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

shining

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.

Further Reading

Press release from PrimeGrid (PDF)
The List of Largest Known Primes
PrimeGrid website
The new twin primes’ entries on the List of Largest Known Primes: n+1, n-1

The University of Leicester is going to sack its whole maths department (and rehire some of them)

uni-leicester-cuts

The University of Leicester says it’s facing a big budget deficit, so it’s got to make some cuts. In the current British climate, that’s nothing unusual. However, the university has decided to cut a lot more from the maths department than elsewhere.

The way they’re going to do this is to sack almost everyone, then ask them to re-apply for slightly fewer jobs than there were before. Once it’s all done, 6 of the 21 mathematicians currently working at Leicester will be out of a job.

There’s some speculation that the reason that maths is going to be hit particularly hard is that it didn’t do particularly well in the last iterations of the REF and the National Student Survey.

The Universities and Colleges Union has started a petition against the cuts, disputing the size of the deficit and the need for so many job losses. They’ve written a response laying out their side of the story. The European Mathematical Society has also said it’s very concerned.

Tim Gowers has written a bit more about what he thinks is going on on his blog. As usual, there’s some good discussion in the comments as well.

via Yemon Choi

Photomath can read my writing

I remember when OCR of mathematics was such a difficult problem that there was no good solution. I remember hints some years ago that the then-current version of InftyReader could do a reasonable job of taking a PDF document and converting it into LaTeX code, but it was far from perfect.

Today my phone told me that the app Photomath has an update and now supports handwriting recognition. This means I can write something like this:

hand-written-maths
and Photomath does this with it: