# Imagining the tenth dimension

1. Jun 28, 2007

### ||spoon||

Hey a friend linked me to this video:
which attempts to explain how the idea of a tenth dimension is feesible.

I have had some trouble understanding some of the concepts which the movie attempts to explain and it made me think of many questions, nopt only about the video but also about dimesnions in general.... so i thought my not ask here??

Well first of all why would "flat landers" that is the imaginary people in a two dimensional world... only be able to see in two dimensions?

the video describes the third dimension as a fold, and i understand the analogy of the ant on the newspaper... but then i dont understand what relevance a "fold" has in creating depth (as opposed to simply length and width)

again when talking about the forth dimension the video explains that... "like the falt landers" we can only see in three dimensions... why is this so?

also why is time given its seperate dimension... it seems kind of a random allocation... why not something else... like the amount of sound or something? (i dont think my point is made clear here and i apologise but i canty explain any better)

before asking any more i think i might just get your ideas (explainations??) on these questions... i need to have another look at the movie for the next dimensions because the mobius strip thing seems to be making sense lol...

well i appreciate any input from you guys... i realise these are probably stupid and irrelevant questions... but the movie has intrigued me and i enjoy understanding things..

thanks alot,

-Spoon

2. Jun 28, 2007

### Demystifier

3. Jun 28, 2007

### DaveC426913

Because the matter(atoms) and energy(photons) that comprise their world follow the 2D surface that is their world. A flatland beam of light will not leave or enter flatland, it will hug the contour. Likewise, their 2D eyes, composed of 2D atoms, will only receive stimulation from light in the plane of their world.

(In fact, if this weren't the case, they wouldn't be able to see at all! 3D light could enter their eyeballs from the side, having never passed through their 2D lens, and all they would see is a white formlessness. It would be 2D the equivalent of our trying to see with our 3D eyes while light was pouring directly onto our retinae from the 4th dimension, bypassing our lenses and cornaeae.)

4. Jun 28, 2007

### Burnsys

Also if Flatland is only a 2D slice of our 3D universe, they wouldn't see the Energy conservation law.. things would magicaly appear and disapear, in and out from their 2D world.

5. Jun 28, 2007

### Klaus_Hoffmann

But, how do we know that there are more than four dimensions (since we can see 3 and experiment the fourth since we age and get older) then, why not 12.34567678 dimensional universe or $$\sqrt -23456483$$ universe or even a Time Cube ??

6. Jun 28, 2007

### cristo

Staff Emeritus
Because 10 (or 11) dimensions fits the requirements for string theory to work!

7. Jun 29, 2007

### Hell_SD

Wouldn't time/space be the first dimension for without it you couldn't have a point in space or time or am i just quibbling ?

I mean if you only had one dimension with nothing else relative to it surely it would be spacetime as in the pre bigbang scenario ?

8. Jun 29, 2007

### CompuChip

Actually we can experimentally verify that the world is 3(+1) dimensional. The other "folded" or "rolled up" dimensions are, as far as I'm aware, only theoretically necessary to make things like string theory work.

9. Jun 29, 2007

### ||spoon||

hey thanks... i think i have actually helped myself understand the first six dimensions.... and i think i have answered all my previous questions...

towards the end of the movie it is stated that the explainations of the dimensions are not really the same as string theory... does this mean that the dimensions for string theory are someting completely different all together, or that it basically doesnt use lots of maths? any input from a ST would be good if there are any on.

Thanks,

Spoon

10. Jun 29, 2007

### Klaus_Hoffmann

the idea of extra-dimensions at least for me sounds like 'psuedo-science' is just an excuse to promote String theory, is similar to the medieval concept of believing Bible was true and hence you matched your beliefs to agree with bible, if you can not proof empirically the existence of 10 dimension as it happened to the existence of aether, you should put down this idea, a theory of gravity must be described into a 4-dimensional space

11. Jun 29, 2007

### Demystifier

The dimensions for string theory are someting completely different all together.

12. Jun 29, 2007

### Demystifier

String theory is MUCH MUCH MUCH (did I said MUCH?) more than a quantum theory of gravity. It so naturally explains so many qualitative features of the Standard Model, that it would really be a surprise if it was a mere coincidence.

13. Jun 29, 2007

### Fra

I personally do not like like the methodology of stringtheory, but my main issues with it is not the extra dimensions as such.

To understand the sense in possible extra dimensions, I think one should try to what the significance of dimensionality is to start with. Consider the case that you are a 3D human beeing evolving in time. Now assume you have been taught that you live in 2 dimensions. You may find out that that idea really makes interpreting what you see pretty akward... maybe even close to inconsistent :) Then what is the resolution to that dissatisfaction? Or perhaps, at minimum a possible resolution? I'd say the insight that the "obvious fact" we all see, that what we see is 3 dimensional, is not that overly obvious after all, is also the key to imagine higher dimensions.

/Fredrik

14. Jun 29, 2007

### Fra

More personal reflections to feed the discussions...

Question: How is it possible that we have not yet "discovered" extra dimensions if they exist?

First I'd question the meaning of "exist", second it is not that strange in principle.

Consider the following thought experiment, brainwash a scientist to make him completely convinced that he lives in 2 dimensions. (I don't know how you'd do that but anyway, thought experiments are rarely realistic anyway:), then the question is, how long TIME will it take for him to find out that he was wrong, and adapt a 3D model? It can hardly be concluded instantly. So there seems to be evolutionary decay time of the 2D model into a 3D model, which is the time it takes for hime to favour the 3D model over the 2D.

If the extra dimensions contains very little information, or information that is of low significance to the questions we ask, our illusion of 3D may be quite stable.

/Fredrik

15. Jun 29, 2007

### Fra

Not also the striking analogy to phase transitions and a general equilibration processes as well as learning processes that clearly requires a certain amount of time and processing to reach "equilibrium". Interesting things happen during non-equilibrium conditions. And IMO, inspiration and understanding can be made at many seemingly different fields. I think this is the easy way.

Also picture, how can you imagine 3D when watching a movie that is projected on a 2D display? Clearly your brain quickly inflates the 2D model to a 3D model because it outperforms the 2D model in terms of effiency of prediction. I think it doesn't have to be more complex that that (put simple), and the generalization to higher dimensions is straightforward.

/Fredrik

16. Jun 29, 2007

### ||spoon||

along the lines of dimensions again but not from the video i originally posted. In the documentary The elegant universe (im sure most of you know of it), brian greene usues the analogy of an ant on a wire a fair distance away to explain different dimensions and the effects of our point of view in seeing different dimensions.
I understand his analogy with the ant, but then when he continues to talk about other spacial dimensions (up to six i believe) he talks about them just being extremely small loops (or similar to loops).
My problem in understanding this, is that wouldn't the loops only be three dimensional anyways?... the only difference between him showing us this TINY loop and say holding up a hula hoop is that one is unbelievably (almost :P) small... i dont really understand how these loops, which appear to me to be only three dimensional themselves, count as extra dimensions. :S

Anyone able to explain a little better??

Thanks alot,
-Spoon
( i will try find the episode on youtube and link it)

17. Jun 29, 2007

### gabee

I didn't really like this video when I saw it. In my opinion, it does a poor job of explaining the higher dimensions and the transition from one to the next.

This is a video of Carl Sagan explaining the 4th dimension which I think is a lot more useful. He examines the hypercube, the "shadow" of a fourth dimensional object in the third dimension . It's a weird concept.

Last edited by a moderator: Sep 25, 2014