It's basically Joe Rogan for smart and sane people. None of the grifters, all of the scientists + academics. Been going on forever, covering a huge range of subjects.
https://www.bbc.co.uk/programmes/b006qykl/episodes/player
And note that when you click to an episode to see who the guests are (usually three professors or other experts on the given topic) there's also a reading list.
I guess it's similar to Joe Rogan's show in that it's a recording of people speaking.
That's how I first encountered him - he was interviewing John Carmack. The later episodes were disappointing, but I spent a year keeping an eye on the guest list. There were maybe 4-5 really good interviews in that year.
In Our Time is like those good episodes but with an extremely high signal-to-noise ratio and generally better.