Quantum Theory - The Measurement Problem

Quantum theory is not a theory about ontology, it's a theory about measurement. We don't know how to describe what the world is made up of. All we can do is describe the measurements we make of it. This creates a big problem, of course, in measurement. When do matter ways become particles? Well, when you measure them. But what constitutes a measurement? That's the big question. And this is where interpretations come in. As many quantum physicists exist, there are interpretations of the measurement problem. You'll find physicists existing on a grand range of spectrums.