Cafe Math

A paradox is a statement that, despite apparently sound reasoning from true premises, leads to an apparently self-contradictory or logically unacceptable conclusion.

In the world of math, many strange results are possible when we change the rules. But there's one rule that most of us have been warned not to break: don't divide by zero.

We have been collaborating on rotational motion, which is timely for some of the videos I've been doing lately.

This video was funded by SNSF under Agora Grant n. 171622 and through the NCCR SwissMAP: The Mathematics of Physics.

When you flip a coin to make a decision, there's an equal chance of getting heads and tails.

You heard the travelers' tales, you followed the maps, and now, you've finally located the dungeon containing a stash of ancient coins. The good news: the wizard who owns the castle has generously agreed to let you have the coins. The bad news: he's not quite as generous about letting you leave the dungeon ... unless you solve his puzzle. Can you solve it and get out alive? Lisa Winer shows how.

You might think that computers are the only things that run algorithms, but you're wrong. Here's a neat mental trick for calculating the day of the week for any day ever, developed by famous mathematician John H. Conway

Do you ever come across a math problem that you know is right but no matter how hard you try, you can't wrap your mind around it?

They say the pen is mightier than the sword, and authorities have often agreed. From outlawed religious tracts and revolutionary manifestos to censored and burned books, we know the potential power of words to overturn the social order. But as strange as it may seem, some numbers have also been considered dangerous enough to ban. Alessandra King details the history behind illegal numbers.

1, 11, 21, 1211, 111221. These are the first five elements of a number sequence. Can you figure out what comes next? Alex Gendler reveals the answer and explains how beyond just being a neat puzzle, this type of sequence has practical applications as well.

A statistical analysis of luck vs skill in sports.

Imagine a group of people. How big do you think the group would have to be before there's more than a 50% chance that two people in the group have the same birthday? The answer is ... probably lower than you think. David Knuffke explains how the birthday problem exposes our often-poor intuition when it comes to probability.

It's a good day to be a pirate. Amaro and his four mateys - Bart, Charlotte, Daniel, and Eliza have struck gold - a chest with 100 coins. But now, they must divvy up the booty according to the pirate code - and pirate code is notoriously complicated. Can you help come up with the distribution that Amaro should propose to make sure he lives to tell the tale? Alex Gendler shows how.

You and your team have crash-landed on an ancient planet. Can you appease the three alien overlords who rule it and get your team safely home? Created by logician Raymond Smullyan, and popularized by his colleague George Boolos, this riddle has been called the hardest logic puzzle ever. Alex Gendler shows how to solve it.

Your research team has found a prehistoric virus preserved in the permafrost and isolated it for study. After a late night working, you're just closing up the lab when a sudden earthquake hits and breaks all the sample vials. Will you be able to destroy the virus before the vents open and unleash a deadly airborne plague? Lisa Winer shows how.

Rubik's Cube world record-holder Collin Burns tells us how he did it.

Have you ever sat down to take a math test and immediately felt your heart beat faster and your palms start to sweat? This is called math anxiety, and if it happens to you, you're not alone: Researchers think about 20 percent of the population suffers from it. So what's going on? And can it be fixed? Orly Rubinsten explores the current research and suggests ways to increase math performance.

The meter is the world's ultimate measure, but how did it become "the" meter? What is this measurement based on? The story of this revolution in measurement traces its roots to the French Revolution. Scientists decided that an equal and united people should have equal and united measures. So they sent a pair of young astronomers out to measure the world, and invent the meter. Little did they know they'd find nothing but war, deception, and strife along the way. As a result of this ill-fated mission, the meter carries an error that still persists today. Still think the metric system is so perfect?

1, 2, 3, 4, 5, 6, 7, 8, 9... and 0. With just these ten symbols, we can write any rational number imaginable. But why these particular symbols? Why ten of them?

Have you ever sat in a doctor's office for hours, despite having an appointment?

You're the realm's greatest mathematician, but ever since you criticized the Emperor's tax laws, you've been locked in the dungeon.