Robert Krulwich

Bats produce "pings" or "clicks," right? They make these high-pitched sounds, too high for us to hear, but when their cries ricochet off distant objects, the echoes tell them there's a house over there, a tree in front of them, a moth flying over on the left. And so they "see" by echolocation. That's their thing. They are famously good at it.

Here's a puzzle I bet you've never pondered.

Imagine you are very, very pregnant. For the purposes of this mind game, you are a married American woman (with an American spouse) and you are about to board a plane and, pregnant as you are, they let you on.

Your flight, on Lufthansa Airlines, will leave Frankfurt, Germany, and travel nonstop to the Maldive Islands in the Indian Ocean. Germany is cold, wet and unhappy-making, and you crave the aquamarine waters, the balmy skies of the Maldives.

What in heaven's name is happening here?

Look at the center of this map, at the little red dot that marks Kansas City. Technically, Kansas City is at the edge of Missouri, but here on this map it's in the upper middle section of a bigger space with strong blue borders. We don't have a name for this bigger space yet, but soon we will.

Let's get dense. If we take all the atoms inside you, all roughly 70,000,000,000,000,000,000,000,000,000 of them, and squeeze away all the space inside, then, says physicist Brian Greene:

Phooey On Flu

Jan 12, 2013

A lot of you have had it by now, or are having it or are about to be exposed. This year's flu is called "H3N2" and this week it's doing big business in about 47 states, Chicago and New York. If you've had a flu shot and if you wash your hands several times a day for 20 seconds, (which is the time it takes to hum "Happy Birthday to You" two times through) you might reduce your odds of getting sick.

These rocks, says the artist, are not glued, not Velcroed. This is not a trick. Go ahead and click through our glossary of photographs. There are big rocks pirouetting on little ones, little ones dangling on top of big ones, pebbles tightly clumped and suspended in air ...

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