1k views

### How do geodesics explain two identical balls thrown up at the different speeds? [duplicate]

As stated in the title, two identical balls, both thrown directly upward, but at different speeds. The slower ball will reverse direction at a lower height than the faster ball. But the curvature of ...
59k views

### How exactly does curved space-time describe the force of gravity?

I understand that people explain (in layman's terms at least) that the presence of mass "warps" space-time geometry, and this causes gravity. I have also of course heard the analogy of a blanket or ...
• 913
8k views

### If gravity is not a force, what makes massive objects spheroid?

For most of my life, the explanation given for why celestial bodies like stars, planets, etc. are round is due to gravitational force. Simply put, if an object has enough mass, it will, in turn, have ...
4k views

### Better explanation of the common general relativity illustration (stretched sheet of fabric)

I've seen many science popularisation documentaries and read few books (obviously not being scientist myself). I am able to process and understand basic ideas behind most of these. However for general ...
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2k views

### What causes time warping in the space-time?

I was reading through some blogs/articles and watching youtube videos that explained to non-physicists such as myself - how time warping or a gradient in time flow around any object can create gravity....
• 217
2k views

### Why does mass bend the temporal dimension more than the spatial dimensions of spacetime?

From my (limited) understanding of general relativity, most of what we experience as gravity is a result of the distortion of the temporal dimension, and not the spatial dimensions. Therefore, most of ...
• 303
5k views

### When objects fall along geodesic paths of curved space-time, why is there no force acting on them?

On cseligman.com, it is written that So, we see things falling with an acceleration which we call the acceleration of gravity,and thinking that we live in a straight line , uniformly moving or ...
2k views

### If gravity is curvature of space why are more massive objects "heavier?"

How does curved space explain why a denser object of the same shape and volume feels heavier?
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### How much of gravity is caused by time dilation?

I just watched this video where it is explained how time dilation causes gravity. It is said in this video that time dilation (caused by masses such as the earth) is the only cause for gravity. But ...
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2k views

### Would objects really be at rest relative to each other in orbit?

I am currently reading Gravitation by Misner, Thorne, and Wheeler (MTW). In the very first chapter on weightlessness they make the following claim: “Contemplate the interior of a spaceship and a key, ...
• 145
1k views

### If gravity is simply a curvature of space, why does it accelerate objects? [duplicate]

I understand how an object moving through space would be affected if gravity were a curvature of space as opposed to being a force. However, I do not understand why this creates a "pull" on ...
• 195
630 views

### Why would geodesics depend on velocity in general relativity?

In general relativity, it's the curvature of spacetime that gives the effect of gravity, due to objects following geodesics. What I learnt about geodesics is that they are like straight lines in ...
615 views

### Understanding causality violation of tachyons in space-time diagrams [duplicate]

I have a hard time understanding how the world lines of tachyons in a space-time diagram imply the violation of causality. Can you explain why that is?
• 173
360 views

### Why do light and masses (like planets) follow different paths through curved space?

It is often said that planets follow a "straight line" through space time. The argument goes that a star like our sun curves space, and the planets follow this path. The argument is also made that ...
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