- Dec 7, 2011
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So, Pluto is getting old, and I want to give AV some more ammunition. So I wanted to start a thread to gather definitions that changed over time with the development of science. I will start with these two:
Meter - officially adopted as an international measurement unit by the Metre Convention of 1875, the definition of this unit has changed many times, and every time it did, something that was 1 meter long before the definition "changed" length after the new definition.
Kilogram - First defined as the absolute weight of a volume of water equal to the cube of the hundredth part of the meter, at the temperature of melting ice, today is defined as the mass of several 90% platinum / 10% iridium standards. But the mass of these standards changes over time (graph below) and scientists are trying to come up with a new definition. When they do, these standards will not weigh 1kg anymore.
So, AV, drop Pluto!
Meter - officially adopted as an international measurement unit by the Metre Convention of 1875, the definition of this unit has changed many times, and every time it did, something that was 1 meter long before the definition "changed" length after the new definition.
Kilogram - First defined as the absolute weight of a volume of water equal to the cube of the hundredth part of the meter, at the temperature of melting ice, today is defined as the mass of several 90% platinum / 10% iridium standards. But the mass of these standards changes over time (graph below) and scientists are trying to come up with a new definition. When they do, these standards will not weigh 1kg anymore.
So, AV, drop Pluto!