September 26, 2017
12:00PM ET
![](https://olsume.org/wp-content/uploads/2020/12/2017-09-26.jpg)
- Jon Bloom (MIT)
- Jerry Orloff (MIT)
March 5, 2019
12:00PM ET
![XKCD Comic](https://olsume.org/wp-content/uploads/2020/12/2019-03-05.png)
January 19, 2021
12:00PM ET
![Jo Hardin](https://olsume.org/wp-content/uploads/2021/02/2021-01-19.jpg)
January 24, 2023
12:00PM ET
![Image of Tim Chartier](https://olsume.org/wp-content/uploads/2023/01/chartier-scaled.jpg)
- Tim Chartier (Davidson College & The Museum of Mathematics)
March 5, 2024
12:00PM ET
![](https://olsume.org/wp-content/uploads/2024/02/kleijn.jpg)
- Niek de Kleijn (TU Delft)