Purple Doesn't Exist

Most of the purples you see have no wavelength behind them. Your brain invents them, to stand in for a green that should be there and isn’t. Which is fun trivia—until you notice it does exactly the same with your reasons. Rather read? I also made this episode into an article: https://btr.mt/analects/purple-doesnt-exist-lecture And the piece it’s based on: https://btr.mt/analects/purple-doesnt-exist. Stuff I mentioned: Purple doesn’t exist—the article this episode is adapted from, and the home of the light-and-photoreceptors diagram I mention: the visible spectrum with the S-, M- and L-cone sensitivities drawn over it. It’s the picture I said I’d put here, and it reads better in place. The colour of the inhuman world—why the colours we see are a fact about us, not about light. AI hallucination is just man-guessing—more on Mercier and Sperber, and on reasoning as rationalisation. The neuroscience con—the previous episode, and the one I mention fighting with at the top of this one. Mercier, H. & Sperber, D. (2017). The Enigma of Reason. Harvard University Press. Publisher Gazzaniga, M. S.—the split-brain work, and the chicken-claw/snow-shovel experiment. Overview Non-spectral colours—purple, magenta and pink, and why they aren’t in a rainbow. Trichromacy—the three-cone system. the btrmt. lectures podcast A note on the audio: I describe photons as moving at different speeds. They don’t—all light travels at the same speed, and what differs is the wavelength (and so the frequency: how fast the wave oscillates, not how fast it travels). The transcript below says it correctly. Related stuff: Everything is ideology—including the section on chromacy: what a fourth photoreceptor would actually be like. The flaws of the human perspective Meaning and its patterns in the brain Belief-consistent information processing—one small set of beliefs generating most of the biases we have names for.