## Friday, October 26, 2012

### Anniversaries: Meitner, van Vleck, Mills, Bohm

If you're a famous physicist, you should be careful today: October 27th is a day when many famous physicists die. This very date turned out to be fatal for Lise Meitner in 1968, John Hasbrouck van Vleck in 1980, David Bohm in 1992 (twenty years ago), and Robert Mills in 1999.

They're known for the co-discovery of the nuclear fission; the van Vleck transformations, determinant, paramagnetism, and other insights about quantum mechanics applied to solids; Aharonov-Bohm effect and the revival of the misguided pilot wave theory by Louis de Broglie; and Yang-Mills theory, respectively.

You may see it's way too many people and way too many topics to discuss.

I already wrote a similar, perhaps complementary, text about her in 2008 but because the lady had such trustworthy initials :-), let me offer you another one so that you may compare.

Lise Meitner was born to a Jewish family in Vienna on November 7th, 1878 (her birthday would later be known as the Great October Socialist Revolution anniversary, proving that leftists prefer communist assholes such as Lenin over great scientists such as Meitner).

In Spring 2011, I watched a program on her fascinating life when I was a jury member at the Academic Film Festival in Olomouc. She faced all kinds of difficulties that would be enough for a strong man. At the same moment, even this very movie convinced me that most of the harassment she has experienced throughout her life had very little to do with her being a woman.

It was mostly about her being Jewish, her bad luck – but she was lucky in many other respects. Not everyone lives for 90 years, for example (that's true despite her heart attack that occurred in 1964). The Jewish girl converted to (Lutheran) Christianity as an adult which is kind of cute but the Nazis didn't pay much attention to this fact even though Meitner herself apparently considered herself a loyal citizen of Germany and perhaps a Christian role model, too. And she actually inherited her detachment from the Jewish identity from her ancestors: it has had quite some roots in her family.

Ludwig Boltzmann, a great statistical mechanic and a forefather of quantum mechanics, was her teacher. She got a PhD in 1905 for "Heat conduction by inhomogenous bodies" (in German) and she was actually not the first woman but the second woman who got a physics PhD over there. Women would be officially discouraged from studying such things a century ago. At the same moment, it seems to me that almost every woman who got the desire as well as talent to become a physicist managed to find a loophole or exception of a sort.

Off-topic: I usually embed this snowy music video on TRF when the first snow of the second half of each year arrives to Pilsen. It's usually but not always at the end of the October and 2012 confirms the approximate rule: the snow is here again. ;-) See a photo gallery.

She rejected an offer to work in a factory and, with some financial backing, boldly went to Berlin and attended Max Planck's lectures – the first woman who was allowed to be there which may sound bad but on the other hand, it also shows that there were no unbreakable barriers imposed by leaders of physics such as Boltzmann and Planck.

Meitner would become Planck's assistant and work with Otto Hahn on radioactive isotopes and beta-decay. She got some medals in Berlin, earned her own lab by 1917, and independently discovered the Auger effect (it is a bit surprising that it still hasn't been renamed as Auger-Meitner effect). In 1926, she became a full professor, and did work that was essential for the discovery of the nuclear fission in 1939.

At that time, however, this "Marie Curie of Germany" as Einstein called her was already in emigration so she wasn't physically present during the final moments of the discovery of nuclear fission. I guess that many people would agree that this fact itself was a sufficient explanation why she didn't share the 1944 Chemistry Nobel Prize for nuclear fission. In some sense, I am more surprised that in 1944, they would still count such nuclear physics things as "chemistry". It sounds stupid.

In 1933, when Hitler came to power, she was actually a director. As a Jew, she was under a clear threat that she denied in front of herself, despite the terror against her fellow Jewish physicists. She continued to work, being partly protected by her Austrian citizenship. This citizenship became worthless with the Anschluss – when Austria was annexed – and she managed to change her identity and escape Germany with 10 marks in her wallet and a diamond ring ready to be paid to border guards (which wasn't necessary).

From the Netherlands, she was able to escape to Sweden and she was able to quickly become the boss of a physics lab in Stockholm. Despite all the comments about "prejudices against women" that were everywhere, I think it is extremely hard to find some tangible evidence of these claims in the actual events that were directing her career.

She continued to communicate with Otto Hahn and she was also meeting Niels Bohr. She was actually the first person in the world to realize the concept of "chain reaction", the reason why $$E=mc^2$$ explained the energy released by the reactions, the main contributor to the discovery of transuranium elements, and so on. I have no doubts that from a broader perspective, she's been a stellar physicist who deserved a Nobel prize. However, she's far from being the only one in this category who wasn't given one, for various reasons: there are tons of men in this category, too. So when I evaluate her life, I would say that there was almost no genuine substantial "discrimination" against women even a century ago.

John Hasbrouck Van Vleck who shared the 1977 Physics Nobel Prize with Phil Anderson and Nevill Francis Mott was born in Connecticut in 1899. His father and grandfather were a mathematician and astronomer, respectively. He studied in Wisconsin, at Harvard, worked in Minnesota, and then at Harvard again.

He is considered the father of modern magnetism as he pioneered the quantum mechanical description of magnetism, especially paramagnetism, as well as the chemical bonding in metal complexes and crystals. He worked on radars during the Second World War and he would understand lots of things about the absorption of centimeter-or-so microwaves by molecules. That was important not only for the military but also for the later birth of radioastronomy. During the Manhattan project, he would help to reduce the size of the Little Boy's firing gun.

The van Vleck determinant is known to theorists as the determinant of an infinitely large matrix, the operator $$\omega^2+U''$$, whose power appears as a normalization prefactor if you're trying to solve various quantum mechanical problems exactly (e.g. the harmonic oscillator in the path integral language).

I wrote a long text about David Bohm in 2007. It was followed by lots of texts explaining why his "interpretation" is based on a deep misunderstanding of how the quantum mechanical phenomena work.

Robert Mills of the Yang-Mills fame was born in New Jersey in 1927. He studied at Columbia from 1944 and won the Putnam Competition in 1948. He earned a degree in Cambridge, spent some time at the IAS, and worked in Ohio.

Of course, the 1954 discovery of the Yang-Mills equations – when these men shared an office in Brookhaven – is his most famous achievement but he actually also studied many-body theory and the theory of alloys. I would say that Oskar Klein knew a "large part" of the spirit behind the Yang-Mills theories back in the 1930s.

Even though the Yang-Mills equations were a bit isolated "superhit" of Robert Mills, all these people were ahead of time, however. Only in the mid 1960s or so, it became meaningful to build realistic models of particle physics that depended on non-Abelian gauge theories. At that time, people wouldn't study proposed theories too carefully unless they were confident that they described the actual Universe around us. We're no longer this narrow-minded today – it's hard to find the experimental evidence revealing some completely new phenomena which is why theorists inevitably have to think about models well before their effects manifests themselves empirically – so it's somewh`t unlikely that the right and relevant equations would remain unnoticed and understudied for many decades. But maybe it could happen again.

He died in 1999.