# Quantum Mechanics and Observables

1. Jul 25, 2013

### quantumfoam

Hi guys! I have one question! I know that in quantum mechanics, observables must be in the form of operators. However, does that mean that all observables are quantized in quantum mechanics?

2. Jul 25, 2013

### mpv_plate

No. Operators can have continuous spectrum, so the observables may by continuous. This is the case of energy of a free particle for example.

3. Jul 25, 2013

### quantumfoam

Oh okay! So if the particle was in a potential then the energy of the particle would be quantized?

4. Jul 25, 2013

### hilbert2

That's true for potentials that are not bounded from above (e.g. the harmonic oscillator potential). Some potentials, like that of an electron interacting with a proton, result in a set of quantized bound states with negative energy and a continuum of unbound "scattering states" with positive energy.

Last edited: Jul 25, 2013
5. Jul 25, 2013

### quantumfoam

I see.(: Thanks guys!