3 ms·
I had a lot of fun working with the maintainers of this utility to better support Gaussian units[1]. This is usually done (incorrectly) by multiplying, say, som
by Rayhem 3y ago
I had a lot of fun working with the maintainers of this utility to better support Gaussian units[1]. This is usually done (incorrectly) by multiplying, say, some number of SI coulombs by a dimensionless constant (actually 2_997_924_580) to produce some number of statcoulombs that represents the same charge. It's very subtle, though, that statcoulombs and coulombs have different dimensions (which is the point of Gaussian units) despite representing the same physical quantity[2], so the conversion is much more involved. I learned a lot about the nature of units and software development working with them.
[1]: https://en.wikipedia.org/wiki/Gaussian_units https://en.wikipedia.org/wiki/Gaussian_units
[2]: A consequence of this is that electromagnetic equations formulated in terms of Gaussian units have goofy things like sqrt(grams) as "base" units. That was the tricky part to handle.
- cb321 3y agoYes - you haven't seen the full scope until you confront unit system conversions as alluded to in my other comment (https://news.ycombinator.com/item?id=36988497 https://news.ycombinator.com/item?id=36988497). There should also be conversions to/from SI|CGS and "natural units" (particle physics) and "gravitational units" (general relativity - G=c=1). The "input/output" can be a bit more subtle, too - since you may need to tell the converter the abstract physical kind/"meta type" of the thing like "energy" or "momentum" or "charge" to fully define what might happen (and in some ideal world get back an expression with powers of G's and c's in there symbolically rather than only numerically). Some of this shows up in an unresolved issue on that Nim library I mentioned[1]: https://github.com/SciNim/Unchained/issues/8 https://github.com/SciNim/Unchained/issues/8 EDIT: { One reason to preserve a symbolic capability is that some constants have resisted precise measurement for centuries - G is still only known to about 5 decimals [2] - and you don't want round-trip unit conversion to add such errors to the calculation. } [1] https://news.ycombinator.com/item?id=36988225 https://news.ycombinator.com/item?id=36988225 [2] https://en.wikipedia.org/wiki/Gravitational_constant#Modern_value https://en.wikipedia.org/wiki/Gravitational_constant#Modern_...