What is a dimension? (Some SPOILERS for games, movies.)

[Dude_Doc]

This is kind of related to science-fiction, since sci-fi sometimes use the word "dimension" to explain "the other side".

There are also games. The creatures in Half-Life comes from the (what they say in the game) "border world of Xen", also in a way a "dimension". In Doom 3, the teleportation experiments they are doing are related to "dimensional travel" - in which the discover Hell, thus vageuly linking Hell not as another world or universe, but as a dimension.

Now, the question here is, of course, what is a dimension?

We know that our world have 3 dimensions, plus 1 which is time. So, as I see it, if I would say "The creature came from another dimension", then wouldn't that be exactly like saying "The creature came from time".

Something can not just "come from time" - just like something can not just be "a centimeter".

So: Is it only a kind of misunderstanding of the word "dimension" that we hear, just like the usual Joe could say "It would take a lightyear for me to do this", or have I missed something? Is the word "dimension" only another word for "another universe"?

[Tezcatlipoca]

It is a misunderstanding in a way (as far as I know). Basically the word dimension is defined as a measurement, or "dimensions" of a point: basically all the measurements you need to positively identify it's position (meaning your three "known" coordinates, and usually time: other dimensions for it are usually 0, but there are... many more mathematically.

The "other" term of the word I think is a misnomer, or maybe better defined as a colloquialism. Sometimes, such as in these cases, people refer to a

[Cyborg]

Many people have the interpretation that if the world was 4D, it would consist of countless parallel 3D worlds.

I think this is what some people mean when they say travel through dimensions.

Just my try at it, though.

[Anathema]

Well, I suppose you could say that all universes (ours, and the supposed paralel ones) have one common dimension: time. Other paralel universes would have their own 3 spatial dimensions that practicly work like ours.

Except, we can't really speak of paralel "universes" in this case. The term universe encompasses the 3 spatial dimensions + time. So another "dimension" in SF would actually be "a different set of spatial dimensions"

That's my throw at it, anyway.

[Dude_Doc]

Okay.... sounds comprehensional.

I've also heard talks about different levels of consciousness, and also, the "M-theory". What I gathered from it, superstrings are the smallest thing beyond neutrons, and that they "live"/exist in different dimensions. So, they mean that they exist in different mathematical dimensions?

[Tezcatlipoca]

Okay.... sounds comprehensional.

I've also heard talks about different levels of consciousness, and also, the "M-theory". What I gathered from it, superstrings are the smallest thing beyond neutrons, and that they "live"/exist in different dimensions. So, they mean that they exist in different mathematical dimensions?

Pretty much, although saying they "live" or "exist" in them is, I think misleading. Instead it's better to say that they occupy, or utilize those normally "unused" dimensions I mentioned earlier. Likewise, some of the dimensions we take for granted (the three spacial dimensions and possibly even time) might not be used for all "things."

[Andrew]

Just thought I'd mention Tezcatlipoca that you have a in your signature, that doesn't seem like it should be there. (as I can see the code )

Messed up dimension?

http://interactive.usc.edu/members/yuechuan/archives/optical-illusion-wheels-circles-rotating.png

[Dude_Doc]

Likewise, some of the dimensions we take for granted (the three spacial dimensions and possibly even time) might not be used for all "things."

Ollright... that reminds me of another link, in which the writer said that the total mass (except space) in the universe is "only" 2%, and 98% space/black matter/whatever. It said that the rest of the 98% mass could be "hidden"(or)/gone to other dimensions... though it don't seem logical that the universe should in some way consist of 100% mass.... (???)...

[Kiyouta]

The 4th dimension is time. Apprantly there are 32 known dimensions but I could just be dreaming that up.

[Edric O]

Take a two-dimensional piece of paper (yes, the paper actually has a third dimension as well, but ignore that for the sake of the argument). This piece of paper represents our universe. Now, take a bunch of other identical pieces of paper and place them on top of each other, forming a 3D stack. This is a 3D object made up of a multitude of 2D "slices". If each slice represents a universe, you have a multitude of parallel universes existing side by side.

Now imagine there are 2D people living on that first piece of paper. Their entire universe is 2D. They don't even understand the concept of moving in a third dimension. But if they could move in this third dimension, they could travel to alternate universes.

Funnily enough, I've recently read a Victorian novel that deals with this very subject, called "Flatland":

http://xahlee.org/flatland/index.html

(well, the first part is a satire of Victorian society, but the second part discusses the matter of higher dimensions)

[Wolf]

I think we misrepresent the concept of 'alternate dimensions' by calling them 'alternate universes.' It's not so much that there's an entirely spearate universe divorced physically from our own -- that's probably impossible, though we can't say for sure since we don't have any way to test that -- it's more that there's an extra dimension to our universe that is literally physically impossible for us to perceive or explore. Consider Edric's paperverse; the 3D stack of paper is really the same universe as the individual sheets of paper; physically they are all in "the same place" (I use that phrase loosely, as Edric's paperverse isn't exactly a perfect analogy, but serves this purpose), only, the higher levels of paper are extra-dimensional from each other, and cannot be sensed or perceived by denizens of an individual sheet. In fact, were the paperverse our universe, each of the dimensions would be existing alongside each other, residing within the same universe. There may be dimensions in our real universe that exist alongside us every day that we cannot perceive or even begin to comprehend.

[Dude_Doc]

Hehe, sounds like trying to think of a color that doesn't exist, or looking at the back of your head without using a mirror.

Okay, so I assume that we all agree that if there are more dimensions to our universe, they can not be percieved by us (in our current stage). So, going further: could there be such things like "extradimensional" beings, living in our universe - maybe even here on earth - without our knowledge (because we can't percieve the dimension "they" are living in)?

Is it possible that we could be the "2D" beings - and that there are in fact, 3D beings?

[Lord J]

Hehe, sounds like trying to think of a color that doesn't exist, or looking at the back of your head without using a mirror.

That's actually a great way of thinking about it.

It is physically impossible for humans to visualize a fourth or higher spacial dimension.  There has been some fiction written on the subject (Flatland, Alice in Wonderland, several H.G. Wells novels...), including a few instances where higher dimensional beings invaded 3-dimensional space.

The problem is that, just as to a flatlander a sphere would resemble a circle that grows and shrinks (depending on how it was positioned vertically on the flatland), but is not really visible in its whole, a higher dimensional being could only be seen, at best, in part by our eyes.

The concept of multiple dimensions is extremely fascinating to me just now, as I am reading Hyperspace by Michio Kaku.  I don't understand some of it, especially quantum theory, but its still really good.

To answer the question about how many dimensions, at the point at which I'm in Hyperspace, there seems to be a requirement for either 10 or 26 dimesions, total, as a superstring is consistant only in a 10 or 26 diminsional universe.  And the interesting thing about it is, if you ask a theorectical physicist why 10 or 26 dimensions, they really don't know!

Do a favor for yourself and read Hyperspace by Michio Kaku.