I've been wondering why electromagnetism is the only force that we really can use in a larger scale. Eventually it came to my mind that with the electron we have an easy to access carrier of charge, and a moving charge creates a magnetic field. So with moving electrons we are pretty well set for electromagnetism. And because electrons are part of atoms, and not too hard to split off them, they are available in large numbers and somewhat easy to access for us. For gravity, I don't even know if there is a charge particle? The strong and the weak force? What do you think? Is the lack of accessible charge carriers the reason why we cannot use these forces well? Furthermore, fi there is no charge particle for gravity, all the sci-fi gravity control technology will stay fiction, because we lack such a particle?