First, people who study physics are called "physicists", not "physicians". The latter are doctors who care about other people's health.
Second, gravity is a fundamental force in Nature, along with electromagnetism, the strong nuclear force, and the weak nuclear force. So all phenomena in the world – including computation – should be explained in terms of (i.e. should be reduced to) these four fundamental forces. The fundamental forces themselves cannot be explained in terms of anything more basic because there isn't anything that is more basic; that's what the word "fundamental" means.
The OP is apparently trying to do the opposite thing, namely to explain fundamental forces in terms of non-fundamental processes such as computation. But that's not how Nature or physics works. They work in the opposite way. Computers are complicated systems with lots of elementary particles that mostly interact via electromagnetism.
Nature doesn't face any limitations of "chips with some number of transistors" because Nature is not a chip with transistors. An apple or a planet isn't a circuit with several transistors (and GPS receivers to measure their distances), either. Nature is a system where the equations such as those describing gravity hold. It's not a free decision of the apple to fall down; the external force is dragging it towards the Earth "automatically". The apple doesn't have to do anything.
When all the appropriate corrections (not only those of general relativity but also those of string theory etc.) are included, the equations of physics exactly hold (well, they only predict probabilities because the fundamental theory is a quantum theory), and even when it is difficult for us and our computers to calculate what will happen, Nature has no problems with the laws because Nature is simply not a "finite brain" similar to ours or a computer similar to one of those we possess. In this sense, when it comes to exact calculations of the outcomes of Her own laws, Nature is "omnipotent" and "omniscient" (and yes, it is also "omnipresent"), like God.
A closely analogous question, "how magnets work and what is the feeling between them?", was asked to Richard Feynman
Feynman has spent much of the time by explaining the conceptual general issues that apply here as well. We must always "believe something" (as an axiom) if we want to explain something; we reduce the questions we didn't understand to those that we did. But we must start somewhere. And fundamental forces (magnetism in his case, gravity in our case) are simply more fundamental than computers and rubber bands.