Thread by @aayushjaiswal07

1/n Duolingo's S1 has lots of amazing things, it shows how learning can be fun & can be gamified.

But behind those numbers is an incredible founder Luis von Ahn. I've seen many of his lectures & I've always felt very inspired.

A thread on his life that people usually miss. 🧵

2/n He grew up in Guatemala, a country in South America. His parents are doctors & he grew up having good access to education.

He learned English early on, which he thinks is a great privilege. He earned his PhD from Carnegie Mellon University & became a faculty member in 2006.

3/n In his early research days, he was the first to provide rigorous definitions of steganography and to prove that private-key steganography is possible.

Steganography is the practice of concealing a message within another message or a physical object.

4/n At age 22, he worked with Manuel Blum doing research in cryptography.

Manuel Blum is someone who received the Turing award earlier for his contributions to Computational complexity theory & its applications to cryptography.

Together, they pioneered Captcha.

5/n Captcha is a computer-generated test that humans are routinely able to pass but that computers have not yet mastered.

Captchas helped tech companies solve one of the biggest challenges they were facing -- bots!

6/n Hackers had to hire people in low-wage countries for Captcha. In one of his lectures, he mentioned how the problem wasn't fully solved but at least they generated employment.

This gave him mainstream recognition & offers from every top university to continue his research.

7/n He joined Carnegie Mellon University & his PhD thesis was the first publication to use the term "human computation".

Human computation refers to methods that solve problems which humans or machines couldn't solve in isolation. His talk at Google ✨

8/n He's also the first to work on "Games with a purpose" - these are fun games for humans that produce productivity as a side effect.

The most famous game was ESP game in which 2 paired users get points to randomly predict the image in isolation.

9/n Google bought the license to this game & implemented it as Google Image Labeler. This helped them make their image search algorithm better.

Remember Google Image search? This is how they made it happen.

10/n Within a couple of years from Captcha, he went on to invent reCAPTCHA.

He realized that the human effort invested in guessing random words/numbers was too inefficient, he thought of deriving productivity from this effort.

He did that by using this time to digitize books!

11/n Captcha needed words that are not readable by computers to guess humans to work. Earlier they did it by skewing the image & making sure the machine can't read it.

This time, he got millions of old books that were not readable by computers & included that as Captcha.

12/n reCAPTCHA was sold to Google in 2009. Today, reCaptcha is transcribing millions of words every single day.

All this formed an entire industry solving complex problems in simple ways.

13/n In 2009, he went on to build a language translator called Duolingo with his student Severen Hacker.

They converted this project into a company with the mission to give access to free high-quality education to everyone.

Here's a simple letter from his with soo much clarity.