RACHEL MARTIN, HOST:

Coincidences confound us. Miracles amaze us. And the chance that the same person could be hit by lightning three different times, well, that just defies explanation. Or does it? David Hand is an emeritus professor of mathematics at Imperial College in London. And he has written a book called "The Improbability Principle: Why Coincidences, Miracles and Rare Events Happen Every Day." He joins us from the BBC studios in London. Thanks so much for being with us.

DAVID HAND: Thank you very much for inviting me.

MARTIN: So, I'm going to put you to the test and ask you to explain what the improbability principle is. You've written an entire book on this, but I'm going to ask you to distill it down to a few sentences.

HAND: OK. So, we've all experienced strange coincidences, perhaps bumping into a friend in a strange city or having a dream and then having the thing happen the next day. We've all heard of people being struck by lightning or people winning lotteries - never us, unfortunately, but we've heard of people winning lotteries. The improbability principle says that those very rare events, those very strange coincidence, in fact should be expected to happen. Now, that sounds like a contradiction. That's what the book does really. It takes that statement of the improbability principle, splits is up into its components and describes why you do get these very rare events happening lots and lots of the time.

MARTIN: Are we predisposed to want to see coincidence in our lives, to see that seemingly random events are actually connected in some way? Is that a human trait?

HAND: That's spot-on, I think. Here's an example. We go to quite a lot of conferences, and in 2012, I went to the Royal Statistical Society conference, checked into my hotel, and the receptionist said, oh, you're the second David Hand to check into the hotel today. And I thought that's very strange. It might have been people with other similar names or anagrams of the names. You wouldn't have noticed. But we did notice that, so we are predisposed to notice these things. Yes.

MARTIN: You write another story in the book. Something had happened to the actor Anthony Hopkins, which I found to be absolutely amazing. Could you recount that tale and what you find significant about it?

HAND: So, Anthony Hopkins was one of the stars in a film called "The Girl from Petrovka." And he went to London to buy a copy of the book so that he could read about the book and the character and so on. But he couldn't find a copy of the book. None of the bookstores stocked it. But then on his way home on the tube station in London, he came across a copy of the book on the seat next to him. Absolutely incredible. Later, when he met the author and told the author this story, the author told him that a year or so before he'd lost a copy of the book in London and it was a particular copy that he'd been annotating to change the English into American spellings and things like that, and he'd lost it on the Tube. And when Anthony Hopkins showed him the copy of the book that he'd found on the tube months later, it turned out to be exactly the same book. So, somehow, this book had traveled through space and time in a loop, in a circle. I think that's one of my favorite examples.

MARTIN: I mean, that's a crazy story. So, I hear that and I think the universe was conspiring to help Anthony Hopkins. And you, David Hand, hear that and what kind of probability is embedded in that scenario?

HAND: So, I think how many people lose books, how much traveling do these people involved do? And the chance of it happening to Anthony Hopkins in particular is incredibly low. But a chance of it happening to somebody is quite high.

MARTIN: What about miracles, divine intervention? Some people just say the stars might align or the universe is conspiring in their favor. Is that something you've looked at?

HAND: It is. But I regard miracles as an attempt to explain these highly improbable events. But it's not really necessary to resort to that sort of explanation if you take into account the number of opportunities for these rare events to occur or one of the other laws of the improbability principle. You can see that you should expect this sort of thing to happen.

MARTIN: So, does that mean, David, that you are a difficult person to amaze?

HAND: I don't think so. You know, obviously, I'm collecting lots more of these stories now. I'm delighted when I come across them. I've got just as much as sense of wonder still. But what it does mean is that I then think, well, how could this be? Is it that improbable? How can I explain it? Should I have expected something like to happen, if not this particular thing?

MARTIN: But it doesn't kill the romance for you of the coincidence?

HAND: No, absolutely not, absolutely not.

MARTIN: David Hand's new book is called "The Improbability Principle: Why Coincidences, Miracles and Rare Events Happen Every Day." Thanks so much for talking with us, Professor Hand.

HAND: Thank you very much indeed. Thanks.

(SOUNDBITE OF MUSIC)

MARTIN: You're listening to WEEKEND EDITION from NPR News. Transcript provided by NPR, Copyright NPR.