earth, and reside in the habitable zone of their stars.

This is the region of space around a star where conditions allow liquid water to exist on the planet and thus support life as we know it. There is a good chance that many planets that are not yet known to us have the right conditions for life to emerge.

But scientists disagree on how exactly to define “life” when it comes to living organisms. NASA defines life as “a self-sustaining chemical reaction capable of Darwinian evolution.” That is, organisms with complex chemical systems that evolve to adapt to their environment.

Life on Earth has evolved over billions of years, from single-celled organisms to large animals and other species, including humans.

Using spectroscopy, a technique for detecting chemical traces of life, scientists are looking for signatures of atmospheric oxygen on other planets that were created by microbes, or signatures of chlorophyll that indicate plant life.

But is Darwinian evolution universal? What chemical reactions could lead to life beyond Earth?

The universal law of evolution in the Universe

All life on Earth evolved from a microbial common ancestor about 4 billion years ago. The same chemical processes are observed in all living organisms on Earth, and these processes may be universal. But they may also be radically different when it comes to other planets.

In a recent study , an international team of scientists took a different view of evolution. They set out to study what processes, biological or not, created order in the universe, in order to figure out how to study the emergence of life very different from life on Earth.

Scientists believe that complex systems of chemicals or minerals, when placed in an environment that allows some configurations to survive better than others, evolve to store more information. Over time, the system will become more diverse and complex, acquiring the functions needed to survive through a kind of natural selection.

Scientists have suggested that there may be a law that describes the evolution of a wide variety of physical systems. Biological evolution by natural selection may be just one example of this law.

In biology, information refers to the instructions stored in the sequence of nucleotides in the DNA molecule, which together make up an organism’s genome and also shape the way the organism looks and functions.

From an information-theoretic perspective, natural selection would lead to the genome becoming more complex because it would store more information about the environment. But it would be wrong to conclude that animals are more complex than microbes.

Biological information increases with genome size, but the density of evolutionary information decreases. Evolutionary information density is the proportion of functional genes in the genome, or the proportion of the total genetic material that expresses fitness to the environment.

Organisms that people consider primitive, such as bacteria, have genomes with a high information density and therefore appear better designed than the genomes of plants or animals.

What could aliens be like?

Scientists have studied alternatives to Earth’s biochemistry. All known living organisms, from bacteria to humans, contain water, and it is the solvent necessary for life on Earth.

But life could potentially arise from other solvents. Scientists have found that such solvents could include sulfuric acid, ammonia, liquid carbon dioxide, and even liquid sulfur.

Alien life may also not be based on carbon, which is the basis of all the basic molecules of life on Earth. Advanced life forms on other planets may be so strange that it is difficult to even imagine. So scientists must be creative to detect life.

The authors of the study believe that it is necessary to search not only for water and oxygen on other planets, but also for other substances that may indicate life.

As for developed extraterrestrial civilizations, it is necessary to search for traces of artificial pollutants of the atmosphere or signs of possible technological activity.

Alien life may be very different from life on Earth, but so far scientists have found no evidence that it exists anywhere else in the universe.