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Black hole science key to WiFi

Unlocking the mysteries of the universe can have some very down-to-Earth benefits. GPS and WiFi are just the start, says Dr Karl.

Generally speaking, you can think of research as fitting into one of two major camps — pure and applied.

It's fairly easy to understand applied research — this research is aimed at a specific goal, such as making a battery that is cheaper, lasts longer, carries more power, has fewer nasty chemicals, and so on. But what has pure research ever done for us?

Actually, lots of stuff, including GPS and WiFi.

Let me start with how relativity gave us GPS — global positioning system — which is that very common navigation system that gives you your location accurate to a few metres.

GPS began back in 1905, when Albert Einstein came up with his Special Theory of Relativity. Relativity was so abstruse, it was claimed at the time that only three people on the whole planet could understand it.

Among other phenomena, it dealt with the effects of 'moving at speed', and the effects of 'gravity'. With regard to 'speed', as you move faster, your mass increases and your time slows down. But with regard to 'gravity', as you move further away from a heavy mass (such as the Earth), the opposite effect happens.

Amazingly, these two effects (which are part of Einstein's Theory of Special Relativity) have to be accounted for to give us an accurate GPS. The GPS satellites are orbiting at 14,000 kph, and at 20,000 km altitude — and the speed and the altitude each separately affect the super-accurate clocks they carry. If Einstein's theory did not 'adjust' for the 'affected' time, your estimated position would be wrong by about 10 kilometres per day.

Because the GPS satellites are moving at 14,000 kilometres per hour relative to us, their 'time' slows down by about 7 microseconds every day.

But, there's an opposing effect. Because the GPS satellites are at an altitude of 20,000 kilometres relative to us, their 'time' speeds up by about 45 microseconds every day.

When you combine these two relativistic effects (45 - 7 = 38) you find that each day the clocks on the GPS satellites move about 38 microseconds ahead of our clocks on the ground. Do the maths, and the error in your location builds up at about 10 kilometres each day.

But back in 1905, and for the next half-century at least, nobody imagined that Einstein's Special Theory of Relativity could be used by slightly inebriated people on a Saturday night to help them navigate their way to a pizza shop to get sustenance in the form of saturated fats.

For my second example, how did the pure research of searching for black holes give us WiFi?

This begins back in 1974, when Stephen Hawking theorised that under certain circumstances, small black holes might "evaporate" — and simultaneously emit radio signals. These hypothesised black holes were about the mass of Mount Everest, and smaller than an atom. Soon after, the physicist and engineer John O'Sullivan tried to find these signals.

If these small black holes were evaporating, they would emit radio signals as they vanished. But because of their great distance from us, these signals would be hard to identify because they would be tiny by the time they arrived, as well being buried in a background of louder 'noise'. Furthermore, this tiny signal would be 'smeared' (turned from a sharp spike into a rounded shape). So he and his colleagues came up with a wonderful mathematical tool to detect these tiny, smeared signals.

As it turned out, they never did find these small black holes.

In 1992, John O'Sullivan was at CSIRO in Australia, trying to develop computer networks that communicated without wires.

But there was a big problem. The signals he wanted to detect were tiny, smeared and buried in a background of louder 'noise'. Just like the black hole signals.

By a wonderful coincidence, his black hole mathematics turned out to be the key to WiFi. CSIRO took out patents in Australia in 1992, and in the US in 1996. By 2000, they had some working chips.

So in 2009 and in 2012, CSIRO received royalty payments of $250 million and $220 million — with probably another half-billion dollars to come. In 2009, John O'Sullivan received the Prime Minister's Prize for Science.

And now John O'Sullivan is working on the Square Kilometre Array Telescope — which is another case of pure research. I wonder what the Square Kilometre Array will give us? Directions to pizza shops on other planets perhaps?

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