All Questions
107
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Is it possible to know if you're moving or standing still due to the definition of Einsteins equivalence principle?
I have a question regarding Einstein's theory of relativity.
Einstein's equivalence principle states that locally it's not possible to tell if you're accelerating or being stationary in a ...
- 23
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2
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81
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Negative Energy and Gravity
Why do many science communicators say that negative masses fall upwards? Is it the same in the physics literature that they say that negative masses fall upwards?
In general relativity, things don't ...
- 11
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2
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129
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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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49
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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 ...
- 323
1
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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 ...
- 391
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161
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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
...
- 391
1
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1
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98
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Inertial Mass = Gravitational Mass. Why? [duplicate]
Okay, so the inertial mass of an object is always equal to the gravitational mass of the object. Conceptually, however, they seem different. Then what makes them identical? Is it because they are ...
- 1,073
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49
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Confusion on a couple of paragraphs on equivalence principles
I'm reading Carroll's GR book. I'm able to follow it for the most part, but a couple of paragraphs are a bit hard to decipher:
According to the WEP, the gravitational mass of the hydrogen atom is ...
- 1,051
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2
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119
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Since when did inertial mass and gravitional mass became equal?
If we think about inertial mass and gravitational mass as independent concepts and develop physics then we would know after a while they are only propotional (by precision we have by now). but it seem ...
- 1,409
2
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1
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74
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When observers moving along different geodesics meet locally, can they detect one another's acceleration?
Consider two free-falling observers in the Earth's gravitational field, A and B, who meet at point C, where A orbits the Earth at a constant radius from the Earth's center, and B falls towards the ...
- 5,318
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188
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Is gravitational mass always the same with inertia mass?
I read an article.
When an object is travelling near speed of light, it's mass increase.
The article argues while the inertia increased, that is, the object will be harder to speed up, the ...
- 601
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209
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Principle of general covariance follows from principle of equivalence?
I am reading the book gravitation from Weinberg. On page 93 he states the principle of covariance. I attach a screenshot below. I think Weinberg is saying (below the enumeration) that the principle of ...
- 115
8
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7
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4k
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Why don't two accelerated clocks behave like two clocks in a gravitational field?
If we immerse two clocks in a gravitational field at different altitudes (with the approximation that both heights share the same g for equivalence to be true), the falling and Schwarzschild observers ...
- 97
2
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6
answers
804
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Is the gravitational force a phenomenon or a theoretical invention? [closed]
We use to say that gravitational force is a phenomenon. But since the theory of General Relativity replaced Newtonian gravitational force, how is it possible for a phenomenon to be replaced by a ...
5
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Einstein Field Equations Derivation
Can someone give a derivation of the Einstein field equations, even a heuristic one? In most of the treatments I've seen, it somewhat falls out of the sky. Is the basic postulate that curvature is ...
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