The Problem of Decoherence in Quantum Mechanics

In quanta mechanics, the environment becomes entangled with you very quickly. This process of becoming entangled with the environment is what decoherence is. Can you shield one kind of system from becoming entangled with another? Yes. You can't shield decoherence for a microscopic system. It's harder to shield out photons than people would think. The word 'decoherence' is not fuzzy because it means something that we see physically happening during the act of measurement.