moving in 2d

[anderscolingustafson]

Moving around in 2d would be extremly restrictive. A 2d creature would have no semitry and therefor would be incapable of ever turning around and walking the other way. A 2d creature would therefore be unable to stay in 1 place on ets own and so a 2d animal would oventualy reach a place et could not live and be unable toturn around and so would die. Even a 2d fish would have to swim upside down to change durection in a 2d world and fish hardly ever swim upside down. 2d animals would probably need to come in 2 forms each whith opposite dimensions from each other. 2d creatures would probably have alternating generations were some would be born facing one way and others born facing the other way. 2d land animals would probably always be born facing in land if born on the coast, while 2d sea creatures would probably be born facing out to sea if born near the shore. 2d creatures would probably also have a hormonal memery telling them the last generation there ancesters were at the end of there habitibable range and if they were at the end of there habitibable range again. When they would get to the end of there habitibable range the hormonle memery would be recet. The way the hormonal memery would probably work would be that the consentration of sertain chemicals would increase over the generations if organisms were facing one way and decrease if the organisms were facing the other way and some chemicals would tell them when they were facing each way and if eather set of chemicals were to reach a certain consentration or if the sets had the same consentration it would mean they would be at the end of there habitable range by the next generation and so the next generation would be born facing the opposite direction as they were.

For 2d nomadick humans it would probably be even tougher because there children would have to stay with them for half of there lives and have reversed dimensions from there pairents meaning for 2d children 2 move whithout geting seperated from the group one adult would need to cary the child ahaid of the other addults and then lett the child run back to the other addult(s). Annother thing about a 2d child would be that the child would never see his/her father because his/her father would have the opposite dimensions as his/her mother so that his/her father would have to move away from his/her mother after seeing her so the childs mothers brothers would probably be the childs father figure. In order for 2d humans to settle down into a non nomatick society they would have to cary people of the opposite dimensions to the edge of the comunity and then allow one of them to return the favore. Another problem 2d humans would face would be that if they were to try to build a city the city would need water and if they were to try to transpert the water through pipes the water would seperate the top of the pipes from the bottom of the pipes causing the pipes to cave in so they would need to have doors that would open and close as the water would flow through and that would open at different times from each other to hold the pipes together.

Another problem for a 2d land animal would be that if et were to come across a tree as would be inevitabe in a farest would be that the animal could not go around the tree et would have to either go above the tree or under et. Some animals are to big however to go under a tree or to climb a tree so the tree would have to be strong enough to not bracke as the animal would go over et.

2d animals would also only need a number of leggs that would be a multiple of 1 because they would have no sides. This means that most mamals and reptiles would have 2 leggs and humans birds and some dinosaurs would have 1 legg so humans would hop instead of walk to get around. also humans would only have one arm on the front of there body so they could not touch there back side, and would have trouble reaching certain parts of there bodies as there hand could not move around very much in 2d as et could only move up and down and bend to move forward and backward.

It would also be impossible for 2d techtonic plates to change possitions as they could not move past each other and so there would be no continintal drift.

[PWrong]

A 2d creature would have no semitry and therefor would be incapable of ever turning around and walking the other way. A 2d creature would therefore be unable to stay in 1 place on ets own and so a 2d animal would oventualy reach a place et could not live and be unable toturn around and so would die. Even a 2d fish would have to swim upside down to change durection in a 2d world and fish hardly ever swim upside down.

Why wouldn't they have symmetry? One eye on each side, and the ability to walk in either direction without turning around? Most 3D animals can walk backwards without turning around if they have to. Also the reason fish rarely swim upside down is because they don't have to.

Another problem for a 2d land animal would be that if et were to come across a tree as would be inevitabe in a farest would be that the animal could not go around the tree et would have to either go above the tree or under et. Some animals are to big however to go under a tree or to climb a tree so the tree would have to be strong enough to not bracke as the animal would go over et.

This one is interesting. If trees are relatively common then it would be easy to get trapped by a pair of trees. However as a tree grows it would be more likely to get trampled by animals than a 3D tree, since that's the only way to get past. So I wonder if trees would even be viable as a species.

2d animals would also only need a number of leggs that would be a multiple of 1 because they would have no sides.

Every integer is a multiple of 1. I'm not sure if you could stand up on one leg all the time. You're probably right that most animals would have two and a few would have one. For most 3D objects, the minimum number of legs is 3, however it's possible for some animals to stand on 2 or 1 if they evolve long feet, toes, and good balance. Be careful about using words like "mammals" and "reptiles", because there's no reason these should exist even on another planet, let alone one with one less dimension. For example New Zealand didn't have any mammals at all until recently.

also humans would only have one arm on the front of there body so they could not touch there back side, and would have trouble reaching certain parts of there bodies as there hand could not move around very much in 2d as et could only move up and down and bend to move forward and backward.

Again, wouldn't it be better to have an arm on both sides?

[wendy]

There's a book hight 'the planiverse', which deals with the mechanics of 2d world, along with such delicies as 'the river' (a general flood), and flying snakes. Still, such things are indeed possible in two dimensions. Reccomended reading.

[anderscolingustafson]

Why wouldn't they have symmetry? One eye on each side, and the ability to walk in either direction without turning around?

The kind of symmetry we have to a 2d life form would be like what radial symmetry is to us. The number of dimensions we have symmetry reflected through is d-2 because we have one dimension of symmetry so any 2d equivalents of us would have 0 dimensions of symmetry. The only animals in a 2d world that would have symmetry would be ones that in our universe have radial symmetry. If a 2d creature were able to walk in either direction wouldn't that be like walking backwards? I think a 2d world would need lenghth and height to function. Also if a 2d human had one eye on each side then were would the ear be?

Again, wouldn't it be better to have an arm on both sides?

Althogh for a 2d equivalent of a human an arm on both sides would make it easyer to grab things from behind it would have the disadvantage that whenever the person would lay down he/she would lay down on his/her back which would be very uncomfterable for the 2d person and might even crush the arm.

[PWrong]

I think you're assuming a kind of 1-1 correspondence between the animals of one universe and the animals of another. There isn't necessarily a 2D version of the platypus for instance.

Intelligent 2D beings don't have to look like humans. They could have bilateral symmetry, an ear on top of their eye, and don't necessarily have a problem with walking backwards. In fact these are exactly the sort of characteristics they'd evolve, because that's what they need to survive. Symmetry evolves wherever it's useful.

You might be right about the arm getting in the way. But maybe the arm grows out the top of the head, or can retract into the body, or maybe they don't even need to sleep?

[papernuke]

Why wouldn't a 2D universe just have a gravitational direction that is perpendicular to the planeland itself? That would simplify so much
An organism living in that enviornment could move by propelling itself via 2D pseudopods or expelling materials in the opposite direction of desired movement.

[Keiji]

But maybe the arm grows out the top of the head

Monoko says hi.

Why wouldn't a 2D universe just have a gravitational direction that is perpendicular to the planeland itself?

Gravity is not just an arbitrary direction; it attracts masses to other masses. So it couldn't point outside of the plane, unless there was some interaction between 2D and 3D.