# Flipped over through fourth dimension. When do I start to notice biological problems?

In the middle of the night, while J. Random Human is sleeping, A. Hypersphere picks him hyper-up extremely carefully (so that none of his matter falls out in a direction he doesn't have), flips him over through a fourth spatial dimension, and puts him back hyper-down in his bed. When he wakes up, the entire world is mirror-imaged to him. Everybody looks slightly weird, finding his way around becomes very difficult, reading is an ordeal.

What biological differences does J. Random notice, and how quickly does he notice them? I know the chirality of biological molecules is going to be an issue (and will probably eventually kill him), but do the foods he eats smell and taste different? What symptoms does he start experiencing?

• I'm not biologist, so I won't attempt an answer, but it occurs to me that when you reverse the flow of electrons in a circuit, you invert the polarity of the induced magnetic field. Wouldn't this be true for neurological electricity? Might there not be immediate brain function issues if everything suddenly started running backwards? Sep 30, 2018 at 19:12
• I suspect he might notice when his antimatter body and the bed mutually annihilate each other. And the energy released takes out the neighborhood. Sep 30, 2018 at 20:02
• I ran the calculations. Assuming Joe Random Human is 100kg, total conversion of 200kg is about 1.8e19 J or about 285,000 Hiroshima bombs worth of energy. Sep 30, 2018 at 20:09
• Hyper-up and hyper-down are an axis in a space-time his body and all it's particles do not have an orientation in. His rotation in this 4+1 space becomes irrelevant when he is back in 3+1 space. So no change at all from his 3+1 point of view. Sep 30, 2018 at 22:24
• This would probably have the same effect than crossing a non-orientable wormhole, which would turn the poor JRH into antimatter, which would then turn into energy, liberating a few gigatons (eq TNT) of energy. Which would probably stop all biological functions of JRT and most anyone living in the same country. Fortunately for JRH, life in anything but 3+1 dimensions is probably impossible as nothing would be stable enough, which means no four-dimensional prankster.
– Eth
Oct 1, 2018 at 11:31

Any situation involving molecules without chirality will be the same for him as they are for us, so he'll be able to taste salt, water, and breathe fine. Molecules with chirality will work the way their opposite does for us. An example; for us, right-handed amino acids tend to be tasteless, left-handed amino acids tend to taste sweet. This would be reversed for him. The problem is, opposite chirality organic molecules are quite a bit rarer. He probably won't starve to death, there are plenty of molecules that will work as calorie sources for him. But he probably will die of malnutrition; the human body needs lots of micronutrients, and while I don't know any specifics, I think its very likely he will be unable to find a substitute for one of them and it will eventually kill him. He may die sooner if a common compound is poisonous when in the opposite chirality.

As for when he notices, it depends what you count. He'll know something is wrong the minute he has a bite of food, or takes a drink of something flavored. But it's a big leap to make from "My sandwich tastes funny" to get to "I went through a hypersphere and now all my molecules are backwards". I think it's likely that doctors would miss this for quite awhile. Taste and smell changes would make them think it was neurologic, while nutritional problems might lead them to suspect hormone or gastro problems. I think it would be quite awhile before they noticed his molecules were all backwards.

• Actually, the doctors would probably notice that his heart and all his other internal organs were on the wrong side right away. That might give them a clue, especially if they had previous medical records. Oct 1, 2018 at 1:42
• @PeterShor I can't remember what it's called but that happens in humans; very rarely, humans have all the organs on the other side. Maybe the doctors will just think he's one of those people. Oct 1, 2018 at 15:50
• To be clear he will eventually starve to death, while calories aren't a problem for him, proteins are. the nine essential amino acids are all chiral and aren't really found naturally as their optical isomers. without them it's very very likely that they would die though this would likely take a while as all theese acids have a long half-life. I expect vitamins would also be a problem. That being said the significant delay could be long enough for this person to obtain an artificial source of their optical isomers, if they figure out whats going on. Oct 1, 2018 at 17:13
• Even without records, J. Random probably knows which side his heart was. Also, he likely has a predominant hand (and remembers which one it was). Oct 1, 2018 at 17:52
• @Wilson Situs Inversus? I have to admit, I only know this from World War Z... Oct 1, 2018 at 19:56

## He will not have time to notice any biological differences...

...because he is made of antimatter, and will instantly annihilate on contact with any normal matter nearby.

The maneuver you're describing--picking someone "hyper-up" and flipping them around--is exactly the operation that a non-orientable wormhole ( https://en.wikipedia.org/wiki/Non-orientable_wormhole ) would do to matter that passes through it. This would affect the chirality of the molecules that pass through it, yes, but it also does something at a deeper level:

As well as turning left-handed screwthreads into right-handed screwthreads, and left-handed gloves into right-handed gloves, reversing the chirality of an object is also usually associated with the idea of reversing the sign of electromagnetic charge – if a positron can be considered as a time-reversed electron, it can also be considered as an electron aging conventionally, but with one spatial dimension reversed. The existence of a traversable nonorientable wormhole would seem to allow the conversion of matter to antimatter, and vice versa.

In conclusion, J. Random would go out in a blaze of total-energy-conversion glory and take a sizable check of the earth's crust with him. [citation needed]

[Edit: I just noticed that @Spencer and @Eth already pointed this out long ago in the comments, including a reference to the oon-orientable wormhole article. I feel properly scooped, but I'll leave my answer up since no other actual answers address this...]

• A. Hypersphere's intention is certainly not to have J. Random instantly annihilate. Is this an intrinsic property of the rotation described, or a feature tied to the way non-orientable wormholes are believed to operate? Oct 1, 2018 at 22:50
• According to my understanding (which is not expert), it would be intrinsic to the chirality of the particles themselves. So any operation that would flip their chirality would "convert" them into their respective antiparticle.
– Qami
Oct 2, 2018 at 16:38
• It depends on how exactly OP's hypersphere works doesn't it? I don't think we know how "deep" the flipping is. Its possible the hypersphere in question just rearranges molecules, not the atoms that make them up. Oct 4, 2018 at 17:28
• Don’t think this is correct. OP isn’t asking about flipping, but rotating through a fourth dimension. This would reverse 3D chirality, but would no more convert him to antimatter than does flipping a 2D sheet of paper over in the 3rd dimension. Oct 5, 2018 at 22:38
• Actually, to get anti-matter, you need to reverse chirality, the direction of time, and the electric charge. If you just reverse chirality, you get elementary particles that don't exist in this universe. So you might as well assume that you reverse chirality, but keep the same elementary particles. May 3, 2019 at 2:39

Many digestive enzymes are chiral and they would stop working on many of the molecules with the wrong orientation. However there should be enough food without this problem that he would be able to survive with a modified diet. He may now be able to digest other things that were just dietary fiber to him previously, which might have some unknown consequences.

The procedure that you're talking about does not time reverse him, so he is not made of antimatter as he would be if he went through the wormhole mentioned in other answers. This is for the same reason your drawings don't explode when you turn the paper upside down.

P.S. I love Flatland too.

• Hey Mathaddict! I'm not any kind of professional physicist, but my understanding is that geometrically speaking, both time reversal and reversing (any) one spatial dimension would accomplish the same thing. Mirroring a subatomic particle is very different from flipping a sheet of paper over...when flipping a sheet of paper, you're only moving a bunch of atoms around, not actually inverting the chirality (and therefore the charge) of the particles themselves.
– Qami
Oct 1, 2018 at 18:07
• But, in the question, he's not actually reversing a dimension, he's just flipping the person over through the 4th dimension. So he is just moving the atoms around, there should be no charge reversal when moving through the 4th dimension for the same reasons that moving a 2 dimensional object through the 3rd dimension doesn't do that either. It really has to do with the wording of the question. Oct 1, 2018 at 18:08
• But if the rotation through the 4th dimension flips the chirality of the whole object, why would it not be flipping the chirality of the constituent parts? (As far as I can see, it would have to flip the chirality of every part)
– Qami
Oct 1, 2018 at 18:22
• It would flip the chirality of every part, but chirality isn't inherent to a particle, it only has to do with how things are oriented in relation to each other. Oct 1, 2018 at 18:45
• Fair point, but if we dig down deep enough, there may not be much left that is "inherent" to a particle--which is, after all, just a waveform in a field. Perhaps a particle's charge is also dependent upon its orientation in relation to other particles. This is, in fact, what is suggested in the article on non-orientable wormholes: en.wikipedia.org/wiki/Non-orientable_wormhole#Consequences
– Qami
Oct 1, 2018 at 19:08

Perhaps he will feel nothing different at all

(And this is only theorizing, because we have never had such a real example to reference).
Yes his entire body was "mirrored" through the 4th dimension, but also his brain, and each and every synapse and neural pattern. Therefore, all the information mapped inside his brain was also mirrored. So, even if he will perceive everything in the world "mirrored" (for example the characters in the newspaper), he will be able to read it normally, because all his memories and learning experiences have also been flipped.

However... all the people around him will notice it almost immediately: "Hey! You had that freckle in your left cheek! Now it is in your right cheek!!"

And of course there will be those molecular differences mentioned before. But... since all his own molecules were also flipped, perhaps (and I am speaking without any solid biochemistry background) perhaps he will be able to assimilate everything the same way (perhaps).

• His own molecules are flipped, but the food he'll be eating is NOT flipped, so he's in serious trouble.
– G_B
Oct 2, 2018 at 0:26

He will immediately notice after opening his eyes:

For him, the outside world looks mirrored: All written signs are mirror images, traffic goes on "the wrong side of the road", the majority of people look left-handed to him, screws are different, faucets have the other sense of rotation, there are lots of hints to his situation.

• Pretty much everything you've said here is already mentioned in the question, and doesn't really feel like a "biological symptom". Oct 13, 2018 at 18:38

A 4-d flip would not turn JRH into anti-matter, just a mirror-image of his previous self. He would become left-handed, part his hair on the other side, etc. Whether his memories would flip in some way can only be conjecture.

He would probably become immune to infectious disease, bacteria are sensitive to isomorphism.