The equivalence-principle tag has no wiki summary.
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accelerated elevator vs remaining at rest in a elevator with a gravitational field? [closed]
When an elevator accelerated with a uniform acceleration, speed of elevator increases uniformly, what about elevator that remaining at rest in a gravitational field?
where acceleration is constant ...
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1answer
56 views
Is the result of (every) research on acceleration equivalent to gravity?
Is the result of an experiment on acceleration equivalent to another experiment in a gravitational field?
If I have an experimental conclusion from research under uniform acceleration, can the ...
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1answer
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Why four velocity under covariant differential is considered to be zero?
In Einstein's general theory of relativity the elements of four velocity $U^{\mu} (\gamma c, \gamma v)$ under covariant differential is considered to be zero, why?
$$\mathcal{D} U^{\mu}=0$$
in other ...
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2answers
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How (or why) equivalence principle led to Einstein field equations?
If equivalence principle was origin of general relativity what was the process that this principle led Einstein to developed his theory of general relativity?
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Can acceleration feel like constant gravity for indefinitely long?
So here's the setup: I'm in a spaceship, without windows as always, and the ship is accelerating upwards at a constant rate of $1\,\text{g}$. So inside the spaceship it feels like I'm being pulled ...
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1answer
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Space time curvature real or theoretical (mathematical)?
Assuming one were in a capsule of some kind, with no window or instruments, and you swung into the gravitational field of a massive object (planet). Assuming no atmosphere to provide friction, could ...
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1answer
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Privileged coordinate system (or lack thereof) in general relativity
What does the following statement mean and why is it true?
The Weak Equivalence Principle (WEP) implies that in general curved space-time there is no privileged coordinate system.
I have looked ...
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Switching from an accelerated frame of reference to a locally inertial reference system
Using the equivalence principle, show that the interval for an accelerated observer ($\textbf{g}$ uniform and constant) has the form
$$
ds^2|_{\text{first order in ...
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0answers
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Use of Principle of Equivalence
Let $x^\mu$ be the coordinates of a reference frame, $K$, where all bodies feel the same constant and uniform acceleration $\textbf{a}=\textbf{g}=-\nabla\varphi$; let $\xi^\mu$ be the coordinates of a ...
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How is space ship's acceleration perceived if the acceleration is perpendicular to the velocity?
Spacecraft in orbit around the Earth are constantly accelerated by the gravitational field of Earth. That's why the spacecraft ($m \ll M$) is in an (elliptical) orbit around the centre of gravity of ...
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4answers
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Equivalence principle question
I understand the equivalence principle as "The physics in a freely-falling small laboratory is that of special relativity (SR)." But I'm not quite sure why this is equivalent to "One cannot tell ...
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Why does weak equivalence principle say gravity is equivalent to acceleration?
I am told that the weak equivalent principle, that $m_i=m_g$ (inertial and gravitational masses are equivalent) is equivalent to the statement that in a small system you can't tell whether you are in ...
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The Role of Gravity among the Fundamental Forces of Nature
If we look at the standard model, we have 4 fundamental forces which include
Gravity,
Electromagnetism,
Nuclear weak force,
Nuclear strong force.
I would like to look at Gravity for a minute. ...
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3answers
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Does the equivalence principle mean that the Earth is expanding?
Popular books suggest that for an observer in the Einstein lift the following situations are equivalent:
1, the lift hangs motionless (relative to the Earth) on a cable in the gravitational field of ...
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1answer
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What's the difference between the equivalence principle and curvature of spacetime?
Calculating using the equivalence principle only accounts for half the deflection of light, whereas the other half is from curvature of space-time.
But isn't the equivalence principle the same thing ...
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3answers
592 views
How did Einstein derive general relativity?
How did Einstein derive general relativity (GR)?
Did he use: the equivalence principle? The principle of least action? Anything else?
Note, I'm not looking for a full mathematical derivation of GR! ...
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4answers
541 views
Questions from elevator ride
I like to play inside the lift (elevator). For instance, there are bars attached at the side of the lift, and I like to hold my body up using my two hands on the bar. I realised that I actually feel ...
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2answers
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Why equivalence principle is principle and not law?
We can prove that the inertial mass and the gravitational mass should be the same (equivalence principle) from the $f=mg=ma$ then $g=a$, so we have equivalence law! But why we said equivalence ...
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5answers
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Why Gravity attracts all objects with the same speed?
Why Gravity attracts all objects with the same speed? Is this question was solved? What is the exact answer?
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1answer
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Are there any well-known theories successfully unifying the inertial and gravitational mass?
From what little I know of general relativity, the equality of inertial and gravitational mass is an axiom of the theory. I suspect that this precludes GR from unifying them in the same sense as ...
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1answer
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Curvature of spacetime in only required to explain tidal forces?
I'm a bit confused about the equivalence principle in GR.
I'm quoting from Wikipedia:
An observer in an accelerated reference frame must introduce what
physicists call fictitious forces to ...
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1answer
60 views
Would we feel the rotation of a rotating habitat?
Assume that a space habitat is shaped like a can with the "top" open.
lets say we attach the can's top to a string with an astronaut standing on the base. We then rotate the can in deep space using ...
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1answer
139 views
Accelerating elevator?
If your in an elevator accelerating downwards faster than gravity, would you be pushed up to the ceiling? Since gravity cannot match the acceleration of the elevator, you're wouldn't be able to move ...
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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 ...
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2answers
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Jumping in an elevator?
I've always been under the impression that jumping in an elevator wouldn't help at all, especially after reading a snippet of physics where Einstein said that free fall was identical to zero gravity.
...
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Equivalence principle and radiation from falling particle
I am currently having a hard time solving a problem of GR from Lasenby's book.
I can't make it more clear than by quoting the exercise:
7.2 A charged object held stationary in a laboratory on the ...
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3answers
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Why can't we think of free fall as upside down rocket?
/\
/ \
| |
| m |
| |
------ <--- floor (Rocket A)
This rocket is accelerated (g) upwards then mass(m) falls on the floor.
...
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1answer
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How does Newton's 2nd law correspond to GR in the weak field limit?
I can only perform the demonstration from the much simpler $E = mc^2$.
Take as given the Einstein field equation:
$G_{\mu\nu} = 8 \pi \, T_{\mu\nu}$
... can it be proved that Newton's formulation ...
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4answers
239 views
Freefall in/out of an enclosed environment
I've just been learning about Einstein, relativity, and the equivalence principle in Physics. I'm fascinated with the idea of being inside a free-falling enclosed environment (such as, e.g., rocket, ...
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1answer
237 views
Why dynamic Casimir effect does not appear in static gravity field?
Dynamic Casimir effect tells us that a constantly-accelerated mirror should emit radiation due to interaction with vacuum. Following principle of equivalence, a similar mirror placed in static ...
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2answers
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Inertial Mass of a scalar field
Does it make sense to talk of the inertial mass of a scalar field? By the equivalence principle, it must be equal to its gravitational mass. We know that the scalar field contributes towards the ...
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3answers
253 views
Is the equivalence principle strictly fulfilled by general relativity?
The equivalence principle states
The outcome of any local experiment in a freely falling laboratory is independent of the velocity of the laboratory and its location in spacetime.
Any real local ...
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4answers
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What is the difference between gravitation and magnetism?
If you compress a large mass, on the order of a star or the Earth, into a very small space, you get a black hole. Even for very large masses, it is possible in principle for it to occupy a very small ...
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1answer
564 views
How do Einstein’s equations support mass gain in particle accelerators? [duplicate]
Possible Duplicate:
Why does the mass of an object increase when its speed approaches that of light?
A charged particle that is accelerated through a particle accelerator like CERN ...
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Masses of all the particles in the Standard Theory [duplicate]
Possible Duplicate:
If photons have no mass, how can they have momentum?
I'm sure this question has been asked here before but I wasn't able to find it clearly answered in one q/a session. ...
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Einstein's “happiest thought”
Einstein described his discovery of the equivalence principle as the "happiest thought of my life". Why? What, in broad conceptual terms, is the logical chain of reasoning that leads from the ...
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5answers
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How are the comoving coordinates NOT a prefered reference frame?
Physics me this:
The equivalence principle has rigorous physical definitions that say, for one, that the laws of physics are the same in all inertial reference frames. This is to say that the ...
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1answer
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Is relativistic motion equivalent to fluctuating gravitational fields?
The theory of relativity makes very precise predictions about how an object's motion through space-time affects the passage of time for both the object and observers in other frames of reference.
I ...
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1answer
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equivalence principle and nontrivial compactifications
it is commonly argued that the equivalence principle implies that everything must fall locally in the same direction, because any local variation of accelerations in a small enough neighbourhood is ...
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Can the equivalence principle be tested to high precision in a human-sized lab falling through the horizon of a black hole, in principle?
Can the equivalence principle be tested to high precision in a human-sized lab falling through the horizon of a black hole, in principle? By "human-sized lab" I mean a lab the size of the ...
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4answers
658 views
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 noninertial frame accelerating in the sense opposite to the gravitational field - is ...
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1answer
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Weak equivalence principle tests
on the wikipedia article about the equivalence principle there is a mention about testing the EP against parity-violating masses;
"The equivalence principle is untested
against opposite ...
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2answers
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What is the effect of temperature on electrostatic-gravitational balance?
We have two identical massive metal spheres at the same temperature at rest in free space. Both have an identical charge and the Coulomb force [plus the black-body radiation pressure if the ...
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8answers
450 views
Gravity theories with the equivalence principle but different from GR
Einstein's general relativity assumes the equivalence of acceleration and gravitation. Is there a general class of gravity theories that have this property but disagree with general relativity? Will ...
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9answers
2k views
How does this thought experiment not rule out black holes?
How does the following brief thought experiment fail to show that general relativity (GR) has a major problem in regards to black holes?
The full thought experiment is in my blog post. The post ...
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4answers
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Water pressure in free fall
The increasing water pressure as you go deeper is generally explained in terms of the weight of the water column above the observation point pressing down. The question, then, is what would happen if ...
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Does the equivalence between inertial and gravitational mass imply anything about the Higgs mechanism?
For example: the role it might play in a theory of quantum gravity (ie causing space-time curvature)?
I realize that inertial mass can result from binding energy alone. Has the equivalence principle ...
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3answers
884 views
Counteracting g-force
Is it possible to counter-act g-force for a jet-pilot, by him putting on a scuba-diving suit
and filling the cockpit with water? On earth we are constantly pulled down, or accelerated with one g. In ...
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3answers
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Why is the equivalence principle so important to general relativity?
In its simplest form, equivalence principle states that the inertial mass and the gravitational mass should be the same. This is easy to understand.
But why is it so important to the formulation of ...
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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?
