Now it's a curious thing, but the official Kilogram (the standard from which the measurement is derived) is losing mass.
Not much, very little in fact, but there's really no good explanation for it. Not yet. Perhaps some of the platinum/iridium used to make it have evaporated, although that doesn't sound like something that metal does. Not over as small a time as 100 years. Maybe it wasn't initially wasn't measured correctly, but I think that possibility would have been raised already and accounted for.
No, it seems that it's gradually losing weight. Minuscule amounts, the weight of a thumbprint, year after year.
Which, as it's so far unexplained, begs some speculation....
Perhaps it's not the mass of the Kilogram that's changing, but the attraction of the mass to the earth (gravity)?
Is it just the Kilogram that's changing, or are all things on earth and throughout the universe losing mass? Is it accelerating? Could it be the expansion of the universe is somehow manifest in the expansion of all things, the weakening of the bonds of matter and hence the universe?
It's a small thing, a small loss, but it raises some possibly big questions.
Further reading: USA TODAY, Science Daily, Wiki on the Kilogram