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When I was a youngling, for some reason my image of chemistry was a man in a white coat doing something with test tubes of orange liquid. I have no idea why the liquid was orange and in fact there probably aren’t many compounds which are that colour. It’s all the stranger that this was my image because my father was an industrial chemist, so one might imagine I was more grounded in that particular respect.
I don’t know how the process worked exactly because he was a rather distant influence on my life in some ways, but by the time I was about seven or eight I had abandoned my childish ambitions to be a nuclear physicist and decided I wanted to be a biochemist. If you imagine science as a three-tier system with biology at the top and physics at the bottom, chemistry is in the middle: the central science. In this schema, biochemistry would be about two-thirds of the way up, with organic chemistry under it down to the middle point and below that would lie inorganic chemistry.
At secondary school (and we’re kind of on homeedandherbs territory here so I won’t dwell on it too much), I excelled at chemistry and out of my year of ninety selective (11+ passers) pupils I got the highest mark at the end of the third year, which is Year 9 or Key Stage 3 in contemporary terms. My year head (who is now a successful folk musician incidentally and has been on TOTP) was very happy about this. However, I had a problem. My best friend was doing German with me and although I was very close to him emotionally I also thought he was a bad influence in the sense that if we were in the same classes it would be difficult for us to concentrate on our work, so I had to eliminate German and the way the block system worked with options, I couldn’t do both that and Chemistry. There was also the question of balance, which I’ll come back to. I therefore gave up Chemistry and instead did the unpopular combination of Biology and Physics at O-level. To my mind at the time, I’d also heard that the concept of molarity was important in chemistry and I’d failed to understand it a couple of years previously and found it intimidating. This was a very unpopular decision with my Year Head, and he later anxiously asked me whether I was planning to do A-level English because again my results during the O-level years had been the best in the year. I did, but it was a bit of a disaster really for reasons I really shouldn’t go into on this blog. In case you’re wondering, I did eventually take GCSE Chemistry at evening classes in the ’90s when it was an entry requirement for my herbalism training and got an A, although to be frank getting anything other than an A at GCSE when you have a postgraduate qualification basically means you’ve failed calamitously. I also have a B in Spanish and it’s worse than my French, which I failed at O-Level.
Continuing with the school theme for a bit, pupils who followed science were generally encouraged either to do one science or Chemistry with either Biology or Physics because the two were closer to each other than Physics and Biology. My approach was different of course. I decided that since biology and physics both impinged on chemistry, studying Biology and Physics would enable me to learn some chemistry from either end, and it did in fact do so to some extent. This is of course because chemistry is the central science of the three.
This phrase, “The Central Science”, is in fact the name of a popular textbook on the subject, first published in 1977, and the idea was also posited by the philosopher Auguste Comte in the nineteenth century. Chemistry can be seen as central because it deals with entities which are the concern of physicists such as electrons, protons and marginally neutrons, and is also used to explain the behaviour of organic molecules such as DNA, proteins and lipids which are the basis of life as we know it. As such, chemistry is isolated from other sciences and is able to develop concepts of its own which may not connect as closely with reality as the other two, although it’s probably true that right now physics isn’t doing too well in that respect either. There’s also the question of turning the current ladder on its head. Right now, most people who think about it at all probably consider physics to be the basis of, well, physical reality, but it’s possible to invert this and consider the Cosmos to be centred on life, which in the carbon-based biochemical form we’re familiar with can be used as the basis of science by implying certain things about the nature of the Universe. For instance, Fred Hoyle, an astronomer, predicted that because there was organic life in the Universe, and carbon was unexpectedly common, the energy of the carbon nucleus must be unusually close to the sum of the energies of three helium-4 nuclei, since that was how it formed in the first place, and he turned out to be correct. We can safely start off from the idea that our kind of life exists and work out what that entails for the nature of reality. It’s therefore fairly simple either to regard biology or physics as the most fundamental science, but the same can’t so easily be done with chemistry because of its central position.
Physics can leapfrog chemistry into biology to some extent: there is such a thing as biophysics. For instance, the way birds and insects fly or the emergence of turbulence in a blood vessel leading to arterial disease rely more on physics than chemistry. By contrast, there’s nothing to leapfrog to in chemistry. It’s either going to become biology or physics on the whole, although there’s also the likes of geochemistry and astrochemistry, though these are more specialities of the subject itself. Chemistry cannot claim, therefore, to be the basis of anything in a fundamental way. It’s always going to have to rely on other sciences to some extent. This is not a criticism of the science so much as a musing on its nature, but it has practical consequences for academia.
Chemistry is impinged on from all sides. In the ’80s, I was unsurprisingly involved in campaigning against cuts in higher education, and at the time they focussed very much on the arts and humanities. I would partly put this down to the influence of another industrial chemist on this country and my life, namely Margaret Thatcher. Thatcher’s government concentrated very much on slashing funding and resources to the humanities while leaving chemistry relatively untouched. Although I can’t remember the details particularly well, I do remember participating in some kind of dispute on campus regarding the injustice of this unbalanced approach to research and teaching, and at one point we found ourselves confronting chemists, who were apparently of the opinion that the humanities were less important than their own faculty and department. Incidentally, the layout of Leicester University reflected the central position of Chemistry because it had three linked buildings dealing with physics, chemistry, biology and medicine, with Chemistry in the middle joining the others together. I don’t know if this is coincidence, architectural conceit or logistical. The chemists’ hostility to us, and at the time chemistry graduates tended to be politically on the Right, was in fact ill-founded because from a twenty-first century perspective this looks like a case of divide and conquer, and Chemistry turned out to be particularly vulnerable to funding cuts. It’s a case of Martin Niemöller’s famous dictum, “first they came for the Socialists. . . “, though in some ways not so serious, but who knows the consequences?
During the ‘noughties, there was a rapid decline in Chemistry departments. This came rather close to home, as one of our closest friends worked for such a department at De Montfort University, formerly and much more appropriately known as Leicester Polytechnic, but all over England Chemistry departments were closing down. Between 1997 and 2002 there was a fifteen percent drop in British chemistry graduations compared to a nine percent drop in graduations overall. Chemistry is an expensive course to teach, which rather annoys me as the Humanities which bore the brunt of the cuts from 1981 on are probably cheaper than any of the natural sciences. Nonetheless a university looking for savings is going to be eyeing Chemistry suspiciously. This has consequences for the pharmaceutical and materials sciences industries in this country, which is particularly serious in the former case as it’s a major British industry (even though it must be nationalised to preserve the NHS and engages in animal abuse on an appaling scale). It’s also a less popular course with students because they see the careers as less lucrative than others, and also see the subject as less exciting than some others, so there was a decline in applications during the ’90s. This may reflect the unhealthy shift towards a “vocational” rather than a truly academic approach to higher education. The way the National Curriculum lumped all the sciences together and for some reason allowed major errors to creep into the syllabus can’t have helped either. However, this is not just a British phenomenon. The same is happening in North America, Europe and Japan, although there has been a rise in interest in China and India. Even so, nowadays only half the universities in the “U”K offer Chemistry per se as a complete degree.
This could easily turn into a discussion about Britain vs the rest of the world but the pressures are the same everywhere. Chemistry is also vulnerable to inroads being made into it due to its central position. Physically-based materials science can advance “upwards” from physics into chemistry and biotechnology can advance “downwards” into it. There’s also nanotech, which does the same kind of job as applied chemistry might’ve done in the past. Biotechnology and pharmacology are difficult to tell apart in some ways. For instance, biotech is used to manufacture drugs and since it aims at altering the function of cells it clearly applies to medicine. Chemical engineering also uses a lot of nanotechnology nowadays. Hence the territory of chemistry is easily invaded.
Ever since I studied it at school, I’ve felt that geography isn’t a real subject. It seems to be more a collection of bits of other disciplines such as economics and geology rather than having a real core. Of course a circle can easily be drawn round a subject and it can simply be called something, but it means it has neither a claim to being fundamental in a way most other disciplines are nor its own theoretical basis. I may of course be wrong about this because of Dunning-Kruger, but my perception of the nature of geography, which is I admit fairly dismissive, has some similarities with how I apprehend chemistry. Chemistry has too many connections with other fields to stand a good chance of holding together in the long run except in a significantly reduced area, although I have a great deal more respect for it than geography. Part of the subject’s predicament could be linked to the rather confusing possibility that scientific and technological progress is actually slowing down rather than speeding up. There was an exponential growth in the number of synthesised substances between the start of the industrial revolution and the 1990s, but it isn’t clear that this has or will continue, and it may be deceptive. For instance, in pharmacology, an area I tend to know more about due to being a herbalist, the so-called “non-steroidal anti-inflammatory drugs” (NSAIDs) are all cycloöxygenase inhibitors despite the fact that there are many possible points along which the inflammatory pathway could be modified and in spite of large numbers of compounds being known to interact with them. Likewise with broad-spectrum antibiotics, there are many antimicrobial compounds out there, but the ones used tend to be quite similar. This is partly due to capitalism of course, because altering a compound you know works and which is already well-known and manufactured on a large scale is easier than coming up with a completely new one. This can also be seen in my post on fibres, where Du Pont owned the patent on Nylon-66, leading to the development of new nylons which were somewhat different from the first but also had a lot in common with them. The restriction imposed by the patent did spur creativity, but in a specific area. Also, it’s notable that the most recent organic synthetic polymer mentioned in that post was first marketed in 1958, and there was a peak of synthetic fibre production in the mid-twentieth century.
The exponential growth in the number of different compounds synthesised in the past two and a bit centuries could be expected to follow other markers of technological change and go into decline. It’s partly driven by population growth, which possibly goes some way towards explaining why India and China now have more chemists than they used to because they’re developing nations with large populations. In principle, the more the population is, the more people there are to have useful ideas, in chemistry and other areas. Once development has got past a certain stage, population growth slows and this is likely to happen for the whole species, potential extinction events notwithstanding. The date for a technological singularity has been steadily postponed and is according to some people now in the early twenty-second century, and some consider it to be the end of exponential progress followed by a decline. In other words it’s a peak. It’s possible for one person to have been born the year of the first powered plane flight and retire during the Apollo programme. By contrast, a person born the last year humans left low Earth orbit will now be forty-nine. By 1970, most of the technologies that made the biggest difference to standards of living were already in place. The exception, of course, is Moore’s Law, but that too has now ceased to operate due to transistors being too small to operate reliably owing to the laws of physics. That doesn’t mean there isn’t another way forward though.
The problem with chemistry is that it was particularly useful for those kinds of mid-twentieth century achievements, such as antibiotics, plastics and synthetic textiles. Once we’ve got those the situation changes, and in particular it’s held back by capitalism and the emphasis on vocational training in universities rather than actual education, although slowing population growth is also likely to be a factor.
Another problem, affecting academia across the sciences, is scientometrics. This is the attempt to measure and quantify research papers and publications, and is used to assess funding and resources allocation in science. It can be seen to encourage the “publish or die” approach, where research is divided up into “minimum publishable units”, which increases the paper count but doesn’t particularly contribute to progress. It also distorts it. For instance, in palæontology there’s been a tendency to report a very large number of species in our genus and I suspect that this is because it’s newsworthy and attracts funding rather than anything else. The result is poor quality research. Recently I noticed that a number of medical papers seemed to have oddly small sample sizes which didn’t seem to be the kind of numbers you could do reliable statistics on. Maybe there’s been some advance in stats which means that tests are now able to be trusted with smaller samples but I strongly suspect this is publish or perish. I cannot see this not having an influence on chemistry, although how is another question.
Finally, there are some philosophical issues associated specifically with chemistry rather than other natural sciences, although of course they would have their own too. Chemistry is in broad terms the science of the structure and transformation of matter, although it’s possible to take issue with that because not all materials science is chemistry and not all matter is atomic. It also impinges on quantum physics a fair bit. For instance, there’s mesomerism. An atom might form a double bond with another but a single bond with a third and fourth at the same time, in which case the two single-bonded atoms would be negative ions, but because of the quantum nature of electrons it’s uncertain which of the three atoms it’s bonded with have the double bonds and which are ionised. There is, I think, no definitive fact about this, and in the many-worlds interpretation this means that we don’t know which universe we’re in, and in fact may be in three different worlds until we are able to observe the fact of the matter, or create that fact. Atoms also lack a definitive radius, and have different radii according to whether the bond they’re making is covalent or ionic. Also, the very distinction between ionic and covalent bonds is not black and white, since some bonds are closer to being covalent and some closer to being ionic but they can’t be neatly pigeonholed. This is partly because atoms are not really atoms. They’re not indivisible (α-τομοι) units of matter.
The idea of describing a compound in terms of a certain number of atoms of each element joined together also doesn’t always make sense. For instance, tantalum carbide’s formula is TaC0.88 because it doesn’t in fact consist of equal amounts of tantalum and carbon. This happens a lot with minerals. Some chemists claim there are chemical properties which can’t be reduced to physics, such as Roald Hoffmann, who questions the reducibility of pH (acidity or alkalinity of a substance dissolved in water) and aromaticity (ring-shaped organic molecules) to non-chemical concepts.
Aromaticity famously came to the chemist Kekulé in a dream where he sees carbon atoms joining hands and turning into snakes who swallow their own tails. I’ve just realised this is going to sound odd unless I explain the difference between aliphatic and aromatic compounds. In organic chemistry there are two main types of compound. Aliphatic compounds are based on chains of carbon atoms and aromatic compounds are based on rings of the same. They’re called aromatic because early on, some of them were noted to be smelly, such as benzene, but this is not an essential feature and many aliphatic compounds are also smelly.
As noted yesterday (to me, not to you), hexagonal rings of carbon are particularly strong, which is why it might be feasible to build a space elevator with their help. The above ring is therefore particularly stable. Each hydrogen can also be replaced with something else. Phenol, for example, replaces one hydrogen with an hydroxyl (OH) group, or a larger entity such as the rest of an amino acid can occur to, as with phenylalanine:
That alternating double and single bond in the hexagonal ring may not represent reality, partly due to resonance structures, and consequently they’re more often represented thus:
There is a problem with drawing it this way, because it’s easy to forget that every carbon has four bonds, leading to impossible structures being drawn if you’re not careful, but it’s plainly quicker and reflects the non-local nature of the electrons, which is where things get a bit imponderable for me. Atoms, and in particular their orbitals, are not spheres but collections of lobes meeting at a point in which the electrons are most likely to be located. This is irreducible probability: there is no hidden mechanism which determines where they are, and there cannot be – it’s been proven. Hence there are situations where two lobes on one atom can overlap with two lobes on another, and these are known as π bonds. They’ve been evoked as an explanation for the existence of free will, as they occur aplenty in human brain cell microtubules. In the case of an aromatic compound there are six of them, each overlapping with two adjacent carbons. Double and single bonds between carbon atoms have different lengths, but X-ray crystallography shows that all the carbon-carbon bonds in benzene are the same length, so the picture above of alternating single and double bonds is unrealistic. It’s also a little hard to imagine how such a molecule could be a regular hexagon, and this leads to knock-on effects in different parts of the molecule if it’s bigger than just benzene. Hexabenzocoranene, for instance, consists of a sheet of thirteen of these rings, and it seems they’d need to tessellate for this to be possible. Therefore the orbitals can be thought of as a pair of parallel tori on either side of the molecule, and the molecule must also be flat even though the classical understanding of the bond lengths would mean it couldn’t be. This is an emergent property of resonance, and as such could be considered a purely chemical concept or property, not reducible to physics.
When this idea became popular, it underwent “mission creep”: chemists started to see these non-localised bonds everywhere. It also changed the definition of what an aromatic compound was again, because for instance that structural formula of phenylalanine above is no longer as neatly alternating as it’s shown to be. Aromatic compounds become compounds including carbon rings with delocalised electrons, themselves in rings.
I mentioned X-ray crystallography. This involves working out what shape a molecule is by crystallising a lot of it together and X-raying it. This leads to a distinctive pattern of X-rays bouncing off it in the same way as a diamond with a beam of light shone through it would produce a distinctive pattern of reflection which would reveal its symmetry, and it’s possible to work back from this scattering to a shape which the molecule in question must be. This was later joined by NMR, nuclear magnetic resonance, since renamed MRI so as not to scare patients that the process was dangerously radioactive. The magnetic fields induced cause the electrons and protons to behave in a distinctive way in aromatic compounds, and therefore the test for whether something is aromatic or not is now several steps away from being the same thing as containing a hexagonal ring of carbon with alternating single and double bonds. Computers also made determining their form faster, and this is significant because it changes the definition of stability. It means that a molecule only needs to be stable enough to last as long as it takes for a NMR scan to be computed of it, meaning in turn that less stable aromatic compounds can be said to exist than before. However, on the other side again, the reason for their instability may be that they are on Earth at a certain temperature interacting with other molecules, and there are in fact polycyclic aromatic hydrocarbons in interstellar space. They do exist, and our understanding of them is in a way parochial, because just as pH makes most sense considering compounds dissolved in water, so does our understanding of polyaromatic hydrocarbons.
It even gets to the point that all that’s needed is for atoms of any kind to form a loop. There’s a square molecule of four aluminium atoms, which probably exists transiently but doesn’t persist but could in a sense be called aromatic, and again in deep space there’s C6, which is just the tiniest and loneliest possible piece of graphite. On Earth it would either oxidise to carbon dioxide or find other carbons and become graphite, graphene or a carbon nanotube.
This brings me back to the minimum publishable unit. At some point the concept of aromaticity got out of hand and it’s suspiciously similar to the plethora of supposèd species of Homo. It seems that it might be quite exciting and publicity-seeking, and maybe in a way fashionable, to declare something an aromatic compound just to crank out a paper, and I’m not blaming anyone here. It’s the system. In doing so, this pressure to publish erodes and blurs the originally nicely defined concept of the benzene ring, and later the delocalised electron thing. It’s an example of how capitalism influences science, not in the sense of forcing scientists to develop new antibiotics which are basically the same as their predecessors and therefore have the same drawbacks and potential to lead to resistance, but in the sense that it subtly pervades the scientific consciousness and very concepts used in it. In a way it was better for this concept before there was a means of measuring the length of atomic bonds, and it was certainly a more sensible environment before scientometrics started to make a serious impact on chemistry.
In conclusion, then, I wonder if anyone at all has read this far, and also that chemistry is in danger of being eroded precisely because it’s the central science, and also due to political and social pressures, the concepts within it, which may be unique to chemistry and not helpfully explicable in reductivist ways to physics, are like much of science in danger from capitalism via scientometrics. The issue of aromaticity is a single but insidious example of that. Also, calling chemistry “the central science” kind of makes it sound fundamental, but in reality what it means is that it’s the most “sciency” science, since it’s the one which is furthest from anything non-scientific. It’s the middle rung of the ladder, and as such has special status, but that also makes it especially vulnerable.
A Box Of Chocolates 