What is General Relativity?
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers, especially mmesser314, point people to it as a more accurate alternative to the rubber-sheet picture of gravity and as a gentle intro to curved spacetime.
Recommended by 2 people across 6 different months, 2022 to 2025.
What it is
A 14-minute animated explainer from the ScienceClic channel that introduces Einstein's general relativity. It covers why objects seem attracted to one another, how gravity is described as curved spacetime, and related consequences such as black holes.
What people said
Recommends mmesser314 · 2022-05 · Physics Stack Exchange · on “Would an accelerated-time space region deflect projectiles?”
Time runs slower in a gravitational well than far above. From this, Einstein derived that light is deflected when it passes near the Sun. He predicted that a star whose apparent position is very near the Sun would appear to move a little away from the Sun. This was observed during a solar eclipse. It was the first experimental confirmation of General Relativity. But the experiment showed twice the deflection that Einstein predicted. He thought it over again came up with the correct description. It turns out that space is also affected. The curvature of space-time is the origin of the gravitational force that deflects an object passing near the Sun. See What is General Relativity? [this video] by
Recommends mmesser314 · 2022-06 · Physics Stack Exchange · on “Amateur question. But could you fix a hole in space-time?”
General relativity is a theory of gravity. There is a very common picture of gravity as a distortion in a rubber sheet. The Sun sits on the sheet, causing a depression. The Earth rolls around in the depression. It is unfortunate that this picture is so popular. While it is easy to understand, it is wrong in many ways. It gives rise to questions like yours. Here is a video that starts with this picture and comes up with a more complicated but more realistic one. A new way to visualize General Relativity [LINK] Here is another with more about General Relativity. What is General Relativity? [this video] To answer your question, spacetime is not a thing like a rubber sheet. There is nothing to tear.
Recommends mmesser314 · 2023-03 · Physics Stack Exchange · on “The ‘fabric’ of space is what exactly?”
The fabric of space is a very common but flawed way to explain the curvature of spacetime and make General Relativity understandable. Here is a couple videos that help make it clear. A new way to visualize General Relativity [LINK] and What is General Relativity? [this video]
Recommends chausies · 2023-04 · Physics Stack Exchange · on “Rotation affecting how spacetime is warped (according to general relativity)?”
According to this excellent ScienceClic video [this video] , satellites don't fall straight towards the center of the Earth, but rather, take a curved path, due to the Earth rotating. A similar thing for black holes rotating. But this seems...off to me, though @.@. Imagining the Earth was a completely uniform homogenous sphere (equally dense everywhere), then even if it's rotating, the physical object will look exactly the same from the outside. Unless you gave each individual atom its own unique name, it'd be impossible to discern whether a uniform sphere was rotating (at a constant angular velocity) or not from the outside, right? Anyways, my main questions are Is this effect actually real? Is
Recommends mmesser314 · 2023-04 · Physics Stack Exchange · on “Curvature of space in a black hole”
That is a reasonable thought, but you might look at this to see how curvature works. A new way to visualize General Relativity [LINK] . ScienceClic make a number of other videos worth watching. What is General Relativity? [this video] and Why Time and Space swap in a Black Hole [LINK]
Recommends mmesser314 · 2024-07 · Physics Stack Exchange · on “Tilting due to Earth's rotation at a distance”
You might start with another Science Clic video - What is General Relativity? [this video] , The phenomenon you are asking about is called Frame Dragging. A lot of sources talk about it, but I don't know of one that gives a simple explanation of why. You might look at this - We know there is no aether, so what is being dragged in frame dragging? [LINK]
Recommends mmesser314 · 2025-02 · Physics Stack Exchange · on “How does gravitational force actually exist?”
See these SciencClic videos for an easy explanation of the idea behind general relativity. A new way to visualize General Relativity [LINK] and What is General Relativity? [this video]
Cites mmesser314 · 2022-06 · Physics Stack Exchange · on “How do gravitational waves propagate?”
Spacetime isn't supposed to be a surface, it is solid It sounds like the idea you were trying for is that space is 3 dimensional, not a 2 dimensional surface. You are right. Spacetime includes time, and is 4 dimensional. So how do gravitational waves travel through a solid medium? Let us start with light, because it is a wave that travels through empty space. This will be a classical description of light as opposed to a quantum mechanical description, because gravitational waves are described by general relativity which is a classical theory. Keep in mind that physics is a mathematical description of the behavior of the universe, not the universe itself. It is never a complete description, b
Cites Quillo · 2023-02 · Physics Stack Exchange · on “Does space-time 'flow' over time in the direction of its curvature?”
TikTok vodeo is unavaliable if you do not have an account. YouTube videos: [LINK] "GR in 7 Levels of Difficulty", [this video] "What is General Relativity?" , [LINK] "A new way to visualize General Relativity" (already linked in previous comment), [LINK] "How Does Gravity Warp the Flow of Time?".