Light
What light does between leaving a star and arriving in your head.
1234 4 pieces, best read in this order
- Poetry The Moon You See Is One Second Old A poem about looking up and seeing the past, from a Moon that is one second out of date to a galaxy whose light set off before there were people. The idea Light travels at a finite speed, about 300,000 kilometres a second, so we see everything as it was when its light set off; the further away something is, the further back in time we are looking.
- Deep Dives The Sky Is Blue Because Air Is Picky The same tiny effect explains the blue of noon and the orange of evening, and why the sky on Mars does the opposite. The idea Air molecules, much smaller than the wavelength of light, scatter it in proportion to one over the wavelength to the fourth power, so blue light is scattered around five times more than red; that makes the daytime sky blue and leaves mostly red and orange light in a low sun's long path through the air.
- Satire & Humour Product Review: The Human Eye (Four Stars) We tested the most popular camera on the planet. It has been on the market for a very long time and it shows. The idea The eye focuses light mostly with the cornea onto a retina whose rods and cones detect it when a pigment molecule changes shape; vision is sharp only in the tiny fovea, every eye has a blind spot where the nerve leaves, and colour comes from comparing three kinds of cone.
The next stop goes deeper into this one.
- Unpacked Your Brain Is Hiding a Hole in Your Eye Our review of the human eye said every eye ships with a blind spot. Here's how to find yours in thirty seconds, and what your brain is doing to hide it. The idea Each eye has a blind spot where the optic nerve leaves, and your brain fills it in so well that you never notice, until you test it. Opens once you’ve read “Product Review: The Human Eye (Four Stars)”