General Relativity Lecture 1

What people said

Recommends user2196351 · 2015-04 · Physics Stack Exchange · on “Why would the curvature in space-time attract photons which have zero mass?”

The simplified answer for this is that gravity basically means that you are in elevator which is accelerating: even if you are standing on the ground. So if you take that constant gravity field is pretty much the same as a constant acceleration, then if a beam of light bends downward in an accelerating elevator, it must bend downward if it is in an constant gravity field. An excellent overview of general relatvity can be found on you tube: [this video]

Recommends Shirish · 2019-12 · Physics Stack Exchange · on “Making tidal forces "disappear" via coordinate transformations”

I'm watching this introductory lecture [this video] on general relativity by Leonard Susskind (see 31:50 onwards [this video] for the relevant part) [Video title: General Relativity Lecture 1, channel: Stanford]. To give context, till that point he'd explained that a uniform gravitational field can be simulated or is equivalent to going to another coordinate frame that's accelerating (constant accelaration in the opposite direction) irrespective of the position . He then moves on to the case of a gravitational field pointing radially inward towards the sun: [LINK] There's a 2000 ft man who's falling legs first towards the sun. He'll feel a stretch since the force on legs is greater than that on his he

Recommends Solidification · 2024-03 · Physics Stack Exchange · on “Showing that trajectories deviate from straight line in accelerated reference frames”

Explanation of light bending in an accelerated frame in a relativistic setting We know the transformation that takes us from one inertial frame to another. In special relativity, the transformation is a Lorentz transformation. For example, in an inertial frame K' that moves uniformly with velocity $V$ along the positive x-axis, relative to an inertial frame K, the transformation reads: $$t'=\gamma(t-Vx/c^2), x'=\gamma(x-Vt),y'=y, z'=z$$ where $\gamma=\sqrt{1-V^2/c^2}$ . This transformation maps a light trajectory $x=ct$ in K frame to $x'=ct'$ in the K' frame i.e. under Lorentz transformation light trajectories in spacetime do not bend. Now consider the case where $K'$ is a non-inertial frame

Cites Andrew · 2021-11 · Physics Stack Exchange · on “Local effects of cosmic expansion”

Short answer: the premise of your question is flawed, and therefore your actual questions don't really have answers beyond "that's not how it works." Longer answer: The issue with the premise of your question is that you cannot compare the velocities of two galaxies separated by 100 Mpc. The velocity is a quantity that is defined locally (formally, the velocity is a vector in the tangent space at the position of the object). On the other hand, 100 Mpc is a large enough distance that spacetime curvature effects due to the expansion are not negligible (we cannot pretend that the two galaxies live in the same tangent space). So the velocities cannot be compared directly. As an analogy, if two a

Cites Zlelik · 2022-02 · Physics Stack Exchange · on “General Relativity Effects Observation in the lab”

Thank you for the interesting link. I do not mean that I want to create gravity with acceleration. I want to detect any General Relativity effects., For example, the lector here [this video] says, that light in the accelerated frame will go by a parabola, but not by a straight line. I mean effects like this. Or do you mean the lector in this video is wrong?