• Current Events & Politics
    Welcome Guest
    Please read before posting:
    Forum Guidelines Bluelight Rules
  • Current Events & Politics Moderators: deficiT | tryptakid | Foreigner

How many dimensions are there in the universe?

the problem with that vid, imo, is that it assumes that our standard logic applies equally to greater "dimensions".
 
Another plane of existence, commonly referred to as multiple dimensions or realities, essentially an infinite number of universes all taking up the same exact space. As far as i know, this is a relatively widespread belief among the scientific community, and i have heard that its been basically proven, however i haven't done much research on the topic. I have heard this from multiple sources, some being scientists on the history/discovery/ etc. channels.
 
there's not infinite parralel universes, only two. this one and the cowboy one.
 
Impacto Profundo said:
dear dr zorn,
big fan, long time reader, upteenth question:
wouldn't a far more simpler example of the mathematician's definition of "dimension" be something like: a cube has 3 dimensions, its colour can be assigned a number to describe it mathematically. that number is a 4th dimension.
??
layly forever
-impacto
Click to expand...

Sort of. Basically, the dimension of a space (or object) is the number of independent continuous numbers needed to specify a point in it. Color is useful to visualize an extra dimension, but you have to use it right. Let's imagine that we can describe colors with one continuous number -- that works if we restrict ourselves to say the colors of the rainbow.** Then the combination of position in space & color forms a 4-D space.

Then if you just have a cube that has one color everywhere in it, that's still a 3-D object, albeit in a 4-D space. Think about it in terms of coordinates (x,y,z,color). Say the cube is blue. Then there's our cube at (1,1,1,blue), and (1,0.9,0.9,blue), and so on, but never at (anything,red). It's like something on a 2d (x,y) graph which only exists at y=2: that's a straight 1-D line. Even if you let the cube be different colors at different places, it's still only a 3-D object.

To get a 4-D object in this (x,y,z,color) space, you have to take the 3-D cube and let it have ranges of colors at each and every point in space. So imagine a cube that exists for all colors in the red-orange-yellow range, but no others. That's a 4-D hypercube. If you start in the center of the hypercube you can move in the left or right directions and still be inside it... And you can also move in a reddish or yellowish direction and still be inside it. :)

A solid 3-d object with one color at each point give you a 3-d object living in a 4-d space, but not a true 4-d object.

-----

** The colors available to human perception actually form a 3-dimensional space. That's because we see colors with 3 different types of cones. So, looking at a point, we can describe how it looks to us color-wise with 3 numbers: how much it stimulates the first cone type, how much it stimulates the second, and how much it stimulates the third. (One dimension corresponds to total brightness, so you could say color is 2-dimensional if you define it not to include brightness.)

That's just one choice for the 3 numbers, the "basis", to use. You can also use other sets of numbers: like amounts of red, green, and blue. Or "hue", "saturation", and "lightness." Etc. The 3-dimensionality of the color space is why there are normally 3 different cables for video signals (like Y, Pb, Pr) and 3 controls in color-pickers.
 
i think i see what you mean. a single colour has no "length" to it. cool :)

the confusion in your original post comes in the distinguishing of horizontal and vertical as different to height and width (of the screen/window).

but even irrespective of this, i have a strong feeling that the OP was not referring to a mathematician's dimensions.
 
Just because you don't understand it doesn't mean it's wrong
Click to expand...
err. i'm aware of that

however, most of us try to understand with our limited capacities

sometimes, we know that we're lost because a topic demands more knowledge or intelligence than we have

other times, we see flaws in an explanation

so, although i of course may be wrong, i don't think that i didn't understand the video but that i understood why it was incorrect

i'm not going to watch it again because i was enough convinced last time not to spend time on it again
so let someone who thinks she's intelligent enough give her opinion on this

And it takes ZERO shortcuts
Click to expand...
because you don't notice them doesn't mean they're not there :)
 
^It takes the same step in every increment, so I don't see how a "shortcut" is possible. Why don't you point out the shortcuts to me if you're so sure they're there...

All it is is an explanation of how our universe could potentially be only a "thread" through a much larger existence, potentially including "alternate realities" or objects/beings that we can't experience because of the form of space/time/our existence/whatever, which is a concept or possibility included in many theories of the universe. It's an exercise to understand that concept, nothing more, nothing less, and I find it extremely effective.
 
don't be a reggie, veggie! just watch the damn viddi-yo one more time so that you can refresh on your specific objections....already!
 
vegan said:
so, although i of course may be wrong, i don't think that i didn't understand the video but that i understood why it was incorrect

i'm not going to watch it again because i was enough convinced last time not to spend time on it again
Click to expand...
Yeah... it's sort of crazy. Everything up through 4-d was fine, though they neglect to mention that time is weird -- it's not quite like the spatial dimensions.

This business of the "5th dimension" being "alternate futures" or "alternate timelines" is total nonsense, though. You can certainly talk about alternate universes/timelines, if you want; there's even a certain amount of physical plausibility in it thanks to the apparent randomness of QM. But it has nothing to do with extra spatial dimensions! It makes no sense to talk about "alternate timelines" being an extra fifth dimension. To even say that and have it be a meaningful statement, you need to assume that, first, all possible timelines can be labeled by a single number (that's to have one dimension -- if you needed two numbers to label timelines, you'd be talking two dimensions). For example, if you assume that the total mass of the Big Bang could have been anything, but everything else was fixed, then you could speak of a one-dimensional space of possible 4-d universes. It still is rather silly to stick this possibility dimension on to the spacetime dimensions -- it's something totally different.

Similarly, if you want to imagine a big higher-dimensional space where various 4-d worldlines of the universe branch out into possible universes, you can. But that's what you're doing -- imagining a space where you could visualize that. The extra dimensions of this imaginary space are not going to have anything to do with the physical dimensions of the universe; they're another thing entirely. It's like drawing a family tree on a sheet of paper: when you arrange things horizontally, you're not drawing another dimension of space, you're just the direction to organize information.

I don't even know what happened to the "6th" dimension in his talk; he seems to have more or less jumped over it entirely. And from there it just sort of loses its connection with real dimensions entirely; he's just talking about stuff and counting up to ten while he does it.

The 10 dimensions of many string theories are completely unrelated to this stuff. Those 10 dimensions are ordinary, normal dimensions -- 9 spatial ones and 1 time one. The spatial dimensions include our usual 3 ones plus 6 "extra" ones. The only difference between those 6 and the normal 3 is in the overall shape of space. The 3 dimensions of our universe are either infinite, or at least really, really big. If they aren't infinite, we could travel straight in some direction and end up back to where we started, and we could see ourselves (our backs) if we looked far away enough. The extra 6 dimensions, in string theories, are not only finite and wrapped up like this, but they're also so small we "take up" the entire way around the dimension. (Alternatively, we're stuck on a 3-space-dimensional brane inside the 10 dimensions.) But they're still just space dimensions, like the 3 ordinary ones. Nothing to do with alternate realities, timelines, etc., and all that.

(It's actually surprisingly easy to do physics in a world with more than 3 dimensions. Much easier than trying to visualize living in it. The # of dimensions shows up in the math as how you label points -- (time,x,y,z) for 3 space+1 time dimension just becomes (time,x,y,z,w) with 4 space dimensions+1 time. You just make that change and that's about it. In string theory, it turns out you have big problems if the number of dimensions is most anything other than 10 or 26, and the 26-dim theories have their own issues. Hence the assumption that you have 10 dimensions; it's the only way string theories work. The extra dimensions are also convenient for other reasons: first, it's long been known that you can re-phrase gauge theories of particle physics in terms of gravity acting in extra spatial dimensions. Second, the hope was that the different ways strings could "wrap around" the extra dimensions could explain the different types of observed fundamental particles.)

The video Trish posted -- http://www.youtube.com/watch?v=uDaKzQNlMFw -- is much better. It's basically correct in talking about the geometry of 4-d space -- how it relates to 3-d space, ways to visualize how 4-d entities would appear, etc.
 
Last edited:
:) thank you for saving me time on 2 points

- watching it again and trying to express what i felt was incorrect
- nobody would have really paid attention anyway whereas they'll listen to you
 
Does anyone know about this idea behind the 26 dimensional folded torus? Supposedly it's supposed to have the maximum amount of symmetry possible, and therefore it's the most likely shape of the universe.
I would really appreciate it if someone could elaborate on this idea because I heard a physics professor mention it once, but he didn't go into detail at all.
 
So seriously no one knows about the 26 dimensional torus thingy? I'm bumping this. This is the first thread I've intentionally bumped in my life, but this is eating away at me.

I have this random memory of a physics professor, and I have this crazy idea that I can't even hope to visualize. That's all I'm going on here. I was hoping some of people who go to colleges slightly more reputable than my community college would be able to help me out.
 
^^^ Not sure what you're referring to; without more info I can't guess what they were getting at.

The only related context I know of where 26 comes up is in bosonic string theories. (That doesn't mean there aren't others that I haven't heard of!) Basically, you can write string theories in terms of "fermionic" strings or "bosonic" strings. Those terms basically tell you how things behave when there's more than one: two fermions can't exist in the same state (this is called the Pauli exclusion principle), whereas as many bosons as you want can exist in the same state. Ordinary electrons are an example of a fermion, light (photons) is an example of a boson.

My understanding is that technical considerations limit the number of dimensions string theories make sense in. If you want to avoid serious problems ("anomalies") in the theory, you need to have 10 spacetime dimensions for fermionic string theories, and 26 dimensions for bosonic string theories. However, I've heard that bosonic string theories run into other problems, and so they're generally not thought to be plausible.
 
You must log in or register to reply here.
Top