4 ms·
If a proton is a [probability] cloud, what exactly does the size measure? where that cloud's probability goes to zero?
by omegaworks 7y ago
If a proton is a [probability] cloud, what exactly does the size measure? where that cloud's probability goes to zero?
- hoseja 7y agoSquare of the complex probability doesn't go to zero anywhere IIRC, the radius is at some arbitrary threshold.
- amelius 7y agoI suppose that if you measure a probability-cloud long enough, you can arbitrarily bring down the inaccuracy of the size (?)
- narag 7y agoI was thinking more or less of the same question. Our intuition of what a particle "is" has a lot to do with how we perceive macroscopic objects. But particles are not really the same kind of thing. Or are they? Is their size correlated with their mass? Do particles consists of some "fundamental matter" or are they more like little machines?
- davrosthedalek 7y agoIt's defined as the slope of the electric form factor at Q^2=0. Since that is not a very helpful definition, with some hand-waving, you can say it's the root-mean-square radius of the electric charge distribution. The proton has also a magnetic radius, defined via the magnetic form factor. And something called a Zemach radius, which is a combination if them both.