What you say is well-put, but to nitpick the last paragraph: the limits of quantum mechanics are well-established. QM is a special case of quantum electrodynamics, which is a low-energy special case of the Grand Unified Theory.
While the latter is not fully fleshed out, its uncertainty only begins in circumstances far weirder than what gives Roger Penrose pause.
Penrose says that "The [QM] equation should describe the world in a completely deterministic way, but it doesn’t." But work such as Bell's theorem shows that no deterministic equation could ever be consistent with quantum mechanics:
"What you say is well-put, but to nitpick the last paragraph: the limits of quantum mechanics are well-established. QM is a special case of quantum electrodynamics, which is a low-energy special case of the Grand Unified Theory."
Somewhat misleading. The difference between quantum mechanics and quantum electrodynamics is not really pertinent to a discusion of the limits of quantum mechanics. Most people who are familiar with quantum mechanics will use the term to refer to the whole tree of theories that require quantization anyway (quantum mechanics (QM), quantum field theory (QFT)). The limits of QM is that we are really not able to calculate things in certain energy regimes.
Also, it is not really accurate to call QM a special case of QFT because different things are being quantized (particle states vs field states). Certain operators in QFT are then interpreted as particles.
Quantum Electrodynamics (QED) is an example of a QFT. People postulate the existence of a Grand Unified Theory (GUT), of which QED would be special case. The only evidence of the GUT is a plot that extrapolates the strength of strong, weak, and electromagnetic interactions over many orders of magnitude.
Indeterministic laws and the non-existence of particle positions and trajectories are difficult to square with general relativity too - and Bohm's interpretation doesn't 'suffer' those problems, while it predicts the exact same observations. (Though I should say this is way out of my amateur-physicist league - I'm taking my cue from 'Quantum Mechanics: Historical Contingency and the Copenhagen Hegemony' http://www.amazon.com/Quantum-Mechanics-Historical-Contingen... ).
http://en.wikipedia.org/wiki/Quantum_electrodynamics http://en.wikipedia.org/wiki/Unified_Field_Theory
While the latter is not fully fleshed out, its uncertainty only begins in circumstances far weirder than what gives Roger Penrose pause.
Penrose says that "The [QM] equation should describe the world in a completely deterministic way, but it doesn’t." But work such as Bell's theorem shows that no deterministic equation could ever be consistent with quantum mechanics:
http://en.wikipedia.org/wiki/Bells_theorem