Radiation, a pencil of radiation carries energy with it, and energy has mass, and therefore, a pencil of radiation must exert some attraction on things beside it. What about getting a pencil of radiation curved into a circle so the light goes around and round, then the attraction it exerts is concentrated as if at the center. So what is it that bends this pencil of radiation into the circle is the gravitational attraction of the pencil of radiation itself. That was the idea of the geon. Actually, if you think of different possibilities for the size of that geon, bigger or smaller, you find that if it's very big, the energy is low, to push the radiation together requires energy. And you climb a hill like the hill of a volcano until you come to a maximum energy, and then, if the pencil of radiation becomes any smaller in size, the energy starts to go down and the thing collapses. So a geon is really an unstable entity. It either blows up into a cloud of radiation traveling away in all directions, or it collapses into a totally collapsed object, something that we today would call a Black Hole. But that stability analysis I didn't have in mind when I first published this work, only later did I see that that's a feature that's dominant. But nowadays, I'm attracted with this idea that this pencil of radiation going around in a circle does not have to be light, it can be gravitational waves. And you can have gravitational waves imploding to make a black hole.