The main source of free energy that allowed life on Earth to develop was our sun. It bombards the planet’s surface with photons of high energy, which provide activation energy for reactions necessary for photosynthesis. Photosynthesis allows plants to grow, and their high-energy organic matter can be consumed by heterotrophs, which can then consume each other as well, etc.
QUESTION: Suppose we have a planet that starts off as a soup of inorganic compounds, as did primordial Earth, but that is quite far away from the nearest star. What might be some other sources/mechanisms by which energy could be harvested and life could form?
- Even if the nearest star is far away, some of its light will still hit the planet, and the occasional high-energy photon might strike the surface. So maybe we might still see photosynthesizing organisms (or something like them) spring up, but with much slower metabolisms and longer lifespans (since they have to wait a long time for less frequent high-energy photons).
- The core of the planet would still be quite hot, meaning that volcanoes and underwater vents could occasionally release hot (and therefore high-energy) bursts of liquid/gas into the environment. Perhaps this could be harnessed, somehow...?
- I think I remember reading that primordial Earth had a lot of electrical storms. Maybe some sort of mechanism could evolve by which organisms harvest electrical energy?
Can anyone provide any other ideas, or flesh out (or even refute) any of my preliminary ideas?