# How would the frequency of particle spin be estimated if it really was rotation?

I understand from reading that particle spin is not real spin as the globe spins. from what I have read particle spin came about because of the magnetic field of a particle. If I understand the text correctly the physical spin of the particle (if it were really spinning) based on its size and magnetic field strength the surface velocity of the sphere would be faster then the speed of light (I understand not possible).

My question is if a particle were a spinning sphere how would you go about calculating spin in revolutions per second? The text said it would be on the order of 10$^{37}$; just wondering how they got that number

• What text said this? Did they have any explanation at all? – Bill N Aug 10 '15 at 1:08
• askamathematician.com/2011/10/… here is one link I have not found the one with the 10^37 number yet but I will – newguy Aug 10 '15 at 1:25
• hyperphysics.phy-astr.gsu.edu/hbase/spin.html here is the link to the site stating the spin rate of an electron would have to be on the order of 10^32 rad/sec to match its magnetic moment – newguy Aug 10 '15 at 2:06

spin rate of some $10^{32}$ radian/s would be required to match the observed angular momentum.
Classical angular momentum is calculated as $I\omega$, where $I = \frac{2}{5}mr^2$ for a sphere. The mass of an electron is $9.11\times10^{-31}$ kg and the site mentions an upper limit of $10^{-3}$ fermis or $10^{-18}$ meters for the size of the electron. With a total angular momentum magnitude of $\frac{\sqrt{3}}{2}\hbar$, you can solve for the angular velocity.