# “π – It’s Complicated” – a talk I gave on Pi Day 2016 at Ustinov College Café Scientifique

I was invited to give a talk for Ustinov College’s Café Scientifique on π Day this year. The turnout wasn’t great and I put quite a bit of effort into the slides, so I wanted to put it online. I’ve finally got hold of the recording, so here it is. Unfortunately they didn’t set the camera’s exposure properly, making the screen illegible, so you’ll probably want to follow along with the slides in another window.

I tried to come up with a way of writing today’s date as a multiple of π Day, but couldn’t make it work. However, I did realise that Halloween (31/10) is the best approximation to π between now and the next π day (I think). Sπooky!

# Maths at the Manchester Science Festival 2016

Here’s our annual round-up of what’s happening in sums/thinking at this year’s Manchester Science Festival. If you’re local, or will be in the area around 20th-30th October, here’s our picks of the finest number-based shows, talks and events.

# Puzzlebomb – October 2016

Puzzlebomb is a monthly puzzle compendium. Issue 58 of Puzzlebomb, for October 2016, can be found here:

The solutions to Issue 58 can be found here:

Previous issues of Puzzlebomb, and their solutions, can be found at Puzzlebomb.co.uk.

# Best way to explain topology: now officially ‘using baked goods’

Nobel Prize news!

The 2016 Nobel Prize in Physics has been awarded to a trio of physicists: Michael Kosterlitz, Duncan Haldane and David Thouless“for theoretical discoveries of topological phase transitions and topological phases of matter”.

And here’s the maths angle – their work is in the field of topological physics, which relates strange matter (superconductors, superfluids and the like) to topology, via the interesting way the properties of the materials change in phases, like the different fundamental shapes of objects in topology. None of the material we’ve taken a cursory glance at so far yields a simple explanation of how these two things are linked, but they have explanatory PDFs on the Nobel website if you’d like a dig around: Popular (PDF) and Advanced (PDF).

Also, impressively many newspaper headlines seem to have failed to notice that ‘strange matter’ is actually a thing in physics, and consequently mangled it in their explanations.

Cue of course an amazing press conference in which Nobel Committee for Physics member Thors Hans Hansson holds up a bun, a bagel and a pretzel to explain the difference. Classic topology.

Official Nobel press release

British scientists win Nobel prize in physics for work so baffling it had to be described using bagels, at The Telegraph (bonus points for ‘Noble prize’ typo, if it’s not been corrected yet)

Physics prize explanations on the Nobel website: Popular (PDF) and Advanced (PDF)

# The world’s smallest Rubik’s cube is 5.6mm wide and absolutely adorable

I just found this video of a very focused man showing off a teeny tiny Rubik’s cube. It’s 5.6mm on each side, which apparently makes it the smallest in the world, beating some relatively gigantesque efforts of 6mm and larger.

Watch this video; I’ll warn you now that the squee factor gives way to some very dry detail quite quickly.

The cube was made by Tony Fisher, by filing down a 3D-printed 6mm cube. I hadn’t heard of Tony before, which surprises me – his site is full of all sorts of incredible twisty puzzles.

# New Twin Primes found

Collaborative prime number searching website PrimeGrid has announced its most recent discovery: on 14th September, user Tom Greer discovered a new pair of twin primes (primes which differ by 2), namely:

$2996863034895 \times 2^{1290000} \pm 1$

Found using PrimeGrid’s Sophie Germain Prime search, the new discoveries are 388,342 digits long, smashing the previous twin prime record of 200,700 digits.

PrimeGrid is a collaborative project (similar to GIMPS, which searches for specifically Mersenne Primes) in which anyone who downloads their software can donate their unused CPU time to prime searching. It’s been the source of many recent prime number discoveries, including several in the last few months which rank in the top 160 largest known primes.

The University of Tennessee Martin’s Chris Caldwell maintains a database of the largest known primes, to which the new discovery has been added.