When searching for signs of extraterrestrial life, we have for the large part focused on carbon-based lifeforms. It makes sense that we would do so, as the only lifeforms we have found (here on Earth) are carbon-based.
It has been suggested that silicone could also provide a base for life, though nothing matches carbon's solubility in water or ability to form stable bonds with other elements. But what about even more exotic forms of life?
According to one paper (and a whole bunch of science fiction) life could emerge within stars. While highly speculative (involving strings of string theory and magnetic monopoles) and by no means suggesting life does emerge in stars, it's an interesting way of thinking about life and how broad it could be.
"If one accepts that life is merely self-replication with mutations that leads to the increasing complexity through natural selection, any system capable of such processes can be viewed as a form of life," the team writes in their paper.
"More concretely, life needs at the minimum of these three hypotheses:
1. The ability to encode information.
2. The ability of information carriers to self-replicate faster than they disintegrate.
3. The presence of free energy: at the minimum ΔF=TΔS, needed to constantly create order out of the disorder by decreasing entropy S through self-replication, where T is the temperature of the system."
Given this definition of life, the team suggests that it could emerge within main-sequence stars like the Sun.
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