Dr Hannah Fry

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62 appearances 2 recordings 1 series first heard Jul 2013 last heard Dec 2013

Dr Hannah Fry’s voice in public audio — every appearance, attributed to the second.

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More or Less · Numbers of the year · 27 Dec 2013 podcast

My number of the year is the number four, and I've chosen this in honour of American mathematician Kenneth Apple, who died earlier on this year at the age of 80.

So Apple is best known for solving the famous four colour problem.

And this problem says if you take any map, so imagine a map of the world, you'll only ever need four colours to fill it in in a way that no two neighbouring countries or regions are sharing the same colour.

So this problem had been unsolved for over a century.

And in 100 years or so when the problem stood, mathematicians had failed to find any map, either real or imaginary, which needed any more than four colours.

But unfortunately, to prove conclusively that a map needing five colours couldn't exist, you'd have to check an infinite number of maps.

But Kenneth Apple and his colleague Wolfgang Haken made a big breakthrough by

by reducing the infinite number of possible maps down to just 1,476 much simpler maps, which contain the characteristics of every possible configuration.

And then they used a computer to find a four-colour solution for every one of those maps, in turn proving that four colours was enough to fill in any conceivable two-dimensional map, so that no two neighbouring regions have to share a colour.

No, that's definitely true.

So at the time, mathematicians thought that the use of computers was really ugly and brutish.

And they liken this proof that the two people came up with as trying to proofread a phone book.

But actually, this proof did do a lot to change the attitudes of mathematicians towards computers because they really managed to demonstrate how powerful they could be.

It happens a lot more.

So you can use a computer to almost piece together proofs without overseeing it at all, without really needing a mathematician at all.

So taking a series of logical steps and bashing them together until you end up with a result that you weren't necessarily expecting.

So some mathematicians are looking at pushing that frontier further

But it also does things like checking for prime numbers, for example.

So actually earlier on this year, the MERS-N prime, a new MERS-N prime was discovered.

And that was discovered using a computer.

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