Thursday, December 15, 2016

More alternative heroes

It was fun to write this piece for Nautilus on who would have made some of the great discoveries in science if their actual discoverers had not lived. And very nice to see it is provoking discussion, as I’d hoped – there is nothing definitive in my suggestions. Here are two more case histories, for which there was not room in the final article.


Fullerenes – Wolfgang Krätschmer and Donald Huffman

In 1985, British spectroscopist Harry Kroto visited physical chemists Richard Smalley and Robert Curl at Rice University in Houston, Texas, to see if their machine for making clusters of atoms could produce some of the exotic carbon molecules Kroto thought might be formed in space. Their experiments led to the discovery of hollow, spherical molecules called C60 or buckminsterfullerene, and of a whole family of related hollow-shell carbon molecules called fullerenes. They were awarded the 1996 Nobel prize in chemistry for the work.

Fullerenes had been seen before 1985; they just hadn’t been recognized as such. They can in fact be formed in ordinary candle flames, but the most systematic experiments were conducted in 1982-3 by experimental physicist Wolfgang Krätschmer at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Krätschmer had teamed up with physicist Donald Huffman of the University of Arizona, for they both were, like Kroto, interested in the constituents of interstellar space.

Huffman studied dust grains scattered through the cosmos from which stars may form. He and Krätschmer began collaborating in the 1970s while Huffman was on sabbatical in Stuttgart, and initially they looked at tiny particles of silicate minerals. But Huffman believed that some of the absorption of starlight by grains in the interstellar medium could be due to tiny particles of something like soot in the mix: basically, flakes of graphite-like carbon.

In 1982 he visited Krätschmer to carry out experiments in which they heated graphite rods in a vacuum and measured the light absorbed by the sooty debris. They made and saw C60, which absorbs ultraviolet light at a particular wavelength. But they didn’t realize what it was, and decided their apparatus was just making unintelligible carbon “junk”.

It wasn’t until the duo saw the paper by Kroto and colleagues in 1985 that the penny dropped. But if it hadn’t been for that, the interest of astronomers in interstellar dust would probably have returned scrutiny anyway to those experiments in Heidelberg, and the truth would have emerged. As it was, the graphite-vaporizing equipment of Krätschmer and Huffman offered a way to mass-produce fullerenes more cheaply and simply than the Rice cluster machine. Once this was understood in 1990, fullerene research exploded worldwide.

Continental drift – Roberto Mantovani, or…

There are discoveries for the time seems right, and others for which it’s just the opposite. For one reason or another they are rejected by the prevailing scientific opinion, offering us the retrospective, appealingly tragic tale of the lone maverick who was spurned only vindicated much later, perhaps posthumously. That’s pretty much how it was for Alfred Wegener’s theory of continental drift. In the 1930s, Wegener, a German meteorologist (so what did he know about geology?), proposed that the Earth’s surface was not fixed, but that the continental land masses wander over time into different configurations, and were in the distant past disposed far from where they stand today. To doubt the evident solidity of the planetary surface seemed absurd, and it wasn’t until the discovery of seafloor spreading – the formation of fresh ocean crust by volcanic activity – in the 1960s that continental drift became the paradigm for geology.

In such circumstances, it seems rather unlikely that anyone else would have come up with Wegener’s unorthodox idea in his own era. But they did. Not just one individual but several others imagined something like a theory of plate tectonics in the early twentieth century.

The most immediate sign of continental drift on the world map is the suspiciously close fit of the east coast of South America with the west coast of Africa. But that line of argument, advanced by American geologist Frank Bursley Taylor in 1908, seems almost too simplistic. Taylor got other things right too, such as the way the collision of continents pushes up mountain ranges. But his claim that the movements were caused by the close approach of the moon when it was suddenly captured by the Earth in the Cretaceous period was rather too baroque for his contemporaries.

In 1911, an amateur American geologist named Howard Baker also proposed that the continents are fragments of an epicene supercontinent that was torn apart. His mechanism was even more bizarre than Taylor’s: the moon was once a part of the Earth that got ripped off by its rapid spinning, and the continents moved to fill the gap.

In comparison, the theory of Italian geologist (and violinist) Roberto Mantovani, first published in 1889 and developed over the next three decades, was rather easier to swallow. He too argued that the continents were originally a single landmass that was pulled apart thanks to an expansion of the Earth driven by volcanic activity. Wegener acknowledged some “astonishingly close” correspondences between Mantovani’s reconstruction and his own.

All of these ideas contain tantalizing truths: breakup of an ancient supercontinent (now called Pangea), opening of ocean basins, mountain building and volcanism as the driving force. (Even Baker’s idea that the moon was once a part of the Earth is now widely believed, albeit for totally different reasons.) But like a reconstruction of Pangea from today’s map, the parts didn’t fit without gaps, and no one, including Wegener, could find a plausible mechanism for the continental movements. If we didn’t have Wegener, then Mantovani, or even Taylor or Baker, could step into the same foundational narrative of the neglected savant. All intuited some element of the truth, and their stories show that there’s often an element of arbitrariness in what counts as a discovery and who gets the credit.


David Brown said...

In the 1930s, Wegener ..." Wegener died in November 1930. He published his theory of continental drift in 1911:
Thermodynamik der Atmosphäre
Is Milgrom similar to a latter-day Wegener? I say that Milgrom is the Kepler of contemporary cosmology — on the basis of overwhelming empirical evidence.

David Brown said...

I have now proved that I don't know the difference between atmospheric thermodynamics and geology. Make that 1912 not 1911.