Symbol rho_M

Its job in the formula

rh$o_M$ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Where the article explains it

For an electron this is $\omega_Z$ $\approx$ 1.55$\times$10^{21}\ $\mathrm{rad\,s^{-1}}$ , an oscillation period of roughly four zeptoseconds in the particle’s own rest frame — a boosted lab observer would clock a longer, time-dilated period by the ordinary factor $\gamma$ , coordinate time and proper time parting ways in exactly the usual manner — with an amplitude of order the reduced Compton wavelength $\hbar$/($m_e$c) , the same length scale, twice $\rho_M$ for a spin-half particle, that bounded the Møller disk above.

Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →