What is information? No one knows for sure, says Hans von Baeyer: "All of us know lots about it without really being able to define it. It's like love."

Not the sort of answer you expect from a physics professor. But von Baeyer is not the sort of physics professor you expect. He spends much of his time writing not for scholarly journals but for magazines like New Scientist, Discover, and Reader's Digest. He's written an Emmy-nominated TV show (The Quantum Universe, for PBS) and five books, most recently Information: The New Language of Science.

Why the popular approach? "Because science is so very influential in our lives," says von Baeyer, who frequently stops to chuckle in mid-sentence. "People should have a nodding, friendly relationship with it."

We reached him at his office on the campus of the College of William and Mary, in Williamsburg, Virginia.

Finish this sentence: Information is...
I can't. I wrote a book about information and I spent the first three chapters explaining that nobody really knows what it is. There are real objects, like the tree outside my window, and there is my brain, which perceives that tree. Information is exactly in the middle. It mediates between object and perception.

So are things really things? Or do they just consist of the information we know about them?
More and more I'm persuaded that we don't know anything about the world except the information we have of it. That's not to say there isn't really a tree out there. That's silly. Unfortunately we don't really know anything about it. All we can do is have information about it. Now for trees we're lucky, because you and I will agree 99.9 percent on what we perceive. But at the level of an atom, that isn't true. One person does something to an atom and gets some information and another does something to that same atom and gets different information.

What is the information explosion? Is it information that's exploding or our ability to perceive it?
When you're looking around, wherever you are, you're getting one hell of a lot of information. That's always been there. When we talk about the information explosion, mostly we're talking about its transmission, which is getting bigger and faster. When I was younger, people thought the 21st century would be about spaceships and better transportation of things here on earth. To our great surprise, none of that happened. What's being transported around the universe in huge quantities is information.

Why is noise important?
Anytime you transmit information it gets noise on it, it gets corrupted. In a way that's good. If there were no noise, you and I would be completely overwhelmed. In a landscape there's an unbelievable amount of information. You could never process it all. But noise covers it like a blanket of snow, so you see beautiful soft hills.

Can you put your finger on the most important piece of information you ever learned?
It's that we never perceive an object, we only perceive information about an object. It's not a new thought by any means but for me it was very important: Pay attention to the messenger! Because the message is never pure and the messenger influences the message.

What tools do you use to manage information?
I'm very bad at it. I have folders all over the place and pieces of paper with bits of information scribbled on them.

Do you think geniuses are people who are better at dealing with information?
There are two kinds of geniuses: ordinary geniuses and extraordinary geniuses. Ordinary geniuses are like that. They can make 10 hypotheses and throw them away before breakfast, while I might take a year to have one hypothesis and prove it wrong. Extraordinary geniuses—like Einstein—I don't think anyone knows how they do it. They have a sixth sense. They transcend information. But ordinary geniuses are people who have a tremendously heightened ability to manipulate information.