I’m looking for an information source on the energy storage density of coiled springs made of various materials. Of particular interest are steel, titanium, carbon fiber, and carbon nanotubes.
Consider the following thought experiment. Electrons are propelled into an ordinary (nonrotating) black hole until the black hole has a sufficient electrostatic charge so that the electrostatic repulsive force on the next electron is greater than the gravitational attractive force. Since both...