My professor wrote this on the blackboard:
$$\Delta E\Delta t \leq \hbar$$
Isn't the $\leq$ sign wrong? Or is this "another" possible formulation of Heisenberg's uncertainty principle?
I am at the very beginning of quantum mechanics, so I am basically not aware of anything-ish. Except for the fact that every note and book I have read so far, mention the principle with $\geq$, no matter if $\Delta E \Delta t$ or with $\Delta x \Delta p$.