Bits and Pieces: Secrets of a Digital World

How does a film studio know if you are sharing movies illegally? How are messages transmitted from space without mistakes? How can a scratched CD keep playing? Dr James Grime take a look at the hidden maths behind the digital world, from WWII to WiFi.



The presentation is a look at the maths behind how we send messages on the internet.

We will look at how photos, videos and messages are turned into 1s and 0s, using binary numbers, and then transmitted.
We will introduce Hedy Lemarr, the woman who invented frequency hopping, an idea we still use in WiFi today.
We will look at how secret messages were sent in World War II, using a machine even more secure than Enigma – and how that code was finally broken.
And we will look at error correction, which allows you to fix mistakes in your messages.

There are several demos of the ideas presented, with opportunties for volunteers to come up and help.
In the final demo I will drill a hole in a CD, live on stage, and show how error correction means the CD will still play.


The Maths

Our aim is to inspire and motivate students in mathematics. We will show the application of mathematical ideas such as binary numbers, error correction, codes and code breaking, and mathematical thinking. And hear the inspiring stories of the men and women who invented them.



The presentation is 45-60 minutes.
The talk is suitable for Y9 – Y12 in UK and non-UK schools, as well as maths clubs, maths societies, colleges, universities and online.



Dr James Grime is a mathematician and public speaker. James travels the world giving public talks on the history and mathematics of codes and code breaking. James is also a presenter of the YouTube channel numberphile.



The fee for a half day (one or  two presentations) is £465.
Travel and accommodation in the UK is typically £140.
The talk is also available online (via Zoom, Teams etc) for £325.



Here is a video of me giving a short version of this talk.


To Book

To book the talk, contact James via the contact page.

Click here to view out cancellation policy.