3 ms·
I've done a lot of philosophizing on the nature of units and there's a bit of an interesting wriggle there. Most people think "length" and "time" are different
by Rayhem 4y ago
I've done a lot of philosophizing on the nature of units and there's a bit of an interesting wriggle there. Most people think "length" and "time" are different things, such that 1m + 1s = garbage. Mathy physics people* say "Aha! They're really the same thing, just set c (the speed of light) to 1!" This, then, raises an interesting question: is there anywhere you can't do this? In other words, is there some irreducible set of dimensions by which the universe operates? I tend to think no, since the units always divide out like this article says. But then, why are lengths what they are? Why did the universe settle on this scale? What even is length, and is "this scale" just an artifact of human perception somehow?
* The same mathy physics people also do fun things like define Gaussian units where charge is proportional to fractional powers of length and mass.
- pvillano 4y agoWhy are cells mostly the same size across all organisms? Well some things get better with area and some things get worse with volume, and since those grow at different rates, there's an optimal size for which the difference is maximized. Pretty much any emergent constant size can be explained by the intersection of two functions. Snowflakes fly up from area and fall down from volume, so there's a maximum size they can stay in a cloud
- Rayhem 4y agoI think this analysis is great and I like it a lot, but it's not quite what I was going for. Here, the size of a cell works against an independent measurement of length like "one meter". But, at a much more fundamental level, I kind of meant why is a meter a meter? If everything in the universe doubled in length overnight, how would we know since our meter sticks would double, too, which admits two possibilities: 1) If lengths are absolutely fixed, why are they fixed at that scale? Why *didn't* things end up doubled (assuming an external absolute to measure against). 2) If they're *not* absolutely fixed, the "fundamental length" appears pretty fixed to us as humans because things kind of look the same day-to-day. Is there a variation we just don't perceive? Is the fixedness we see just us imposing part of our perception on the world? It's sort of like this illustration of gauge fixing[1] -- just like "how do you know the cylinder is twisted?", you can ask "how do you know your fundamental lengths?" [1]: https://en.wikipedia.org/wiki/Gauge_fixing#An_illustration https://en.wikipedia.org/wiki/Gauge_fixing#An_illustration
- pvillano 4y agoSeven https://wikipedia.org/wiki/International_System_of_Units https://wikipedia.org/wiki/International_System_of_Units or four https://wikipedia.org/wiki/Natural_units https://wikipedia.org/wiki/Natural_units or maybe two https://wikipedia.org/wiki/Geometrized_unit_system https://wikipedia.org/wiki/Geometrized_unit_system