And there's a lesson in that: new flashy gizmos aren't always better. Old-fashioned blackboards enforce slower, deeper thinking, Australian National University mathematician Pierre Portal believed.

"The blackboards, we love them because they are critical to creating the bit of magic which happens when mathematicians manage to really communicate with one another," he said.

When the ultra-modernist Hanna Neumann Building was designed for the ANU's mathematicians, they insisted on blackboards throughout. In one room, there are eight blackboards. There are blackboards outside. They line the corridors inside.

"There were a lot of discussions about what we wanted in this building," Dr Portal said.

"The point was that no matter what the building ended up being, it needed to have as many blackboards as possible".

There are blackboards in the best mathematics departments across the world, even in the toilets. "If you go to the Isaac Newton Building in Cambridge, you will find them in the bathrooms," Dr Portal said.

Mathematicians in the best American universities from Berkeley to Columbia swear by boards and chalk.

The reason, Dr Portal believes, is the restrained speed of writing on a blackboard suits the pace of human thought. It slows the process down so thinking is deep and, well, thoughtful, rather than speedy but shallow.

"The current IT pushes us to process the largest amount of information the quickest. The blackboard takes us the other way. It is enforced slowness," the mathematician said.

Even the speedier, smoother whiteboard is too fast. "You can write much quicker on a whiteboard but a blackboard forces you to slow down," Dr Portal said.

Each step in a maths argument depends on the one before, and blackboards help that process. "A good mathematics auditorium has six blackboards," Berkeley professor David Eisenbud said.

"A good lecturer can fill them one at a time, systematically, so at the end there's a whole panorama of what happened. With slide talks, you think your own thought for a minute, you're dead. Because it's gone."

Dr Portal believed there were wider lessons for all of us, namely the newest technology not always being the most useful.

"It's about understanding our technology as it pushes us towards handling information in the way the computer handles information - processing large amounts quickly rather than thinking deeply," he said.

And he just likes the feel of the blackboard.

"There is something very physical about it. You get chalk over you. You erase the board. You get tired. You get sweaty and, in a way, you go through all the mental challenges that come from designing a correct mathematical argument. It feels like you're battling with the difficulties of the problem while on the board," he said.

"Mathematicians can get very particular about which board they like and which chalk they like. Depending on how you express yourself, some boards will be too fast. Some boards will be too slow, depending on the friction.

"We like a good piece of chalk. It follows you in your thinking. Beautiful chalk! Not only is it nice to write with but the sound is pleasant. It feels fluid, so somehow because the visual is fluid, the sound is fluid, it also makes your reasoning more fluid."

He gets passionate about a particular brand of chalk. For him and lots of other mathematicians around the world, Hagoromo is the bee's knees. It doesn't disintegrate into crumbly dust. It is smooth on the board.

It's made by a South Korean company which took over the Japanese company which had been producing it. University of California maths professor David Eisenbud has hoarded a lifetime's supply of "the Rolls-Royce of chalk - even the Michael Jordan of chalk".

And it doesn't screech on a blackboard.