Gravity Visualized

What people said

Recommends k0pernikus · 2014-01 · Physics Stack Exchange · on “How do I explain to a six year old why people on the other side of the Earth don't fall off?”

What helped me to understand gravity is to model spacetime as a trampoline or a stretched bed sheet. Now put a melon on it, saying "This is earth which bends space." Now take a marble and say "This is you, also bending space, yet not as much". And no matter where you put the marble, it always goes "down" towards earth, as earth bends spacetime the most. Yet what I think is important to convey that not only does stuff fall towards earth but that every mass has its own gravity field not entirely unlike a magnetic field. You can go crazy with this experiment, saying the melon is the sun, a larger marble is the earth. Instead of letting the earth marble fall give it a sideway push and it will or

Recommends user73879 · 2015-07 · Physics Stack Exchange · on “What force causes massive objects to bend space?”

The visualization of gravity as shown by this video [this video] is pretty good at explaining how massive objects bend space, and such bending causes objects around it to fall towards it (a.k.a: gravity). However, here's what I do not understand. The reason why the experiment in the video works in the first place, is because real gravity -the one in that room- is acting on the marvels and causing those marvels to bend the sheet. In the real world, there must be a force that causes massive objects to bend space in the first place. What is that force? To put my question in a simple set of equations: Experiment: Marvel + Sheet + Real Gravity = Sheet Bending (Fake Gravity). Real World: Planet + Space

Recommends prfarlow · 2015-08 · Astronomy Stack Exchange · on “Why do objects all orbit in the same direction?”

This video provides a visual answer: [this video] objects orbiting in different directions are more likely to collide with each other. By the process of elimination, eventually one direction of orbit dominates.

Recommends DarthPlagueis · 2015-10 · Physics Stack Exchange · on “How did planets start to spin and do all of them spin in same direction?”

It is a statistical reason, that the turbulent disc from which the solar system formed would have been chaotic, some objects moving in one direction and some in another. However, there may be a slight bias in one direction, i.e., more objects moving in one given circular direction (say, for example, we have more objects moving clockwise). Once all of the anti-clockwise objects collide with the remainder of the disc they will become knocked out. Best way I can describe it is by this video: [ [this video] ]

Recommends athena · 2016-01 · Physics Stack Exchange · on “Is it possible that Gravity is a Repulsion phenomenon instead of an attractive "force"?”

This isn't a perfect duplicate. There is a difference between gravity as a repulsive force between masses, and gravity as a repulsive force between mass and space. Here is a nice practical demonstration how a space distorsion creates the illusion of an attractive force [this video] .

Recommends Dupontrocks11 · 2016-06 · Astronomy Stack Exchange · on “Why do the planets orbit in the same direction?”

Here's a simple visualization to aid SirC's answer. Visualization of Gravity [this video] The visualization of angular of opposite orbits correcting themselves occurs around 2:45. This demonstration is geared towards high school students, however it's still useful.

Recommends Farcher · 2016-10 · Physics Stack Exchange · on “Since quantum mechanics give you that photons have (relativistic) mass $m=\frac{hf}{c^2}$, why gravity does not accelerate it?”

Quantum mechanics or any other mechanics that I know of does not give an equation for the mass of a photon. Saying that a photon has mass is an invalid concept. The bending of light travelling from a source to an observer because it has passed some matter which is between the source and the observer is a prediction of the general theory of relativity and was proved correct when Eddington observed the solar eclipse of May 1919 [LINK] . It comes from the idea that matter can bend space(time). Here is a demonstration which tries to illustrate the point [this video] . Another important example of the bending of a beam of light is gravitational lensing [LINK] using which astronomers have been able to

Recommends Skyminer · 2017-04 · Physics Stack Exchange · on “In 3D visualizations, why does spacetime curve toward, not away from objects?”

By 2D visualizations, I presume you mean this: [LINK] As you can see in the picture, spacetime is bending down toward the object, Earth. This way, if there is an object near Earth, they will travel toward each other, similar to two objects on a stretched blanket. In contrast, if spacetime bent up and away from the objects, they would be pushed apart. See this video for a visualization. You may find it interesting. [this video] The reason for why spacetime curves toward objects and not away is because if it curved "away", the objects would be pushed apart. In the 2D model, spacetime curves toward the object. In a 3D model, spacetime also curves toward the object. There is far more to this answer i

Recommends Garf · 2018-11 · Physics Stack Exchange · on “Are photons affected by Earth's gravity?”

I think you're right to be uncomfortable in calculating a "mass" of a photon. The true reason that light is deflected around any massive object is because all massive objects distort spacetime. You've probably heard the phrase "Light travels in straight lines", and we can apply this line to the bending of spacetime too. Without too much mathematical detail, we can imagine what would happen to a "straight line" on a flat piece of spacetime when the spacetime itself is bent. The classic demonstration is a trampoline sheet with heavy balls on it. Anything trying to zip past a heavy ball (including light) is bent - see this popular YouTube video [this video] . (Using more precise terminology, light f

Recommends Stamatis Tzanos · 2019-08 · Physics Stack Exchange · on “How does an object gain energy when it enters a potential field?”

General relativity in short says that masses bend space itself so the geometry objects move in, changes. This video is very popular and it may help: [this video]