## Gravity

Ideas about how a world with more than three spatial dimensions would work - what laws of physics would be needed, how things would be built, how people would do things and so on.

### Gravity

Ed Witten says the (approximate) 1/d^2 rule of gravity in general relativity comes directly out of there being three spatial dimensions. So we could expect in N D that the rule is 1/d^(N-1).
PatrickPowers
Tetronian

Posts: 393
Joined: Wed Dec 02, 2015 1:36 am

### Re: Gravity

They were discussing this before, or sometimes just assuming it. In fact, you were involved in the first discussion, although it was five years ago.
viewtopic.php?f=27&t=1695&p=26208&hilit=distance
viewtopic.php?f=27&t=2324&p=26384&hilit=distance
viewtopic.php?f=27&t=2546&p=27889
You made the interesting point that even in 3D, not all forces obey an inverse-power law.

New Kid on the 4D analog of a Block
Dionian

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Joined: Mon Jul 16, 2018 2:27 am
Location: Pacific Northwest

### Re: Gravity

That's true. But Ed Witten is the smartest man in the world so I pay attention to him.
PatrickPowers
Tetronian

Posts: 393
Joined: Wed Dec 02, 2015 1:36 am

### Re: Gravity

I personally use 1/d^2 even in 4D, just to make it so you can have orbits.
Vector_Graphics
Mononian

Posts: 9
Joined: Sat Sep 16, 2023 7:35 pm

### Re: Gravity

??? Did my post go through? I personally use inverse square even in 4d to allow stable orbits to exist.
Vector_Graphics
Mononian

Posts: 9
Joined: Sat Sep 16, 2023 7:35 pm

### Re: Gravity

Vector_Graphics wrote:??? Did my post go through? I personally use inverse square even in 4d to allow stable orbits to exist.

So do I. The pedagogical value of a planet orbiting a sun in 4D is too high to pass up. But it appears the smart money says no dice.
PatrickPowers
Tetronian

Posts: 393
Joined: Wed Dec 02, 2015 1:36 am