The dimensions tag has no wiki summary.
13
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3answers
516 views
Can light exists in $2+1$ or $1+1$ spacetime dimensions?
Spacetime of special relativity is frequently illustrated with its spatial part reduced to one or two spatial dimension (with light sector or cone, respectively). Taken literally, is it possible for ...
3
votes
2answers
660 views
Why does string theory require 9 dimensions of space and one dimension of time?
String theorists say that there are many more dimensions out there, but they are too small to be detected.
However, I do not understand why there are ten dimensions and not just any other number?
...
-1
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1answer
386 views
Total Number of Dimension in universe?
I read somewhere that there are many dimensions and each diff, i read the whole article but i kinda forgot it, so my question is how many dimensions are there???
0
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0answers
25 views
How can we know the size of a dimension? [duplicate]
Possible Duplicate:
Measuring extra-dimensions
I was watching a layman's documentary and it said:
"The 11th dimension is incredibly small, like a long tube about $10^-30m$ in diameter".
...
-5
votes
1answer
216 views
What do scientists believe about existence in dimensions? [closed]
I couldn't really think of a suitable question title, I'm not sure if it's completely related or not.
But this is as far as I know (well, I thought it all up last night and it seemed extremely ...
0
votes
1answer
343 views
Regarding possibility of infinite Dimensions
Recently i was taking a look at a video explaining the existence of fourth dimension and thereupon that infinite dimensions are possible. Also it showed that what Einstein told about time being a ...
5
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2answers
95 views
Is the “dimension” in dimensional analysis the same as the “dimension” in “three spatial dimensions”?
When we talk about the dimension of a quantity (e.g. the dimension of acceleration is$[ L \ T ^ {-2}]$) are we talking about the same "dimension" as when we talk about three dimensional space?
Are ...
3
votes
2answers
197 views
About space-time and its four dimensions
I explained to someone I know about General Relativity (as much as I know).
He said that he didn't see how it could be correct.
He argued:
How is 4-dimensional space-time space different to ...
3
votes
2answers
495 views
Why does the force of gravity get weaker as it travels through the dimensions?
Some theories predict that the graviton exists in a dimension that we of course can't see, and that is why the force of gravity is so weak. Because by the time gravity has got from the dimension in ...
2
votes
1answer
124 views
Why do Calabi-Yau manifolds crop up in string theory, and what their most useful and suggestive form?
Why do Calabi-Yau manifolds crop up in String Theory? From reading "The Shape of Inner Space", I gather one reason is of course that Calabi-Yaus are vacuum solutions of the GR equations. But are there ...
2
votes
2answers
727 views
Electric potential due to a point charge in Gaussian/CGS units
I learned electrostatics in SI units. In SI, the electrostatic potential due to a point charge $q$ located at $\textbf{r}$ is given by
$\Phi(\textbf{r}) = \frac{q}{4 \pi \epsilon_0 |\textbf{r}|}$.
...
1
vote
1answer
839 views
Why are electrons and quarks 0-dimensional?
Disregarding String Theory, which says that electrons and quarks are 1-dimensional, why are electrons and quarks 0-dimensional?
The way I look at it is that they have mass, and if we were the same ...
1
vote
2answers
236 views
What could we observe if we see a 4 dimensional object and how could it change our physics view about our universe ?
My question is little bit philosophical.
I would like to explain my ideas with a 2 dimensional universe model.
If we had lived in 2 dimensional universe like a plane, What could we observe when ...
3
votes
2answers
334 views
How can one imagine curled up dimensions?
Actually I'm learning String Theory, and one of its proposals is that there are actually 25+1 dimensions of which only 3+1 are visible to us-- and the remaining are curled up. However, superstring ...
5
votes
3answers
581 views
How can we be so sure the universe has 3 dimensions?
I'm just a layman here so please bear with me if I don't get all the words or theories by correct name or whatever. I hope it will be clear enough what my question is. Here goes:
When I read articles ...
4
votes
1answer
85 views
What is the connection between extra dimensions in Kaluza-Klein type theories and those in string theories?
This follows to some extent from a question I asked previously about the flaws of Kaluza-Klein theories.
It appears to me that Kaluza-Klein theories attach additional dimensions to spacetime that are ...
1
vote
2answers
157 views
$2+1$ dimensional physics theory of our universe?
Is there any physics theory that depicts our universe as $2+1$ dimensional?
I heard that black holes seem to suggest that the world might be $2+1$ dimensional, so I am curious whether such theory ...
4
votes
3answers
257 views
Measuring extra-dimensions
I have read and heard in a number of places that extra dimension might be as big as $x$ mm. What I'm wondering is the following:
How is length assigned to these extra dimensions?
I mean you can ...
3
votes
1answer
97 views
Scaling of Static Electric Field
The electric field of a point charge goes like $\displaystyle\frac{1}{r^2}$
The electric field of an infinite line goes like $\displaystyle\frac{1}{s}$
The electric field of an infinite plane is ...
2
votes
3answers
228 views
Can extra dimensions be too large to be observable
String theory postulates 6 extra dimension, all too small to be observed. The best description of a small dimension is that of an ant walking on a flagpole: The ant observes that the flagpole allows ...
4
votes
3answers
588 views
Why are there 4 Dimensions and 4 Fundamental Forces?
Is it a coincidence that there are four fundamental forces and four spacetime dimensions ? Does a universe with three spacetime dimension contain four fundamental forces? Can magnetism be realized in ...
1
vote
2answers
156 views
What is the relation between extra dimensions and unification of theories?
One of the most used methods in unification of theories is the use of higher dimensions. How does it actually work? If these dimensions are extremely small curled up, how does it affect the universe. ...
7
votes
3answers
736 views
Maxwell in multiple dimensions: What happens to curl?
I read this answer a while ago, and while thinking about $\nabla$, I realized something. Since the cross product can be written as a determinant, in higher dimensions we require extra vector inputs. ...
5
votes
5answers
426 views
Is time fundamentally different from space?
Note: This is a rewrite of the original question, which was titled What would time be for 2D beings?
In my current, non-physicist's understanding, every instant of our three‑dimensional world ...
2
votes
1answer
541 views
Nanotech - zero dimensional fullerene
Not really a physics junkie, and I think this is a chemistry question, but since there's no chemistry.stackexchange.com (yet) I think here is the best place.
I was just reading up on nanotech and ...
14
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2answers
485 views
Has the concept of non-integer $(n+m)$-dimensional spacetime ever been investigated by theoretical physicists?
The following image serves to aid the reader in understanding the "privileged character" of $3+1$-spacetime.
The wikipedia article on spacetime, and the sub-article "The priveleged character of ...
6
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2answers
370 views
Some questions regarding $n+m$-dimensional spacetime [duplicate]
Possible Duplicate:
Has the concept of non-integer $(n+m)$-dimensional spacetime ever been investigated by theoretical physicists?
The following image:
serves to aid the reader in ...
3
votes
1answer
455 views
How many types of chirality are there?
My question arise and is connected to the "strange" fact
that many things seem to come in pair or in number of two
similar "objects".
6
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0answers
64 views
String landscape in different dimensions
For D = 11 large (uncompactified) spacetime dimensions, the only "string theory" vacuum is M-theory
For D = 10, there are 5 vacua. Or maybe it's more correct to say 4, since type I is S-dual to ...
1
vote
1answer
245 views
A quantum particle in a box (with a catch)
I am reading Shankar's Quantum Mechanics and I am looking at the case where there is one particle inside a box, where the potential is zero inside the wall and abruptly goes to infinity outside the ...
4
votes
2answers
400 views
Consequences for causality if superluminal neutrinos were explained by extra dimensions
One suggestion for explaining superluminal neutrinos (assuming for the sake of argument that the OPERA results should hold up) is that the neutrinos have taken a route through extra dimensions, with ...
1
vote
3answers
225 views
Is there a single metric for a given system?
Let imagine a tunnel that connect two distant places at the globe (eastern-western or north-south)
There are a lot of posible "distances" or metrics, defined by maps, routes, "as the crow flies", ...
-1
votes
2answers
179 views
length, width, and time
is it possible to have length, width and time. A 2D or 1D object with the 4th dimension (although then there would not be 4 dimensions so would it b 3D?) .
26
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5answers
1k views
Is 3+1 spacetime as privileged as is claimed?
I've often heard the argument that having 3 spatial dimensions is very special. Such arguments are invariably based on certain assumptions that do not appear to be justifiable at all, at least to me. ...
8
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7answers
1k views
Why are extra dimensions necessary?
Some theories have more than 4 dimensions of spacetime. But we only observe 4 spacetime dimensions in the real world, cf. e.g. this Phys.SE post.
Why are the theories (e.g. string theory) that ...
1
vote
1answer
195 views
Could extra dimensions be or become clustered?
String theory - for example - requires extra spatial dimension. Say for example in 10 dimensional string theory, what theoretically prevents clustering of the extra 6 dimensions in 2 timeless 3 ...
11
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1answer
2k views
How to define angular momentum in other than three dimensions?
In classical mechanics with 3 space dimension the angular momentum is defined as
$\mathbf{L} = \mathbf{r} \times \mathbf{p}$
In relativistic mechanics we have the 4-vectors $x^{\mu}$ and $p^{\mu}$, ...
8
votes
3answers
557 views
Understanding counterintuitive units like s^2
One of the things I never understood but was too afraid to ask is this: how should I think of things like kg/s^2. What exactly is a square second? Square foot makes sense to me because I can see it, ...
2
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4answers
332 views
Does time have a special status in general relativity?
In a lot of laymen explanations of general relativity it is implied that the four dimensions of the space-time are equivalent, and we perceive time as different only because it is embedded in our ...
1
vote
5answers
399 views
what are dimensions?
First, discrete examples.
In a computer screen I can specify any "2D" point with just one single number
(pixel order starting count from first at upper left, and going on, left2right and up2down ...
1
vote
1answer
469 views
What is the 4th dimension? [closed]
I have heard before that the 4th dimension is time, however, another theory makes a lot more sense to me. This is that the 4th dimension is the third dimension stacked on top of each other in a ...
4
votes
3answers
324 views
Why (in relatively non-technical terms) are Calabi-Yau manifolds favored for compactified dimensions in string theory?
I was hoping for an answer in general terms avoiding things like holonomy, Chern classes, Kahler manifolds, fibre bundles and terms of similar ilk. Simply, what are the compelling reasons for ...
8
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6answers
1k views
Experimental evidence of a fourth spatial dimension?
As human beings, we observe the world in which we live in three dimensions. However, it is certainly theoretically possible that more dimensions exist.
Is there any direct or indirect evidence ...
32
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5answers
2k views
Does Coulomb's Law, with Gauss's Law, imply the existence of only three spatial dimensions?
Coulomb's Law states that the fall-off of the strength of the electrostatic force is inversely proportional to the distance squared of the charges.
Gauss's law implies that a the total flux through a ...
