Tuesday, 10 July 2018

The two people who discovered radio

David, GM4JJJ, recently introduced me to this podcast "Great Leap Years" by the polymath and boulevardier Stephen Fry


In it, Mr Fry outlines the development of science and technology from the dawn of tools to the modern day. You have to sit through rather a lot of it (6 episodes, 50 minutes each), and there is just one person talking all the time. However, I found it very interesting.

You can find it "by searching for Great Leap Years wherever you get your podcasts" (as they say).

It is similar but has a wider scope than the BBC "In Our Time" science thread. These progammes go into more detail about particular subjects which might interest a radio amateur, like the Sun, the development of Radio, Plasma, Radiation, Conductors and semi-conductors, the Electron etc. And at least in "In Our Time" there are four people talking.


However, there seems to be a gap between all these programmes. The earliest idea of radio seems to fall between them. So here comes how I understand it - I am sure I have got some of this wrong but I will try.

This posting seems to flow from what Adam Rutherford said this week in another podcast I follow - the BBC Inside Science programme - he said that diverse science is good science.

The two key people in this story could hardly be more diverse. They did not fit easily into society. One was the son of a labourer who had little education as a result of his poor upbringing. Yet this man, Michael Faraday, made the crucial experiments that paved the way for those who came after him. While had a had a limited education he was no slouch as a thinker - he came up with his field theory which reshaped our idea of physics right down to today's quantum theory. The other was a rather impractical awkward genius, a man who spent his entire life in academic study. He was born into a world where he could afford to go to university when few others could. This second key person was James Clerk Maxwell, whose equations explained radio before we knew what radio was.

Or course neither of these men knew what radio was, nor what it could be used for. However, they fathomed out that there must be radio. This is an outstanding achievement. Faraday found the key by proving to himself that light was a form of electromagnetic energy, and Maxwell picked the idea up and drew the remarkable conclusion that between the low frequency fields in motors, transformers, etc., and light, there must be an entire spectrum of electomagnetic waves. Maxwell produced a mathematical proof that light was an electromagentic phenomenon, and he established the rules by which this radio energy would propagate. Not bad for two people who only had the idea of something which might be radio in their heads. They had no proof, but yet they were right. 

Scientists fit into a flow of progress. They do not work in isolation. They "stand on the shoulders of giants", and can take what was proved before as read. In this case the person who went before was the Danish academic Hans Christian Oersted (1777-1851). Oersted had recognised the relationship between electricity and magnetism in 1820. This opened the door for further experimentation into what use this relationship might be (apart from moving compass needles).

Enter the field at this stage Michael Faraday (1791-1867). Faraday was born in London. His father  was a blacksmith who had moved from the North of England to seek employment. Michael had a poor upbringing and he was apprenticed to a bookbinder. He became a very skilled craftsman and found a job as assistant to Sir Humphry Davy, an eminent scientist of the time. This was very much a master-servant relationship, as Faraday's lowly background was likely to mark him out for a limited career. Instead he became a more distinguished scientist than Davy.

While Faraday prospered under Davy and eventually achieved eminent status himself, he remained an experimenter. His was practical science. He was not much into theory and it could be argued that his "field theory" was in fact a layman's way of explaining what he was finding. Anyway, it was perhaps the first "non-Newtonian" approach to physics and it certainly makes a lot of sense to me. At the time he was seen as being rather "left-field".
Michael Faraday giving the Royal Institution Christmas Lecture in 1856 - Wikimedia Commons
Nevertheless, Faraday's gift for experimentation was prodigious and he is mainly remembered for developing the understanding of electromagnetic induction. "Faraday's law of Induction" is still with us, and we have him to thank for the development of electric motors, transformers and inductors.

He never quite shook off his non-academic background, despite accepting an honorary university degree. His experiments made many developments possible and he continued to make apparatus and search for the links between various phenomena.

Eventually in 1845 he hit on the one experiment which opened the door to radio. He was placing crystals inside a strong electrically generated magnetic field. He tried various type of glass before trying a piece of glass with a high lead content which he has cast for an earlier experiment.

He noted that when light was shone through the glass the polarisation of the light changed when the voltage (and hence the strength of the magnetic field) was varied. Indeed, if he varied the field strength the polarisation varied in proportion to the change in field strength.


This is an interesting result but maybe not dramatic if you did not have Faraday's natural understanding of physics. He was certain that this result was produced because light is a form of electromagnetic energy (and he was right). This was quite a leap. You can see what he was getting at, as this effect must be due to an interaction between the light and the changing field it was passing through. He knew that the field is electromagnetic, so he deduced that the light must be too.

While the result of Faraday's experiment was just a finding, the conclusion he drew was dramatic. He had his field theory so he was sure that this proved that light is another form of electromagnetic energy, just like the energy he had been using with motors and transformers. It was a huge leap of faith but he immediately staked his career and reputation on it. Remember, this was a man who was largely self-taught. He could have exposed himself to ridicule if he had been proved wrong.

Sometimes I wonder at how Faraday was so certain he was right. I know he was right, but then I know that his field theory is now accepted as "the way things work". Back then he was seen as rather cranky for stepping beyond Newton's theory of objects bumping into each other. He was known for transforming voltage using transformers in his electromagnetic fields, and suddenly he has placed light in the same world. It must have been a brave thing to do.

Now James Clerk Maxwell (1831 - 1879) enters the stage. Maxwell's story could hardly be more different to Faraday's. Born into a well-to-do Scottish family Maxwell had a good formal education. Not for him an apprenticeship, he attended university and was a gifted mathematician. What he lacked was Faraday's practical skills. This is where the two great men built on each other's strengths.

Maxwell looked at all of Faraday's work and trawled it through his mathematician's filter. Eventually out of this Maxwell formulated twenty equations in 1861 and 1862 which basically define the electromagnetic world. He had come up with a unified theory of electricity, magnetism and light.

Why did this matter? Well, Faraday had found the particular - that polarisation of light can be affected by electromagnetic (EM) fields in the specific case of his experiment. Maxwell generalised the idea into a set of principles that can be applied all the way from DC right up to gamma rays, with the then undiscovered radio spectrum in between.
James Clerk Maxwell at Cambridge University in the 1850s - Wikimedia Commons
Today we know four Maxwell equations, because Oliver Heaviside (it's that man again) later generalised and simplified (!) them further. I am not going to explain them as I do not have the mathematical skill to do it. But the result was immediately apparent even in the original form. If these equations were all true then the property we know as electromagnetic energy will exist in a continuous spectrum of wavelengths and with frequencies from fractionally above DC to infinity.

One way of proving that the equations were true was to find the speed of these phenomena. The equations predict that they travel at the speed of light. And, luckily, light does travel at the speed of light, and so did the low frequency waves they already knew about. Once we had found radio, guess what, it travels at the speed of light too.  Maxwell predicted that these were all the same phenomenon (and he was right about that).

If we had discovered radio before we measured the speed of light, maybe we would say that light travels as the speed of radio.

In Faraday's time they knew about low frequency EM fields which were used in motors and transformers. And then he concluded that light was also an EM phenomenon. Maxwell reasoned that there must be every frequency in between. Neither of them had any idea what radio might be, but together they worked out that it must be all around them. Up to that time, nobody had tried to detect any of this radiation. Nobody knew it was there.

Faraday and Maxwell met and corresponded. Faraday once said that he had a perfect idea about his theories until Maxwell came and did all his mathematics on them, and now he didn't understand them at all. Maxwell said that without Faraday's experiment with the polarisation of light he would never have grasped the point at issue. I think that neither of them could have functioned without the other.

Then, as always, science moved on. It fell to the German Heinrich Hertz (1857-1894) to prove that frequencies between light and AC existed as EM waves of different wavelengths. He successfully created and detected radio waves. They were then called "Hertzian Waves". Thus in a sense Hertz "discovered" radio in 1886, but in reality he was seeking to establish what Maxwell had already proved - that radio must exist. It seems to be a pity to me that it was not Faraday who did the necessary experiments, but they were done in university laboratories after his death.

Finally, despite my contention that these two discovered radio, it was "invented" by others. Faraday and Maxwell may have proved it was there but they were silent about what use it might have. Hertz who did actually find it saw no practical application at all. So it had been discovered, but Marconi and others "invented" a use for it. And we are where we are now.

Fifteen years ago I visited Parton Kirk in Galloway where Maxwell is buried. He has a simple memorial, for like Faraday, he was not given to airs and graces. I stood and thought by his grave stone for quite a while. It is strangely fitting that these two great thinkers who took great leaps of faith in their science should be modest individuals. They stuck by their principles, whether they were scientific or ethical. They were awkward characters, and neither fitted into society easily. Yet they had the ideas, and stuck to their beliefs.

I think it was because these men were so different that they made such remarkable progress.

It took a different, more outgoing, personality to push radio into the public's consciousness. Marconi was more of a showman, more of an applier of science than a theoretician (though he did plenty of experiments). He "borrowed" ideas from far and wide. In any team you need people with many different skills.

I think that there is room in our hobby for all sorts. These two scientists were fundamentally just a good self-taught mechanic and an academic thinker. We still have these types amongst us - the practical circuit builders and the theoretical egg-heads. The hobby needs them and all the rest if we are to progress.

Frankly, I cannot see the point of many aspects of our hobby. Then again, who am I to judge others? It takes all sorts. Difference is good. Otherwise, we wouldn't have had radio in the first place. Maybe nobody would have looked for it if we had not had these two odd-balls.




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