You pan a mono signal from left to right. Simple, right? Actually, no. In the center, there’s a 3 dB RMS volume buildup because the same signal is in both channels. Ideally, you want the signal’s average level—its power—to have the same perceived volume, whether the sound is panned left, right, or center. Dropping the level when centered by 3 dB RMS accomplishes this. As a result, traditional hardware mixers tapered the response as you turned a panpot to create this 3 dB dip.
Definitely in the “rocket science” category. The final takeaway of the article is that pan laws will effect audio processed in different DAWs. If the panning is set “the same” in Logic Pro X and Studio One the output might not be identical.
In Logic Pro X the pan law is set on a project level. Normal is -3 dB compensated, not applied to stereo balancers.