Distinguishing Einstein Cartan from GR: Experiments

In summary: It's a review paper that discusses some of the alternative theories of gravity that are in competition with GR and discusses how some of them predict different types of experimental signatures. The paper does not mention torsion, but I think it's worth mentioning that some of the theories that predict torsion as a possible GR violation also predict that the BH collapse "bounces" in Einstein-Cartan theory.
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Dale
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Are there any experiments either already performed or even simply proposed that could be used to distinguish Einstein Cartan gravity from GR?

My current understanding is that they are the same in vacuum, and only differ in matter. In matter the Einstein Cartan metric can have torsion, unlike the GR metric, but in vacuum they agree. Because of the way spin is related to torsion in Einstein Cartan and how important spin is in QM, it seems like that might be a viable candidate for GR violations.
 
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I'm not aware of any observation of torsion yet. It's difficult, because all our tests of GR vs. alternative theories of gravitation rely on huge (astronomical) macroscopic objects. So spin doesn't play a role but only macroscopic descriptions of matter (aka hydrodynamics) and the electromagnetic field, which in the gauge approach to gravity a la Kibble lead to standard GR.
 
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The University of Washington gravity guys tried to build a high angular momentum source/target. It was a mix of two materials magnetized in opposite directions, but one had more spin than the other. This would allow them to test spin-dependent gravity. I don't know how far they got with this.

Even so, this device was many tens of orders of magnitude less sensitive than they would need to distinguish GR from Einstein-Cartan.
 
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vanhees71 said:
I'm not aware of any observation of torsion yet. It's difficult, because all our tests of GR vs. alternative theories of gravitation rely on huge (astronomical) macroscopic objects. So spin doesn't play a role but only macroscopic descriptions of matter (aka hydrodynamics) and the electromagnetic field, which in the gauge approach to gravity a la Kibble lead to standard GR.

In neutron stars the spins align resulting in a total big spin. That should result in some modification in the state/equilibrium equation of the star, I think.
 
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Poplawski writes a lot about Einstein-Cartan theory. https://www.sciencedirect.com/science/article/pii/S0370269310011561 has a high citation count, it may or not be helpful. Unfortunately, I think Poplawski focuses on the aspect of the theory that predicts that BH collapse "bounces" in Einstein-Cartan theory, which may not be the sort of experimentally testable prediction you're looking for.
 
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FAQ: Distinguishing Einstein Cartan from GR: Experiments

What is the difference between Einstein Cartan and General Relativity (GR)?

Einstein Cartan theory is an extension of GR that includes the concept of spin, while GR does not. Spin is a property of fundamental particles that determines their angular momentum and can affect the curvature of spacetime.

How can we distinguish between Einstein Cartan and GR experimentally?

One way to distinguish between the two theories is through experiments involving the behavior of spinning particles. In Einstein Cartan theory, the spin of a particle can affect the curvature of spacetime, leading to observable effects that differ from those predicted by GR.

Are there any experimental results that support Einstein Cartan over GR?

There are currently no definitive experimental results that prove the superiority of Einstein Cartan theory over GR. However, some experiments, such as the Gravity Probe B mission, have provided evidence that supports the inclusion of spin in the theory of gravity.

Can Einstein Cartan theory explain phenomena that GR cannot?

Yes, Einstein Cartan theory can potentially explain some phenomena that GR cannot, such as the origin of dark matter. The inclusion of spin in the theory allows for additional effects that may account for the observed behavior of matter in the universe.

Is Einstein Cartan theory widely accepted in the scientific community?

Einstein Cartan theory is still considered a theoretical concept and has not been widely accepted by the scientific community. It is still an area of active research and further experimental evidence is needed to fully validate the theory.

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