# Questions tagged [equivalence-principle]

In general relativity, the equivalence principle is the equivalence of gravitational and inertial mass, along with the observation that the gravitational "force" experienced on a massive body is the same as the pseudo-force experienced by an observer in a non-inertial (accelerated) frame of reference.

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### Equivalence principle(s) and geodesic equation(s)

The equivalence principle (EP) is often stated in many different forms, sometimes leading to different interpretations. To make things easier for beginners to understand, I find it useful to give a ...
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### Connection between pseudometric and Einstein elevator

I have a hard time understanding GR. I understand a lot (from a math point) about (pseudo)Riemannian manifolds, and I also learned about Einstein's elevator thought experiment. So let me elaborate: ...
1 vote
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### Equivalence principle and gravitons

If gravitons exist, are they always detectible in any frame? I'm asking because if I'm in a freely falling frame in a uniform gravitational field, and I detect gravitons, I will no longer be able to ...
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### Gravity is not a Force? [duplicate]

I don't know much about this topic, but I read something saying that gravity is not a force using an example of inertial observation. I started thinking about the topic again when I was researching ...
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### What will I feel if I experience a force in an accelerating frame of reference?

If I am in an inertial frame of reference, and I experience a force, what will happen is that I will accelerate relative to this inertial frame of reference. Say I am 60 kg and the force is 5 N and ...
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### On quantization of gravitational potential?

Imagine I am doing Einstein's famous thought experiment: I'm in a lift and I'm asked to do local experiments to determine if I am accelerating in a non-inertial reference frame or in some ...
1 vote
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### Equivalence Principle in Newtonian Physics vs GR: A Thought Experiment

I have a question regarding the equivalence principle as it applies in Newtonian Physics and General Relativity. Consider a thought experiment involving a free-falling elevator. Inside the elevator, ...
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### What if the linearized gravity equation was the fundamental equation instead of the full Einstein Field Equations?

In Wald's "General Relativity," he discusses two key ideas that motivated Einstein to develop the theory of general relativity: The Equivalence Principle: All bodies fall the same way in a ...
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### How the equivalence principle leads to the idea of curved spacetime? [duplicate]

In wikipedia https://en.wikipedia.org/wiki/Equivalence_principle, there are three forms of equivalence principle ( equivalence of gravitational and inertial mass ) : Weak version (Galilean) : The ...
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### If gravity is fictitious force why we search for gravitons? [duplicate]

If gravity is fictitious force why we even search for gravitons? I mean, centrifugal or coriolis force don't have carriers, because these forces dont exist.
1 vote
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### Geodesic equation and inertial reference frame

When your covariant derivative of your 4-velocity is zero, you are in geodesic. Now, what if I measure your 4-velocity from a non-inertial reference frame, and see that it is constant with respect to ...
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### Equivalence principle near a black hole

At every spacetime point, there is a locally inertial frame in which the effect of gravitation is absent. Can this point be taken near the center of a black hole?
1 vote
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### Does a metric theory of gravity plus torsion violate the equivalence principle?

I have read that the Einstein-Cartan theory introduces torsion into general relativity in a way that produces coupling between gravity and the spin of particles. Then, the gravitational field is able ...
1 vote
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### Why does general relativity assume that the torsion is equal to zero?

I do not understand why the torsion is set equal to zero in the general theory of relativity. The geodesics would be the same. Is there even a way to test it? Pg 250 from the 2017 edition of MTW says ...
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### Field of Inertial Forces

Although inertial forces are just our mathematical creation to help apply Newton's law even in non-inertial frames, can we assume or is it (mathematical proof) that inertial forces also create its ...
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### Are objects in an uniform field inertial?

It is currently understood that gravity is not actually a force, and a fact that is often used to show this is that an object in free fall doesn't "feel" that it is accelerating and is thus ...
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### When doing general relativity in practice, how do we choose the appropriate manifold describing the scenario?

The theory only deals with the local curvatures, not the global topology. Hence any manifold with an allowed metric is allowed. These can be infinitely many, especially for negative curvature space-...
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### How is the intensity interpretation of Bohr's correspondence principle equivalent to the frequency interpretation?

The frequency interpretation of Bohr's correspondence principle seems obvious, given that a photon emitted after a dexcitation of an electron has to have the frequency that corresponds to the ...
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