Microwaves, magnetism and machine grease: a paean to tool-driven science

Unfortunately, Radar as it stood in 1939 was extremely poor at thwarting an enemy invasion. Britain’s Radar defenses all relied on meter-wave radio detection. They were plagued by poor resolution and low power and could detect enemy aircraft only to a range of about 100 miles. They were fairly good at detecting distance, but not angle. And they were abysmal at detecting low-flying aircraft. The trick was to somehow design microwave transmitters, which could significantly ameliorate all these problems. The amelioration turned out to be quite a scientific and engineering feat, but it won the British the Battle of Britain and The War. Even more than the atomic bomb, it was Radar that saved Queen and Country.

 

A few years before, two other Britons had investigated how to determine the structure of molecules using beams of x-rays. The father and son duo of William and Lawrence Bragg found out that they could finely interrogate molecular crystals with x-rays, the way a handsome movie star would obsess over combing his hair with a fine-toothed comb to plough through every single fiber. By knowing the wavelength of the x-rays and the angle at which the x-rays were scattered, the two could determine the location of atoms in the crystal, an amazing achievement considering how small atoms are.

 

Half a world away on the other side of the pond, another physicist named Isidor Rabi was experimenting with a different kind of beam- a molecular beam of magnetic particles. A supremely confident physicist without a hint of arrogance, Rabi had been educated in the best center of physics in Europe during the 1920s. Now at Columbia University in New York City, Rabi was observing something startling. A beam of ions passing through a magnetic field could be manipulated by another magnetic field perpendicular to the first one. Rabi noticed that at certain frequencies of the second magnetic field, there was a sudden dip in intensity of the beam, indicating a sharp absorption of energy. Rabi had been intrigued by this phenomenon which had turned out to be very general. The absorption of energy seemed very similar to the phenomenon of resonance in physics that can lead to glasses being shattered by unbearably shrill opera singers and bridges being shattered when soldiers march in lockstep on them. Rabi saw an analogy in his experiments and named the phenomenon "nuclear magnetic resonance".

 

If modern molecular biologists can be grateful to a handful of founding physicists for bequeathing them an enormous legacy, Randall, Rabi and the two Braggs should be on top of their list. Rabi’s experiments were enhanced and finessed to perfection. They were turned into one of the two most important methods in chemistry- Nuclear Magnetic Resonance spectroscopy. Randall’s microwaves became valuable tools in determining molecular structure (it was microwave spectrosopy for instance that has brought Harry Kroto to Lindau for his discovery of fullerenes) and in astronomy. More importantly, after the war, Randall switched fields and turned to the fledgling science of molecular biology. He pioneered study in this field when it was just getting jump started. He was the person who brought Maurice Wilkins and Rosalind Franklin to King’s College, London. They in turn collaborated with James Watson and Francis Crick- recruited by Lawrence Bragg- at Cambridge University to make the epochal discovery of the structure of DNA. Others under the guidance of Bragg such as Max Perutz and John Kendrew pioneered the study of protein structure.

 

I narrate the story of these physicists because they illustrate two of the best examples of what we can call ‘tool-driven scientific revolutions’. Today, NMR spectrcopy and x-ray crystallography are at the heart of molecular biology. X-ray diffraction especially is the single-most important tool in the field. It is as close as one can get to taking a direct photograph of a molecule. Molecular biology today would be unthinkable without it. In fact all of chemistry and biology would still be struggling to get its feet off the ground without these two techniques. Not only have the techniques given us the structure of DNA and proteins, but they conitnue to supply us with insights that lead to better drugs to combat disease. It should not surprise us at all that a few dozen Nobel Prizes have been awarded to pioneers and users of these techniques.

 

 

Top: Working on the Manhattan Project; Ernest Lawrence, Enrico Fermi and Isidor Rabi. Bottom: John Randall

 

X-ray crystallography and NMR spectrocopy seem to fly in the face of those who commonly believe that science is idea and concept-driven. The whole business of grand ideas driving scientific revolutions got a tremendous boost when Thomas Kuhn’s "The Structure of Scientific Revolutions" was published in 1962. The story goes that Kuhn got the idea for his book when he had been asked to teach a course on Aristotlean science at Harvard. Going over Aristotle’s works, Kuhn was astonished how someone who was of such a supreme intellectual caliber could get his basic physics so woefully wrong. Pondering over this paradox, Kuhn’s eyes were opened when he realized that he was looking at the subject all wrong; look at the subject through Aristotle’s eyes and the world of five elements and four causes seems to make sense. Aristotle had the right mind, but he was working with the wrong paradigm. What he needed was a paradigm shift.

 

Since then, the term "paradigm shift" has become part of everyday language, and it has been misused outside its context of science much more than it has been used inside it. Kuhn himself toward the end of his life was furious at its misuse and used to ferociously insist that he was "not a Kuhnian". But the basic idea that science is essentially concept-driven has stuck. However, the history of crystallography and NMR spectroscopy seem to indicate that scientific revolutions can also be engendered by more mundane developments of machines and practical tools; what physicist Freeman Dyson calls the "craft of science". What would medicine and biology look like for example without the invention of the microscope? As Dyson says, the tool-inspired paradigm has been best explained by Harvard University philosopher Peter Galison, especially in his 1997 book "Image and Logic". The book is full of diagrams of scientific instruments, circuits and schematics, unlike Kuhn’s book which is full of words. Everyone remembers Kuhn’s book; few seem to recognize Galison’s name.

 

Galison even points us to the most popular twentieth century example of an apparently idea-driven scientific revolution and demonstrates how tools played a crucial role in it. He is talking about Einstein’s theory of relativity, whose formulation crucially depended on thought experiments on clocks and moving rods which the young patent clerk obsessed over. In fact Einstein was fascinated by clocks, and he happened to be in Bern which at the time was a world leader when it came to clock manufacture and design. As he got on the train everyday, he undoubtedly would have wondered how the clocks on different train stations were so precisely synchronised. Einstein’s Clocks became an integral part of Einstein’s Theory.

 

As another example of tool-driven science, consider another supremely accomplished scientist of the twentieth century- Ernest Rutherford. An experimentalist who often scorned theorists, Rutherford was nonetheless responsible for a paradigm shift in our view of the structure of the atom. But one would be hard-pressed to find anyone else who reveled so much in the joys of machine oil, sealing wax and duct tape. Rutherford undoubtedly liked to roll his sleeves up and get his hands dirty. He hardly fits our conception of the philosopher-scientist who heralds revolutions by power of thought alone. And yet Rutherford without a doubt led a scientific revolution in a laboratory which has produced no less than 29 Nobel Prize winners. Yet another example of a brilliant tool wielder was the American physicist Ernest Lawrence, whose invention of the cyclotron opened the curtain on a new era of research in atomic and nuclear physics.

 

The list can be endless if you look in the right places. The fact is that tool-driven science has been as responsible for scientific revolutions as have grand ideas. Let us appreciate the laboratory toilers covered with sweat as much as we appreciate the deep thinkers. Science needs both to progress. And it is only fitting that tool-driven science has culminated in in the 2010 Nobel Prize in chemistry. We will look at this in the next post.