GEOMETRY LECTURES 2003/4

Professor Harold Thimbleby
Gresham Professor of Geomety
Director of UCLIC -- University College London Interaction Centre

For over 400 years Gresham College has presented free public lectures in the City of London. Gresham College is based in Barnard's Inn in Central London, very near to Chancery Lane Tube Station.The Royal Society was founded in Gresham College. More details about the College and its history can be found at Gresham College's own web site.

In the sixteenth century, the first Gresham Professor of Geometry, Henry Briggs, made logarithms easier to use (developing what we now call common logarithms, sometimes called Briggsian logarithms). Today we are surrounded by computers that should take much of the effort out of work, yet they no longer seem to be making things easier! Almost everything is difficult to use, whether it is a digital alarm clock or an office word processor. The starting point of Harold Thimbleby's lectures at Gresham College is understanding the real potential of computers, and how we succumb to unnecessary complexity. The lectures are free and open to the public.

Computers have changed modern society more than any other invention of the last century. It's inevitable they will get everywhere and do more things. This year's series of lectures shows that we can have a lot more fun understanding how they work and what they can do, and it shows that as we become more dependent on computers we need to take a serious look at how we should build them to be more reliable.

Harold Thimbleby is the 28^th Gresham Professor of Geometry.

Previous years' lectures: 2001/2, 2002/3.

Computers are used everywhere, and we are all supposed to be "computer literate." Yet most computer literacy is about plugging in computers and getting them to do boring office work. There is a lot more to computers that is fun and interesting, and has nothing to do with work. Let's unplug them, look at their principles and see what computers really can and can't do. This seminar for computer science lecturers follows a full day workshop for children and teachers at Gresham College.

The seminar discusses the successful (and fun) educational approach, which has been used for motivating people from children through to undergraduate and postgraduate computer science students. The seminar will include some hands-on cryptography and other ideas.

Computers are used everywhere, and we are all supposed to be 'computer literate.' Yet most computer literacy is about plugging in computers and getting them to do boring office work. There is a lot more to computers that is fun and interesting, and has nothing to do with work. Let's unplug them, look at their principles and see what computers really can and can't do.

There was a craze about 3D pictures (autostereograms or "magic eye" pictures) a few years ago. How do they work, and how do computers draw them? (And what could possibly go wrong?)

A hands on afternoon at the Royal Institution takes the lids off differentials and explains the maths behind how cars stay on roads, and how four wheel drive cars stay in control in mud.

When a car goes round a corner, all its wheels go at different speeds. If they went at the same speeds, some of them would slip and the car could skid out of control, or if they didn't slip it'd be impossible to steer. In mud all the wheels slip, and they go at different speeds even when driving in a straight line! How does a single engine drive the wheels at different speeds so that they each grip? Mathematically, the car solves some equations. Mechanically, it uses differential gears. Ordinary cars have a single differential, which gives them good performance on the road, but a car like a Land Rover has three -- and the maths gets muddier and the driving more exciting or is it that the driving gets muddier and the maths more exciting?

This schools afternoon is sponsored by the Land Rover, The Royal Institution, and Gresham College.

When computers are plugged in, they can do amazing things. We'll take some topics suggested by the audience from Unplugging computers (lecture on 9 October), and take computers for a spin. Possible topics for this lecture include the Game of Life and fractals.

Computer languages let us tell computers what to do. And we use computer languages to tell computers how to understand the languages we use to tell them what to do. It's possible to use the same language for everything, and we end up with fascinating circular explanations of what computers do. And while it all looks remarkably neat, we can end up hiding big problems and make our programs very unreliable!

Lecture by Prof Sir Tony Hoare. The evening lecture will follow an all-day workshop on computer science's grand challenges.

Computers are used in many important and potentially dangerous areas. It is important to know that they can be relied on, and that they do what is intended. Verifying compilers give the highest possible assurances of the safety, security and serviceability of computer software. They are urgently needed if computers are to be relied on. Building verifying compilers is proposed as a Grand Challenge for research in the current century.

Science advances when researchers discover, publish, test and learn new techniques. Unfortunately computer science advances so fast that nobody ever really has a close look at anything, and often -- as we all know! -- things don't quite work as well as promised. Fortunately computers can provide tools that make reliable work easier. This final lecture looks at the entire context of programming, how programmers talk to each other, as well as how they talk to computers.