Understanding the nature of life is one of the most difficult and at the same time interesting mysteries for humanity. Over time, this mystery inevitably went beyond the question of whether life exists only on Earth, or whether it exists somewhere else in the universe. Is the emergence of life due to a random and fortunate coincidence, or is it just as natural for the universe as the universal laws of physics?
Scientists have been trying to answer these questions for a long time. One of them is Jeremy England, a biophysicist at the Massachusetts Institute of Technology. In 2013, he hypothesized that the laws of physics could trigger chemical reactions that allowed simple substances to organize in such a way that they eventually acquired "life" qualities.
In the results of the new work of England and his colleagues, it is noted that physics is able to naturally create processes of self-reproducible reactions, which is one of the first steps towards creating “living” from “non-living”. In other words, this means that life directly derives from the fundamental laws of nature, which virtually excludes the possibility of a hypothesis of accidental occurrence. But that would be too loud a statement.
Life had to come out of something. Biology has not always existed. It, too, emerged as a result of a chain of certain chemical processes that led to the fact that chemicals somehow organized into prebiotic compounds, created the “building blocks of life,” and then turned into microbes, which eventually evolved into an amazing collection of living things. existing on our planet today.
The theory of abiogenesis considers the emergence of life as the emergence of living nature from inanimate and, in England's opinion, thermodynamics can be the basis and key through which inanimate chemical compounds could turn into living biological ones. However, as the scientist himself notes, the latest research does not aim at creating a connection between the "vital properties" of physical systems and biological processes.
"I would not say that I have done work that could answer the question of the very nature of life as such," England shared in an interview with Live Science.
"What interested me was the very proof of the principle - what are the physical requirements for the manifestation of living behavior in inanimate compounds."
Promotional video:
Self-organization in physical systems
When energy is applied to a system, the laws of physics dictate how that energy will dissipate. If this system is affected by an external heat source, then the energy begins to dissipate until thermal equilibrium is organized around this system. Place a hot cup of coffee on the table and after a while the place where the cup stood will become warm. However, some physical systems can be non-equilibrium, therefore, through "self-organization" they try to use the energy of an external source in the most efficient way, as a result of which quite interesting, as England points out, self-sustained chemical reactions that prevent the achievement of thermodynamic equilibrium are triggered. It is as if a cup of coffee spontaneously triggered a chemical reaction causing only a tiny area of coffee in the center of the cup to be kept hot,preventing its cooling and transition to the state of thermodynamic equilibrium with the table. The scientist calls such a situation "adaptation to dissipation", and this mechanism is precisely what, according to England, endows inanimate physical systems with living properties.
The key behavior of life is the possibility of self-reproduction or (from a biological point of view) reproduction. This is the basis for any life: it is read as the simplest, then it is reproduced, it becomes more and more complex, then it is reproduced again and this process is repeated again and again. And it just so happens that self-replication is also a very effective way of dissipating heat and increasing entropy within this system.
In a study published July 18 in the journal Proceedings of the National Academy of Sciences, England and co-author Jordan Horowitz describe the test of their hypothesis. They conducted several computer simulations of a closed system (a system that does not exchange heat or matter with its environment) containing a "soup" of 25 chemicals. Despite the fact that their system was very simple, it is such a "soup" that most likely could once cover the surface of the ancient and lifeless Earth. So it turned out that if these chemicals are found together and they are exposed to heat from an external source (for example, a hydrothermal well), then these substances will need to somehow dissipate this heat according to the second law of thermodynamics, which saysthat the heat should dissipate and the entropy of the system at this moment will inevitably increase.
By creating certain initial conditions, the scientist found that these chemicals can optimize the impact on the energy system through self-organization and subsequent active reactions for self-replication. These chemicals naturally self-adjusted to the changed conditions. The reactions they created also produced heat, which corresponds to the second law of thermodynamics. Entropy in the system will always increase and chemicals will also continue to self-organize and demonstrate life behavior in the form of self-reproduction.
“In fact, the system first tries many small-scale solutions, and when one of them begins to show a positive result, then organizing the entire system and adjusting to this solution does not take much time,” England shared in an interview with Live Science.
A simple biology model goes like this: molecular energy is burned in cells, which are naturally out of balance and govern the metabolic processes that support life. But as England points out, there is a big difference between the discovered life properties and behavior in the virtual chemical soup and life itself.
Sarah Imari Walker, a theoretical physicist and astrobiologist at the University of Arizona, who was not involved in the research discussed today, agrees.
“There are two paths that need to be taken to try to combine biology and physics. One is to understand how life qualities can be obtained from simple physical systems. The second is to understand how physics can create life. Both of these conditions need to be addressed in order to really understand which properties are truly unique to life as such and which properties and characteristics are characteristic of things that you can mistake for living systems, for example, prebiotics, - Imari Walker commented Live Science.
The emergence of life outside the Earth
Before we start answering the big question of whether these simple physical systems could influence the emergence of life elsewhere in the universe, we first need to better understand where such systems might exist on Earth.
“If by life you mean something that is as impressive as, say, bacteria or any other form with polymerases (proteins that connect DNA and RNA) and DNA, then my work doesn’t tell you how easy or difficult it can be. to create something so complex, so I would not want to prematurely try to make assumptions about whether we will find something similar anywhere else in the universe, except for the Earth,”says England.
This study does not define how biology emerged from non-biological systems, it is only aimed at explaining some of the complex chemical processes through which the self-organization of chemicals occurs. The computer simulations carried out do not take into account other life properties, such as adaptation to the environment or reaction to external stimuli. In addition, this thermodynamic study of a closed system does not take into account the role of the transfer of accumulated information, notes Michael Lassing, a statistician physicist who also works in quantitative biology at the University of Cologne.
“This work certainly shows the amazing result of the interaction of nonequilibrium chemical networks, but we are still far from when physics can explain the nature of life, in which one of the key roles is assigned to the reproduction and transfer of information,” Lassing commented to Live Science.
The role of information and its transport in living systems is very important, Imari Walker agrees. In her opinion, the presence of natural self-organization present in a "soup" of chemicals does not necessarily mean that it is a living organization.
“I believe there are many intermediate stages that we need to go through in order to move from simple ordering to creating a fully functional information architecture like living cells, which requires something like memory or inheritance. We can certainly get order in physics and non-equilibrium systems, but this does not mean that in this way we get life,”says Imari Walker.
Experts generally believe that it would be premature to say that England's work is "conclusive proof" of the nature of life, as there are many other hypotheses trying to describe how life could have formed from almost nothing. But it is definitely a fresh look at how physical systems are able to self-organize in nature. Now that scientists have a basic understanding of how this thermodynamic system behaves, perhaps the next step will be to try to identify a sufficient number of non-equilibrium physical systems appearing on Earth, says England.