I agree with the question and disagree with the notion that spurious, capricious, not (by physics reasons) explained downvotes are just a "nonissue" here because
Many people have noticed them recently and asked about them on meta, see for example this question. The number of capricious potentially not by physics reasons explainable downvotes HAS increased this year and can not be neglected.
Capricious not explained downvotes on perfectly good sometimes even technical posts discourage new users or people who have not a large impenetrable self confidence from posting on the main page.
Downvotes of from a physics point of view correct posts bias the general picture of the site concerning what is a correct and legitimate question or answer. Admittedly, the same is true for upvotes of wrong posts.
Leaving votes of any sign without comments is a somehow intended feature of the system, even though explaining the downvote by pointing out the error or what is otherwise wrong with the post such that it can be corrected is encouraged I think.
My advice for people who get such unexplained downvotes, is to ask on chat or meta a broader audience about what is wrong with the question or answer from a physics point of view. If anything is wrong with the post after all ...