Kaluza-Klein Theory Q&A: Inducing EM Field & Ricci Tensor

In summary, Kaluza-Klein theory suggests that a gravitational field could induce an electromagnetic field in a universe with five dimensions, where the fifth dimension is curled up into a tiny circle at each point of four-dimensional spacetime. The Einstein Field Equation for gravity in five dimensions can be split into two pieces, one being the Einstein Field Equation for gravity in four dimensions and the other being Maxwell's Equations for electromagnetism in four dimensions.
  • #1
lightfire
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I know this is technically not orthodox GR, but it is closely related. I was reading about Kaluza-Klein theory, but I don't completely understand it. Under what circumstances would could a gravitational field induce an electromagnetic field under this theory. Also, how is the Ricci tensor different?
 
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  • #3
lightfire said:
Under what circumstances would could a gravitational field induce an electromagnetic field under this theory.

Under the circumstance that the universe has five dimensions, not four, and the fifth dimension is curled up into a tiny circle at each point of what we call four-dimensional spacetime. Then the Einstein Field Equation for "gravity" in five dimensions can be split up into two pieces: one is the Einstein Field Equation for gravity in four dimensions; the other turns out to be Maxwell's Equations for electromagnetism in four dimensions.
 

Related to Kaluza-Klein Theory Q&A: Inducing EM Field & Ricci Tensor

What is Kaluza-Klein theory?

Kaluza-Klein theory is a mathematical model that attempts to unify the fundamental forces of nature by adding an extra dimension to the traditional 4-dimensional spacetime. It suggests that gravity and electromagnetism can be described by a single geometric framework.

What is the significance of inducing an electromagnetic field in Kaluza-Klein theory?

Inducing an electromagnetic field in Kaluza-Klein theory is significant because it provides a way to explain the existence of electromagnetism within the framework of a unified theory. This theory proposes that the extra dimension is curled up and small, and the electromagnetic field arises from the vibrations of this extra dimension.

What is the Ricci tensor in Kaluza-Klein theory?

The Ricci tensor is a mathematical object that describes the curvature of spacetime in a multi-dimensional space. It is a crucial component in the mathematical formulation of Kaluza-Klein theory and is used to describe the gravitational and electromagnetic fields.

How does Kaluza-Klein theory relate to string theory?

Kaluza-Klein theory is considered a precursor to string theory, as it also attempts to unify the fundamental forces of nature. However, string theory goes beyond Kaluza-Klein theory by proposing that the extra dimensions are not just curled up but exist as tiny strings.

What evidence supports Kaluza-Klein theory?

Currently, there is no direct evidence that supports Kaluza-Klein theory. However, some of its predictions, such as the existence of a hidden extra dimension and the unification of gravity and electromagnetism, have been incorporated into other theories, such as string theory. Additionally, Kaluza-Klein theory provides a compelling mathematical framework for unifying the fundamental forces of nature.

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