Recently, I watched a lecture with Alan Guth. He made an interesting statement. He said that to create an electric field requires work, because the like-charges prefer to repel one another, therefore this requires energy to bring them together. However; because gravity is attractive, it requires no work to create a field, simply because the particles attract to one another, and will assemble themselves into a large gravity field without work. He went on to say that it is even possible to extract energy from a system while a gravity field is being created in this way (falling matter can render energy and do work, leaving behind a large gravity field). By this definition he claims that the resultant gravity field must have a negative energy associated with it, while an electric field must have a positive energy by nature of its configuration. He uses this argument to demonstrate part of his inflation theory, in that the gravitational force increases while new particles are being created during inflation. This creates the tremendous momentum of expansion along with the huge quantities of mass, in a kind of cosmic trade off, where total energy equals zero. I'm having trouble with this concept, because It doesn't seem intuitive. It seems that the gravity field is already there just separated out with each particle. And the new resultant field is simply these separate fields being assembled. So no new field has been created right? At least not in the sense that more energy (or negative energy) had to be added to the field. Thoughts?