“It is only through labor and painful effort, by grim energy and resolute courage, that we move on to better things.” -Theodore Roosevelt
Energy is a fundamental property of nature, and yet it’s also one of the most purely understood phenomena from a conceptual point of view. Some objects have energy inherently, such as in the form of rest mass. Other types of energy include binding energy, which is negative, and kinetic energy, which is the energy of motion. Regardless of the form it appears in, energy cannot exist without being attached to some other physical phenomenon.
We thought there might be a way to push energy into the fabric of space itself, as the inspiral and merger of massive objects appeared to lose energy. However, this gravitational radiation is itself a form of radiation, and carries energy at the speed of light, no different from photons. There’s only one hope left for pure energy at this point in time: dark energy, responsible for the expansion of the Universe.