Originally Posted By: Bill S.
Could there be a 4th?

The Universe is a gravitational field, particles of matter are distortions in that field. Energy is a distortion in the gravitational field. All other fields and particles are subsidiary to this.

Just a thought.

That is actually the same as 2 ... and now you have converted a classic gravity field theory to a quantum gravity theory.

Remember we did that in QFT.

I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.