As the parent comment says, everything in physics depends on how you observe ("... best described"). Like Sean Carroll said in the Veritassium video about the

As the parent comment says, everything in physics depends on how you observe ("... best described"). Like Sean Carroll said in the Veritassium video about the "many worlds" [1], there's no such such thing as "pressure", it is just the interaction of fluid molecules. For practical purposes though, it is best described as a scalar called "pressure". [1] https://youtu.be/kTXTPe3wahc?t=1043 https://youtu.be/kTXTPe3wahc?t=1043