Is life 2D?

Great Debates
1

I was reading some random magazine the other day, possibly Pop Sci, and they had a feature on the top scientists and theorists in their field. One of them caught my eye with a mind-stretching theory.
His theory was that the world as we know it is not three-dimentional, but two-dimentional. He said, and I’m abbreviating this as space and memory allow, that there is more information stored on the surface of an object than we realize and that we simply percieve the universe as having three dimentions.
One is inclined to simply call this malarky and go on with life, but I’m curious enough to pursue this. However, I don’t even know where to begin to run a search, thus, I come to the dopers. Is this a common theory? I’m missing some major points here, so what are they? Thanks y’all.

Lost in thought,
:confused: Ozzy :confused:

2

It sounds like a rehash of Sense-Datum theory. A Sense-Datum theorist sees a stick appear to be bent when submerged in water, and avers that there are in actuality two objects: the straight stick and the bent stick. He considers both data-sets to be informationally harvestable.

His opponent is the Perception theorist.

3

Apparently all our eyes perceive is light or photons, so there is no colour “out there”, rather colour is created in the brain/mind from signals sent from the eyes.
If “colour” includes all shades and graduations, and depth, then it is all created. What is actually “out there” we don’t know.

So we perceive ourselves and the world as three dimensional in which I don’t think two dimensionality exists. Two dimensionality is used to refer to flat things, but all flat things have three dimensions.

Is a shadow three dimensional or two?

Is the world 2D? Well we don’t even know if it exists.

4

A 2-D world* doesn’t work too well for many reasons. Perhaps most notably because you couldn’t live there.

Draw a person on a piece of paper and include an open mouth, tube for the throat to the stomach and out the backside. You’ll notice that this neatly cuts your person into two separate pieces.

As a result we most definitely live in an at least 3-d world. While what may really be ‘out there’ may be very different from how we perceive it (heck your dog perceives the world differently…a bee very differently) you can count on three dimensions at a minimum.

[sub]*Technically I guess one could say we do live in a 2-D world as it is by its very nature wrapped into three dimensions but I don’t think that was what the OP was getting at.[/sub]

5

I’m just a physics layman, but I read a bit about this in the last chapters of Stephen Hawking’s The Universe in a Nutshell. I’ve never heard of the theory anywhere else though, so I doubt it’s commonly accepted. I remember him presenting it more as an “interesting hypothesis” and said that there were some aspects of current physics that were better explained by the model, but that’s about it.

To be honest, I didn’t understand most of it.

6

Sound like the same difference to me; there’s a surface that has length and breadth, but no height, however any point on the surface has a set of attributes that behave in every way as if they were capable of storing height information.

Bleh. If it looks like a duck and quacks like a duck, maybe it’s a duck.

7

This is probably irrelevant, but have you ever noticed that your perception of “up and down” is very different from your perception of left, right, forward, and backward?

Most of our life is spent in horizontal movement. Vertical movement is “unusual” in a psychological sense.

(To be really doofus about it…many of us have a fear of heights, but who the heck has a “fear of west?”)

I think that most of us have the “two dimensional thinking” that Kirk exposed in Khan in STIII…

And here’s a GQ: why is it that, when you look up at a mountain, it doesn’t look like it’s really so high…but when you’re at the top and looking down, it looks like it’s much, much higher! The angle to the top from the bottom is the same as the angle to the bottom from the top…but it sure doesn’t look that way from the summit!

Trinopus

8

Trinopus wrote:

Well, there’s dextrophobia (fear of things to the right), levophobia (fear of things to the left), and general kinetophobia (fear of movement).

9

IIRC, there’s some device in our ears that orients your brain to gravity. The “up/down” sense.

Because when you’re focused at the top of a mountain from the Ground, you’re focused on a relatively small field of view from the complete panorama that you can see. (+/- 205 degrees)

From the top, looking down, you see farther and broader than at a lower height, so I guess your sense of height is accentuated with increasing height

10

i guess it all depends on the way you define dimension. since it’s a mathematical construct, its application is rather arbitrary. for example, there are many physicists that believe there are as many as 13 dimensions, because 13 dimensions go a long way toward explaining (mathematically) the physical universe, even though most of us only perceive 4 dimensions (l, w, h, and t).

if he means dimension in the classic sense, i would be interested to know how he feels about non-planar graphs (the peterson graph for example), that can’t be constructed in 2 dimensions without their edges interesecting, and their 3 dimensional constructions that we could do out of such things as wire and balls.

for a hopefully brief hijack, what would it be like if we could actually see in 4 dimensions? if we could actually see a distance in time?

11

I think you need on this case to distinguish between time as the fourth dimension and a fourth spatial dimension. We actually do experience time as a dimension right now. E.G. From the Washington Monument meet me 2 miles east, 1 mile north, 50 meters above the ground at 10 a.m. on February 8, 2003. You’ll note I gave you four coordinates there and with that I have defined a point in space (a different time would be a different point…not relative to the earth but relative to the solar system/galaxy/universe).

If you could acces a fourth spatial dimension all sorts of neat tricks become possible. You could see ‘through’ walls (not actually through them but around them in a way no one else could). There wouldn’t be a prison that could hold you. You could reverse spirals in shells (not very useful but maybe there’d be a practical application to that I haven’t thought of). You could perform surgery without cutting the patient open…all sorts of fun things to do in the fourth dimension.

12

Time isn’t a fourth geometric dimension (at least not outside of strange places like the event horizon of a black hole/gravastar) - if there was a fourth geometric dimension that we couldn’t perceive for some reason, but we were then plunged into it, it would propbably be very difficult for us to understand; more so to explain.
I think we would be able to view all sides of a solid cube simultaneously.

Flatland by Edwin (forget his surname) is a good read on the subject.

13

Yes time is not a spatial dimension, but it is a dimension of spacetime, which is not the same thing.

14

If we didn’t have our senses somehow expanded to view the fourth dimension then putting you or me or anyone in the fourth dimension wouldn’t seem any different than the world does now. If I pulled out a hypercube (or tesseract?) and showed it to you all you’d see is a cube.

15

That’s an awfully good point, however, I don’t feel convinced enough to cast it aside just yet.
A few posts and a friend of mine got me to thinking about a more fundamental problem. Does everyone have the same idea of what 2D and 3D is? The way I see it, a sheet of paper, and even pencil markings, are 3D. Therefore, life as we percieve it can’t exist there. That’s not to say that life can’t exist in the second dimention, does it?
-Ozzy

16

If our universe is really two dimensional even though we perceive it as three dimensional, then we live in a “2 1/2 dimensiion” universe similar to Doom. We’ll get to live in three dimensions for real as soon as Creator Software releases the upgraded engine, although converting us from sprites to polygons is going to be arduous. :wink:

17

  1. Which two, anyway?

  2. Kant would say the following (heavily paraphrased):
    (a) Since our minds filter all data received, we cannot say that what we perceive is “reality” with certainty.
    (b) Therefore, whether the “real world” is 2-D or 3-D is, in one sense, totally irrelevant. We live in 3-D. Just as speculating about whether there is causation in the “real world” is also irrelevant: our brains work on the idea of causation, so speculation as to its actual existence is similarly pointless.

I’m gonna go with the big man on this one.

-Ulterior

18

According to the Holographic Principle all of the information in our 3 dimensional universe can be contained on a 2 dimensional sheet in a 5 or greater dimensional space.

I don’t know much about the Holographic Principle, so I did a search and I think I found the article that the OP referred to.

Raphael Bousso wonders: Is the world just a holographic illusion?

19

Probably you are referring to the Holographic Principle. The Holographic Principle is an idea that arised in attempts to obtain a quantum theory of gravity. Let me try to explain some of this.

Everything around us is made of building blocks (electrons, quarks and what not) that talk to each other through messengers. In physics, we know of four such interactions among the building blocks: electromagnetism, weak interactions, strong interactions and gravity. The first three work according to the rules of Quantum Mechanics, but writing down a theory of quantum theory of gravity is famously difficult, superstring theory being our best current shot at it.

Currently we don’t have an experimentally tested and unanimously accepted theory of quantum gravity, and theoretical physicists have tried to pin down properties that such theory should obey. The Holographic Principle is purported to be such a property, and it originally arised by thinking about some very peculiar features of black holes. In its original encarnation, it can be roughly presented as saying:

The amount of entropy [=information] one can place in a given region of space is bounded, and that bound grows with the area of the surface enclosing that region of space.

So, even if we observe three spatial dimensions, all the information needed to describe what’s going on in our world could in principle be encoded in a two dimensional surface [the proverbial Wall in the Cave of Plato?]. Hence, the name of hologram, and the provocative slogan that “the world is 2D”.

If true, this is terribly non intuitive, since one would expect that the amount of information you can place in a region of space, grows with the volume of that region of space. Let me try to give an intuitive analogy. The question we are asking is: how much information (=entropy) can you place in the room where you are in? For instance, consider filling the room with books, and accept that there is a minimum size of font for the letters in the books (ok, and a minimum thickness for the pages of the books!). That means that there is a bound in the amount of information you can place in the room. Furthermore, you can pile up books all over, from the floor to the ceiling. It you have a room twice bigger, you can put twice the number of books. So in this example, the maximum amount of information grows with the volume of the room.

That’s certainly the behavior we are used to in physics (“the entropy grows with the volume”), but the Holographic Principle claims that once you take gravity into consideration, things change dramatically (very briefly, if you try to pile up too much stuff together, it forms a black hole and the entropy of a black hole grows as its area). This is one of many hints that gravity is quite different from the other interactions.

Going back to the previous analogy, you could think of the Holographic Principle as saying that most of the books you tried to put inside the room are redundant, they just repeat information that is somewhere else in the room. If you keep only the books that are not redundant, you discover that at best you can cover the walls (and the floor and the ceiling), but they can’t pile up inside the room.

Amazingly, the holographic principle has been realized in wonderful detail for specific spacetimes, in the framework of string theory. On the other hand, no theory of quantum gravity (including string theory) has been tested experimentally, so we still don’t know if the Holographic Principle applies to the real world.