***Let me for a moment redefine the word "truth" so that it means "a theory of reality which works", or something like that. For instance, if physics says "momentum conserves", and we accept the physics definition of "momentum" and "conserves", we will verify through experiments that "momentum conserves" is "true". The key point here is to forget metaphysics and concentrate on pragmatism, on getting things done.***
If one defines truth in this instrumentalist/operationalist fashion, then 'yes', physics is as close to truth as one can express since physics is closest to a instrumentalist and/or operationalist means by which to demonstrate one's model as meeting this criteria. For example, if I say that 'truth' is being able to perform an experiment where I can demonstrate what I mean by velocity, then it only takes an experiment in any situation to demonstrate that a phenomena in question has velocity.
The problem with operationalism and instrumentalism is that they are weak arguments for defining truth. In the case of both of these views, there is the whole problem of verification within the context of a theory. That is, you need to accept the background theory before the experiments which you are using to define 'as true' make any sense. There are many unobservables in an experiment which we cannot actually see. What is observed is the observables and this is used to show that the theory is true (i.e., if the observables are predicted by the theory which is assuming the effect of unobservables - eg., quarks, photons, mesons, etc).
***So if you accept my way of saying it, would you agree that physics is as close to "truth" as it gets? If you agree, then the next question is, what next?***
As you can see, I cannot accept this kind of approach to truth. I think it is terribly misguided. What it does, in effect, is ride on the coattails of a scientific success, which is giving real meaning to theoretical terms, while at the same time disavowing this process when the implications of 'knowing unobservable reality' come back to haunt those who lack that kind of conviction.
You can't have it both ways. Either one must accept that science is about human conventions (sort of like politics), or one must step up to the plate and be willing to accept that our science is approximating in some loose fashion the way that reality actually is 'out there'. The question we cannot answer is how accurate of a depiction scientific theories give us, but it is beyond question (in my opinion) that we are better at approximating the way the world is than ever before.
Warm regards, Harv