Speaker 1: Welcome to brain Stuff production of I Heart Radio. Hi
Speaker 1: brain Stuff, I'm Lauren Vogelbaum, and this episode is another
Speaker 1: classic from our erstwhile host, Christian Sager. This one breaks
Speaker 1: down the conundrum of the birthday paradox, which isn't a
Speaker 1: true paradox, but rather a thought experiment in probability theory
Speaker 1: and a good way of demonstrating exactly how bad we
Speaker 1: humans are at probability math off the top of our heads. Hey,
Speaker 1: brain Stuff, it's Christian Sager and today's question is what
Speaker 1: is going on with the birthday paradox. You've probably heard
Speaker 1: this one before, the idea that if there are twenty
Speaker 1: people in a room, there's a fifty fifty chance that
Speaker 1: two of them will have the same birthday. So how
Speaker 1: can this be? Well, it really is called the birthday paradox,
Speaker 1: and it turns out it's useful in several different areas,
Speaker 1: for example, in cartography and hashing algorithms. You can try
Speaker 1: it yourself the next time you're at a gathering of people. Know,
Speaker 1: just ask everyone for their birthday. I mean, don't be
Speaker 1: creepy about it. Play cool, say you know something like
Speaker 1: I'm trying to prove this for science or whatever, and
Speaker 1: it's likely that two people in this group will have
Speaker 1: the same birthday, not around the same time, they will
Speaker 1: have the exact same day. And this really surprises people.
Speaker 1: So the reason isn't so surprising. It's because we're used
Speaker 1: to comparing our particular birthdays with some other individuals particular birthday. So,
Speaker 1: for example, you meet somebody randomly and you ask her
Speaker 1: what her birthday is, the chance of the two of
Speaker 1: you having the same birthday is only one out of
Speaker 1: three hundred and sixty five, or four point to seven percent.
Speaker 1: In other words, the probability of any two individuals having
Speaker 1: the same birthday is low. Even if you asked twenty
Speaker 1: individual people, the probability is still low, it's less than
Speaker 1: five percent. It's natural that we feel like it's very
Speaker 1: rare to meet anybody who has the same aimed birthday
Speaker 1: as our own. But when you put twenty people in
Speaker 1: a room, however, the thing that changes is the fact
Speaker 1: that each of these twenty people is now asking each
Speaker 1: of the other nineteen people about their birthday simultaneously. Each
Speaker 1: individual person only has a small chance, less than a
Speaker 1: five percent chance of success, but everyone's trying it at
Speaker 1: the same time, and that increases the probability dramatically. So
Speaker 1: the next time you're with a group of twenty or
Speaker 1: thirty people, why not give it a try. You might
Speaker 1: be surprised. Today's episode was written by Ben Bolan and
Speaker 1: produced by Tyler Clang. Brain Stuff is production of I
Speaker 1: Heart Radios has to Works. For more andes and lots
Speaker 1: of other mathmagical topics, visit our home planet has toff
Speaker 1: works dot com. Plus for more podcasts for heart Radio,
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Speaker 1: listen to your favorite shows.