# Rotating Particle - Violation of Einstein Equivalence Principle

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How does adding rotation to a freely falling particle violate the Einstein equivalence principle?

I realize there is a similar post here:

An example of a theory that respects the Weak Equivalence Principle but violates the Einstein Equivalence Principle

but I failed to understand the response after reading it a number of times.

This post imported from StackExchange Physics at 2016-11-08 14:03 (UTC), posted by SE-user Optimus Prime
Just to clear, because I have a related question, not an answer, is this the extract that is the problem for you We could imagine a theory of gravity in which freely falling particles begin to rotate as they moved through a gravitational field. Then they could fall along the same paths as they would in an accelerated frame (thereby satisfying the WEP), but you could nevertheless detect the existence of the gravitational field (in violation of the EEP). Such theories seem contrived, but there is no law of nature that forbids them.

This post imported from StackExchange Physics at 2016-11-08 14:03 (UTC), posted by SE-user CountTo10
Yes, it's from Carroll.

This post imported from StackExchange Physics at 2016-11-08 14:03 (UTC), posted by SE-user Optimus Prime
Wouldn't the gravitational field have to have torsion for this to happen, if it was GR?

This post imported from StackExchange Physics at 2016-11-08 14:03 (UTC), posted by SE-user Bob Bee
Could you explain more please @Bob?

This post imported from StackExchange Physics at 2016-11-08 14:03 (UTC), posted by SE-user Optimus Prime

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