Opportunity for life in the early universe
I just learned from the internet, that generation one, two and three stars in astrophysical terminology run under population III, II, and I, respectively. This is another example for the difficulties pondering easy understanding between experts and lay people as I am as a biochemist and brain researcher. In the following, I will keep to the first naming style that better fits with our spontaneous intuition.
As I also learned, no one has ever seen a first generation star. Allegedly the James-Webb telescope during its recent measurement campains might have detected some faint spots containing a few of them. Their 'collective spectral glow' (© google KI) is 'virtually devoid of metal spectral lines' (© google KI). Here comes another astrophysical peculiarity into play: For astrophysicists, all elements heavier than lithium are 'metals' (bewildering the chemist in me: NOT including lithium).
It is still not clear how precise these most recent measurements will be to estimate the composition of putative flocks of first generation stars. On theoretical grounds, we would expect ¾ hydrogen, ¼ helium, and traces of lithium. In active stars, light elements as H and He are gravitationally pressed together, stripped off their electrons, and their nuclei are fused to heavier elements, setting free fusion energy, mostly as high energy electromagnetic radiation.
Second generation stars arose from the debris of exploded first generation ones ('supernovae'). I just learned - again from the internet - that typically this 'recycled' fuel contains 73-75% hydrogen and 24-25% helium. To make things worse, even third generation stars (like our sun) contain 71-74% hydrogen and 24-27% helium. But we see at least a slight trend: The hyrogen content slightly slips below the ¾ at the start, while the helium seems to be on the rise (it is used as fuel itself, but also results from the burning of H).
What really matters for the distinction of star generations are the ashes: While first generation stars do not contain any, it can be detected in the light from second generation ones as absorption lines at frequencies typical for each element. The James Webb telescope is actually in the process of detecting light from a few faint spots without absorption lines, and from many more with lines indicating the presence of 'metals' as carbon, nitrogen, and oxygen (not to mention that neither of these IS a metal).
These may be first signals ever from first generation stars, and many more from second generation ones. The latter are no complete novelty, since in some regions even of our own galaxy (dominated by third generation stars) some of these (actually rare) beasts have survived to these days. They are poor in heavy metals as silicon or iron, but contain nitrogen, oxygen, and abundant carbon. Astrophysicists refer to them as CEMPs (for carbon-enhanced metal-poor). Model calculations suggest that they may form proto-planetary discs dominated by carbon compounds.
It is assumed that 'roughly at an age of 200 to 500 million years' (© google KI) the universe was dominated by carbon-rich solar-systems (up to 100%).  Although they missed sufficient heavier 'metals' to form rocky planets as we know them (as e.g. our earth), carbon may have jumped in to establish solid crusts of a mineral character. In that period, the 'temperature' of the cosmic background radiation dropped from roughly 60 to 30 Kelvin (reaching 2.73 °K today). Already the first figure is slightly below the melting point of molecular nitrogen (N2, 63.2 °K).
Could there be a chance for the emergence of first self-propagating and energy-consuming complex entities in this very early period? Provided that 'pseudo-rocky' planets really form in a carbon-dominated rotating dust-disc (model calculations point to this possibility), why not? If the combined energy influx from central star and cosmic background allow for a liquid arena, either hydrophilic as on the early earth, or hydrophobic as actually on Titan, the biggest moon of Saturn, the most important components would be present.
Organic heterocycles with C, N, O, S and eventually even B (unlikely) might form spontaneously. Also magnesium, able to coordinate N-containing heterocycles, was prominantly present in 2nd generation stars. By pure chance, during millions of years, chains of such rings may have facilitated the emergence of similar chains. Eventually solid carbon surfaces would have lent a 'catalytic hand'. Maybe such carbon-rich planets were the cradle of all further biological developments, also in other 'worlds'. Propagation of effective atomic aggregations to neighboring planets would have been easier than later on, due to shorter distances and more frequent catastrophic encounters in the very early universe.
The scientific community impatiently looks forward to the first identification of extraterrestrial life forms. They may exist in our own solar system. If they were truly endemic to their location (e.g. on Mars or the moon Europa), they might exhibit distant similarity to earthly life forms, not so much due to cross-contamination within our solar system, but due to common roots, maybe even reaching down to the first life-tolerant very early period of the universe.
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A. Loeb (2014) The habitable epoch of the early Universe. Int J Astrobiol 13, 337-9
EI Vorobyov, DJ Whalen, MA Latif, A Skliarevskii, C Jessop, R Matsukoba, T Hosokawa, D Nandal (2026) Planet formation at cosmic dawn: Planetesimals in H2O-rich disks around low-mass stars