Curiosity Daily

How LEDs Work (w/ LED Pioneer George Craford)

Episode Summary

Learn about the “birthday paradox.” Then, George Craford — one of the pioneers of LED lighting — talks LED innovation. The Birthday Paradox by Cameron Duke Science Buddies. (2012, March 29). Probability and the Birthday Paradox. Scientific American. https://www.scientificamerican.com/article/bring-science-home-probability-birthday-paradox/  TED-Ed. (2017). Check your intuition: The birthday problem - David Knuffke [YouTube Video]. In YouTube. https://www.youtube.com/watch?v=KtT_cgMzHx8  Understanding the Birthday Paradox – BetterExplained. (2021). Betterexplained.com. https://betterexplained.com/articles/understanding-the-birthday-paradox/  Learn more about George Craford and the QEPrize: The Queen Elizabeth Prize for Engineering: https://qeprize.org/  George Craford's bio: https://www.nae.edu/128635/Dr-M-George-Craford  Follow Curiosity Daily on your favorite podcast app to learn something new every day withCody Gough andAshley Hamer — for free! You can also listen to our show as part of your Alexa Flash Briefing; Amazon smart speakers users, click/tap “enable” here:https://www.amazon.com/Curiosity-com-Curiosity-Daily-from/dp/B07CP17DJY

Episode Notes

Learn about the “birthday paradox.” Then, George Craford — one of the pioneers of LED lighting — talks LED innovation.

The Birthday Paradox by Cameron Duke

Learn more about George Craford and the QEPrize:

Follow Curiosity Daily on your favorite podcast app to learn something new every day with Cody Gough and Ashley Hamer — for free! You can also listen to our show as part of your Alexa Flash Briefing; Amazon smart speakers users, click/tap “enable” here: https://www.amazon.com/Curiosity-com-Curiosity-Daily-from/dp/B07CP17DJY

 

Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/how-leds-work-w-led-pioneer-george-craford

Episode Transcription

CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.

ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about the extreme weirdness of the birthday paradox. Then, you’ll learn about the hidden science of LED lighting, with help from one of the pioneers of LEDs: George Craford.

CODY: Let’s satisfy some curiosity.

The Birthday Paradox (Cody)

Here’s a puzzle for you: If you gathered a group of random strangers into a room, what are the odds that any two share a birthday? Better yet, how many people would you need for there to be a 50/50 chance of there being at least one shared birthday in the room? I’ll give you a hint: It’s not nearly as many as you think. That’s why this problem is called the Birthday paradox.

 

Alright, let’s set this up. As with any thought experiment, we first need to address our assumptions. First, let’s assume none of these people are twins, and their birthdays are completely random. So what’s the answer? The number of people you would need for there to be a 50 percent chance of a birthday match is… 23. That’s right. I know there are 365 days in the year and this sounds impossible, but it’s 23. Please don’t get mad. 

 

Here’s how you figure it out. Let’s say that I am person A, and [host 2] is person B. The probability that Person B and I share a birthday is a 1 in 365, or about a .003 percent chance. There is only one comparison to consider here: we either match or we don’t. If we add a person C, things get more complicated. This doesn’t add a second comparison, but instead adds two: Person C has to compare to both Person A and Person B. Adding Person D means that we now have to consider six comparisons. In a room of 23, there are 253 pair combinations to consider. 

 

Naturally, our brains have a really hard time imagining all those pairs that don’t involve us.

 

To prove that we only need 23 people, we have to work backward. Person B has a 364 out of 365 chance of not matching my birthday, so person C has a 363 out of 365 chance of not matching either of us. Person D has a 362 out of 365 probability of a unique birthday, and this goes all the way to Person W — that’s the 23rd person — who has a 342 out 365 chance. If we convert those fractions to percentages and multiply them, the result is a 49.27 percent chance that nobody in the group shares a birthday with anyone else. Or, in other words, there is a 50.73% chance that there is a birthday match in the room, somewhere.

 

We can use this type of thinking to analyze why people play the lottery. Seeing lottery winners on TV causes us to overestimate our chances of winning. It’s difficult to reconcile the difference between the chance that I will win, which is small, versus the chance that someone will win, which is much bigger. Our brains just aren’t built to consider things like that. That’s why it seems like a paradox. 

George Craford - LED lighting (Ashley)

There's a cutting-edge piece of technology that's helping to boost our energy efficiency and slow the effects of climate change. But this breakthrough tech isn't new — it's been around since the 1960s, and it's in everything from car brake lights to flat-screen TVs. I'm talking about light-emitting diodes, or LEDs. LEDs work completely differently from your garden-variety lightbulb, and today, we're going to find out just how they work from a pioneer of the technology. George Craford has been a leader in the development and implementation of light-emitting diode (LED) technology for nearly 50 years. He was recently named a winner of the Queen Elizabeth Prize for Engineering. That’s a prize of 1-million- British pounds awarded to an engineer or group of engineers responsible for a ground-breaking innovation that has been of benefit to humanity, and today, he's going to tell us just what makes LEDs work so well.

[CLIP 6:03]

So to summarize: to make an LED, you have to combine the right elements to get the kind of light and kind of semiconductor you want, then you just send a current through it and it glows for tens of thousands of hours — no hot wires or burnt-out bulbs here! Again, that was George Craford, a leader in the development of LED technology and a recipient of the Queen Elizabeth Prize for Engineering. You can find links to learn more in the show notes.

RECAP

Let’s recap the main things we learned today

  1. ASHLEY: The birthday paradox says that if you get 23 strangers together in a room, there’s a 50/50 chance two of them will share a birthday. It’s the same reason people play the lottery: it’s virtually impossible for YOU win, but when you multiply a bunch of fractions together, you get realistic odds that someone will win. 
    1. CODY: My brother’s fiance and I have the same birthday. My niece on my wife’s side share the same birthday. 
  2. CODY: With conventional light bulbs, you’re seeing light produced from a filament that gets heated up by an electrical current. The heat is just wasted energy, so efficiency is low. With LED lights, different combinations of elements cause different color currents, so you’re seeing the current itself. It’s a totally natural process, so when it’s done really well, it can last tens of thousands of hours.
    1. ASHLEY: And the key to doing it really well is coming up with stable mixtures of elements so they can produce different types of lights that are more efficient as advances are made. Red was the first color of LED, which is weird when you’re used to light bulbs just having white light. But yeah, red LEDs have been around for about 50 years now, and engineers are hard at work on new colors all the time.

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ASHLEY: Our writer for today’s first story was Cameron Duke.

CODY: Our managing editor is Ashley Hamer, who was also an audio editor on today’s episode.

ASHLEY: Our producer and lead audio editor is Cody Gough.

CODY: Join us again tomorrow and we’ll bring you some more BRIGHT IDEAS… to help you learn something new in just a few minutes.

ASHLEY: And until then, stay curious!