ELI5: Explain Like I'm 5

Lars Hörmander

Lars Hörmander was a really smart guy who studied math and physics. He was born in Sweden and he became famous for his work in something called "partial differential equations." That's a big, long name, so we'll call them "PDEs" for short.

Now, PDEs are a type of math problem that deals with how things change over time and space. For example, let's say you're sitting in a bathtub filled with water. When you move your foot, the water in the tub moves too. That's because the water is always changing and moving around. PDEs help us understand these kinds of changes.

Hörmander was really good at solving these PDEs. He came up with lots of new and clever ways to solve them, which helped scientists and engineers solve problems in all sorts of fields, from physics to economics.

One of the things that made Hörmander so special was that he was able to take really complicated math problems and break them down into simpler pieces that other people could understand. This made a lot of people very happy, because it meant they could use his ideas and solve problems that they never could have before.

Overall, Hörmander was a brilliant mathematician who did amazing things with PDEs. His work helped lots of other people understand complex problems in science and engineering, and he will always be remembered as one of the great minds of the 20th century.