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, ...

Let's compare two kinds of nothing: an empty patch of deep space and an empty piece of paper that was once beautiful. There's nothing to see in either. Or is there?

This being my last weekend with this blog, I wanted to repost a story I wrote a few years ago that has continued to intrigue me ...

I'm going to show you two kinds of nothing.

The first is a small patch of space, way, way out in the universe, ...

Meet two animals. Both are teeny. Both live in water. Both mature extra fast. But while one dies in about a week, the other — well, prepare to be amazed.

A puzzlement.

Why, I wonder, are both these things true? There is an animal, a wee little thing, the size of a poppy seed, that lives in lakes and rivers and eats whatever flows through it; it's called a gastrotrich. It has an extremely short life.

Hello, Goodbye, I'm ...

NPR (in the form of a super top executive) sat me down and, after four years of generously supporting this blog, told me it can't anymore. It needs to cut costs and — you know the phrase — it has chosen to go "in new directions." So at the end ...

They are small. They are weak. They are vulnerable. But these little bees take on a humongous predator in the most ingenious way.

I know, I know. You have Putin to worry about, ISIS to worry about, Britain's near breaking, Washington's broken, and the globe keeps getting warmer — so why bring up Japanese giant hornets? You have worries enough. But I can't help myself. I've got to mention these hornets because, ...

Draw a planet (a circle, right?). Now draw a star (a pointy thing, yes?). Now ask yourself, aren't stars all round? Our sun is. So why do we make them pointy? Come learn the answer.

Can a colicky baby's piercing scream be militarized? As in, made (literally) into a weapon of war? Oh, absolutely, says this scholar, smiling ever so slightly.

If you have ever seen, or spent time with (or, God forbid, had to live with) a colicky baby, this will make perfect sense to you. It may not make actual sense, but when the baby is crying you don't think very straight.

Speaking at the first BAHFest in ...

Notice what Tyler Nordgren does in these posters. He's an artist, an astronomer (from Cornell, Carl Sagan's department); he's worked for NASA. He's an expert in dark matter, and a full professor at the University of Redlands. He's knows much, much more than I do about astrophysics and stars, ...

Every fall, birds head south and, around Sept. 11, New York sends two beams into the sky. When birds and lights collide, that could mean trouble — but New York is surprisingly gentle.

Every fall, birds head south and, around Sept. 11, New York sends two beams into the sky. When birds and lights collide, that could mean trouble — but New York is surprisingly gentle.

There's much more to Stonehenge, it turns out, than meets the eye (or, for that matter, Spinal Tap).

Researchers from Birmingham University used high-tech equipment to map 17 ritual monuments in the area. That's in addition to the iconic circle of stones that has stood there for thousands of ...

We live on a planet, next to a star that's part of a galaxy that's part of ... ah, here comes the new discovery. We are at the very tip of a giant galactic "supercluster." Take a look.

When I was a boy I had a globe. I could take it in my hands, rest it on my lap, give it a spin and look down on Africa, Europe, North America and Asia spinning by.

In 1961 (I was 13), cosmonaut Yuri Gagarin left the planet and ...

It's a puzzle — the deepest puzzle I know. The question is: What are we?

One answer, from physicist-novelist Alan Lightman, is we are stuff. Just stuff.

Let me explain. A highly unpleasant idea, but one that has been accepted by scientists over the last couple of ...

I am made of atoms — 7,000 trillion trillion of them. How did I teach them to tie my shoes? Or did they teach me?

What's going on here, I can only guess, but here's what you're about to see: In the video below, the great musician Glenn Gould, supreme interpreter of Bach, is sitting at his living room piano on a low, low chair, his nose close to the keys. He's at his Canadian ...