All of us are aware of the passing of time.

We felt it in the changing of the seasons, the rhythms of song and dance, our kids growing

up and getting older. Like it or not, time is a fundamental

part of life. And over the millennia, scientists have generally regarded time as a one-dimensional

thing, an arrow that keeps moving forward, never backward. But the closer we look at time,

the more complicated and mysterious it gets.

Scientists today are divided over whether time, or our experience of it at least, is real or illusory.

Perhaps we're not really moving through time. Perhaps the present, past, and future are all equally real.

I'm Steve Strogatz, and this is The Joy of Why, a podcast from Quantum Magazine, where my co-host,

Jan 11 and I take turns exploring some of the biggest unanswered questions in math and science

today.

In this episode, we'll ask theoretical physicist Frank Wilcheck, what is time?

How have we defined it in the past?

And how might quantum physics redefine it in the future?

Frank is the Herman Feshbach Professor of Physics at MIT,

a distinguished professor at Arizona State University, and a professor at Stockholm University. He's

the winner of the 2004 Nobel Prize in Physics and the 2022 Templeton Prize. And he's the author

of a number of books, including most recently,

Fundamentals, Ten Keys to Reality. Frank, welcome to the Joy of Why. Thank you. Happy to be here.

Well, I'm very happy to be chatting with you again. I loved your whole book, Fundamentals. And

the explanation you gave of time and how to think about time

for me was one of the most poignant and beautiful. But I like to begin with a sort of personal

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