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Gravity shares many of the characteristics of Yang-Mills gauge theory. For example, the affine connection plays the similar role as the gauge potential in gauge theory, the Riemann tensor plays the same role as the field strength in gauge theory. And both theories can be well described by Fiber bundle.

I know there is a correspondence between gravity and gauge theory in string theory. But as mentioned above, can't gravity just be a gauge theory itself? The similarity is so strong that I do think gravity emerging from other possibilities is extravagant such as emerging as the requirement of the vanishing of Beta function. Actually, there are indeed some physicists do think that gravity is exactly a gauge theory of Yang-Mills type with gauge group being Poincare group, but it seems that this view is generally neglected by string theorists. Please give me some convincing reasons that this similarity should not be taken seriously. Thanks very much!

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closed as primarily opinion-based by ACuriousMind, John Rennie, Kyle Kanos, CuriousOne, Martin Apr 8 '16 at 12:19

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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The similarity are strong, but the point is that treating gravity as a quantum field theory doesn't work. At best you can work with an effective field theory of the spin 2 graviton on a fixed background, and within the validity of the effective theory you can even extract predictions, for instance the quantum gravity shift to the Mercury's perihelion.

Nevertheless, gravity is perturbatively non renormalizable, so at energy near the Planck Scale the QFT breaks down.

In string theory you can find the open-closed strings scattering amplitudes relations, so it's not true that string theorists are indifferent to the idea. These relations tells you that in some sense gravity is a "squared gauge theory", at least at tree level. Indeed the gravity amplitudes are the square of the Yang-Mills ones, with the color/kinematical factors opportunely exchanged. If you want to know more about this check KLT relations, BCJ duality and Double Copy.

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