Perhaps physics is progressing to the point where hypotheses which successfully explain observed phenomena are no longer testable. Either the apparatus required is beyond the capability of any possible engineering, or the energy releases necessary exceed those available from natural reactions. Ideas like string theory and inflationary cosmology may or may not be true, but there's no way to tell for sure. Physics may be getting to the point where philosophy and religion started out from: we can't really create a Big Bang just to see if our ideas about it hold up, and we can't build telescopes as big as the universe just so we can see far enough.

Cleverness can only take us so far, eventually we will have to recognize the fact that some phenomena simply cannot be duplicated for purposes of investigation, and some signals will simply be lost in the noise. The laws of physics may provide natural limits to the type of experiments and operations we can perform. For some questions, the experimentum crucis may require the entire universe be tested to destruction. Granted, this point may lie a long way off yet in most areas, but in some fields of inquiry we may have already reached it.