Steven Weinberg (1933-2021)

I was quite saddened to hear about the passing of Steven Weinberg, perhaps the dominant living figure from the golden age of particle physics. I was especially saddened since he seemed to be doing fine, as indicated by a lecture he gave at the Texas Science Festival this March. I think many of us thought that he was going to be around for at least a few more years. 

Weinberg was one of a select few individuals who transformed our understanding of elementary particles and cemented the creation of the Standard Model (he coined the name), in his case by unifying the electromagnetic and weak forces; for this he shared the 1979 Nobel Prize in physics with Abdus Salam and Sheldon Lee Glashow. His 1967 paper which heralded the unification, "A Model of Leptons", was only 3 pages long and remains one of the most highly cited articles in physics history.

But what made Weinberg special was that he was not only one of the most brilliant theoretical physicists of the 20th century but also a pedagogical master with few peers. His many technical textbooks, especially his 3-volume "Quantum Theory of Fields", have educated a generation of physicists; meanwhile, his essays in the New York Times Book Review and other avenues and collections of articles published as popular books have educated the lay public about the mysteries of physics. But in his popular books Weinberg also revealed himself to be a real Renaissance Man, writing not just about physics but about religion, politics, philosophy, history including the history of science, opera and literature. He was also known for his political advocacy of science. Among scientists of his generation, only Freeman Dyson had that kind of range.

There have been some great tributes to him, and I would point especially to the ones by Scott Aaronson and Robert McNees, both of whom interacted with Weinberg as colleagues. The tribute by Scott especially shows the kind of independent streak that Weinberg had, never content to go with the mainstream and always seeking orthogonal viewpoints and original thoughts. In that he very much reminded me of Dyson; the two were in fact friends and served together on the government advisory group JASON, and my conversation with Weinberg which I describe below ended with him asking me to give my regards to Freeman, who I was meeting in a few weeks.

I had the good fortune of interacting with Steve on two occasions, both rewarding. The first time I had the opportunity to be with him on a Canadian television panel on the challenges of Big Science. You can see the discussion here:

https://www.tvo.org/video/the-challenge-of-big-science

The next time was a few years later when I contacted him about a project and asked whether he had some thoughts to share about it. Steve didn't know me personally (although he did remember the Big Science panel) and was even then very busy with writing and other projects. In addition, the project wasn't something close to his immediate interests, so I was surprised when not only did he respond right away but asked me to call him at 10 AM on a Sunday and spoke generously for more than an hour. I still have the recording.

Steve was a great physicist, a gentleman and a Renaissance Man, a true original. We are unlikely to see the likes of him for a long time. 

One of the reasons I feel particularly wistful with his passing is because he was among the last of the creators of modern particle physics. He worked in an enormously fruitful time in which theory went hand in hand with experiment. This is different from the last twenty years in which fundamental physics and especially string theory have been struggling to make experimental connections. In cosmology however, there have been very exciting developments, and Weinberg who devoted his last few decades to the topic was certainly very interested in these. Hopefully fundamental physics can become as involved with the productive interplay of theory and experiment as cosmology and condensed matter physics are, and hopefully we can again resurrect the golden era of science in which Steven Weinberg played such a commanding role.

A terrible year for academic organic chemistry

In the last one year, academic chemistry has lost Jack Roberts, Jerome Berson, George Olah, Gilbert Stork and now Ron Breslow. The last two in just one week. 

It's been a terrible loss. All these chemists were world-renowned pioneers in their areas who laid the foundations of much of what graduate students now learn in their textbooks and what professional chemists apply in their laboratories. They were the last torch bearers of the golden age of organic chemistry, the age which laid the foundations of the three pillars of organic chemistry: structure, reactivity and synthesis.

Jack Roberts pioneered NMR spectroscopy in the United States. He should really have received a Nobel Prize for this contribution in my opinion. But in addition to this, he was also one of the foremost practitioners of molecular orbital theory and made very significant contributions to conformational analysis and carbocation chemistry.

Jerome Berson was another important physical organic chemist who also wrote what I consider to be a very unique contribution to the history of science - a book titled "Chemical Creativity", that traces creativity in the work of leading chemists, from Hückel to Woodward.

George Olah was the father of modern carbocation chemistry and an inventor of superacids that allow us to stabilize carbocations. He contributed massively to work that is used in the petrochemical industry and, along with Martin Saunders, delivered the coup de grace that settled the famous non-classical cation controversy for good.

Gilbert Stork about whom much has been written since he passed away just a few days ago was one of the most original synthetic organic chemists of the 20th century. His work on enamine alkylations, radical cyclizations and other key reactions is now part of the textbooks, and so are his several elegant natural product syntheses.

And now Ronald Breslow. Primarily known as a physical organic chemist, Breslow was one of the most versatile chemists of the 20th century whose contributions ranged across the entire chemical landscape. He is famous for many things; for discovering the simplest aromatic system - the cyclopropenium ion, for d-orbital conjugation, for very intriguing work on chemistry in aqueous solvents, for building artificial enzymes, for inventing the marketed drug SAHA (the first histone deacetylase inhibitor) and for exploring the origin of chirality during the origin of life. How many chemists can claim that kind of oeuvre?

Breslow received pretty much every award for science there is out there except the Nobel Prize - the National Medal of Science, membership in the National Academy of Sciences and presidency of the ACS among others. He also saw his share of controversies, although the chemical community always came out wiser for learning from them. 

Most notably, in an age when senior professors are often criticized for using graduate students and postdocs as cheap labor, Breslow was an extraordinary educator. Among his students and postdocs are Robert Grubbs, Robert Bergman and Larry Overman. There is probably not a continent on which some student of his is not doing chemistry. More than once during his talks, he made a pitch for hiring the student or postdoc who had done the work. Breslow belonged to an older, more gentlemanly generation of professors who would make calls to get their students jobs.

I last heard Breslow speak only one year ago at an ACS meeting. Before that I had heard him speak at an ACS meeting about ten years ago. The remarkable thing is that between those ten years he did not seem to have aged, displaying the same boyish enthusiasm and curiosity for chemistry that was always his hallmark. When he received the Priestley Medal in 1999, one of his students said the same thing: "He just doesn't seem to age, certainly not intellectually. Talking to him now is like talking to him 30 years ago. He's got the same enthusiasm, the same excitement about chemistry."

We are all poorer for the loss of Breslow and these other pioneers, but the best thing is that they will be part of the textbooks as long as there is a science of chemistry.

Roger Tsien (1952-2016): Tool builder extraordinaire

The scientific world is noting with sadness the unexpected passing of Roger Tsien at the untimely age of 64. It's not clear what led to his demise but it seems to have happened on a bike trail in Oregon.

Tsien is of course one of the fathers of Green Fluorescent Protein (GFP), and the one who probably did more to bring it to the masses than anyone else. It's amazing to see the diversity of applications that has mushroomed from the use of this protein. In one fell swoop a new world of color exploded on the stage of chemistry and biology. Everything from reporter gene assays for drugs and biological events to potential precision targeting of tumors can be enabled by the use of this stunningly versatile tool. The discovery of GFP is also almost a poster child for how basic curiosity-driven research can lead to great and unexpected leaps. The scientific child that Tsien fathered has now undoubtedly spread beyond his wildest expectations, into far realms of biochemistry, synthetic biology and surgery. It will undoubtedly keep conquering new domains in the years to come.

Sydney Brenner once said that "Revolutions in science are made possible by new tools, new ideas and new discoveries, in that order", and Brenner could have been talking about Roger Tsien here. Peter Galison and Freeman Dyson have emphasized how it's often new techniques and tools rather than new theories that really change the face of science, and a select few people like Tsien exemplify this tradition to a superlative degree. Chemistry especially is intrinsically an experimental science and driven by tool-driven revolutions. Most chemical systems are too complex to yield to first-order theorizing, so often it's only tools like Tsien's GFP that can enable us to unravel their complexities. 

Tsien is also an exemplar of another paradigm, that of the hedgehog and the fox. Hedgehogs do one thing exceedingly well, while foxes do many things well. Tsien the hedgehog did one thing so well that his work led to countless other hedgehogs and foxes adopting his work. He showed us how hedgehogs and foxes can build on each other's work.

The UC San Diego obituary noted that Tsien was "exuberant and resourceful", and I can attest to witnessing these qualities. I saw Tsien speaking and interacting with students at the Lindau Nobel Laureate meeting a few years ago. One memory especially stands out, and I think it's a testament to his prowess as a master of practical tool-building. There was a session on climate change which included a panel of Nobel Laureates and IPCC officials; Tsien was in the audience. The panel spent about an hour talking about all the problems with climate change and how humanity was responsible for them. When time came for questions, while everyone else was more interested in asking about the controversy and the politics, Tsien got up and impatiently noted that nobody on the panel had talked about specific, cutting-edge technologies or tools that could help us actually deal with climate change. In a discussion that seemed to be bogged down in assigning blame and laying out problems, he was talking about solutions.

That was Roger Tsien, a man driven by an obsessive and laser-like focus to discover new tools that could better the world of science and humanity. He lived and ended his life breathing a Churchillian mandate: "Give us the tools, and we will finish the job." RIP.

Image: HHMI