Wrong formulation of Heisenberg's uncertainty principle

Question

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 $\Delta x \Delta p$.

Answer 1

Don't be confused. It is definitely $$\Delta E \Delta t \geq \frac{\hbar}{2}$$.

Your professor typo'd here, as if what he wrote: Then we could measure energy with any arbitrarily small error. We want to break the uncertainty principle and quantum mechanics, so it is $\geq$. We don’t want the error to be smaller than something, so it must be $\geq$, not $\leq$.