[theothermkn]

One thing that's slightly interesting about Dyson Sphere's is that spherical shells of matter exert exactly no gravitational pull at any point in their interiors. That is, the integral of gravitational pull over the whole shell is identically 0 for every point inside the shell.* This goes for any force that falls off by the inverse square rule, e.g. the electrostatic force.

In short, there's no practical way to stick an atmosphere, much less a civilization composed of life forms that depend on gravity, to the inside of the sphere, even if the other engineering challenges could be overcome.

* One thing that's suddenly more interesting to me now is if the space at any point is being "pulled" equally in all directions, resulting in zero force, or if the bends in space-time cancel out. In the limit, for example, could you "tear" space-time inside a dense enough and/or heavy enough shell of matter?

[papreclip]

think about the 2d equivalent - a ball rolls down a hill because the potential gradient directs it that way. a ball sitting on a flat pedestal isn't being pulled in every horizontal direction at once by some forces that are proportional to the height of the pedestal. it's not being pulled horizontally at all

there is zero space-time curvature within the sphere, it's "flat", so there's no force. nothing is "cancelled out", force is the derivative of energy with respect to space. it's like a 3d pedestal (or rather, a cylinder excavated from the earth with a flat bottom)

[aeorgnoieang]

> there's no practical way to stick an atmosphere, much less a civilization composed of life forms that depend on gravity, to the inside of the sphere

Why not spin the sphere? Given the immense surface area, it wouldn't even matter that the centripetal force would only be strongest around the 'equator'.

So, the plan would be:

1. Create a giant rotating sphere around our Sun.

2. Create a ring world around the 'equator' of the inside of the sphere (i.e. a ring of walls high enough to hold in the resident's preferred atmosphere).

3. Install solar panels everywhere else.

4. Profit!

[saijanai]

Why not just a ring, instead?

It's been done, of course...