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.
Questions tagged [equivalence-principle]
602 questions
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If gravity is a pseudoforce in general relativity, then why is a graviton necessary?
As far as I’m aware, gravity in general relativity arises from the curvature of spacetime and is equivalent to an accelerated reference frame. Objects accelerating in a gravitational field are in fact inertial and are moving through geodesics in…
Thatpotatoisaspy
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Why does a free-falling body experience no force despite accelerating?
Note: For the purposes of my question, when I refer to free fall assume it takes place in a vacuum.
From my (admittedly weak) understanding of the equivalence principle, falling in a gravitational field is physically indistinguishable from floating…
AdamJames
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Does quantum mechanics violate the equivalence principle?
I have a question about equivalence principle in quantum mechanics.
Consider a Schroedinger equation under gravitional field
$$\left[ - \frac{1}{2m_I} \nabla^2 + m_g \Phi_{\mathrm{grav}} \right]\psi = i \partial_t \psi \tag{1} $$
where $m_I$ and…
user26143
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If I drop a ball in an accelerating rocket, will it bounce? If so, how?
Einstein's equivalence principle says that you cannot distinguish between an accelerating frame or a gravitational field. However, in an gravitational field, if I drop a tennis ball, it will bounce, but I don't think that it will in the accelerated…
user189508
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Why did we expect gravitational mass and inertial mass to be different?
I've read many times that the fact that gravitational mass is equal to inertial mass (as far as we can tell) used to be a puzzle. I believe that Einstein explained this by showing that gravity is itself just an inertial force.
When I first…
user1551817
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Why can’t gravitons distinguish gravity and inertial acceleration?
If gravitons mediate the gravitational force, couldn’t the detection of gravitons by an observer be used to distinguish whether they are experiencing gravitational acceleration vs. inertial acceleration, contradictory to general relativity? If this…
Jack Edwards
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Is there a fundamental reason why gravitational mass is the same as inertial mass?
The principle of equivalence - that, locally, you can't distinguish between a uniform gravitational field and a non-inertial frame accelerating in the sense opposite to the gravitational field - is dependent on the equality of gravitational and…
ravithekavi
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Is floating in space similar to falling under gravity?
In the case there is no air and your eye are closed,
then does falling from the sky under gravity have the same feeling as floating in space? Can our body feel that we are accelerating without the air hitting us.
If not how are they different?
Also…
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Why do objects follow geodesics in spacetime?
Trying to teach myself general relativity. I sort of understand the derivation of the geodesic equation $$\frac{d^{2}x^{\alpha}}{d\tau^{2}}+\Gamma_{\gamma\beta}^{\alpha}\frac{dx^{\beta}}{d\tau}\frac{dx^{\gamma}}{d\tau}=0.$$ which describes "how"…
Peter4075
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Can general relativity be completely described as a field in a flat space?
Can general relativity be completely described as a field in a flat space? Can it be done already now or requires advances in quantum gravity?
Anixx
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Would it help if you jump inside a free falling elevator?
Imagine you're trapped inside a free falling elevator. Would you decrease your impact impulse by jumping during the fall? When?
user145
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If gravity is not a force, then how come gravitational assists work?
I have learned about general relativity and how gravity arises from spacetime curvature. And I have always been taught that gravity is not a real force in the sense that
$$\frac{dp}{dt} = 0$$
And from this, gravity does not accelerate objects while…
Tachyon
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Does a person inside a falling bus fall to the front of it?
So I was watching Final Destination 5 and something caught my attention. There's a part where a bridge collapses and everything falls apart, so there's this bus that has a person inside (unaware of what was happening) and it falls vertically (the…
R Los
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Flywheel half-way through the event horizon of a black hole vs the equivalence principle
Imagine I am inside an isolated rocket of arbitrarily small size, and I have a spinning flywheel right next to me. Now suppose my rocket passes through the event horizon / Schwarzschild radius of a simple Schwarzschild black hole.
By the equivalence…
MaximusIdeal
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Do accelerated charges radiate or not?
This questions has been asked all over the net (here included) but I can't find a satisfactory answer or discussion. Some say it does not radiate if the acceleration is caused by a uniform gravity field. Some even say that it radiates in linear…
Physics_maths
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