Topic
Light
13 articles
Physics
Why is a rainbow always in the same place?
Rainbows never turn up in a random corner of the sky. They sit at exactly the same angle from the shadow of your own head, every single time, and the person standing next to you is looking at a different one.
Technology
Why does wifi go through walls but light doesn’t?
Both are the same kind of wave, traveling at the same speed, made of the same stuff. One crosses a brick wall without noticing it and the other cannot get through a sheet of paper. The difference is size.
Physics
Why does a desert get so cold at night?
Sand that could blister a bare foot in the afternoon can be chilly enough for a coat by midnight. All that heat goes somewhere, and where it goes is not where most people guess.
Physics
Why can you hear around a corner but not see around one?
A voice from the kitchen reaches you in the hall, around the corner, without any trouble at all. Light from that same kitchen stops dead at the door frame.
Biology
How does a young sunflower follow the sun?
A sunflower has no muscles and nothing inside it that moves. A young one still swings its head halfway across the sky each day — and swings back overnight, in the dark.
Astronomy
How do we know what the stars are made of?
Nobody has ever been to a star, and nobody has brought a piece of one home. Yet astronomers will tell you what any star contains, in order, with amounts. The answer is hiding in the parts of a rainbow that are missing.
Biology
Why does a bruise turn purple, then green, then yellow?
You knock your shin, nothing bleeds, and days later a mark appears and works through three colors in a fixed order. Nothing else on your body behaves like that. So what is happening underneath?
Physics
Why does a mirror swap left and right but not up and down?
Raise your right hand at the bathroom mirror and the person in the glass raises a left one. Nothing in the room has moved sideways. So where is the swap actually happening?
Biology
Why do some leaves turn red before they fall?
The yellow in an autumn leaf was hiding under the green all summer long. The red was never there at all. A tree builds that color from scratch, in the last two weeks of a leaf it has already decided to drop.
Astronomy
Why can’t light climb back out of a black hole?
Light is the fastest thing there is, and nothing has ever overtaken it. Yet there are places it sets off from and never leaves. The explanation most people are given was worked out in 1783, and it is wrong.
Physics
Why is the sky blue at noon and red at sunset?
The same sun, the same air, and two completely different colors twelve hours apart. Nothing overhead has been swapped out, so something else must be doing the work.
Physics
How does sunscreen stop a sunburn?
Rub it in and you can still see your skin, still feel the sun, still get warm. Nothing looks blocked at all. So what has that invisible film actually done?
Technology
Why do sunglasses turn a screen black?
Tilt a pair of sunglasses in front of a laptop and the picture vanishes. Nothing has been switched off. The screen is doing something to its light long before it reaches your eyes.