This is a bit of sunshine. It’s made of pure energy. It has no mass—nothing you can hold, touch, or (accurately) draw. It’s called a photon. Some think of it as a little rat-a-tat of energy packets.
But, being pure energy, it goes so fast (at the speed of light) that its true nature is hard to detect—unless it bumps into something. Here it is colliding with an atom, kicking electrons up into higher, more energetic orbits …
… and then, an instant later, those electrons settle back, energy is released, and —whoosh!—our photons are off again. This is what photons do: They get passed from atom to atom, absorbed and spit out, absorbed and spit out. For those of you who like spice in your lives, be grateful you’re not a photon, especially when you remember that most photons are gathered in dense clumps of burning plasma called stars.
Stars are crammed so tight that atoms get crunched, their electrons stripped away to form vast, free-floating electron clouds. So if you’re a typical photon, you spend most of your time slamming into electron after electron.Fwwaaack! Fwwaack! Fwwack! Your energy is absorbed, then released. You may be able to fly at the speed of light, but because you’re stuck in the middle of the sun, when you finish with one electron, you get to swoosh less than 1/63rd of an inch before you’re absorbed again.
If there were ever a shy photon, one that didn’t like crowds, I imagine that it would yearn to escape the madcap crunch of electrons. I see it deep inside the sun, crawling closer and closer to the surface, electron by electron, until—with any luck—it gets scooped up by one of those giant solar flares and then flung …
… Whoosh! … across the quiet, empty highway of space, careening along at a crazy 670,616,629 miles per hour, free, free at last, like a happy racehorse.
This happens to real photons. Some do get free of their stars, do escape into space as solar radiation. And if they happen to crash into Earth, we call them “sunshine,” and when we go to beaches, lie down, and rub ourselves with lotions, we wait for them to bang into atoms and warm us up.
But consider this: We don’t appreciate how long it takes for sunshine to escape the sun. Every bit of sunshine warming your skin has a long history—wonderfully, fantastically, ridiculously long. Next time you’re at the beach looking up, think about this story. …
How birds learn foreign languages
Biologists have succeeded in teaching wild birds to understand a new language.
After only two days of training, fairy wrens learnt to flee when they heard an alarm call that was foreign to them, showing that birds can learn to eavesdrop on the calls of other species.
The research, led by biologists at The Australian National University (ANU), could be used to help train captive animals to recognise signals of danger before they are released in to the wild.
“The first bird we tested lived on the ANU campus near my office. There was general disbelief and excitement when the bird learned the task perfectly,” said the leader of the study, Professor Robert Magrath, from the ANU Research School of Biology.