Question: Which area of physics do you think has the greatest potential to unify all 4 fundamental forces?

David Freeborn answered on 20 Jun 2013:

Hi alexlw18 ,

This is a really interesting question!

To unify the four fundamental forces, we will need a theory of quantum gravity. That’s going to be a theory that uses both quantum mechanics, and Einstein’s theory of relativity, so it should be able to describe physics on any scale, from the very big to the very small.

Two areas of cosmology; the Big Bang and Black Holes are particularly associated with the search for quantum gravity. Both are associated with objects that push our current physics to its very limits: they are systems that are very small, on the quantum mechanical scale, but also heavy enough that big gravitational effects matter a lot. As cosmologists improve their understanding of black holes and the big bang, they might take a step forward towards understanding quantum gravity.

The other area is the theories of particle physics. Right now, the most promising theory is String Theory, which promises to be a theory of everything. One of the problems is that there are so many different possible types of string theory, it’s almost impossible to know which could be right. Some physicists also think string theory is too elaborate and complicated.

It might be that the theory to unify the 4 forces comes from somewhere completely unexpected. Just recently, a paper was published that suggested gravity wasn’t a “real” force at all; it’s just a statistical effect arising from the probabilistic movements of other particles, and that’s why it has been so difficult to unify with the other forces. A lot of physicists are doubtful, but it’s a good idea.
I think something like that might be the key: a completely new idea in physics that nobody has even thought of yet.