Scotland’s forgotten Einstein?
An intrepid camera man ventured down George St in Edinburgh
and asked 100 passers by who the man in this statue was.
Most of them had no idea.
Graham Bell? Carlisle? Fleming? Stevenson? Lord Kelvin?
Nope, none of them.
So the universe is full of invisible
signals. There is a lot of noise out there.
Radio telescopes listening out into the far reaches of space
to try and work out the origins of the universe, to hear the noises made at the
time of the big bang.
Consider microwaves.
Gamma rays.
MRI Scanners and mobile phones?
The all use electromagnetic radiation… which was discovered by….
Well in 1865 Scotland’s
greatest physicist, James Clerk Maxwell put down his pencil after working out a
huge set of equations that had proved electromagnetic
radiation. Then he slipped quietly through the cracks of history.
The man was a geek. He saw all things in terms of pure
mathematics. Einstein kept a picture of him in his study, saying that ‘he stood
on Maxwell’s shoulders’ Maxwell was to electromagnetics what Newton was to
gravity.
James was born in Edinburgh in 1841, the only child of a
land owning family with an estate in Dumfries. He was a bright kid. We all, as
kids, made a series of small drawings, each slightly different so that we could flick them together and see the drawing move. But Maxwell worked out just how fast that optimal flicker had
to be.
At 14 years of age he published his first mathematical paper.
He then went to Cambridge, publishing three further mathematical
papers. The University held a competition to see if anybody could explain how
Saturn’s rings were held in place. The two vast concentric circles, 250 000 km in diameter, could be either rock,
fluid or individual particles. Maxwell didn’t look at the planet- he looked at
the maths. He worked out that the rings could be solid, but only on one side of
the planet. If they were fluid, the
forces that held them there would also destroy them. Then he worked out that
the theory of small of particles orbiting on their own could be correct. And then went on to work out
the number of particles that it might be.
He won the competition of course. Years later, it was proved the number of particles was
correct, and that led to the Higgs boson
and all the craft that have voyaged out into the galaxy since. The
voyager probe proved him right about the rings. The gap between the rings is
called the Maxwell gap. And now, when astronomers see a star being born, the
start of a new solar system, it’s Maxwell’s maths that are still used.
After Cambridge, Maxwell became one of Britain’s first theoretical
physicists. He became professor at Aberdeen University at the age of 25. His
mum had died when he was 8, his dad when he was 24 and that early experience shaped
him as a very humane man. Always wary of being a machine, his science had to do
good.
All his colleagues were twice his age but he was befriended by Daniel Dewar, the principal of Aberdeen university and
married Dewar’s daughter after proposing to her with a poem he had written. The
marriage was very happy, they shared a sense of humour and a passion for poetry.
And dogs. Maxwell’s had many dogs. All called Toby.
He was fascinated by colour. Newton had already split
sunlight into the colours of the rainbow and it was known that white light is all colours, whereas black is
no a colour at all. Artists knew that
with three primary colours, they could mix any other colour. But nobody
knew why that was.
Thomas Young thought that it was something to do with biology
and that the human eye might have three receptors for each colour and the human
eyes blended them together. Maxwell wanted to test this so he mixed the colours
with mathematical precision, and then asked people what colour they actually saw
– by using a simple colour wheel with different amounts of red, yellow and blue and then spun the wheel 20th
of a second per revolution which is what the eye can see. Red and blue gave
magenta as expected. But it needed red, green and blue to give white.
So there are primary lights, and primary colours. As paint absorbs
light, the circle emanates light. Maxwell worked out exactly what combination
was sensitive to our eyes and demonstrated the range of colours the human eye
could see. He did that in 1861 with a colour demo. Three photographs of the
same tartan ribbon- one filtered with red, one with blue, one green.
If all three pictures were projected
onto the wall at the same time – the coloured ribbon appeared. And the
screen you are reading this on, is formed in exactly the same way.
Being smart, he then
explained red green colour blindness. At 29 he was inducted into the Royal
Society!
He then went to Kings College Cambridge, and started working
with Faraday to try and unravel the greatest mystery of the age - electricity
Faraday thought there was a connection between magnetism ( as in a compass) and electricity
( as lightening). Maxwell went on to
prove that there are invisible electric
fields all over space. Static charge generates
an electric field. He proved that electric poles always come in pairs. Then changing
a magnetic field generates an electric field.
And then that an electric current surrounds itself with an electric
field.
I have no idea what this is but I am impressed.
The theories of Faraday and Maxwell were inextricably
linked, and it was all proved by pure maths.
But Maxwell wasn’t finished. He investigated Faraday's idea
that electro magnetic field lines can be disturbed by waves travelling along
them (like ripples on water). He noticed that the fields fluctuated in time
with each other, and then he measured the speed. Deep in that equation was the exact speed the wave form travels at.
300 000 km a second. The speed of light.
What an Eureka
moment.
He theorized that light was an electromagnetic wave, but it
was a few more years before he was
proved right by Mr Hertz. But Mr Hertz didn’t think it had any practical
application.
He was wrong about that.
There is now a movement to get James Clerk Maxwell onto a new banknote. And not before time.
Caro Ramsay 04 02 2016
