Timeline for Why is the candela a base unit of the SI?
Current License: CC BY-SA 3.0
11 events
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| Dec 1, 2022 at 17:46 | comment | added | Jagerber48 | "This makes the candela ever so slightly washier than the other six SI base units, because you need to rely on physiological measurements of the average human" I would say this is EXTREMELY washier than the other six SI base units. The other base units have had a major historical push towards eliminating reliance on arbitrary "artifacts". The "average human eye" is a super arbitrary artifact. SI would work fine and be much better without it. | |
| Apr 13, 2021 at 14:09 | comment | added | gardenhead | @EmilioPisanty Thanks! | |
| Apr 13, 2021 at 8:02 | comment | added | Emilio Pisanty | @gardenhead See If the candela is a base SI unit, why isn't the sone an SI unit at all? | |
| Apr 13, 2021 at 0:53 | comment | added | gardenhead | This is a great answer, but I have to wonder, why don't we do the same for sound, i.e. create a separate unit for perceived loudness? | |
| Nov 18, 2018 at 17:44 | comment | added | Emilio Pisanty | As you say, usefulness is almost certainly part of the criteria used originally to define the canonical set of seven base units; the candela probably made the cut because you get a lot more lights sold rated in lumens than any of the competitors. As I've argued elsewhere, the concept of a base unit (or at least, the canonical set in current use) makes very little sense come the New SI, but it seems the historical inertia is by now too great to overcome. | |
| Nov 18, 2018 at 17:42 | comment | added | Emilio Pisanty | @jinawee I don't see the case for "temperature as perceived by humans". I don't understand equivalent radiation doses well enough, but I do see the potential for a case that as a spectral-weighted quantity it is equivalent to the luminous intensity; a clearer equivalent is the sone as a unit for loudness, but it has large drawbacks in the larger variability in human hearing (both between individuals and over time for each individual) as compared to luminous intensity. (cont.) | |
| Nov 18, 2018 at 17:33 | comment | added | jinawee | I understand that the candela is useful. But on purely theoretical ground, shouldn't effective radiation dose have its own base unit. What about temperature as percieved by humans and things like that? I guess they aren't as useful. But you could apply a similar reasoning, right? | |
| Mar 27, 2018 at 4:51 | comment | added | gen-ℤ ready to perish | (+1) That was elegant, informed and illuminating (ba-dum-ts), but the conclusion at the end was especially compelling! | |
| Jan 27, 2016 at 21:13 | history | edited | Emilio Pisanty | CC BY-SA 3.0 |
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| Jan 20, 2016 at 2:10 | history | edited | Emilio Pisanty | CC BY-SA 3.0 |
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| Jan 19, 2016 at 22:21 | history | answered | Emilio Pisanty | CC BY-SA 3.0 |