Remembering Alex Müller (1927-2023), the ‘Woodstock of physics’, and defiance

Thomas Kuhn’s philosophy of scientific revolutions popularised the concept of paradigm shifts. What his principle doesn’t seize, nonetheless, is the historic and biographical wealth of paradigm shifts.

By advantage of being united in character, in Kuhn’s description, they reveal an in any other case elusive Ariadne’s thread in these watershed moments within the historical past of science. It’s potential to see, for instance, in Dan Shechtman’s discovery of quasicrystals within the early Nineteen Eighties parallels to stories in 2018 that scientists on the Indian Institute of Science (IISc), Bengaluru, had found room-temperature superconductivity, and actually to the invention of high-temperature superconductors within the late Nineteen Eighties.

This final one was a milestone in some ways. For greater than a decade till 1986, the best temperature at which a fabric grew to become superconducting – that physicists had been conscious of – was 23 Okay (-250.10º C). This modified in 1986 when Karl Alexander Müller and J. Georg Bednorz found lanthanum barium copper oxide (LBCO) turning into superconducting at 35 Okay. In numbers this was solely a 12 Okay bounce, however within the historical past of physics, it was the autumn of a barrier that physicists had taken to imply was a subject nearing full understanding. As if to garnish the second, LBCO was additionally a ceramic – supplies that scientists on the time thought of to be insulators.

Müller handed away on January 9 this yr on the age of 95. He was born in Basel in April 1927. He completed faculty in 1945, served briefly within the Swiss navy as a part of his civilian obligations, after which enrolled at ETH Zurich. Certainly one of his professors right here was Wolfgang Pauli, of Pauli’s exclusion precept fame and one of many knaben of the knabenphysik. Müller accomplished his PhD in 1958 and joined IBM 5 years later, the place he continued work he had began for his PhD, on supplies referred to as perovskites.

After his and Bednorz’s discovery, however earlier than the tip of the yr, analysis teams in Tokyo and Texas, led respectively by Shoji Tanaka and Paul C.W. Chu, had independently confirmed it. Chu et al. additionally found yet one more cuprate high-temperature superconductor, yttrium barium copper oxide (YBCO), which transitioned at 93 Okay.

A number of issues occurred at this level.

Georg Bednorz at ETH Zurich in October 2013.
| Photograph Credit score:
IBM Analysis

Clearly the group of condensed-matter physicists was excited. Within the phrases of Douglas Finnemore, “The discovery of superconductivity in the cuprate class of conducting oxides brought a flash of sunlight on one of the fields … that many of us had thought was rather mature and fairly well understood”.

The American Bodily Society made a last-minute addition to its annual assembly in March 1987 for Müller and the others to current their findings, in mild of the YBCO discovering. The occasion has since been referred to as the “Woodstock of physics”. Greater than 2,000 physicists gathered on the New York Hilton, the venue, two hours prematurely, spilling over the seats into the aisles and outdoors, the place TV screens displayed the proceedings that lasted from 7.30 pm till 3.15 am.

In 1987, Müller and Bednorz obtained the Nobel Prize for physics for his or her discovery. It was a document for the shortest time between a contribution to physics and receiving the award. Recall {that a} attribute requirement to win a Nobel Prize is that your work ought to have had demonstrable advantages to humankind. That is testomony to the plain significance of the work of Müller, Bednorz, Chu, Tanaka, and so forth. In the identical yr, researchers in Tsukuba, led by Hiroshi Maeda, found the primary so-called triple-digit superconductor: bismuth strontium calcium copper oxide (BSCCO, a.okay.a. bisko), which transitioned at 107 Okay.

Aside from remaking historical past, greater and better transition temperatures additionally spoke to an important engineering problem. In 1911, the Dutch physicist Heike Kamerlingh Onnes found superconductivity in mercury as a result of he had beforehand invented a way to chill supplies to extraordinarily low temperatures. Mercury transitions at 4.2 Okay. Supplies that transition at 4.1 Okay or beneath should be cooled utilizing liquid helium, whose boiling level is 4.15 Okay. Supplies that transition beneath 77 Okay can then again be cooled utilizing liquid nitrogen, which is less complicated to deal with.

LBCO broke the liquid-helium barrier whereas YBCO and BSCCO broke the liquid-nitrogen barrier. The most recent objective on this highway is to discover a room-temperature superconductor, which is why the IISc stories in 2018 raised a lot curiosity.

Then once more, whereas it has been greater than three a long time because the discovery of those marvellous copper-oxides, physicists are nonetheless working to know their microscopic construction and to develop a principle that may clarify why they superconduct. That is tougher than it sounds regardless of the supply right now of superior probing and modelling strategies. Researchers are additionally discovering new superconductors that oppose current theories in little methods. For instance, a gaggle on the Tata Institute of Basic Analysis, Mumbai, reported in 2016 that elemental bismuth superconducts at a bristling 0.00053 Okay, in circumstances that the related principle couldn’t clarify.

Defiance is a necessary a part of scientific revolutions. Shechtman famously defied Linus Carl Pauling to face by his knowledge, which confirmed the existence of a form of crystal that Pauling had deemed unimaginable. In comparable vein, as “news of the discovery started to spread” in 1986, Bednorz recalled twenty years later, “we experienced mixed reactions ranging from silent scepticism to polite (cautious) congratulations”, main finally to full-blown pleasure when Tanaka and Chu reported their unbiased affirmation.

Iowa State University professor Daniel Shechtman in Ames, Iowa. Shechtman won the 2011 Nobel Prize in chemistry on Oct. 5, 2011, for his discovery of quasicrystals, a mosaic-like chemical structure that researchers previously thought was impossible.

Iowa State College professor Daniel Shechtman in Ames, Iowa. Shechtman received the 2011 Nobel Prize in chemistry on Oct. 5, 2011, for his discovery of quasicrystals, a mosaic-like chemical construction that researchers beforehand thought was unimaginable.
| Photograph Credit score:
AP Photograph/The Ames Laboratory, File

Defiance is particular as a result of it challenges the concept of scientists bravely following theoretical predictions to usually unlikely conclusions, though that is as a lot a touch upon the social circumstances wherein scientists function as on how they create and enhance theories.

For instance, although they finally discovered one thing that threw the gates of superconductor physics huge open, Müller and Bednorz weren’t precisely groping at midnight. They’d anticipated to discover a high-temperature superconductor primarily based on predictions of the BCS principle of superconductivity and one thing referred to as the Jahn-Teller impact. ‘BCS’ stands for Bardeen-Cooper-Schrieffer, three physicists who developed the primary microscopic principle to clarify superconductivity in metallic supplies that transitioned at a low temperature, like mercury. However as historian of science Gerald Holton famous within the 1998 version of The Scientific Creativeness, each the BCS principle and the Jahn-Teller impact had been subsequently discovered to have “little to do” with high-temperature superconductivity.

But, as Holton continued, Müller additionally wasn’t certain if they might succeed. He labored at IBM in Rüschlikon, Switzerland, was made an IBM fellow in 1982 and recruited Bednorz in 1983. IBM printed an obituary on the day of Müller’s passing saying, “Despite his managerial role, Müller still found time to do research. He started a project with the ambitious goal to synthesise new superconducting materials together with J. Georg Bednorz.” But Müller didn’t inform his managers on the time nor others that he was engaged on superconductivity. Amongst different causes, he hoped that if he and Bednorz hit a dead-end, they may quietly bury their work “in order to not jeopardise Bednorz’s career”.

One thing comparable occurred when Dov Levine found quasicrystals across the time Shechtman had, however Paul Steinhardt suggested warning earlier than publishing his findings. No less than one physicist additionally thought Müller and Bednorz had been “crazy” to search for an oxide high-temperature superconductor.

The romantic notion of a scientific revolution, along with its promise to beget futuristic new applied sciences, belies its profound messiness, particularly the dangers its central actors assume after they stand by their findings. Then once more, to adapt the knowledge of Subrahmanyan Chandrasekhar, greatness amongst scientists reveals itself after they know which questions are price answering – and which dangers are price taking. Müller, on this regard, got here out on prime.

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