CECIL: HEAD IN THE CLOUDS?
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Nobody appreciates what I go through on this job. The biggest problem your average columnist deals with is having ticked off some politician. I have to fend off the freaking theoretical physicists. Dave and I had a lengthy exchange via E-mail, which I paraphrase below:
Dave: Nonsense. Weight has a precise scientific meaning.
(They ponder.)
C: Shoot, you’re right. Now that I think about it, even if I were falling straight toward the earth, I would be able to detect tidal variation due to the fact that the strength of gravity diminishes rapidly with distance. A wrench at the front of the spacecraft would drift forward, but one at the back would drift rearward. The equivalence principle obviously applies only to single points (center of mass). As a practical matter, in the real world of three-dimensional objects, free fall can always be distinguished from zero gravity. But Dave, this proves my point! Even in the lofty realm of theoretical physics, we’re obliged to consider practical matters! And as a practical matter clouds and orbiting astronauts are considered to be “weightless” because they behave as such. True, the letter writer’s coworker was clearly talking about clouds’ weight in the strict sense. I was just giving the guy a chance to weasel out of an argument in which he was, technically, wrong. You may think this unworthy. But weaseling is obviously a highly useful skill.
