I found one of Steinhardt's lectures "Inflationary cosmology on trial" on youtube. Fortunately, he encouraged questions from the audience. Although the questions were inaudible, his answer to one presumably about the energy driving inflation in the big bang was revealing. He said (at 33:00-35:00) the source was [Newtonian] gravitational potential energy and that gravity is a unique form of energy which is bottomless. The notion that gravity is an infinite well of energy is dubious. I attempted to show how gravitational potential energy can be reformulated using special relativity in last year's essay. In its modernized form, the potential energy that is available through free-fall would be limited to the rest energy of the falling object. In other words the free-fall energy from a test mass, m, can be no greater than mc^2 no matter how strong the gravitational field. This reflects Mach's principle that rest energy of an object is potential energy due to its elevation from the rest of the matter in the universe, and kinetic energy can be no greater than potential energy.
In my opinion this gives an advantage to the cyclic hypothesis because the expansion mechanism is different. The upcoming experiments Steinhardt refers to ought to spark more interest.
Thanks for the leads. It is much appreciated.
Colin