So to start, let's assume that this hypothetical life form relied on something similar to LNG (liquefied natural gas) - mainly relying on ethane - as a solvent in the same way humans rely on water. Let's also assume that they breathe hydrogen, use acetylene as glucose, expel methane, and that they are carbon based like us.

Knowing that they do not use oxygen, what element makes for the optimal choice in acting as a hydrogen carrier at cryogenic temperatures, in the same way hemoglobin uses iron to act as an oxygen carrier?

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    $\begingroup$ acetylene as glucose - nice! $\endgroup$
    – Willk
    Feb 7, 2017 at 16:07
  • $\begingroup$ Chemical reactions don't occur at −182.8 °C, so your question is unanswerable. $\endgroup$
    – RonJohn
    May 15, 2017 at 5:50
  • $\begingroup$ Fine. Then what temperature range can intelligent, methane-based life function at? $\endgroup$
    – Wildcat
    May 16, 2017 at 8:41
  • $\begingroup$ @RonJohn Respectfully, that's bullcrap. Chemical reactions useful to our kind of life may proceed uselessly slowly at those temperatures without proper catalysis, but a wide variety of chemical reactions most assuredly still happen. $\endgroup$ Aug 16, 2017 at 4:47
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    $\begingroup$ Polymerization and tholin formation: en.wikipedia.org/wiki/… Formation & decomposition of FOOF, and oxidation (sometimes violent) of nearly anything else by FOOF: en.wikipedia.org/wiki/Dioxygen_difluoride Azatozome formation: thisscienceiscrazy.wordpress.com/2015/03/18/… $\endgroup$ Sep 23, 2017 at 17:02

1 Answer 1


I like the premise!

Your critters could use a metal hydride.


You would need to bake up some heme ring equivalent to carry the hydride metal and control its uptake / release of hydrogen.

Or how about oxygen! You could have a large ether in which the oxygen reversibly forms an alcohol, accepting and donating the hydrogen.

  • $\begingroup$ Chemical reactions would be really slow at that temperature (if they even happen at all). $\endgroup$
    – RonJohn
    Sep 22, 2017 at 16:14

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