Is a Dyson sphere or swarm even possible? It seems to me that the sun's gravity could collapse the sphere, since it wouldn't actually be orbiting. A swarm has similar problems: is it possible to orbit within an orbital plane that doesn't intersect the center of gravity of the sun?
Dyson's original concept was basically to completely obscure the star in a cloud of satellites. It would be a little inefficient, insofar as some satellites would obscure others at any given time, but it's at least physically possible.
There's been some speculation that the integrity of a Dyson shell (the thing most people know as a Dyson sphere) could be maintained by basically running large masses in orbits along the shell. Again, it would be a little inefficient (you're using some of the star's energy to power "not collapsing"), but we don't necessarily know it's impossible.
