Planck frequency

Noun

 * 1)  A repeating event that occurs once every Planck time, with a frequency of $$ F_p = \frac{1}{2\pi}\sqrt{\frac{c^5}{\hbar G}} = E_P/h \approx  2.952 \times 10^{42} \mbox{ Hz}.$$  this frequency is said to be the upper bound for the frequency of an electromagnetic ray or cosmic rays.