History Main / MirrorChemistry

** Possibly this effort is doomed to failure, as a brain that doesn't receive an actual (right-handed) glucose rush in the wake of eating a sweet-tasting flavoring is likely to start registering that flavor as ''non''-sweet after several exposures. (As this argument applies to all low-calorie sweeteners, it is probably flawed.)
** Another probelm is that if the sugars can't be absorbed in the gut, there could be mild laxative effects from osmosis. This one seems actually likely, since "sugar alcohols" used as "non-caloric" sweeteners (such as sorbitol) really ''are'' laxatives in large doses.

* In ''[[WilliamSleator The Boy Who Reversed Himself]]'' by William Sleator, the protagonists gain the ability to enter the fourth dimension and therefore end up reversed. They learn that mirror-ketchup is an extremely addictive drug.

** In her bar on Ilium, Matriarch Aethyta warns Shepard against eating the beer nuts in the [[ColorCodedForYourConvenience red bowls]] because they're for turians and quarians. She also speaks of a NoodleIncident where a krogan drank liquefied turian on a dare. Krogans are infamous for SuperToughness to the point where it's a RunningGag, but according to Aethyta "no one came out of that one looking pretty."

** Another probelm is that if the sugars can't be absorbed in the gut, there could be mild laxative effects from osmosis.

Most of the molecules required for life have the property known as [[http://en.wikipedia.org/wiki/Chirality_(chemistry) chirality]] or "handedness". That is, they are not the same as their mirror image, like a left shoe which will not fit properly on your right foot no matter how you rotate it. That wouldn't have been that much of a problem, if not for the one insignificant fact that most of the stuff our bodies are made of, mainly the amino acids, which are the building blocks for the proteins we consist of, are chiral. And ''all'' multicell organisms on Earth are made of L-(or levo-)amino acids: that is, most of the molecule's atoms are on the left side.[[note]]This is not to be confused with the molecule's optical activity: that is, if we shine a light through its solution, l-isomer will rotate its polarization plane (a plane the EM-wave is oscillating) to the left, that is, counter-clockwise, and d-isomer, or dextrorotatory one, will do it to the right, or clockwise. Many L-isomers are in fact l- (or (-), as chemists now prefer to designate them) isomers, and vice versa, but it's not true for all of them.[[/note]] Dextro-amino acids (except cysteine) are exceedingly rare in Earth organisms and are used only by some bacteria and in a few very specialized cases by larger creatures. Referencing this fact is a fairly common way for science-fiction writers to ShowTheirWork. It generally comes up in one of two situations:

* Many colony worlds in the ''[[TabletopGame/{{TwentyThreeHundredAD}} 2300AD]]'' universe have dextro-based life. To get around this, human colonists sterilize large patches of ground and use "pay dirt" from Earth to set up a localized biosphere suitable for growing crops. On the other hand, many native creatures from dextro-worlds (most infamously [[EverythingIsTryingToKillYou Aurore]]) will take a bite out of humans or their livestock without worrying whether it will make them sick.

* Many colony worlds in the ''[[2300AD]]'' universe have dextro-based life. To get around this, human colonists sterilize large patches of ground and use "pay dirt" from Earth to set up a localized biosphere suitable for growing crops. On the other hand, many native creatures from dextro-worlds (most infamously [[EverythingIsTryingToKillYou Aurore]]) will take a bite out of humans or their livestock without worrying whether it will make them sick.

* Many colony worlds in the ''[[ptitlec4o48xnc 2300 AD]]'' world have dextro-based life. To get around this, human colonists sterilize large patches of ground and use "pay dirt" from Earth to set up a localized biosphere suitable for growing crops. On the other hand, many native creatures from dextro-worlds (most infamously [[EverythingIsTryingToKillYou Aurore]]) will take a bite out of humans or their livestock without worrying whether it will make them sick.

** If a female Shepard romances her turian teammate Garrus, Dr. Mordin Solus warns her against swallowing turian semen.

* An important plot point in Marti Steussy's ''Dreams of Dawn''. Juvenile (and not yet sentient) Kargan natives like the taste of terrestrial food, but it can cause their metamorphosis process to go fatally awry [[spoiler:thanks to some meddling by AbusivePrecursors]]. The side effects of Kargan food on terrestrial species likewise range from indigestion to fatalities. [[spoiler:Solved at the end by altering the colonists' biochemistry to match that of the native species, after much [[HeroicSacrifice trial and error]].]]

Most of the molecules required for life have the property known as [[http://en.wikipedia.org/wiki/Chirality_(chemistry) chirality]] or "handedness". That is, they are not the same as their mirror image, like a left shoe which will not fit properly on your right foot no matter how you rotate it. That wouldn't have been that much of a problem, if not for the one insignificant fact that most of the stuff our bodies are made of, mainly the amino acids, which are the building blocks for the proteins we consist of, are chiral. And ''all'' multicell organisms on Earth are made of L-(or levo-)amino acids: that is, most of the molecule's atoms are on the left side.[[note]]This is not to be confused with the molecule's optical activity: that is, if we shine a light through its solution, l-isomer will rotate its polarization plane (a plane the EM-wave is oscillating) to the left, that is, counter-clockwise, and d-isomer, or dextrorotatory one, will do it to the right, or clockwise. Many L-isomers are in fact l- (or (-), as chemists now prefer to designate them) isomers, and vice versa, but it's not true for all of them.[[/note]] Dextro-amino acids (except cysteine) are exceedingly rare in Earth organisms and are used only by some bacteria and in a few very specialized cases by larger creatures. Referencing this fact is a fairly common way for science-fiction writers to ShowTheirWork. It generally comes up in one of two situations:

* In ''Franchise/MassEffect'', the turians and quarians have roughly humanoid biochemistry, but with opposite-chirality proteins, while several other species have the same chirality of protein as humans do. Eating food intended for an opposite-chirality species will at best pass through one's system without providing any nutrients and at worst lead to dangerous allergic reactions.

** Referenced darkly in AlanMoore's ''LeagueOfExtraordinaryGentlemen''; in a text feature in Vol. 2, it is revealed that Alice emerged from the Looking Glass world with her entire body mirror-reversed. As a result, she was unable to eat normal food, and ultimately starved to death.

** Possibly this effort is doomed to failure, as a brain that doesn't receive an actual (right-handed) glucose rush in the wake of eating a sweet-tasting flavoring is likely to start registering that flavor as ''non''-sweet after several exposures.
* Receptors for proteins, hormones, and other organic chemical compounds are made to fit certain molecular structures of a certain chirality. If a molecule does not have the correct chirality, it doesn't fit in the receptor, or worse, can actively harm the organism. As if that's not enough, the human body can sometimes metabolize a useful structure into its harmful mirror image. This was what happened with Thalidomide - a certain chiral structure (also called an enantiomer) of the compound was useful for the effects of morning sickness in pregnant women, but the other enantiomer of it caused terrible birth defects. This is also the case with the cancer-fighting drug Platinol, which only causes sickness because scientists can't separate the helpful enantiomer of the drug from the toxic one, so it's sold as a mixture of the two (any mixture of both enantiomers of a compound is called a racemic mixture).

* One StargateSG1 fanfic mentions a right-handed world being used as a prison planet. Plenty of oxygen, but if you escape the prison camp there's absolutely nothing to eat. Unless you [[spoiler: dismember the guards]].

* In ''The Boy Who Reversed Himself'' by William Sleator, the protagonists gain the ability to enter the fourth dimension and therefore end up reversed. They learn that mirror-ketchup is an extremely addictive drug.

* In ''[[Literature/AliceInWonderland Through the Looking Glass]]'', Alice speculates that looking-glass milk might not be good to drink. This is probably the UrExample; in fact, it predates the coining of the word "chirality" by several years. In ''The Annotated Alice'', MartinGardner discusses the chemical reasons why this would be true, before moving on to point out that looking-glass milk would likely be made of antimatter, making it ''[[StuffBlowingUp really]]'' bad to drink.

Most of the molecules required for life have the property known as [[http://en.wikipedia.org/wiki/Chirality_(chemistry) chirality]] or "handedness". That is, they are not the same as their mirror image, like a left shoe which will not fit properly on your right foot no matter how you rotate it. That wouldn't have been that much of a problem, if not for the one insignificant fact that most of the stuff our bodies are made of, mainly the amino acids, which are the building blocks for the proteins we consist of, are chiral. And ''all'' multicell organisms on Earth are made of L-(or levo-)amino acids: that is, most of the molecule's atoms are on the left side.[[hottip:*:This is not to be confused with the molecule's optical activity: that is, if we shine a light through its solution, l-isomer will rotate its polarization plane (a plane the EM-wave is oscillating) to the left, that is, counter-clockwise, and d-isomer, or dextrorotatory one, will do it to the right, or clockwise. Many L-isomers are in fact l- (or (-), as chemists now prefer to designate them) isomers, and vice versa, but it's not true for all of them.]] Dextro-amino acids (except cysteine) are exceedingly rare in Earth organisms and are used only by some bacteria and in a few very specialized cases by larger creatures. Referencing this fact is a fairly common way for science-fiction writers to ShowTheirWork. It generally comes up in one of two situations:

* In ''MassEffect'', the turians and quarians have roughly humanoid biochemistry, but with opposite-chirality proteins, while several other species have the same chirality of protein as humans do. Eating food intended for an opposite-chirality species can (at best) pass through one's system without providing any nutrients and (at worst) lead to dangerous allergic reactions.

* ''Spock Must Die!'' by Creator/JamesBlish, the first ''Franchise/StarTrek'' ExpandedUniverse novel, has a mirror-reversed copy of Spock created in a transporter accident. He's unable to eat anything, and so he finds himself slowly starving while he works with a chemistry set in order to create mirrored food he can eat and survive.

* ''TourOfTheMerrimack'': The crew aren't worried about picking up any diseases in the Myriad because life on those worlds uses opposite-handed proteins, which are are incompatible with human biology. It's likened to attempting to attach a four-bolt wheel to a five-bolt axle with opposite-thread bolts. It is also mentioned that [[HordeOfAlienLocusts the Hive]] is unique among all known species in that it is able to digest proteins of either chirality.

* ''TourOfTheMerrimack'': The crew aren't worried about picking up any diseases in the Myriad because life on those worlds uses opposite-handed proteins, which are are incompatible with human biology. It is also mentioned that [[HordeOfAlienLocusts the Hive]] is unique among all known species in that it is able to digest proteins of either chirality.

* In ''ThereAndBackAgain'' by Pat Murphy, anyone who passes through a wormhole gets mirror-reversed. Any gathering of people who have done a lot of wormhole travel needs two cooks: one for the travelers who are currently "right-handed" (having passed through an odd number of wormholes) and one for the ones who are "left-handed" (having passed through an even number).

* ''Destiny's Road'' by LarryNiven is set on a planet whose indigenous life uses right-handed proteins. This is initially problematic as they need to entirely sterilize an area of the planet so as to have somewhere to grow edible food, but it proves to have some advantages; it means they're immune to native diseases, and they discover that the planet's sea life is the perfect diet food as their bodies are incapable of metabolizing it into fat.
* ''Spock Must Die!'' by James Blish, the first ''Franchise/StarTrek'' ExpandedUniverse novel, has a mirror-reversed copy of Spock created in a transporter accident. He's unable to eat anything, and so he finds himself slowly starving while he works with a chemistry set in order to create mirrored food he can eat and survive.

* One of the stories in ''Literature/CallahansCrosstimeSaloon'' has a "Mirror Earth" with right-handed proteins in the place of our left-handed ones. The protagonists eventually discover that this inverts the perceived quality of liquor: our swill is their Wonderbooze and vice versa.