The search for extraterrestrial life combines several scientific disciplines to determine whether we are alone in the universe. Scientists chase atmospheres in exoplanet, explore potentially habitable worlds in our own solar system such as Mars and Europe and scan for artificial signals that could indicate intelligent civilizations. This process forces us to question our definition of life, since extraterrestrial organisms could use biochemistry that differs greatly from the carbon base of earth. Despite a final contact, the discoveries of potentially habitable worlds and extremophiles, which thrive in the toughest environments on earth, indicate that life can be common throughout the universe.
Image of Milnesium Tardergradum in the active state.
If life on other planets could be so different than that of the earth, it will be difficult to know what signs you have to look for. Akshit Goyal (Tata Institute of Fundamental Research) and Mikhail Tikhonov (Washington University) suggests in Nature Communications (Tata Institute of Fundamental Research) and concentration on ecosystems and not on certain life forms. By modeling how organisms compete for resources and interacting ecologically, it can be possible to identify universal biosignatures that do not depend on earth such as biology or specific metabolic processes.
An aspect that is recognized as a universal feature of life is the consumption of energy consumption and transformation. While earlier approaches suggested that life to be identified by chemical imbalances or energy flow patterns, they lacked specific criteria to distinguish biological from non-biological processes. In work, the researchers combine the energy perspective with a key observation: life forms are practically never isolated, but develop into competitive ecosystems with ecological interactions. With just a known exception on earth, the formation of ecosystems for life seems to be almost as fundamental as evolution itself.
Volcanoes such as the Augustinus volcano in Alaska can create chemical signatures that can be kept to life. (Credit: Alaska Vulcano Observatory)
Even if we look for those who can look for, find these universal signs of life with challenges. While energy consumption is common for life, the distinction between biologically from non-biological processes in today's technology remains difficult. This paper completes a new approach: search for spatial stratification of chemicals that are arranged by their energy content! This layer naturally results from two universal characteristics of life: self -streaming and competition between species.
Together, these characteristics create patterns in which energy -rich resources are exhausted faster and different organisms are separated. In contrast to conventional biosignatures that are bound to certain earth such as metabolisms, this pattern would be created regardless of the associated biochemistry from the ecosystem competition. While non-biological processes can create layered structures, they are usually not organized according to energy. However, the main limitation is practical implementation, since such patterns could be difficult to recognize with current technology, in particular through remote exploration. Unfortunately, traveling to distant alien worlds around other star systems are also outside of our ability and we have to rely on remote exploration techniques.
Source: Energy -oriented resource stratification as an agnostic signature of life
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