Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [equivalence-principle]

The tag has no usage guidance.

0
votes
1answer
73 views

Is it true that when you accelerate due to a non-gravitational interaction gravity is pulling you in the direction opposite to the acceleration?

We don't feel acceleration when we are only in a gravitational field due to equivalence principle as I understand it says gravity is simply inertia in spacetime. Is there any other type of force ...
1
vote
2answers
64 views

Now when we can measure gravitational field, how does the principle of equivalence hold true?

LIGO measured gravitational field waves. The whole thought experiment of Einstein, leading to ‘principle of equivalence’, assumes that there is no way to know inside the rocket that whether its ...
1
vote
1answer
65 views

Does general relativity (GR) solve mass-equivalence problem or just renames it?

It is usually said that GR solved problem of equivalence of gravitational and inertial mass. Yet, my objection is: OK, there is no gravitational mass in GR, but Einstein had to introduce mass as "...
0
votes
1answer
46 views

How does the Equivalence Principle imply that derivatives of the metric vanish in a freely falling frame?

Why do the first derivatives of $g_{\mu\nu}$ vanish in a freely falling coordinate system? I would like to start from the Equivalence Principle that for any point in spacetime there exists a locally ...
1
vote
1answer
69 views

Equivalence Principle and bending of light

Basically, the equivalence principle (EP) states that if someone is in a rocket in empty space with acceleration $g$ equal to that at the surface of the earth, any experiment he does cannot ...
2
votes
2answers
51 views

How come planets with different masses can orbit at the same velocity at the same altitudes?

Angular momentum is equal to r × p and angular momentum is also what gives planets with lower orbits a higher speed (because angular momentum is conserved). So as r decreases either m or v (p=mv) has ...
1
vote
1answer
45 views

Why acceleration due to gravity is not reliably defined?

In Sean Carroll's Spacetime Geometry, there is the following line on Page No.50 in 2014th edition: "The acceleration of a charged particle in an electromagnetic field is uniquely defined with respect ...
6
votes
1answer
83 views

Does a charge in a gravitational field make a magnetic field?

I know that general relativity unifies the electric charge with the magnetic field via relative motion. So if I accelerate a charge then anyone in another inertial frame will see a magnetic field. ...
3
votes
1answer
41 views

Detecting external 'forces' in an inertial frame

Disclaimer: Science noob here, I may not use all terms correctly. I've read somewhere of the following situation: An observer is inside a room (elevator) with no ...
1
vote
5answers
120 views

Einstein's Elevator - Constant acceleration eventually reaches $c$. Can't that be used to detect gravity vs acceleration?

Objects with mass that continuously accelerate will eventually approach $c$, but cannot exceed it. So if I find myself in an elevator, unable to determine if I'm in a uniform gravitational field or ...
1
vote
2answers
90 views

Christoffel symbol

In flat space, it is possible to find a coordinate system in which the Christoffel symbols are equal to zero at every point on the flat manifold. However, I was wondering if it is possible to find a ...
4
votes
4answers
480 views

Falling electric dipole contradicts equivalence principle?

Consider an electric dipole, with total mass $M$, consisting of charges $q$ and $-q$, separated by a distance $d$. The total mass $M$ includes the mass defect due to the negative electrostatic energy ...
0
votes
1answer
37 views

Equivalence Principle: from falling bodies to all physical processes [duplicate]

Einstein's elevator thought experiment considered that in the Minkowski space-time of special relativity, all bodies fall identically. What grounds did Einstein have to generalise this falling bodies ...
1
vote
1answer
76 views

Einstein Elevator thought experiment

Were there any background theories for Einstein's elevator thought experiment which developed the equivalence principle. Can Newton's equivalence principle (the equality of inertial and gravitational ...
1
vote
1answer
40 views

How did Einstein generalise the Einstein elevator thought experiment to conclude with the equivalence principle?

Suppose a reference frame S1 is accelerated in the x direction with a constant acceleration g. A second frame S2 is at rest in a homogeneous gravitational field which imparts to all objects an ...
1
vote
1answer
66 views

Special and general relativity

Is the light postulate in special relativity (that the speed of light is constant in all frames of reference) correct if the equivalence principle shows that light slows down in gravitational field? ...
0
votes
0answers
23 views

Why do bodies fall identically in uniform acceleration and uniform gravitational field? [duplicate]

In his reformulation of Einstein’s Elevator thought experiment, James Robert Brown (1993) says that an observer in a uniformly accelerating spaceship in space (free of gravitational effects) will see ...
1
vote
4answers
121 views

Gravity, falling bodies, and the equivalence principle

Why is that bodies in a box accelerating uniformally in space that is sufficiently removed from gravitational fields fall identically to bodies in a box located in a homogeneous gravitational field (e....
0
votes
1answer
33 views

How did Einstein use the conclusions of special relativity to reach the equivalence principle (using the Elevator thought experiment)?

Could someone please explain how Einstein used the Elevator thought experiment and the principles of special relativity to conclude that uniform accelerates creates uniform gravitational field (...
1
vote
1answer
80 views

Einstein's Elevator thought experiment and relativity

Einstein's elevator thought experiment contains the following premise: An observer in a box will see free bodies moving identically between when the box is uniformly accelerating in gravitational ...
67
votes
7answers
4k views

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 ...
8
votes
1answer
364 views

Is quantizing acceleration equivalent to quantizing gravity?

It's been said that gravity is locally equivalent to acceleration. It is also been said, that we need to quantize gravity. But doesn't that imply that this would have to be equivalent to quantizing ...
0
votes
1answer
105 views

Is the gravitational field an illusion, a by-product of geometry? [duplicate]

The principle of general covariance from the Equivalence Principle (EEP) tells us that there is no way in principle to locally distinguish between an inertial acceleration and the effects of a ...
1
vote
0answers
31 views

Experimental evidences satisfying charged particle emits radiation in gravitational field

Is there any experimental evidence exist that a charged particle at rest in gravitational field emit radiation and charged particle in free fall don't emit radiation ( According to equivalence ...
2
votes
3answers
80 views

Do centrifugal force and gravity differ in their effects on objects?

If the type of object matters, consider the human body. If the situation matters, consider standing on the inside wall of an O'Neill cylinder compared to standing on the surface of Earth. "Differ in ...
1
vote
2answers
52 views

Reason of no reaction force on a person in a lift falling freely under gravity

a person in a lift falling freely under gravity feels weightlessness because the force of reaction between the person and the plane with which he is in contact vanishes. why force of reaction vanishes?...
2
votes
2answers
157 views

Rindler Coordinates and homogeneous Gravity Field

I understood from the equivalence principle that an accelerated observer in free space is equivalent to a stationary observer in a gravitational field. As far as I understood further, this means to ...
3
votes
1answer
88 views

How does Rovelli's idea of time and gravity relate to inertia?

In "The Order of Time" (pg 12-13) Rovelli says "If things fall, it is due to this slowing down of time. (near a mass) Where time passes uniformly, in interplanetary space, things do not fall. ...
1
vote
2answers
90 views

Equivalence principle and local inertial reference frames

Local inertial reference frames are defined as follows: Pick a set coordinates for the manifold (assuming the manifold can be described by global coordinates) $\{x^i\}$ such that $g(p) = \eta$ is the ...
6
votes
1answer
121 views

Relativity of Jerk

Popular expositions of general relativity start with a thought experiment showing that it is impossible to distinguish a constantly accelerating frame of reference in a free fall from a free floating ...
1
vote
1answer
86 views

Near-relativistic car speeding over a bridge

I have read this problem / exercise (I don't remember the exact numbers, so I put my own) in William Burke's "Applied Differential Geometry" and it has always puzzled me regarding the relation between ...
0
votes
1answer
92 views

Are mass or inertia the same thing, the same properties?

I think so. But I wold like to know another opinions to confirm.
-2
votes
2answers
77 views

Can the origin of mass or inertia depend only of the gravitational field of matter? [closed]

The gravitacional field is directly proportional to mass or inertia. It doesn't have another property or field like this, with this power. I think that when we apply a force to an object, the ...
1
vote
1answer
90 views

Can an Observer Distinguish between Unruh Effect and Hawking Radiation by Measuring Temperature?

In Unruh effect, the temperature of background appears to be proportional to acceleration. On the other hand, the temperature of a black hole is inversely proportional to its mass. If the two ...
-4
votes
1answer
96 views

Does Bell's Theorem suggest both Nonlocality and “Temporal Nonlocality”? [closed]

Bell's Theorem pretty much rules out any local hidden variable theories, and any hidden variable theory that's nonlocal is just regular quantum mechanics with an extra variable thrown in. But, since ...
3
votes
2answers
155 views

Why must the worldline for a freely-falling body be straight?

If spacetime were on an xy graph, the x-axis being time and the y-axis being space, an object that is in interstellar space with no noticeable gravitational influences on it will have a worldline that ...
2
votes
2answers
121 views

How to infer from Einstein Equivalence Principle that a test particle should follow geodesic?

Einstein Equivalence Principle (EEP) states that A frame linearly accelerated relative to an inertial frame in special relativity is LOCALLY identical to a frame at rest in a gravitational ...
1
vote
1answer
82 views

Gravitational acceleration in GR

What is the meaning of gravitational acceleration $g$ in the General Theory of Relativity, given that objects in free fall experience weightlessness? Can gravitational acceleration be thought as a ...
1
vote
1answer
68 views

Equivalence principle and bending of a light ray

In some explanations of a phenomena of curved spacetime we have an example of a light ray emitted in a freely falling space ship perpendicular to the direction of a free fall. In this case, for an ...
0
votes
0answers
36 views

Equivalence Principle and Exapansion and Shear Tensor

I read in my class notes that the professor said using equivalence principle, it is always possible to choose around any point $p$, a 2-dimensional space-like neighborhood such that the expansion and ...
0
votes
0answers
77 views

Electron and gravity- equivalence principle

According to equivalence principle, we cannot distinguish gravity with inertial force. Let's assume that there is space shuttle which contain observer and electron. There is some force that is gravity ...
0
votes
0answers
22 views

Is there any gravitational time dilation for an observer at the Earth's centre of gravity? [duplicate]

The Equivalence principle lets me suppose that 'if there is no gravitational acceleration' there is no difference in ticking rate between the clock of a very distant observer and the clock of an ...
2
votes
2answers
143 views

Equivalence principle, is gravity a fictitious force that we feel everyday?

I am currently self studying general relativity. I have a question regarding the equivalence principle. If an observer is in the elevator in deep space (or Minkowski space) where there is no ...
7
votes
2answers
355 views

Equivalence principle and the meaning of the coordinate speed of light

Short version: Does the equivalence principle give us a means to tell if variations in the coordinate speed of light have absolute or only relative significance? Background In general relativity ...
6
votes
3answers
631 views

Confusion with the equivalence principle and inertial frames

This is an explanation of the equivalence principle. A. says accelerating frames can simulate gravity. Then, I am confused. Are the frames presented in A. inertial frames? Compared to B. I have the ...
0
votes
0answers
25 views

How do entangled matter condensates fall?

Is there any experimental measurement of how highly entangled matter states fall (or highly entangled photons curve) in a gravity well? I've found some preliminary experimental setups in this paper ...
1
vote
0answers
121 views

Is Thomas rotation compatible with equivalence principle?

I have designed a thought experiment for which I cannot find a clear solution: An infinitesimal laser gun and a point target both move with a velocity $v$ towards a deep rhomboidal hole dug in the ...
6
votes
2answers
180 views

Why can't Newton's 1st law be expressed as an autoparallel transportation in space?

I'm following this series of lectures on differential geometry and general relativity. In the linked lecture (Lecture 9), at around 24:24, professor Frederic Schuller made the conclusion that one can ...
42
votes
3answers
16k views

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, ...
0
votes
2answers
114 views

Why model spacetime as a semi-Riemannian manifold?

I'd like to collect arguments for the use of a semi-Riemannian manifold as a mathematical model for spacetime. I think this is closely linked to the equivalence principle, but I can't shape this into ...