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Letter to Prospect Magazine

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18th Mar 2005 | 09:47

Pedantry about basic units... (I hope these URLs work.)



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Comments {3}

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Tony Finch

from: fanf
date: 20th Mar 2005 21:18 (UTC)

It was originally, but that definition doesn't provide a sufficiently accurate repeatable experiment.

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from: anonymous
date: 8th Apr 2005 22:11 (UTC)

If you define the kilo in terms of counting actual atoms as they whoosh past, you simultaneously define Avogadro's number.

Question: do you count radians as units? Think carefully.


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Tony Finch

Re: Metrology

from: fanf
date: 9th Apr 2005 17:20 (UTC)

The problem with that definition is that it isn't currently practical, i.e. you can't use it to calibrate machinery.

You can treat radians as a unit or as a ratio, depending on what's convenient. However a significant difference between radians and physical units is that they are defined mathematically rather than based on some experiment.

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