From the medicine wheel to the building blocks of DNA, the number four has represented structure and stability. But four is also a troublemaker: a portal to realms like the fourth dimension. Our series, The Greatest Numbers of All Time explores how the number four helps us understand the world — both by making the rules, and by breaking them.

More in the series:

Listen to The Curse of 13

Listen to 12 is Sublime

Listen to 27 Club Lore

Listen to The 33,000 Horsepower Gamechanger

Guests in this episode:

Joyce Perreault is an Ojibway Anishinaabe children's book author and elementary school teacher at Donald Ahmo School in Crane River, MB.

Brian Katz is a composer, instrumentalist, improviser, and guitar instructor at University of Toronto and York University.

Lauren Fink is a professor of cognitive neuroscience at McMaster University.

Alex Fisher is a professor of musicology and area coordinator for early music at the University of British Columbia.

Tyrone Ghaswala is an assistant professor teaching stream with the Centre for Education and Computing (CEMC) and an adjunct professor in the Pure Mathematics department at the University of Waterloo.

Wenran Jiang is the founding director of the China Institute at the University of Alberta.

Stephan Reuter is an associate professor for plasma physics and spectroscopy at the Engineering Physics Department of Polytechnique Montréal

Sarah Hart is professor emerita of mathematics at Birkbeck College and author of "Once Upon a Prime: The Wondrous Connections between Mathematics and Literature."

There is nothing random about featuring 33,000 in our number series. It's very powerful. So much so, that the number put millions of horses out of work. Inventor James Watt used “33,000 foot-pounds a minute" to measure the capabilities of a horse when trying to market his new and improved steam engine. The engine was a big success, saving horses from the drudgery of manual labour. Now, a similar process is underway with artificial intelligence — but are we the horses, or the steam engine? *This episode is part of our series, The Greatest Numbers of All Time.

For more in the series:

Listen to The Curse of 13

Listen to 12 is Sublime

Listen to 27 Club Lore

Guest in this episode:

Stephanie Dick is a historian of mathematics, technology, computing, and AI, and an assistant professor at Simon Fraser University.

Twenty-seven can be a pivotal and tumultuous age. It’s held up as the year of peak performance in many sports and it's also seen as a cursed age for pop and rock stars, exemplified by the so-called 27 Club. Artists like Jimi Hendrix, Janis Joplin, Kurt Cobain and Amy Winehouse, all died at 27. As part of our series, The Greatest Numbers of All Time, IDEAS producer Chris Wodskou makes the case for a number that may not stick out in your mind but is more significant than you think.

More episodes in this series:

Listen to 12 is Sublime

Listen to The Curse of 13

Listen to The 33,000 Horsepower Gamechanger

Guests in this podcast:

David Awosoga is a PhD student in Statistics at University of Waterloo and sports performance data analyst.

Alan Cross is a music historian, broadcaster, and host of The Ongoing History of New Music podcast

Dianna Kenny is a professor emerita of psychology and music at University of Sydney and psychotherapist in private practice.

Michael Owen is a retired clinical psychologist and author of The 27 Club.

Maria Westerstahl is senior lecturer at Karolinska Institutet in Sweden.

Complete. Whole. Divine order. That's just the start of what makes the humble dozen extraordinary. It's one of only two numbers ever discovered in mathematics to be “sublime.” Twelve makes a number of appearances in pop culture, in religion, in non-fiction, everything from the 12 days of Christmas to the 12 people it takes to form a criminal jury. Still need convincing of 12’s perfection and indispensability? Check your watch.

More episodes in our series, The Greatest Numbers of All Time:

Listen to The Curse of 13

Guests in this episode:

Glen Van Brummelen is a professor of mathematical sciences at Trinity Western University.

Ainsley Hawthorn is a cultural historian and nonfiction writer. She has a PhD in Near Eastern Civilizations from Yale University.

Has there ever been a number more maligned in western culture than 13? So feared, it's got its own horror-film franchise. So infamously unlucky, a good many of us avoid it en masse. We've just blindly accepted its bad reputation. As part of our series, The Greatest Numbers of All Time, IDEAS explores where our irrational fear and uncomfortable feelings about 13 began. *All five episodes in our number series will be available daily in our feed this week.*

Listen to 12 is Sublime

Listen to 27 Club Lore

Listen to The 33,000 Horsepower Gamechanger

Guests in this episode:

Stephen Winick is a folk life specialist at the American Folklife Center of the Library of Congress.

Barry Markovsky is distinguished professor emeritus of sociology at University of South Carolina. His latest book is Everyday Extraordinary: A Scientist Ponders a Lifetime of Magical, Bizarre, and Paranormal Experiences.

Claire Potter is an author of parenting books, including Getting the Little Blighters to Behave and the creator of the online programme Tiny Bites for parents of picky eaters.

Rabbi Heschel Greenberg is the founder and director of the Jewish Discovery Center in Buffalo, New York. He has written many books including Tefillin: Judaism's Crown.

It's tempting to think suffering should be avoided at all costs, but moral suffering has its own distinct standing. It signals a moral conscience. Every day people consume real time violence, grief, war and genocide through screens and experience moral upending. Without a moral compass there’s no motivation to address necessary issues.

Guests in this episode:

Cynda Rushton is a nurse and a professor of nursing and bioethics at Johns Hopkins University.

Robert Meagher is an emeritus professor at Hampshire College in Amherst, Massachusetts.

Thea Lim is a novelist, culture writer, and creative writing teacher in Toronto.

Former IDEAS writer-broadcaster David Cayley passed away at his home on Wednesday June 10, surrounded by family. To honour his legacy, we wanted to share part of a 2006 conversation David had with Irish philosopher Richard Kearney on the space for theism within atheism, and/or atheism within theism.

Richard Kearney is a philosophy professor at Boston College and University College, Dublin. He has written many books on modern philosophy and culture, including The God Who May Be: A Hermeneutics of Religion and Anatheism: Returning to God After God.

There may be no one alive who saw Houdini perform magic. Yet we still know his name and his legend. Dua Lipa namechecked the escape artist in a 2023 dance hit and she's not alone. Houdini is still a cultural reference point, despite having died 100 years ago. And that’s pretty much what he would have wanted. IDEAS explores why his name persists in our imaginations and how his magic helped his family escape poverty.

Guests in this episode:

Adam Begley is a biographer living in London, and author of Houdini: The Elusive American.

David Ben is a conjuror, writer, and consultant in Toronto. He’s writing a graphic novel featuring an imagined adventure for Houdini.

Katie Bender is a playwright and actor. Her interactive performance about Houdini is called Instructions for a Seance.