## Mathematics

## Quantum Gravity Lesson 38

##### 20 April 2019

Bose-Einstein condensates have a condensate fraction which is closely related to the Riemann zeta function, as we vary the Hamiltonian.

## Today’s Rejection Letter

##### 16 April 2019

## Quantum Gravity Lesson 38

##### 01 April 2019

Every math undergraduate loves their torus, with the 18 triangles needed to compute homology. With quantum cubes, we automatically label axes discretely with powers of a letter.

So when does a square include a 2-cell? Look at the bottom left square.

A category theorist will immediately see that this is a limit diagram for the product of X and Y. But the square defined by the generator of H1 does not yield a nice square, although it does commute.

## Paper of the Week

##### 29 March 2019

Speaking of prisms ... this is nice:

## Quantum Gravity Lesson 37

##### 24 March 2019

Some years ago, at Arcadian Functor, we looked at this paper about graphs looking like manifolds. There are three obvious geodesics on the hexagon with halving chords, for S3.

## Prismatic Cohomology

##### 21 March 2019

When I was working in Los Angeles last year, my main focus was thinking about motivic cohomology with Michael Rios. Other quantum gravity colleagues were less mathematically inclined, and only Michael and I appreciated the depth of the new theory and its potential for deriving classical spaces. Mike likes to wear Pink Floyd T-shirts with prisms on them, and he put the picture on an arxiv paper some time ago.

This week at UCLA (oh, Los Angeles) a mathematician is talking about a new theory of motivic cohomology, which is called Prismatic Cohomology, after the Pink Floyd album cover (for the Dark Side of the Moon).

Terence Tao links to new seminar notes by anonymous audience members. Take a look.

As you know, q-deformations are what happens to classical algebras when we go to braided structures. And from quantum gravity, we determined that the cohomology underlies the emergence of coordinates.

## p-adic Langlands Program

##### 17 March 2019

## Thinking About Riemann

##### 14 March 2019

In a simple and entertaining talk about the life of Euler, Dunham shows us that the Riemann hypothesis is equivalent to a simple statement about the (divergent) harmonic series (see photo above). The function sigma is of course the divisor function: the sum of all divisors of n, including n.