History of Science and Math Stack Exchange
History of Science and Math Stack Exchange

Questions tagged [units]

A unit is a quantity chosen as a standard in terms of which other quantities may be represented. Examples include Joules, Moles, Seconds, etc.

Questions with this tag should be about the history of (the use of) units, which are standard measures of some quantity, e.g. length, weight or current.

48 questions
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What happened to the meter bars?

Throughout the centuries the meter has been redefined a number of times. At one point it was defined in relation to the distance from the north pole to the equator. Seeing how that is a bit of an awkward standard to use, a set of platinum bars was…
Justin Gerhardt
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Two competing definitions at the birth of the unit "meter"

It might be famous that $\pi^2$ is a good approximation to the gravitational acceleration in the unit "meter per second squared". My explanation for this is the seconds pendulum, which was proposed as the definition of "meter" back to the birth of…
Hao Chen
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Former definitions of MKS units

The meter and second, at least, have been redefined several times since they became common in science. Sometimes when referencing historical documents, it's useful to know how the units of the time relate to units in the modern day, but I'm finding…
David Z
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Where did the notation for dimensions of a quantity come from?

The current SI Brochure defines the dimension of a certain physical quantity as something separate from its units, and treated in detail in its §2.3.3: This is, by now, pretty bread-and-butter stuff in the handling of dimensional analysis, and…
Emilio Pisanty
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On Units of Arc

Why aren't turns used more often in math? It seems much more fundamental of a unit compared to degrees and radians. The value of a turn is definite, and other units can be derived from it. The problem with radians is we'll never know exactly what a…
Expectator
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What is the importance of SI units in Physics?

Every quantity has some SI units like distance, time, speed etc. Why do we prefer SI units for these quantities?
Shubham Prateek
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What if we measure a physical constant to higher accuracy?

So, the SI system of units has the basic philosophy of defining all 7 of the base units in terms of universal constants such as the plank constant, the speed of light, etc. These are all measured, then defined to be that number. But what if we we to…
Brandon Myers
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Weights & Measures - barleycorn GRAIN

The medieval and non-metric Imperial data is that 7000 grains make a Pound weight avoirdupois; 5760 grains for Troy & Apothecaries. Inconveniently, the only scientific data I can find of a fair age is 1824 Encyclopedia Britannica which has each…
J King
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