First of all, I’d like to state that I know the entire premise of this question is hypothetical and the life probably quite unlikely to form in the first place at best. Despite that, I’d like answers to critique if this sketch makes sense and any potential problems. Just assume that the miniscule possibility of life forming in the core of a rocky planet is handwaved, so it just happened in this scenario. I also understand that communication with the outside world would be almost impossible, but that simply isn’t important to my story (the other aliens can find them simply enough).

The rocky planet’s core, is basically the same as earth’s. It is majority composed of iron, nickel, and noble metals like gold or cobalt. The planet has an inner and outer core, roughly comprising the same percentage of the planet that earth’s cores do (I only say this because the planet is slightly larger than earth).

The Proposed Sketch

The proposed life forms could use liquid metal as a solvent, and use the heat of the core to produce energy possibly by turning heat into electrical signals using metals that conduct electricity (that no doubt would be common in the core), like some sort of autotroph would do on earth.

I also found this question asking about germanium life, and it suggests that germanium, being a siderophile, might work well as the base of all life in a planetary core like how carbon is on earth. The life could presumably use germanium and metal polymers (which would be more like extremely temperature and pressure-durable metal alloys) as a cell membrane to protect its insides and maintain a fixed temperature and pressure inside the organism.

These organisms would also probably have no need to evolve movement. Some would be sessile on the surface of the inner core while others would move using the convection currents of the outer core.

To conclude, I’d like you to assess if this sketch makes sense and what I should change if anything to make this more plausible.

  • 2
    $\begingroup$ "use the heat of the core to produce energy possibly by turning heat into electrical signals using metals that conduct electricity" Hmm. The trouble with energy extraction is you need a couple of volumes each with different energy levels, then to extract energy from the flow of energy between them. That doesn't seem to be available in the core as everywhere is equally hot. $\endgroup$ Commented Apr 5 at 22:29
  • $\begingroup$ I’m not really an expert, but I don’t think everything is really equally hot. There probably would be some temperature fluctuations/variations, but the question is if they are significant enough to be used as an energy source. $\endgroup$
    – Neil Iyer
    Commented Apr 5 at 22:31
  • $\begingroup$ There's also the difficulty of - there isn't a question here, rather a what do you think of my idea. We work best with a (single focused) problem to solve. Could you state one. $\endgroup$ Commented Apr 5 at 22:31
  • $\begingroup$ Maybe “is this idea plausible enough to be sort-of realistic?”, but I don’t know if that is focused enough, $\endgroup$
    – Neil Iyer
    Commented Apr 5 at 22:33
  • $\begingroup$ Then the internal-consistency tag should be used instead of the science-based one. $\endgroup$ Commented Apr 5 at 22:36

1 Answer 1


I have doubts on some points:

The proposed life forms could use liquid metal as a solvent

whatever is down there in the core, due to the high pressures the core is either solid or an extremely viscous liquid. Not something a la water.

use the heat of the core to produce energy possibly by turning heat into electrical signals

you are confusing life with electrical motors. Electricity is only a carrier of energy, not a source of energy. Moreover, what would be the cold end of the thermodynamic chain in the core? Here we have sun and environment or hot thermal source and environment as hot and cold ends.

  • $\begingroup$ while i agree with your assessments mostly thermal energy is still a really good energy source for living beings. Such life forms already do exist on the bottom of our oceans. $\endgroup$ Commented Apr 6 at 6:52
  • $\begingroup$ @Fallenspacerock, but those life forms have a high temperature source (the thermal vent) and a low temperature well (the surrounding water) to obey thermodynamic laws. Those two are not present in the core. $\endgroup$
    – L.Dutch
    Commented Apr 6 at 7:17
  • $\begingroup$ i don't know to much about Thermodynamics though wouldn't a temperature difference between organisms and environment suffice? Also if we move them into higher parts of the earth crust would this solve the problem? $\endgroup$ Commented Apr 6 at 7:23
  • $\begingroup$ Actually, people now think that the viscosity of metal in the outer core is similar to that of water on the crust. Do a simple google search like I did, and you should see results that confirm that, so the only real issue is using electricity for energy, but maybe the temperature difference could be internal vs the environment like @Fallenspacerock proposed. $\endgroup$
    – Neil Iyer
    Commented Apr 7 at 0:32
  • $\begingroup$ @L.Dutch by that metric, humans should not exist, since no temperature gradient we can exploit exists on the surface. Simplistic assumptions like that don't account for waterbags supported on mobile calcium structures, using proton-motive force to generate ATP in mitochondria... Who knows what quirks of physics could subcrustal beings could use? $\endgroup$ Commented Apr 8 at 14:12

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