I’ve mentioned the problem before, about three years ago: the platinum/iridium cylinder in France that is the official reference for the kilogram is losing weight, for reasons that currently baffle science. Any reference object is useless if it can’t be relied on to stay the same, so the science community is making a determined effort to retire it, replacing it with a definition based on Planck’s Constant, a measurement “reflecting the sizes of quanta in quantum mechanics.”
Which is a good idea… but software developers have a maxim: “constants aren’t, variables won’t.” (For the non-developers out there: it’s a shortened version of “constants aren’t constant, and variables won’t vary.” It refers to the rare but baffling behavior of things we declare as constant in our programs, which should never be able to change but sometimes do, and that of variables, which are supposed to change but sometimes don’t. We’ve known it for decades, from painful experience.)
Sometime in the next century, scientists are going to learn that rule themselves, when they improve their measurement methods and discover that the size of quanta vary too. Remember, you heard it here first. 😉
If Plank’s constant changes size, if I remember correctly, atoms start flying apart and the like, so I don’t find that likely. It’s a constant because it’s an elementary characteristic of the universe. If it does change, either complete destruction of the universe will happen as we know it, and we won’t be around to figure out what happened, or our understanding of what Plank’s constant is makes no sense at all. 😉
Let’s hope that it turns out to be the latter. 😉