Dear Steve, thanks for your comment.
Dear Narendra, you said:
"One gets trapped in the intricacies of the existing theories and tend to make them more complex whle Nature has simplicity!"
This is nice, and I confess that I strongly believe that the laws of Physics are simple. But I want to emphasize that this is a belief, so I have no proof. I don't know these simple laws, and nobody proved me that he or she knows them, or at least that they are simple, although we don't know them. So I don't really know that they are simple, I just believe this, and I will not use this as a precondition to analyze the current theories. The first condition I ask is that we find a consistent description of all physical laws. Then, I will require that this description doesn't add stuff which doesn't exist. Then, we will see if we can simplify it.
Is Nature simple? If so, it manifests so complex, that we don't understand it, and we don't know how it will work in different situations. So, even if Nature is simple, the most complicated things you can imagine are obtained from this simplicity. The same holds for a theory: from a simple set of principles, we develop unimaginable consequences. Is Newton's theory simple? Now we say yes. Is the Newtonian motion of three bodies (viewed as points) which interact gravitationally, simple? Now we understand that the answer is definitely no. Aren't the (only) three rules Feynman presented in his book "QED: The Strange Theory of Light and Matter" simple? But are their consequences simple?
Assuming that we obtain a theory of all physical laws, how do we decide that it is simple enough? Can it be simple and still use high mathematics? Or should it be simple in terms of concepts we learn as children? For example, it is hard to imagine something simpler than General Relativity: it is just a space with 4 dimensions, which admits differentiability, has a Lorentz metric at each point, and its curvature is related to matter via Einstein's simple equation. That's all. Incomprehensible consequences follow from this. What is "a space with 4 dimensions, which admits differentiability"? We have to know differential topology. Can we avoid this? No, if we really want to use curved spacetime in our theory. We can't. There is nothing to replace with, so if the definition of a differentiable manifold looks to us complicated, it is because we don't understand it. After that, it will look simple, but nobody will believe us that it is so simple. It is something more primitive than the Euclidean space, and it relies on fewer assumptions. Yet, it allows/forces us to construct vector and tensor fields. If we add a small ingredient, the metric, we are led to a natural connection and a natural curvature, which are very difficult to grasp, yet they are simple and natural. And so on.
So, it is simple to say "the Nature is simple and our theories are not simple, therefore they must be wrong". General Relativity and the Quantum version of the Standard Model explain almost all what we see. Are their consequences more complex than the natural phenomena are? Which part would you throw away? Which part would you simplify? Can you find something simpler than Semiriemannian Geometry to describe spacetime and gravity? I think that, if spacetime is continuous, we need to use a sort of space. The vicinity is described by topology. The distances by metric. Space provides 3 dimensions, time 1, even if you don't accept the connection between them, as it is done by Theory of Relativity. Can we find something simpler than this? If spacetime is discrete, we need to use some discrete structure: a lattice, a graph, a spin network etc. Are these simpler than the continuous description?
Can we find something simpler than Gauge Theory to describe the forces? The fields are just ways to associate a vector at each point of spacetime. So, if we accepted that spacetime is continuous, we need to use vector bundles to represent the fields. The simplest/most natural objects constructed on a vector bundle are the connection and its associated curvature. (They are the simplest and most natural objects, but this doesn't mean that we can grasp them easily, especially without using math. Because the vector fields are nothing like the corn fields, which we have seen enough to conceptualize them. Yet, vector fields are much simpler than corn fields.) And these are just the potential and its associated force field. Can we find something simpler than this, having the same explanatory power? Are we sure that Nature obtained the same results by using a simpler mechanism?
So, what do you mean when you say generically "Nature is simple"?