Tag: Schaffer, Simon

In Our Time: Robert Boyle

I know of Robert Boyle because of Boyle’s Law (which I must’ve learnt in GCSE physics about 25 years ago although I couldn’t give you the details now), but as In Our Time explained his part in developing the scientific method is probably the more important part of his legacy. And in his own time his piety and religious writings were also important. The three experts who discussed it were Simon Schaffer (University of Cambridge), Michael Hunter (Birkbeck College, University of London) and Anna Marie Roos (University of Lincoln).

Robert Boyle was born in 1627 as the 14th child and 7th son of Richard Boyle, 1st Earl of Cork. The Boyles were fabulously wealthy. Not all of the children survived to adulthood, of those that did the daughters were married off advantageously (although not always happily) and the sons inherited their father’s land. Robert Boyle as the youngest son probably had the least lands and income, but this still inclued lands in County Limerick and a manor in Dorset. And an income of around £3,000/year (if I remember right) which made him ludicrously wealthy at the time. An anecdote the experts used to illustrate this was that Boyle funded Hooke’s telescope for the Royal Society, which was almost not built because it was too expensive and Hooke couldn’t secure funds – Boyle stepped in and paid, and the programme gave the impression that this wasn’t a stretch for him.

Boyle was educated at Eton for a few years starting when he was 8 years old, just after his mother died. Then in his mid-teens he went abroad, with a tutor, and spent several years in Continental Europe including France and Italy on a sort of Grand Tour. During that time he began to develop an interest in science, but more important to him he had the opportunity to debate religion with various scholars of the day. At some point in these years abroad he had a type of religious conversion experience during a thunderstorm in which he thought he might die. On his return to Ireland (and then England) in the 1640s he began to write essays about his understanding of religion, seeing this as his life’s work. One of the experts, Hunter I think, said that if this was all Boyle had done then we probably wouldn’t remember him – his style and his thinking weren’t particularly novel or readable.

Boyle’s practice of religion was a fairly practical matter. He was part of a school of thought that felt the best way to live a godly Christian life was to carefully examine your past to determine if you’d taken the actions most pleasing to God (and then presumably you have a pattern for the future). It’s an ongoing process and would require meticulous attention to detail and thinking about other alternative things you could’ve done and so on. His scientific interests were also an outgrowth of his piety – a belief that the best way to learn about God was to learn about his creation. Bragg asked a few times if there had been a “scientific conversion” moment to match Boyle’s religious turning point, but either Hunter or Schaffer pointed out that our division between religion and science as separate things with different spheres of relevance is anachronistic when thinking about the 17th Century.

During the 1650s and later Boyle became involved with a group of men who met regularly in Wadham College, Oxford and who would later form the nucleus of the Royal Society. They were mostly university educated, and so Boyle was a bit of an outlier (although I think not the only one) with his lack of formal education past his schooling at Eton. Whilst here he formed a close working partnership with Robert Hooke, who was particularly gifted at building apparatus and the practical side of chemistry & physics experimentation. The work Boyle is remembered for on air and gases was done in collaboration with Hooke. Boyle also corresponded with one of his sisters, Lady Ranelagh, about his work – and in later life he moved to London and lived in her household (which didn’t include her husband, her marriage hadn’t been a happy one).

Boyle was meticulous about writing down his experiments, and also wrote about how one should both carry out and record scientific experiments. Roos pointed out that modern day Materials and Methods sections in scientific papers are the direct descendants of Boyle’s ideas about the scientific method. He said that one should write down exactly what had been done, so that another person could do the same experiment again. He also said that the experimenter should come to the experiment with an open mind, instead of already already decided what they expected to happen. Hunter finished up the discussion by saying that this initial development of the scientific method is Boyle’s greatest legacy.

Boyle turns out to’ve been a much more interesting man than I’d expected from my half memory of his law about the relationship between gas volume & pressure!

In Our Time: The Invention of Radio

Sunday morning we listened to the In Our Time episode about the invention of radio, which we’ve had sitting on the ipod for a while – it’s not a subject that caught either of our imaginations in advance. It did turn out to be interesting, but it also felt like a series of vignettes – this person, this date, this advance, now move on to the next – so I’m approaching writing it up with some trepidation! The three experts on the programme were Simon Schaffer (University of Cambridge), Elizabeth Bruton (University of Leeds) and John Liffen (Science Museum, London).

At the beginning of the show Bragg introduced the subject by talking about Marconi and the patents he filed in the early 20th Century that mean he is often credited as the father of radio. When they discussed him, towards the end of the programme, they talked about how he liked to present himself as coming up with the whole thing himself. He didn’t give many (if any) of the people who’d previously worked in the field credit for their achievements. But as the programme had just demonstrated, radio wasn’t invented in a single flash of genius but was instead the result of an accumulation of nearly a century of small advances.

Before the 19th Century if you wanted to send a complex message a long way, then it could only travel as fast as you could transport a person carrying it. Experiments with electromagnetism in the early 19th Century started to change this, and by the 1830s a system of transmitting messages along a wire had been developed – the telegraph. At first the pioneers of this technology had envisioned something that would twist a needle to point at the required letter of the alphabet, but the work of Morse & others established a technically easier method involving a simple code. The telegraph took off pretty rapidly, but developing a wireless method would take much longer.

James Clerk Maxwell came up with a theory of electromagnetism that predicted electromagnetic waves. At first this was purely in the realm of theory, and proving it experimentally posed a variety of technical problems. You have to design and build apparatus to emit these waves, which was eventually done in the form of a spark-gap transmitter – I don’t think they explained how this worked on the programme. And then having done this you need to reliably detect the resulting waves. They talked about a few of the ways that were developed, but I didn’t really follow any of them and so have forgotten the details :/ Over a period of several years successive scientists and engineers made their own contributions to the field, but the definitive experimental proof came from the work of Hertz in the late 1880s.

This is still science rather than technology – none of the people involved so far in the story were thinking in terms of commercial applications, it was just an interesting phenomenon to investigate and try to explain. The Post Office, in Britain, oversaw the domestic telegraph network and was beginning to be interested in possible applications of wireless technology. However there was some pushback because the telegraph system worked so well, so why develop something new? There was a similar thought process at work in the early days of the telephone system too – the postal system worked so well, why would anyone need a phone?

Even once it was known to be theoretically possible to transmit and receive electromagnetic waves wirelessly there were still several practical obstacles that needed to be overcome. For instance at first transmitters transmitted across a wide range of frequencies – so if there were two transmitters relatively close together then their signals would overlap and a receiver wouldn’t be able to pick out the message from one or the other. So one of the advances that had to be made was in the concept of tuning – restricting the transmitter to a particular subset of frequencies and then only listening to one of these bands. Another obstacle to be overcome was in the sensitivity of detectors. This was done in part by a man called Bose, who was working in Calcutta. The detectors used didn’t operate as well in the humid environment of India, and so Bose had to develop a modification of the design – which was then better in other environments too.

And we’re back to where Marconi enters the story. He was a young man from a wealthy Italian family, and despite his protestations otherwise what he did was to put together all the various prior work on wireless technology and figure out a commercial product. He’s helped in this by the fact that he’s rich, well connected and good at publicity. He also came up with a niche for the technology – ships! Obviously it’s not practical to trail a telegraph wire after a ship that’s sailing across the Atlantic, so this is an application where wireless has obvious answers to the “why bother?” question. Most people at that time (including people like Tesla) thought that electromagnetic waves would move in straight lines, so this is a case where Marconi not really understanding the science worked out in his favour – he just set up trials at doing a transatlantic transmission from Cornwall to the US. This was a success and he was then able to market his devices for use in shipping.

These radios were still transmitting code rather than sound. The programme didn’t spend much time covering the next stage because it was getting towards the end of the time they had available. But basically instead of transmitting bursts of waves, instead this built on the work of Tesla (I think) and transmitted a continuous radio signal. The modulations of this signal were then used to carry information that could be decoded into the original soundwaves recorded by the microphone.

I’m not sure I’ve done the programme justice with this write-up – in particular there were a lot of little biographical snippets for the various figures involved in the story that made them come alive as people, and I haven’t conveyed that at all.

In Our Time: Absolute Zero

Absolute zero, or 0°K is the minimum possible temperature, and there has been a race of sorts over the last couple of centuries to reach that temperature in the laboratory. The experts discussing it on In Our Time were Simon Schaffer (University of Cambridge), Stephen Blundell (University of Oxford) and Nicola Wilkin (University of Birmingham).

The programme started with the Greeks (as a sort of in-joke I think) and mentioned their idea of cold as being radiated in the same way heat is. And then we fast-forwarded through a couple of millennia to the 17th Century when Boyle (amongst others) was speculating about the existence of a supremely cold body which was in effect the essence of cold. And in the 18th Century a French man (Guillaume Amontons) was measuring temperature by means of an air thermometer. He saw this as the effects of heat on the “springiness” of air which increased as the temperature went up. So he postulated that at some low temperature there would be no springiness left in the air and so this must be the lowest possible temperature. In the 19th Century this was taken further, by Kelvin, who used thermodynamics to calculate the lowest possible temperature and set this as the zero point on his temperature scale which is still used by physicists today. 0°K is -273°C, and Bragg unfortunately kept misspeaking through the programme and saying “-273°K” when he meant absolute zero.

By the end of the 19th Century (i.e. before quantum mechanics was thought of) there was a theoretical consensus that temperature could be measured by the energy of atoms of the substance. As the temperature increases the atoms move around more, as it decreases the atoms move around less. Absolute zero is the point where the atoms and their electrons etc. have stopped moving, everything is fixed in place.

And so practical physicists started to try and reach this temperature. The first experiments were done by Faraday, who used pressure to liquify chlorine. The principle behind this is the same was why tea made up a mountain doesn’t really work – as the pressure lowers (because you’re up high) then the water for the tea boils at a lower temperature and so boiling water is no longer hot enough to make tea properly. So in these experiments Faraday increased the pressure that the chlorine was under until the boiling point of it was above room temperature, so the chlorine liquefied. They didn’t spell out the next bit, so I’m guessing here – but I think it’s that once you return the pressure to “normal” then you end up with very cold chlorine liquid (-30°C). He liquefied several gases, but regarded the noble gases as being “impossible” to liquefy, this became the next goal for physicists interested in absolute zero.

At this point in England (which was at the forefront of such research) there were two main players, James Dewar and William Ramsay. Both Scots working in London, and they loathed each other. Which was a shame, as that meant they didn’t work together instead trying put the other one down or prevent him from getting hold of reagents for experiments. Both were interested in liquefying the gases thought to be impossible – as a side-effect of building his research equipment Dewar invented the thermos flask, and Ramsay discovered (and liquefied some of) the noble gases. Ramsay had control of the country’s supply of Helium, which was one of the newly discovered gases (first seen in the sun before being discovered on Earth, hence the name), and prevented Dewar from getting enough to be able to try liquefying it. So instead this was left to a German scientist called Heike Kamerlingh Onnes to achieve. Helium liquefies at about 4°K so we’re down to pretty close to absolute zero here.

Onnes also started to investigate the properties of materials at these low temperatures. In particular he looked at electrical resistance in mercury as you lowered the temperature – one major theory had been that as you reduced the temperature then the electrons would slow down, so resistance would increase. However Onnes found the exact opposite – mercury at the temperature of liquid helium had no measurable resistance at all. He set up an experiment with a loop of mercury at this low temperature and introduced a current to it, after a year the current was still flowing just the same as it had been to start with.

This superconductivity was the first quantum mechanical property to be seen at a macro scale – normally you don’t see quantum mechanical effects at this scale because the jittering around of the atoms disguises and disrupts it. Superfluids are the other property seen at these low temperatures – this is where a liquid has no viscosity.

One other effect of quantum mechanics on the story of absolute zero is that it has changed the understanding of what it actually is – the 19th Century understanding was that everything had stopped moving, there was no energy. However this cannot be the case because the Heisenberg Uncertainty Principle states that you can either know where a particle is or how it’s moving but not both. And if everything has stopped moving then you’d know both, so this can’t be the case. So now there is a concept of “zero point energy” for the energy that remains at absolute zero.

Modern physicists are still trying to reach as close to absolute zero as possible, but it is now thought to be a limit in the mathematical sense – they can tend towards it but not reach it. Part of the reason for this is Zeno’s Paradox – any cooling method cools a body by a fraction, say half. So you can halve the temperature, and halve it again, and halve it again and so on, but if you do that then you never reach your goal. But they’ve got within a billionth of a degree.

This has all been very blue skies – science for the sake of curiosity alone. But along the way there have been inventions and engineering solutions that have had significant practical applications. I mentioned the thermos flask above, but the much more significant invention is the fridge which relies on principles and apparatus designed in this quest for absolute zero and now underpins modern civilisation (think of a world where we couldn’t freeze or refrigerate our food).

And right at the end Bragg flung in a “rabbit out of the hat” question, as he called it. A group of German scientists have managed to get a substance to below absolute zero. Wilkins answered this with one of those physics explanations that makes it all seem like black magic to me – whilst it has a negative temperature in one sense it will be hotter than absolute zero in another sense. And even tho that temperature was reached it won’t’ve been reached by going via absolute zero. She didn’t have a chance to expand before they were out of time, but I rather suspect it would require both high level mathematics & a strong grasp of quantum mechanics to understand!