Is That Your Card: The Math Behind It

If you’ve seen at least one card trick in your life, you’ve probably seen this one. You pick out a card, put it back magicians rummages through the deck, pulls out a card, exclaims, “Is this your card?” That one.

When I was younger, I studied math at the University of Toronto and so I loved this explanation by UK math teacher, author and comedian, Matt Parker about the math behind about guessing what card someone chose. Because as it turns out that with just about everything to do with probability and statistics, that our intuitions are almost always wrong. And not just a little bit wrong, but wrong by a lot.

Now of course no sensible magician would do this trick by guessing. There has to be something else going on. But they might pretend they were guessing for dramatic effect. You never can trust those magicians.

James Randi (1928-2020)

Over the weekend, we lost a celebrated magic icon: James “The Amazing” Randi. Randall James Hamilton Zwinge was born in Toronto. On multiple interviews, I heard him discuss getting on the bus and going to see Harry Blackstone Sr. in theatre.

Throughout his life, he was an inspiration to many. He earned his living as a magician and escape artist and even provided behind the scenes consultation for Alice Cooper’s tour.

He went on to become one of the world’s foremost paranormal investigators, and helped thousands, if not millions of people help think more critically about the world around them. He preferred “investigator” instead of the more inflammatory “debunker” used by the media, because “debunking” implies that you have already made up your mind and aren’t open to new evidence. He was one of the luminaries that abused phrase “I want to keep an open mind, just not so open my brains fall out.”

In that role as investigator, he founded the James Randi Educational Foundation. The foundation offered a famed “Million Dollar Prize” for anyone who could demonstrate psychic, paranormal or extrasensory phenomena under mutually agreed upon controlled conditions. Many applied, none ever succeeded.

He worked on something called “Project Alpha” where he got two young magicians insinuated into a parapsychology lab so they could be tested for ESP. The magicians were on their honour: if anyone ever asked if they were just doing tricks, they had to answer honestly. The researchers never asked — again, they were working towards their desired predetermined conclusion — and found out with the rest of the world at a press conference.

You can see his take on science, skepticism and investigating the paranormal in this clip that was just released by Michael Shermer from a lecture in 1992 at CalTech:

Magicians like Randi are extremely important to me. While technically I was a math major, I always feel as though I was brought as a scientists — reading the popular books by Richard Feynman, Stephen Hawking, Richard Dawkins — and when you care about truth, there’s always a little voice in the back of your head that’s not quite on board with magic — which is essentially carefully crafted deception. But you could put it pejoratively and say it’s lying for a living.

And it’s lying in a way that’s different from acting. Magic tends to have a much more academic feel to it, like a science demonstration. After all, if you want people to be impressed when you escape from the box, it helps if you give them time to examine it carefully to understand how sturdy it is. That amount of exposition can make it feel like you are doing magic “for real” — who will take what we do as proof of the supernatural or that we are in league with the devil. It was people like Randi that showed that you can do magic in an intellectually responsible and grownup way where you still get all the fun of the illusion without giving shelter to the wing-nuts.

Of course, he didn’t stop there. He went on to come out as gay when he was into his eighties. Old magicians can learn new tricks.

In 2014, he was the feature of a full-length documentary The Honest Liar, which you can track down and stream in various places.

The magic community mourns the lost of one of our great role models.

David Copperfield on some of his most well-known Illusions

Almost everyone grew up getting to watch one famous magician on television. In the 70s and 80s, that was Canadian Doug Henning. In the 80s and 90s, that was David Copperfield. For over a decade, David defined for the world what it meant to be a magician!

Here with GQ, he revisits some of his most famous illusions, in a fairly long interview:

David is still performing in Las Vegas at the MGM Grand Hotel.

Bring Magic Home for Thanksgiving

It’s been a very stressful few months, and as we head into the fall, we’ve been hearing about new restrictions about gatherings and getting together. Thanksgiving weekend is coming up and I know that many people across the country will be unable to travel to be with family for the long weekend. So I thought I would do something nice in the virtual space for anyone who is feeling the strain of continued social distancing.

Need a break from cooking this Thanksgiving weekend? Grab a warm drink and get comfortable for a fully inteactive live magic performance on Zoom. 

James Alan is one of Canada's premiere sleight-of-hand magicians. For over three years he starred in the acclaimed show Magic & Martini with over two hundred sold out performances. Now his entire show has been reimagined for virtual, physically distanced world.

Note: Each ticket allows one device to log in to the show. You can purchase multiple tickets to invite family and friends to participate from anywhere in the world.

Sunday, October 11 & Monday October 12
1:00 PM (Eastern)

This year has been stressful for so many of us, being told it's not safe to travel get together with loved ones for the holidays. You can participate with family and friends together at home, or from multiple screens anywhere in the world.

The show is fully interactive. No need to mute your microphone or type in a text window. There is even magic that will happen through the screen at home in your own hands.

Math, Magic and Testing

I was out walking, catching up on podcasts when I came across this episode from BBC’s More Or Less. Its focus is math and statistics issues that come up in the news and (unsurprisingly) a lot of that has been about statistics surrounding COVID 19.

I was surprised when the episode contained a magic trick!

The trick in question is a math/mindreading trick which is quite old. It’s not uncommon to find it in children’s math sets. It’s most commonly known as the “Age Cards”. The way it works is that the magician has six cards with a bunch of random numbers printed on them, usually from one to sixty-four. You think of a number and look at the cards one by one and say “Yes” or “No” depending on whether or not you see your number. And that information is enough to determine what number you’re thinking of.

What’s really cool is that this concept is being applied to the technique of “Pool Testing” which is a method of grouping together multiple virus tests so you only have to run the test once but can still sort out who (probably) has the virus.

I was at convention some years ago with the legendary British magician Paul Daniels (who probably performed more magic on TV than any other person in history). He said that it was performing the “Age Cards” for someone randomly on a train led to his first TV show.

Derren Brown: TedX Vancouver

What’s he doing here?

Derren Brown is one of the world’s most well-known mindreaders. For years he was a star in his native England with multiple specials and touring shows. More recently, some of the programs became available in North America on Netflix. Soon he’ll be heading to Broadway to perform his new one-man show.

Apparently, he stopped off in Vancouver, Canada with white tie and tails to show off some good old fashioned mind reading: