Questions tagged [gravity]
Gravity is an attractive force that affects and is affected by all mass and - in general relativity - energy, pressure, and stress. Prefer newtonian-gravity or general-relativity if sensible.
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Why are our planets in the solar system all on the same disc/plane/layer? [duplicate]
I always see pictures of the solar system where our sun is in the middle and the planets surround the sun. All these planets move on orbits on the same layer. Why?
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Why aren't there spherical galaxies?
According to the Wikipedia page on Galaxy Types, there are four main kinds of galaxies:
Spirals - as the name implies, these look like huge spinning spirals with curved "arms" branching out
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What is the weight equation through general relativity?
The gravitational force on your body, called your weight, pushes you down onto the floor.
$$W=mg$$
So, what is the weight equation through general relativity?
user17093
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Why is the gravitational force always attractive?
Why is the gravitational force always attractive? Is there another way to explain this without the curvature of space time?
PS: If the simple answer to this question is that mass makes space-time ...
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Why does the speed of an object affect its path if gravity is warped spacetime?
I think I understand the idea of thinking about gravity not as a force pulling an object towards another object but instead a warping of space so that an object moving in a straight line ends up ...
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Explaining to a five year old - why don't bubbles run like water
My five-year old daughter was asking about astronauts the other day and why they float in space. After me showing her a few bits on the kids section on the NASA web site I started explaining about the ...
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Is it theoretically possible to shield gravitational fields or waves?
Electromagnetic waves can be shielded by a perfect conductor. What about gravitational fields or waves?
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If spacetime is curved, how would anyone know? If anyone could tell, would that really be spacetime curving?
I never had a problem accepting that spacetime is curved as a result of matter, until I learned the LIGO experiments showed that evidently the curvature of spacetime can be measured. This, to me, is ...
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How to escape the center of a room without gravity? [closed]
Imagine you're an astronaut on the International Space Station and your fellow astronauts played a prank on you by taking all your clothes and putting you in the center of a module so that you cannot ...
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Would we even notice the merger with the Andromeda Galaxy?
I have read this question:
When galaxies collide it is not that their stars crash into each other, because their individual cross-sections are extremely small when compared to the space between them. ...
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If the gravitational force were inversely proportional to distance (rather than distance squared), will celestial bodies fall into each other?
If gravity was inversely proportional to distance, will the dynamics of celestial bodies be much different from our world? Will celestial bodies fall into each other?
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What is the proof that the universal constants ($G$, $\hbar$, $\ldots$) are really constant in time and space?
Cavendish measured the gravitation constant $G$, but actually he measured that constant on the Earth. What’s the proof that the value of the gravitation constant if measured on Neptune would remain ...
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How does gravitational lensing account for Einstein's Cross?
Einstein's Cross has been attributed to gravitational lensing. However, most examples of gravitational lensing are crescents known as Einstein's rings. I can easily understand the rings and crescents, ...
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Why are planets not crushed by gravity?
Stars can be crushed by gravity and create black holes or neutron stars. Why doesn't the same happen with any planet if it is in the same space time?
Please explain it in simple way. Note: I am not a ...
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What is the smallest item for which gravity has been recorded or observed?
What is the smallest item for which gravity has been recorded or observed? By this, I mean the smallest object whose gravitational effect upon another object has been detected. (Many thanks to Daniel ...
