# “4K-metal chelated” A chemical term used in Sagan's Cosmos

Maybe this question doesn't belong here. It's about a hypothetical xenobiology imagined by a prominent scientist in a seminal work of popular science. So I dunno. Tell me to go away and I'll see if some other SE can help me.

I'll never forget the races Sagan made up in his book Cosmos. He gave descriptions of them in the form of excerpts from his imagined Encyclopedia Galactica, a compendium of all the races in the galaxy.

There was one term that never made sense to me: "4K-metal chelated". What does the "4K" part mean? Here is the context:

Civilization Type: 2.3 R
Society Code: 1H1, "We Who Became One".
Interstellar civilization, no planetary communities,
utilizes 1504 supergiants, OV, BV, AV stars and
pulsars.
Civilization Age: 6.09 * 10^15 s.
First local initiated contact: 6.09 * 10^15 s ago.
Receipt first galactic nested code: 6.09 * 10^15 s ago.
Source civilization, neutrino channel.
Local Group polylogue.
Biology: C, H, O, Be, Fe, Ge, He. 4K metal-chelated
organic semiconductors, types various. Cryogenic
superconducting electrovores with neutron crystal
dense packing and modular starminers; polytaxic.


(By the way, if anyone knows what "Local Group polylogue" is supposed to mean, I care about that too.)

• If you can't find an answer here, maybe the people from worldbuilding.stackexchange.com will be able to help – Lucademicus Oct 9 '16 at 18:01
• Never actually heard of it, sorry. – orthocresol Oct 9 '16 at 18:05
• If you didn't get it already there's some of fictional terminology. Fortunately you don't ask about 2.3 R type ;) Still it's quite possible that "4K" was made up. – Mithoron Oct 9 '16 at 19:44
• Sounds suspiciously like 4 kelvin, i.e. the boiling point of liquid helium under atmospheric pressure, since it mentions cryogenic and superconducting in the next sentence. – Nicolau Saker Neto Oct 9 '16 at 20:50
• @NicolauSakerNeto -- I think that's our answer. Helium is in that list of elements. – MackTuesday Oct 10 '16 at 2:15