We do not know how exactly it happened, but poor John Doe made a space-time trip along a three dimensional analog of a Möbius strip (a Klein bottle). He is now back on Earth, but he is now the mirror image of his former self: His heart beats on the right side, he is left-handed now, and even worse: All the molecules in his body (peptides, sugars, DNA and RNA) are mirrored, too.

Water is still drinkable and air is still breathable, but all the food on Earth is inedible or even poisonous to him.

Scientists quickly diagnose and confirm John's state, but how can he be fed?

I am asking about a plan to prepare food for him, not only noticing the fact that normal food is not available for him and he's in trouble. That I know already.

To be realistic, any programme to feed poor John Doe must be set up in reasonable time before he dies of starvation. You may use mirror bacteria extracted from John's skin or from John intestinal tract.

Doing the space-time trip again or going back the way he has gone is unfortunately not an option.

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    $\begingroup$ Possible duplicate of Flipped over through fourth dimension. When do I start to notice biological problems? $\endgroup$
    – dot_Sp0T
    Oct 13, 2018 at 18:21
  • $\begingroup$ @dot_Sp0T: Intersting question, but with a different focus. The answers give no hints on preparing food for the flipped-over man. $\endgroup$ Oct 13, 2018 at 18:24
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    $\begingroup$ Many chemical reactions which produce chiral molecules produce equal amounts of the enantiomeres. This is actually a problem when synthesizing chiral substances. So, no sweat, just synthesize the required sugars and amino acids and feed him the racemic mix -- he will assimilate what he needs and pass the molecules with wrong chirality. Or feed the mix to ordinary bacteria who will eat the ordinary food and leave what John needs untouched. $\endgroup$
    – AlexP
    Oct 13, 2018 at 18:28
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    $\begingroup$ @AlexP That sounds like an answer, not a comment. :) $\endgroup$
    – IMSoP
    Oct 13, 2018 at 18:33
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    $\begingroup$ You may appreciate wikivisually.com/wiki/Technical_Error (Asimov was a chemistry PhD), and en.wikipedia.org/wiki/Chemical_chirality_in_popular_fiction in general. $\endgroup$
    – Law29
    Oct 14, 2018 at 12:57

2 Answers 2

  • If all that's happened to John is that the sugars and amino acids in his body flipped to the other chirality, then we can feed him without too much trouble. (But it will be expensive; I'm hoping he's rich or has a gold-plated insurance.)

    Without a chiral influence (for example a chiral catalyst, solvent or starting material), a chemical reaction that makes a chiral product will always yield a racemate. That can make the synthesis of a racemate cheaper and easier than making the pure enantiomer, because it does not require special conditions. (Wikipedia, on Racemic mixture)

    In plain words, many chemical reactions which produce chiral molecules will produce equal amounts of the enantiomeres. This is actually a problem when trying to synthesize such substances, because biology only wants one of the enantiomeres.

    That's why we need a way to separate the enantiomeres; this is called chiral resolution. There are several well known methods of chiral resolution; see for example "Simultaneous Enantioseparation of Monosaccharides Derivatized with L-Tryptophan by Reversed Phase HPLC" by Mami Akabane, Atsushi Yamamoto et al., in Analytical Sciences, Vol. 30, July 2014. It's not economic to do so, because normally we get the right chirality food from nature, but we can do it. If more and more people end up in John's condition it is likely that efficient methods will be developed.

    So, long story short, John will have to eat synthetic sugars and amino acids synthesized from scratch; natural fats and minerals are all right. We can feed him the racemic mixes, and his body will assimilate the right molecules and pass the others; or we can feed the mix to ordinary bacteria and feed him what the bacteria could not assimilate.

  • Ah, and what has this to do with quantum parity? Nothing -- both ordinary D-glucose and exotic L-glucose are made of atoms containing protons and neutrons and electrons with their ordinary parities. If the question is seriously asking what would happen to John is the parity of his constituant electrons and protons and neutrons was reversed, then the answer is we don't know. There is a lot of speculation about mirror matter, but nobody has ever seen it.

  • $\begingroup$ :-) I suspect that a good guess as to what would happen to Joe if we really are talking about mirror matter is that he'd die - since in the story's universe, the only way to produce it is to make the trip through the Klein bottle. $\endgroup$
    – JBH
    Oct 13, 2018 at 20:22
  • $\begingroup$ Reading the linked things about "mirror matter": I think it is different enough, such that John Doe still consists of usual protons, neutrons, and electrons and not of mirror particles (that may have different masses from their non-mirror counterparts) $\endgroup$ Oct 14, 2018 at 20:19
  • $\begingroup$ @jknappen: That's why the bulk of the answer is about what to feed John if all that's happened to him is that his sugars and amino acids have been flipped. But then the title of the question says "parity transformed"... $\endgroup$
    – AlexP
    Oct 14, 2018 at 21:35
  • $\begingroup$ Elementary particles are parity eigenstates. The worst thing a parity transform can do to them is changing the the sign of their wave function. Those mirror particles or Alice particles are something very different: Kind of partners to the usual particles with different behaviour under a parity transform (i.e., when the particle has positive parity, its Alice partner has a negative one and vice versa). $\endgroup$ Oct 14, 2018 at 21:45
  • $\begingroup$ @jknappen: That depends on what is meant by parity transform; it could mean flipping the signs of the intrinsic parities of elementary particles. But the question says that water remains drinkable, so I dismissed this possible understanding. $\endgroup$
    – AlexP
    Oct 14, 2018 at 21:55

I don't know if that suita your settings, but i am going to give it a try.

Cultivate huge ammounts of bacteria from his bowels and skin. Have you seen those leather funghi stuff? That ammount.

Well, the bacteria can't feed on normal stuff, YET. They are survivalists and adapt to many environments, so even though not all population will survive, some individuals of each generation might do a little better and you select those until you have a mix of mirrowed baxteria feeding from normal stuff.

Then, just make a ration of it, purify the toxines and stuff. Gnarly ration, but better than starving.


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