I know it’s an unpopular opinion given current circumstances, but I’ve always been a huge nerd about Russia. The history, the geography, the music, etc. And as an American, I’ve always found it fascinating how U.S.-Russian relations have fluctuated over time. We’ve gone from allies, to enemies, to frenemies. This doesn’t mean I support Z or Putin, of course. What are you a nerd about?
Baseball - its’ history, I can go off on teams and players from a century ago.
Music - rock of nearly all genres, electronic, soul, jazz, blues, some classical and contemporary.
Cinema - I used to screen films for a local cultural center, everything from gritty psychedelic British crime thrillers like Performance to French new wave gems like Pickpocket, from classic Hindu cinema like Pather Panchali to twisted Japanese horror like Suicide Club, and anything in between.
Cosmology and Physics - a lifelong passion, I have some astronomer friends (there’s an institute in my city) and can hold my own in conversation with them. Lately I’ve been getting a handle on things like Lorentz Transformations and Bell’s Inequality Experiment (aka Quantum Entanglement).
Painting - the history of the medium, and although I prefer Modern Art, starting in the mid-19th century onwards, I can now navigate and appreciate the styles that have appeared through the centuries, say the differences between Renaissance, Baroque and Rococo.
EDIT: How did I forget Science Fiction?
I’ve read all of Isaac Asimov’s stories on Foundation and the Galactic Empire, including some of the more obscure ones like “The Stars, Like Dust”, “The Currents Of Space” and “Pebble In The Sky”. Also, many of his standalone stories, such as “Nightfall” and “The Gods Themselves”.
Hands down, Asimov is my favorite Sci Fi author, and I love the original “Foundation” trilogy like no other.
The first four books of Frank Herbert’s “Dune” saga.
A whole bunch of Harlan Ellison’s short stories.
Several of Philip K Dick’s novels.
Throw some JG Ballard and William Gibson in there, for good measure.
You might really enjoy looking into Neil Turok’s cosmological theory if you haven’t seen it:
https://insidetheperimeter.ca/a-mirror-universe-might-tell-a-simpler-story-neil-turok/
Started as a very elegant solution to the asymmetry of matter to antimatter, and by now he and his coauthors have found the theory fits a number of different unexplained open questions in cosmology and have testable predictions we’ll probably start having answers to in the next decade.
There’s been a recent head scratcher with this one too. While it is typically referred to as a variation of Wigner’s friend, a recent experiment that was perhaps better described as a recursive Bell’s Inequality found a similar set of three assumptions, one of which must be false:
https://www.science.org/content/article/quantum-paradox-points-shaky-foundations-reality
Then another recent “one of three must be false” was a mathematical paradox around quantum theory:
https://www.quantamagazine.org/frauchiger-renner-paradox-clarifies-where-our-views-of-reality-go-wrong-20181203/
You might enjoy some of these rabbit holes.