# Rest mass, electron movement

1. Jan 24, 2009

Hello all,

First off, I am not sure if these questions belong in this category.

For a couple of years now I have been interested in physics/quantum mechanics, and a while ago I decided it was probably my main interest. After realizing my school did not offer physics, and therefore not being able to get taught what I love, I resorted to books. I am trying to teach myself as much as possible about the subject.

After reading basic 'beginner' books (the maths free ones ;)) I had a few questions. They are probably really basic, but I can't seem to turn to anyone to ask.

First off, electrons 'orbit' an atom. I read somewhere there is actually a cloud of probability of finding the electron, so then, is the electron actually orbiting if the location is pure chance?

It appears quantum mechanics is really probability based - is it really pure chance? Or is it a simple matter of finding all the inputs and environmental effects and then you can predict accurately?

Whats is 'rest mass' and what is mass that is not 'rest mass' ^^

I am only curious, thats why I ask all these questions, and I am sure people out there know the answers :)

Cheers,

2. Jan 25, 2009

### malawi_glenn

i) The word 'orbit' in a residue from older Atomic models such as the Bohr model. So if one uses the same definition for orbit to atoms as one has from classical mechanics, it becomes wrong.

ii) Yes, according to the copenhagen interpretation of QM, it is pure chance. But there are other interpretations as well, Eistein didn't beleive in pure chance QM, he thought it was ugly and he said "God does not play dice". But today, and almost the entire history of QM, the copenhagen interpretation is the paradigm of quantum physics.

iii) Rest mass, is a concept in Special Relativity, not quantum qhysics really, but anyway - rest mass is the mass of an object measured in its own restframe.

3. Jan 25, 2009

### QuantumBend

Rest mass is when not moveing. Photon is energy calculated to mass converted.

Quantum chance use probables in calculations ampliteude density squares.