I can’t recommend the In Our Time podcast enough. It’s a fabulous library of high quality discourse.
They have an absolutely huge library of old editions of the programme. I quite like looking at their twitter feed https://twitter.com/bbcinourtime for suggestions about old episodes to listen to, because it gives me some of the randomness of listening to the latest weekly edition.
He did struggle to follow along just a little bit in the P vs NP episode, though :-) Worth a listen for the HN crowd if only to see what trying to get to grips with computational complexity feels like to a true outsider.
And Melvyn Bragg, the host, is such a character. I’d listen to it for him alone.