So, I understand that there are multiple theories describing how many dimensions we have in the Universe. However, I found this very well made (10 minute) video describing all 10 dimensions. At the end it puts up a disclaimer basically saying that it’s a departure from traditional interpretation, although it seemed to make quite a bit of sense.
My question is not whether the theory is “correct”, but whether the video outlines a well-accepted/scientifically sound theory or a wild controversial departure from String Theory and more mainstream attempts to describe multiple dimensions. And if so (in as plain a language as possible) how?
The first, second and third are a standard way to explain spatial dimensions to a lay person (which I am).
The fourth is a standard way to explain how time can be thought of as a dimension–but it’s not a good explanation of what it would mean, in general, for there to be a fourth dimension. A temporal dimension is just one (special) kind of dimension.
The fifth dimension in the video is a nice metaphor if you start with the idea of the fourth dimension as temporal, but does not, to my knowledge, reflect how physicists model a fifth dimension (much less mathematicians.)
The sixth dimension seems to me to simply go off the rails but I didn’t take too long to puzzle it out. Maybe someone can make sense of it.
It’s not controversial for the simple reason that everyone who works in physics or math all agree that it’s wrong. Nor is it all that wild: There are plenty of armchair academics out there who come up with completely unsupported things.
Can you explain to me how and why it’s wrong? The principle appears sound to a lay person like myself (especially the whole “folding” thing to get the ant to jump to a different point in the 2nd dimension).
Thanks, MikeS. That link sufficiently answered my question. I especially liked this comment:
Any chance you (or anyone else out there) has a link to a video or page that accurately describes multiple dimensions in a way that is in agreement with mainstream science? Again, I know that there are multiple theories on this, some more controversial than others. I’m looking to get the most widely accepted viewpoint(s).
Oh, that’s easy. Just like the second dimension is perpendicular to the first, and the third dimension is perpendicular to the second and to the first, the fourth dimension is perpendicular to all of the first three, the fifth dimension is perpendicular to all of the first four, and so on. Any method of mathematically describing the first three dimensions can be extended to describe any number of dimensions.
That implies (to me) infinite or near infinite dimensions. Is this the case?
And is there a consensus as to what the dimensions are? Obviously, the first three are width, height, and depth. Is the fourth one time? What’s the fifth one? Etc…
There’s a three-hour Nova program, The Elegant Universe, which explains current thinking (at least as viewed from the superstring paradigm) about as well as can be done without lots of math; you can watch it in its entirety here, or see Brian Greene giving a 20-minute talk about the concepts here.
You can model any number of dimensions, all the way up to infinity.
How many dimensions there actually are is an empirical matter that hasn’t been settled.
Our best theories right now model the world as having three spatial dimensions and one temporal dimension. (Temporal dimensions behave differently from spatial dimensions.)
In string theory, the theory is that there are 10 spatial dimensions and one temporal dimension. Seven of those spatial dimensions curve very tightly–so tightly that there are no distances in those dimensions larger than, IIRC, the plank length. (The plank length is, IIRC, the smallest measurable length.)
I have heard here and there of attempts to model the world as having a fifth macro-spatial-dimension in order to unify the electromagnetic and gravitational forces, but I think those have so far turned out not to work empirically.
If there are more than three spatial dimensions, what the additional dimensions are is just exactly the same kind of thing as length, width and depth. The additional dimensions are just directions along which objects can travel back and forth. They’re just “curled up” so small they are, basically, indetectable.
Here’s a follow-up question: Length, width and depth all measure distance. Time could easily be argued as a measure of distance (that we measure with clocks -right?). In the theoretical sense, should all dimensions be a measurable distance? If we were 10th dimensional beings, should we be able to take out a ruler (or whatever device) and measure out the 7th dimension of our coffee table?
She tries very, very hard to make it all understandable, with lots of analogies and stories and diagrams. It’s still a slog in places.
I wouldn’t attempt to try to cut any of it down to a paragraph, but a couple of points are relevant.
The size of the hidden dimensions can be much larger than the Planck length. Randall’s own paper gives a length of 10[sup]16[/sup] longer. Other theories make it as large as a millimeter, though experimentation brought that down to a tenth of a millimeter. And it’s ten-dimensional superstring theory with strong coupling that is dual to eleven-dimensional supergravity at low energies.
In theory, absolutely. It may be much more complicated that this. Randall talks about branes, which are lower-dimensional spaces that exist in these higher-dimensional ones. Theory tells us that open-ended strings can be thought of as having one end stuck to a brane, thereby creating all the particles we know. Gravity is a closed-loop string so it can travel freely. That may also answer why gravity is measurably so much weaker: there is a four-dimensional strongbrane and a weakbrane connected through a fifth dimension and we live on the weakbrane.
Nitpick: The Planck length is just a reasonable SWAG as to what the smallest measurable distance might be. Nobody would be at all surprised if the actual smallest distance turned out to be half the Planck length, or pi times it, or something like that. It may also be that the smallest measurable distance might have no particular resemblance to the Planck length, or that there is no smallest measurable distance.
On another note, the numbering of dimensions is purely arbitrary. It doesn’t really make sense to ask “what’s the fifth dimension”, since that could be any of them. You could say that the first three dimensions are width, height, and length, instead of length, width, and height, or you could say that those are dimensions 3, 7, and 8 with the “extra” dimensions (the ones we don’t notice) between them in the list.