Arithmetic topology studies analogies between algebraic number theory and topology. In some informal sense, number fields and primes correspond to $3$-manifolds and knots. The first part of the talk is about a dictionary between basic objects in these two fields, and the second part addresses arithmetic analogues of linking numbers, Milnor invariants, and Massey products.
Links:
[1] https://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] https://www.mpim-bonn.mpg.de/node/3444
[3] https://www.mpim-bonn.mpg.de/node/5518