It's Monday, October 7th, 2019, and you're listening to Inquiring Minds. I'm Indyvis Gontas.

And it's my birthday. Each week, we bring you a new in-depth exploration of the space where science,

politics, and society collide. We endeavor to find out what's true, what's left to discover,

and why it all matters. You can find us online at inquiring. Show, on Twitter, at Inquiring

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This is the third in our three-part series on very small things.

And today we're getting to pretty much the smallest things that we know exist, quantum mechanics.

It's my great pleasure to have Sean Carroll, theoretical physicist from Caltech, and one of the world's most celebrated science

writers back on the show. His latest book, Something Deeply Hidden, Uncovers a Secret that

physicists have been keeping from all of us, the fact that even they don't really understand

quantum mechanics. I mean, hey, I thought it was just me. This book also resided with me because I recently read

a Ted Chiang short story from his collection Excellation about a possible future in which we can

actually contact people in the many other worlds that might exist outside of our own.

If every time there's a quantum event, we make a decision and all of a sudden

that changes the course of our lives, what would happen if we could speak to the person who

we would have been had we not made that decision? That's what Ted Chiang writes about and it's a really

interesting concept and it raises some really fascinating questions. And who better to answer those questions

than Sean Carroll? Sean Carroll, welcome back to inquiring minds. Thanks. Thanks very much for having me.

I was so delighted to receive your book. And of course, it blew my mind again, but in a very different

way from the big picture, which is the previous book we covered here. And so I want to start with

...