Principle: Upward constraint · Emergence
The Keyhole
Chapters 3 and 7Move along the electromagnetic spectrum, from gamma rays to long radio waves. Watch for the moment your eyes can see anything at all.
What you found
Human eyes respond to light between about 380 and 750 nanometres, a sliver of the electromagnetic spectrum.
How small the sliver looks depends on how the spectrum is drawn: a vanishing fraction of one per cent on a linear scale, closer to two per cent on a logarithmic one.
Two identical greys look different against different surrounds, because the brain judges brightness by context.
Colour is constructed by the brain from the light that reaches the eye; it is not a property carried by the light itself.
Further in the book
Chapter 7, The Exquisite Bottleneck, asks why a narrow window is the precondition of a usable world rather than a defect in it.
If you would like to hear when the next laboratory opens, join the reader circle. Join the reader circle