Measurement Memes

Okay so someone's out here fighting the good fight and I'm here for it. The candela (cd) is one of the seven SI base units, measuring luminous intensity, but here's the kicker: it's literally defined using other fundamental units. It's basically kg⋅m²⋅s⁻³⋅sr⁻¹, which makes it about as "fundamental" as calling a sandwich a basic food group just because you eat it every day. The candela is defined as the luminous intensity of a light source emitting monochromatic radiation at 540 THz (green light, where human eyes are most sensitive) with a radiant intensity of 1/683 watt per steradian. So yeah, it's derived from watts (power) and steradians (solid angles), which themselves come from more fundamental units. It's basically a unit that exists because humans decided "we need to measure light the way our eyeballs perceive it" rather than any actual fundamental physical property. This person is absolutely right to be upset, and frankly, we should all be joining them at this table. The candela is the imposter among the SI units, and it's time we had this conversation.

Devil: "My child will use Kelvin in analysis" versus Jesus blessing us with Rankine, Rømer, and Réaumur scales. The unholy trinity of temperature scales nobody asked for! While Kelvin actually serves a purpose in thermodynamics (absolute zero at 0 K, no negative temperatures, makes equations cleaner), these other three are like that drawer in your kitchen filled with gadgets you've never used. Rankine is basically Kelvin's American cousin—it uses Fahrenheit-sized degrees but starts at absolute zero. Rømer was an early attempt from 1701 where water freezes at 7.5° (because why not?). Réaumur sets water's boiling point at 80° instead of 100°. These scales exist purely to torture engineering students who stumble upon old European scientific papers and have to convert everything back to something remotely usable. Fun fact: There are actually even MORE obscure temperature scales like Newton, Delisle, and Wedgwood. Scientists really went wild inventing these things before everyone agreed to just stick with Celsius and Kelvin.

Just a regular green circle claiming to be a "quantum circle" that was apparently a yellow square before observation. Classic quantum mechanics joke playing on the observer effect—where particles exist in multiple states until measured. The difference is that real quantum particles don't lie to your face about what they were. My PhD advisor would call this "creative data interpretation."

The eternal battle between metric and imperial units gets a hilarious upgrade! Kilogram and pound duke it out like movie monsters, but both are utterly demolished by the electron-volt—the tiny yet mighty unit that particle physicists use to measure energy at subatomic scales. It's like watching two bodybuilders flex while a quantum physicist walks in with a particle that could power a small galaxy. The scientific measurement hierarchy has spoken, and electron-volts reign supreme in the tiniest corners of reality!