Monday, March 2, 2020 12:30 PM
Dan Dore

The Fourier transform is a fundamental symmetry of functions on the real line, 

intertwining additive and multiplicative structures. It turns out that this symmetry

is not at all unique to R, and can be defined in the exact same way for functions 

on the p-adic numbers. We'll describe how this works and see some examples:

in particular, the p-adic "Gaussian" is the indicator function of the unit "interval"!

In John Tate's incredible Ph.D. thesis, he discovered that you can take the Fourier

transform "over all p at once", and used this to prove the functional equation for the 

Riemann zeta function and its variants. To do this, we must consider functions over

the ring of adeles: this is a huge topological ring built out of all of the Q_p's and R. 

We'll introduce this beast and see how its Fourier transform encodes fundamental 

facts of number theory. 

 

We'll construct everything "from scratch", so analysts and algebraists alike should 

find something enjoyable here.