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Questions tagged [kaluza-klein]

Kaluza-Klein theory is a classical theory that unifies gravity and electromagnetism by showing that general relativity in 5-dimensions reduces to the equations of 4-dimensional general relativity and the Maxwell equations in 4 dimensions.

theory is a classical theory that unifies gravity () and electromagnetism (). Kaluza - Klein theory shows that in 5 dimensions is equivalent to plus in 4-dimensions.

is an extension of which also unifies the weak force and the strong force, and with .

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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 supporting a fourth dimension?
George Edison
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Does Kaluza-Klein theory successfully unify GR and EM? Why can't it be extended to the Standard Model gauge group?

As a quick disclaimer, I thought this might be a better place to ask than Physics.SE. I already searched there with "kaluza" and "klein" keywords to find an answer, but without luck. As background, I've been reading Walter Isaacson's biography of…
Warrick
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Compactifying on a circle and the exchange of R and NS sectors

I've noticed a general phenomenon in compactifying on a circle where if you start with, say, an NS field, then the KK fields with an index along the circle will be in the R sector, and those without will of course remain in the NS sector. I am…
Ryan Thorngren
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Geometric interpretation of Electromagnetism

For gravity, we have General Relativity, which is a geometric theory for gravitation. Is there a similar analog for Electromagnetism?
Mahl-Deneb
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Could mass just be light moving in another dimension?

Could mass just be perceived as light moving along a geodesic through an additional spatial dimension (either invisible or somehow curled up into itself)? Since the light would be moving in another dimension, to us its velocity will be less than the…
Tachyon
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How can two-time theories be compactified to 3+1 without any Kaluza-Klein remnants?

I have recently been looking into the two-time theories and the implied concepts. For me this seems slightly hard to grasp. How can I see the basic concept in this theory in a fundamental way based on its implied interaction with normal 3+1…
Argus
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Heterotic string as worldvolume theory of two coincident 9-branes in 27 dimensions?

The heterotic string is a combination of right-moving excitations from a $\mathrm{D} =10$ superstring and left-moving excitations from a $\mathrm{D} =26$ bosonic string, with the left-movers behaving as if the extra 16 dimensions are compactified.…
Mitchell Porter
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The difference between The Dilaton and The Radion?

I have read this question on the Dilaton, but I am a little confused with the distinction between the Dilaton and the Radion. I definitely have the feeling that these two scalar fields are different particles. I am fimiliar with the Diliton being…
Flint72
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Does Kaluza-Klein Theory Require an Additional Scalar Field?

I've seen the Kaluza-Klein metric presented in two different ways., cf. Refs. 1 and 2. In one, there is a constant as well as an additional scalar field introduced: $$\tilde{g}_{AB}=\begin{pmatrix} g_{\mu \nu}+k_1^2\phi^2 A_\mu A_\nu & k_1\phi^2…
Jold
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Measurement of kaluza-klein radion field gradient?

I've been very impressed to learn about kaluza-klein theory and compactification strategies. I would like to read more about this but in the meantime i'm curious about 2 different points. I have the feeling that there are no precise answers to these…
lurscher
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Why would a particle in an extra dimension appear not as one particle, but a set of particles?

I was reading an article in this months issue of Physics World magazine on the three main theories of extra dimensions and stumbled across something I didn't quite understand when the author began talking about detecting particles in extra…
ODP
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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 theory says that there are 9+1 dimensions; and M…
funtime
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Betti multiplets in Kaluza Klein compactifications

It is well known that if the compactification manifold of a supergravity theory has non-zero Betti numbers, this may lead to the so called Betti multiplets in the spectrum of the low dimensional theory. A famous example is compactification of IIB…
user24155
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Is classical Kaluza Klein theory stable or not?

Set Up In the original classical Kaluza Klein theory, you have a $d+1$ dimensional manifold where one space dimension is a circle $S^1$. In the "low energy limit," none of the metric components depend on this compact dimension. This independence of…
user1379857
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The action of the Kaluza–Klein reduction (Chapter 4 of "D-branes (Clifford Johnson)")

In the first part of Section 4, the author gives \begin{equation} S = \frac1{16\pi G^N_{(5)}}\int(-G_{(5)})^{1/2}R^{(5)}d^5x = \frac1{16\pi G^N_{(4)}}\int(-G_{(4)})^{1/2}\Big(R^{(4)} - \frac32\partial_\mu\phi\partial^\mu\phi -…
KoKo_physmath
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