Kellogg S. Stelle
Kellogg S. Stelle
These pages are dedicated to the memory of Kelly Stelle and aim to celebrate his rich life and important scientific achievements.
Kelly became ill while travelling in Egypt with his wife, Marise, and passed away on 23rd October 2025.
Kelly was a truly remarkable man, a brilliant scientist and a wonderful human being. His kindness, intellectual curiosity, mischievous sense of humour and love of life inspired all who knew him.
He will be greatly missed.
Kellogg Stelle 1948-2025
Kelly was a truly remarkable man, an outstanding scientist and a wonderful human being. Kelly was not only a brilliant researcher and inspirational teacher of physics. He was a true polymath, possessing an encyclopaedic knowledge of politics, literature, the arts and languages, speaking Russian, French and Italian in addition to his native English. (Our Russian colleagues were unable to tell he was not Russian.) His kindness, intellectual curiosity and love of life inspired all who knew him.
Kelly made groundbreaking contributions to supersymmetry, supergravity, quantum gravity and M-theory. He was awarded the IoP Rayleigh Medal in 2020 for “his seminal contributions to fundamental physics: the first quantum theory of gravity, the construction of braneworld cosmologies, and the discovery of the supermembrane and fundamental work on supersymmetric field theories and supergravity.” He was a Fellow of the Institute of Physics and a Fellow of the American Physical Society.
Kelly studied History and Science at Harvard and then spent 1970-2 at the Antarctic, observing Cosmic Rays at Amundsen-Scott South Pole Station. He returned to study for a PhD at Brandeis with Stanley Deser. As a graduate student, he found what is arguably the only quantum theory of gravity that we have to date. He showed the curvature squared gravity theory is renormalizable and so is a consistent quantum theory. However, this came at a price: the theory is not unitary as there are negative norm states. Yet many have tried and are still trying to find ways around this problem and his paper now has almost 3000 citations.
He held postdoctoral positions at Kings College London, Imperial College London, CERN, and the École Normale Supérieure in Paris. He returned to Salam’s theoretical physics group at Imperial with a SERC Advanced Fellowship in 1982, leading to appointment as Lecturer in Physics in 1983, followed by promotions to Reader in 1988 and Professor in 1995. He was Head of the Theoretical Physics Group from 2002 to 2007 and presided over a significant strengthening of the Group. Then from 2007 to 2024 he served as an outstanding Course Director for the MSc course Quantum Fields and Fundamental Forces, inspiring generations of students.
He was a pioneer of supersymmetry and supergravity and wrote many seminal papers. With Howe and West, he showed that N=4 supersymmetric Yang-Mils theory is finite. There was much speculation that supergravity could also be finite but with Deser and Kay he found the candidate counterterm that was the first indication that supersymmetry alone is not enough to save supergravity from UV divergences. The issue of divergences in supersymmetric theories has been a major theme of his research over the years. With Duff, he found the supermembrane solution of D=11 supergravity (a paper written on a long-haul flight back from a conference in Singapore). With Lukas, Ovrut and Waldram, he went on to do much great work on branes in supergravity, and to pioneer brane-world scenarios.
Kelly was a great traveller and adventurer and that was one of his sources of his many great anecdotes. His breadth of knowledge together with his mischievous sense of humour and great stories made him great company at dinner, and he was an enthusiastic participant in seminars and conferences and especially the dinner opportunities that they afforded. There was never a menu so grand that Kelly could not home in on its most expensive item. With Kelly you would dine like a king but go home a pauper.
Since his demise, we have received many messages from colleagues all round the world about Kelly saying how much Kelly had meant to them and telling of the kindnesses he had shown them. Many wrote with ‘Kelly stories’: stories about where they had met Kelly, often in strange and exotic places, or about wonderful adventures they had shared.
Kelly married his long-time partner Marise on 14th September 2025 in a beautiful wedding in Sicily. The wedding involved three days of good food and good wine, combined with time on a lovely beach. The climax was the wedding ceremony at a spectacular Norman castle on the Sicilian coast near Catania. Many of Kelly’s friends from many parts of the world and from many different stages in Kelly’s life were there to celebrate the wedding and to swap stories about Kelly.
For their honeymoon, Kelly and Marise went on a cruise on the Nile, followed by further travelling in Egypt. While in Egypt, Kelly fell ill and was hospitalised in Alexandria. He fought the illness for four weeks before passing away on 23rd October 2025.
Kelly will be greatly missed. We extend our sincere condolences to his family and loved ones, and above all to Marise.
Chris Hull and Mike Duff
Gallery
Messages and memories
Share your messages and memories. You can also post photos in the Gallery below..
March 26, 2026
It is really a painful loss to the physics community, the sudden demise of Kellog Stelle. My research life has been significantly impacted by his work on quadratic gravity and renormalizability. In recent years, I had pleasure to interact with Kelly on several occasions in recent years. I had long conversations with him in 2024 at our NORDITA quantum gravity workshop. Kelly insisted on the importance of renormalizability to the younger generation who are producing countless EFTs without anchor. We dedicated our recent work to the memory of Kellogg Stelle and Alexei Staorobinsky where we proved Stelle gravity is renormalizable and also unitary with our new understanding of turning ghost into an Inverted Harmonic Oscillator like instability https://arxiv.org/abs/2603.07150
March 26, 2026
I was shocked to hear of Kelly’s passing. To write this is painful and brings back memories. I met Kelly when we both arrived at Imperial as post docs in 1978.. we have been friends ever since despite us only being in the same place for 3 years (2 at Imperiall then 1 at CERN). Kelly was special. He was fun, generous kind and always interested. Last time we met, at Nordita in summer 2024, we discussed endlessly after my talk. Kelly spent time digging into the literature to see if he could help. We were going to continue, but never did. Over the years I’ve skied with Kelly (I’m awful) hiked with him and had many, many dinners. The dinners were great fun, even when they were after PhD vivas, and we’ve done a few vivas together over the years.. Kelly’s company made up for how terrible some of the theses were!
Kelly will be solely missed by all that knew him.
Kelly will be solely missed by all that knew him.
March 18, 2026
Kelly was such a special person, kind, generous and brilliant. His was the first seminar I attended as a graduate student in Newcastle in 1982, and it remains a wonderful memory as he told us about life in Antarctica over lunch before introducing me to supersymmetry in the seminar. Whilst I was at Imperial as a postdoc in 1985-87, Natalie and I were lucky enough to spend lots of time with Kelly, he loved art and was thrilled that she was a paper conservator. He even introduced her in his wonderful apartment to Roman Jackiw because he needed to have his Polish birth certificate conserved.
In 1993, I flew with Kelly to Sochi where we gave some lectures at a summer school for students from Moscow State University. It was on that trip I realised quite how brilliant his Russian was, as he took me under his wing as we dealt with the peculiarities of travelling in the Soviet Union whilst it was breaking up.
His teaching was legendary, I was the external examiner for their MSc programme Quantum Fields and Fundamental Fields, and Kelly’s lectures were always praised by the students for their clarity. Over the following years, whenever I met up with Kelly, he asked how things were, he was genuinely interested. It nearly always ended up in a trip to the pub followed by an expensive meal.
The last time I saw Kelly, in June 2025 we sat together at the Royal Society Faraday Discovery panel meeting and then went for a beer. He was so happy, and full of life, he was getting married. He was a wonderful friend, I feel so lucky to have known him, and still struggle to think he won’t be there when I next visit Imperial.
My sincere condolences go to his wife Marise and his family.
In 1993, I flew with Kelly to Sochi where we gave some lectures at a summer school for students from Moscow State University. It was on that trip I realised quite how brilliant his Russian was, as he took me under his wing as we dealt with the peculiarities of travelling in the Soviet Union whilst it was breaking up.
His teaching was legendary, I was the external examiner for their MSc programme Quantum Fields and Fundamental Fields, and Kelly’s lectures were always praised by the students for their clarity. Over the following years, whenever I met up with Kelly, he asked how things were, he was genuinely interested. It nearly always ended up in a trip to the pub followed by an expensive meal.
The last time I saw Kelly, in June 2025 we sat together at the Royal Society Faraday Discovery panel meeting and then went for a beer. He was so happy, and full of life, he was getting married. He was a wonderful friend, I feel so lucky to have known him, and still struggle to think he won’t be there when I next visit Imperial.
My sincere condolences go to his wife Marise and his family.
February 28, 2026
I was fortunate to know Kelly Stelle from his first visit to Moscow for the Second Quantum Gravity Seminar mentioned by Mike Duff. At that time, I was a young postdoctoral researcher and took part in organizing the meeting, including welcoming arriving participants. Kelly was one of them.
In the years that followed, I met Kelly many times at conferences in Russia and abroad. He also gave a talk at the seminar of my home institute, the Lebedev Institute. I remember that talk especially well, as it was based on his joint paper with Eric Bergshoeff and Miles Blencowe, “Area-Preserving Diffeomorphisms and Higher-Spin Algebra” (Commun. Math. Phys. 128 (1990) 213), which was closely related to my own research interests. As far as I recall, this was the only direct scientific interaction I had with Kelly, but it proved to be a very productive one. The published version of the paper contains a footnote acknowledging my comments.
Of course, Kelly and I discussed many other scientific matters at meetings and conferences we both attended. Yet, in truth, the most memorable conversations with him were about culture and history. Kelly had an exceptional breadth of interests and a deep appreciation of history and art. Once, when I was in London, he suggested that we visit together an exhibition on the Assyrian Empire at the British Museum; it was a remarkable experience. On another occasion, Kelly guided my wife Olga and me through an ancient Christian church in Istanbul, sharing his knowledge of its remarkable wall paintings.
Whenever I met Kelly in Moscow or in other scientific cities, such as Tomsk, I would ask him what interesting events were taking place around us. He always seemed to grasp the broader cultural and intellectual landscape far better than most.
Kelly Stelle was a person of rare character—a distinguished scientist, an inspiring companion, and a truly remarkable individual. He will be deeply missed.
In the years that followed, I met Kelly many times at conferences in Russia and abroad. He also gave a talk at the seminar of my home institute, the Lebedev Institute. I remember that talk especially well, as it was based on his joint paper with Eric Bergshoeff and Miles Blencowe, “Area-Preserving Diffeomorphisms and Higher-Spin Algebra” (Commun. Math. Phys. 128 (1990) 213), which was closely related to my own research interests. As far as I recall, this was the only direct scientific interaction I had with Kelly, but it proved to be a very productive one. The published version of the paper contains a footnote acknowledging my comments.
Of course, Kelly and I discussed many other scientific matters at meetings and conferences we both attended. Yet, in truth, the most memorable conversations with him were about culture and history. Kelly had an exceptional breadth of interests and a deep appreciation of history and art. Once, when I was in London, he suggested that we visit together an exhibition on the Assyrian Empire at the British Museum; it was a remarkable experience. On another occasion, Kelly guided my wife Olga and me through an ancient Christian church in Istanbul, sharing his knowledge of its remarkable wall paintings.
Whenever I met Kelly in Moscow or in other scientific cities, such as Tomsk, I would ask him what interesting events were taking place around us. He always seemed to grasp the broader cultural and intellectual landscape far better than most.
Kelly Stelle was a person of rare character—a distinguished scientist, an inspiring companion, and a truly remarkable individual. He will be deeply missed.
February 25, 2026
Kelly was a kind and considerate man who took an interest in my singing and singing teaching career. He never did let me help him with his throat clearing though! He came to concerts and operas where I was singing. I also enjoyed meeting him many times at his favourite restaurants with my husband, and he came to our house for meals too and met our children.
February 23, 2026
As with so many others. I was shocked and greatly saddened when Kelly Stelle passed away. He was not just a phenomenal lecturer, researcher and PhD. supervisor, but also an incredibly kind and caring person. The world is truly diminished by his absence.
February 16, 2026
(This is from my response to friends at the International School of Geneva upon hearing from Lynette Xi of Kelly''s passing.)
Thank you, Lynette for this information. I am very sad. Kelly was a close friend of mine. I have a lot of good memories and funny stories about Kelly, including how I discovered in Mr. Stock's French class through surreptitious Morse code messages with Kelly that his mother and my mother were freshman college roommates. Kelly and I were both in Gary Abrecht's boy scout patrol in troupe Gottard. Because of his erudition and energy on all hikes with the troupe he was given the scout name "Chamois scientifique." That was kind and deserved. Many names were not flattering. Mine was Raton loufoque. I had to look that one up and wasn't too pleased when I found it. Kelly left Ecolint to attend Philips Andover Academy. He then went to Harvard. At Harvard he wanted to major in physics but also take Russian and Italian. The physics department said he couldn't do that because at Harvard the physics curriculum was prescribed and there was no space for Russian and Italian. So Kelly majored in the "History of Science," took the entire physics curriculum and also Russian and Italian. In his senior year he applied to the Harvard Ph.D program in physics. They turned him down, saying they only accepted physics majors. So Kelly went to Brandeis for his Ph.D and studied theoretical physics with Einstein's colleagues who had left Germany at the same time as Einstein. Kelly worked at CERN and was a professor at Imperial College, London, for decades. The bureaucracy at Harvard didn't hold him back. I saw him a few times over the years--in DC, the Copper Mountain reunion, and London--and he was always his fun, energetic, perceptive self, though I thought his gentle sense of humor became slightly more acerbic, in a good way. I'm so glad he finally got married. The last few times I talked with him he sounded extremely happy.
Stephen
Thank you, Lynette for this information. I am very sad. Kelly was a close friend of mine. I have a lot of good memories and funny stories about Kelly, including how I discovered in Mr. Stock's French class through surreptitious Morse code messages with Kelly that his mother and my mother were freshman college roommates. Kelly and I were both in Gary Abrecht's boy scout patrol in troupe Gottard. Because of his erudition and energy on all hikes with the troupe he was given the scout name "Chamois scientifique." That was kind and deserved. Many names were not flattering. Mine was Raton loufoque. I had to look that one up and wasn't too pleased when I found it. Kelly left Ecolint to attend Philips Andover Academy. He then went to Harvard. At Harvard he wanted to major in physics but also take Russian and Italian. The physics department said he couldn't do that because at Harvard the physics curriculum was prescribed and there was no space for Russian and Italian. So Kelly majored in the "History of Science," took the entire physics curriculum and also Russian and Italian. In his senior year he applied to the Harvard Ph.D program in physics. They turned him down, saying they only accepted physics majors. So Kelly went to Brandeis for his Ph.D and studied theoretical physics with Einstein's colleagues who had left Germany at the same time as Einstein. Kelly worked at CERN and was a professor at Imperial College, London, for decades. The bureaucracy at Harvard didn't hold him back. I saw him a few times over the years--in DC, the Copper Mountain reunion, and London--and he was always his fun, energetic, perceptive self, though I thought his gentle sense of humor became slightly more acerbic, in a good way. I'm so glad he finally got married. The last few times I talked with him he sounded extremely happy.
Stephen
February 2, 2026
Kelly was.a true intellectual, a linguist as well as a scientist, (and one who also knew lots of good restaurants).
He leaves behind an impressive scientific legacy: in gravity, notably his first two papers which included curvature squared terms in the classical action, in quantum field theory, supersymmetry and in string theory.
It was a great pleasure to have had the opportunity to work with him on more than 20 papers.
He will be greatly missed.
He leaves behind an impressive scientific legacy: in gravity, notably his first two papers which included curvature squared terms in the classical action, in quantum field theory, supersymmetry and in string theory.
It was a great pleasure to have had the opportunity to work with him on more than 20 papers.
He will be greatly missed.
January 29, 2026
Kelly was a real intellectual, a linguist as well as a scientist, who also knew lots of great restaurants; my wife and I greatly appreciated some of his recommendations while on holiday in France.
He leaves a very impressive scientific legacy, mainly in quantum field theory, gravity (notably his first two papers), supersymmetry and string theory. It was a great pleasure to have worked with him on more than twenty papers. He will be greatly missed.
He leaves a very impressive scientific legacy, mainly in quantum field theory, gravity (notably his first two papers), supersymmetry and string theory. It was a great pleasure to have worked with him on more than twenty papers. He will be greatly missed.
January 25, 2026
Kelly was a wonderful person and an outstanding scientist. Already his
entree with his work on the renormalization of higher derivative gravity was a brilliant achievement. I had the privilege of knowing Kelly since the early 80ies (I still remember him in our kitchen in Thoiry more 40 years ago discussing physics, politics and the merits of good food!), thus being able to interact with him for a long time. I won't repeat here all the beautiful things previous contributors on this memorial website have already said about him, save to say that I can
fully confirm from my personal experience everything that has been said!
In spite of having known each other for so long, it took us almost
30 years to finally team up and collaborate (on the BPS structure of
stationary supergravity solutions, together with Guillaume Bossard).
This was when Kelly was awarded the Humboldt Prize which enabled him to spend extended periods of time at the Potsdam institute. During this time we had the pleasure of his continued presence, after which he remained a regular visitor so we continued to benefit from his wit and wisdom.
My condolences for this terrible loss go to his wife Marise and his family. I will retain shiny memories of Kelly, as a scientist and a human being.
January 21, 2026
It is with sadness that I only just found out of Kelly’s passing. 2025 represents the year I lost two fathers, my dad and my physics dad. I was Kelly’s graduate student, and lucky to be one. I learned a lot from Kelly. I remember the first problem he gave me; a gigantic calculation which he did not want to do - Kelly never liked to do large calculations as reflected by his many insightful papers. A couple of months later I came back with the result, and without looking at it, he told me I was wrong. I kept re-doing that calculation and each time, without looking, Kelly told me I was wrong, until one day I argued with him about why the result must be true, going back to the physics of the problem, not just the calculation. When I did that, I saw a glint in his eye and a smile on his face. He had been trying to teach me a great lesson, and the smile said it all. He was saying I had finally understood the lesson he was trying to teach me. I have followed his lessons my entire life and they have served me well. I didn’t say it in life, but thank you Kelly, for everything. Thank you for everything you taught me, first as my third year academic tutor, when I was an undergraduate and then as your graduate student. You were my physics father, and I am lucky to have had you as such.
January 21, 2026
I had the privilege of interacting with Kelly during my postdoctoral years at Imperial in 2001–2003. His brilliance and intellectual depth were profoundly inspiring, matched by a genuine love of life and an infectious curiosity about the world. Kelly was forever young at heart, completely down to earth, and always willing to engage with us the postdocs and PhD students, with no barriers whatsoever. Conversations with him could range effortlessly across physics and far beyond, and his shockingly perfect Russian never failed to impress. Interacting with Kelly remains one of the most lasting and cherished memories of my time at Imperial.
January 21, 2026
As a student on the QFFF, I fondly remember Kelly's stories that used to accompany the Standard Model and beyond course. It felt like we were there when the Standard Model was actually being developed!
Perhaps that is one of the reasons why I chose to be a TA for this course throughout my PhD. Even though he must have had extensive experience with the Rapid Feedback sessions, Kelly was always open and supportive whenever I came up with suggestions to change the format, the order of questions etc.
I also remember our tea time conversations, on physics and so much more
Perhaps that is one of the reasons why I chose to be a TA for this course throughout my PhD. Even though he must have had extensive experience with the Rapid Feedback sessions, Kelly was always open and supportive whenever I came up with suggestions to change the format, the order of questions etc.
I also remember our tea time conversations, on physics and so much more
January 20, 2026
I first heard of Kelly second hand through stories told by Chris Pope and Mike Duff, who were visitors to Texas when I was a graduate student in Austin. So he was already a legend when I first met him face to face (I think at CERN). My appreciation of his wit and wisdom grew as I came to know him better myself over the years. What sad news it was to hear he was taken from us so unexpectedly and in such sorrowful circumstances. A real prince among men.
January 1, 2026
Kelly was a unique colleague and friend that will be missed.
I attach several pictures of him from the RTN Meeting in Kolymbari Crete in 2004.
I attach several pictures of him from the RTN Meeting in Kolymbari Crete in 2004.
January 1, 2026
Kelly and I met in October 2014, in the German language class run by Imperial College. This encounter would change my life. We soon started to have dinners at the nearby Italian restaurant ‘Da Mario’ after class. These dinners merged into cultural outings; our first trip abroad materialized within a few months.
From the beginning, I was attracted to Kelly’s curiosity and his unusually open mind. I never fell out of love with his habit of suddenly brightening and sharing an anecdote about a distant time or place.
It didn’t matter to Kelly if he had already been someplace or seen a particular movie. Sharing an experience with me added a whole new dimension for him, and he took pleasure in showing me the most interesting places he had discovered around the world.
Kelly took a genuine interest in my PhD work. Towards the end of my time at Imperial, he even proposed a collaboration on the application of the renormalization group to the path integrals I had been studying.
What I valued most in my relationship with Kelly was his never-ending love and kindness. Whenever I had difficult emotions to work through, Kelly would hold me – literally and figuratively. He would cook for me or glue my broken watch strap back together.
Kelly and I married in Sicily, on the 14th of September 2025. Our wedding ceremony was one of the most beautiful moments of my life. I will never forget the way Kelly smiled and thanked me quietly after I concluded my wedding speech. Even though we were husband and wife, Kelly maintained that first and foremost, we were friends. Friendship was the essence of any of Kelly’s relationships.
A new year has just begun. While my grief will take a long time to process, I will take Kelly with me wherever I go. I love you, my best friend.
From the beginning, I was attracted to Kelly’s curiosity and his unusually open mind. I never fell out of love with his habit of suddenly brightening and sharing an anecdote about a distant time or place.
It didn’t matter to Kelly if he had already been someplace or seen a particular movie. Sharing an experience with me added a whole new dimension for him, and he took pleasure in showing me the most interesting places he had discovered around the world.
Kelly took a genuine interest in my PhD work. Towards the end of my time at Imperial, he even proposed a collaboration on the application of the renormalization group to the path integrals I had been studying.
What I valued most in my relationship with Kelly was his never-ending love and kindness. Whenever I had difficult emotions to work through, Kelly would hold me – literally and figuratively. He would cook for me or glue my broken watch strap back together.
Kelly and I married in Sicily, on the 14th of September 2025. Our wedding ceremony was one of the most beautiful moments of my life. I will never forget the way Kelly smiled and thanked me quietly after I concluded my wedding speech. Even though we were husband and wife, Kelly maintained that first and foremost, we were friends. Friendship was the essence of any of Kelly’s relationships.
A new year has just begun. While my grief will take a long time to process, I will take Kelly with me wherever I go. I love you, my best friend.
December 29, 2025
I met Kelly Stelle in Cambridge, Massachusetts in November of 1968. There are few people I have known longer. Although we travelled different directions in life, this remarkable friend remained in touch throughout the decades. Whenever I had the good fortune to see Kelly — In Washington, D.C., in London, in Paris, in Spain, each time in widely differing circumstances, I was struck anew by his kindness and consideration. The tributes of his colleagues and former students testify to the unflagging concern for others that made Kelly a kind of constant north star for each of his friends.
My own memories of his generous kindness include the afternoon he sat with my octogenarian father, an ex-Navy pilot later involved in developing a new kind of cockpit display. Kelly gave my dad his full attention for a good part of the afternoon, asking insightful and somewhat technical questions that roused enthusiasm I had not seen for a long time. One summer day on the Cantabrian coast, Kelly’s conversation with local fisherman on the methods of collecting gooseneck barnacles enhanced the moment and pleased the fishermen so much that they gifted us two kilos of the precious harvest. Kelly cheered us on at significant moments. When our twin daughters were born in Paris he arrived within days to pay his compliments. Thirty years later, when one of these daughters married, he — and Marise — were in attendance. Kelly’s interest, his presence or his recognition of key events in our lives has enriched us. We, like so many others, have been the beneficiaries of his steadfast, genuine consideration and support. We will miss him but are eternally grateful to have known him.
My own memories of his generous kindness include the afternoon he sat with my octogenarian father, an ex-Navy pilot later involved in developing a new kind of cockpit display. Kelly gave my dad his full attention for a good part of the afternoon, asking insightful and somewhat technical questions that roused enthusiasm I had not seen for a long time. One summer day on the Cantabrian coast, Kelly’s conversation with local fisherman on the methods of collecting gooseneck barnacles enhanced the moment and pleased the fishermen so much that they gifted us two kilos of the precious harvest. Kelly cheered us on at significant moments. When our twin daughters were born in Paris he arrived within days to pay his compliments. Thirty years later, when one of these daughters married, he — and Marise — were in attendance. Kelly’s interest, his presence or his recognition of key events in our lives has enriched us. We, like so many others, have been the beneficiaries of his steadfast, genuine consideration and support. We will miss him but are eternally grateful to have known him.
December 29, 2025
My farewell to Kelly at the funeral:
Dear Kelly, Your festivity in Catania was very nice. We were all happy when we left you. Now we remember this festivity together with so many nice moments that we had together. Despite what happened, I will never forget these nice moments with you in my life.
In conferences, I was always looking for you; for a chat in the coffee break and for arranging to have dinner together.
You knew so many things, and you could tell them in a beautiful way: with some humour. Not the humour that we all started to laugh loudly, but a humour that made you think. Your sentences kept me happy for several days.
I enjoyed the dinners with you, and we did also many other things together. We were in the mountains together, as you also enjoyed the walking in nature: in the Alps, in Benasque in the Pyrenees, cross-country skiing in the Jura, and even walking in the sea in the Netherlands.
You were a physicist in your way of thinking. I was often struck how you described the 'ordinary life' with physics concepts. When I had to make a decision for yes or no, you said " put yourself in an eigenstate". When money was flowing easily you said " living at very low Reynolds number" (which means the flow is smooth). You wanted to be "disentangled from heads of groups meetings".
You became a key figure in our European string community. You cared that your institute always made part of the European collaborations, and you were always there to help the community. That community was important for European high-energy physics. But that community is also a group of friends, in which you will be missed.
I liked to find you always when possible, and you seemed also to be happy to meet me. Indeed, each time you passed through Belgium, you took contact with me to meet. We were good friends. We had also nice moments together with Marise and my partner, Laura. I wish Marise that she will continue her life being happy with all these special memories.
Oh, Kelly, I will miss you a lot in the next years, but in my mind your beautiful voice will remain.
Dear Kelly, Your festivity in Catania was very nice. We were all happy when we left you. Now we remember this festivity together with so many nice moments that we had together. Despite what happened, I will never forget these nice moments with you in my life.
In conferences, I was always looking for you; for a chat in the coffee break and for arranging to have dinner together.
You knew so many things, and you could tell them in a beautiful way: with some humour. Not the humour that we all started to laugh loudly, but a humour that made you think. Your sentences kept me happy for several days.
I enjoyed the dinners with you, and we did also many other things together. We were in the mountains together, as you also enjoyed the walking in nature: in the Alps, in Benasque in the Pyrenees, cross-country skiing in the Jura, and even walking in the sea in the Netherlands.
You were a physicist in your way of thinking. I was often struck how you described the 'ordinary life' with physics concepts. When I had to make a decision for yes or no, you said " put yourself in an eigenstate". When money was flowing easily you said " living at very low Reynolds number" (which means the flow is smooth). You wanted to be "disentangled from heads of groups meetings".
You became a key figure in our European string community. You cared that your institute always made part of the European collaborations, and you were always there to help the community. That community was important for European high-energy physics. But that community is also a group of friends, in which you will be missed.
I liked to find you always when possible, and you seemed also to be happy to meet me. Indeed, each time you passed through Belgium, you took contact with me to meet. We were good friends. We had also nice moments together with Marise and my partner, Laura. I wish Marise that she will continue her life being happy with all these special memories.
Oh, Kelly, I will miss you a lot in the next years, but in my mind your beautiful voice will remain.
December 23, 2025
My recollections of Kelly Stelle
The unexpected and untimely death of Kelly Stelle became a shock for all his friends andcolleagues. It is still difficult for me to realize that we will never meet again on the earth. We were on friendly terms with Kelly for approximately 40 years and I would like to present below some memories about my distinguished friend.
For the first time we came across in the middle of eighties, at the Winter School in Karpach (Poland) organized by Jurek Lukierski, though maybe I listened to his talks on auxiliary fields in
N=1 supergravity earlier, at some conferences in Moscow, not being yet personally acquainted with him. Besides his great knowledge in the most urgent problems of gravity and supergarvity, I was very surprised by Kelly’s fluent Russian in which we preferred to talk in view of my rather pure practice in the spoken English that time. We discussed not only the science, but also politics and especially the so-called “perestroika” which started in USSR approximately in
those years. It proved that our views of all that were rather close. I also remember that he was very interested in the history of inventing the harmonic superspace approach which was one of
the subjects of my lectures and which he frankly admired. Once we with him and Dima Sorokin decided to climb the highest summit of the Krkonoshe Mountains nearby Karpach, “Snezhka”
(“Snow Mountain”). It was situated just near the board of Poland and Czechia and the guard on the board carefully checked our passports, that caused a few ironical comments from Kelly’s
side (I should say that he disliked all these officials, especially the military ones). Anyway, we have crossed the board and successfully on the pick which rose approximately 1000 metres above Karpach. Dima Sorokin was a former mountaineer and of course seriously passed ahead us with Kelly, though we tried to do our best to keep pace of him. Finally, we drunk cups of coffee in the bar on the tip and just looked on the very steep wall by which the mountain
descended to the Czechian side. On the way back we passed by some yard with a big hound barking rather ferociously. Kelly told us that he knew how to make it quiet: he squatted and moved some distance along the fence, leaning on the hands and barking a way quite similar to the dog which was highly surprised by such a strange behavior of the human being and stopped any threats in our address.
Later on, Kelly frequently visited our Laboratory in Dubna and closely contacted our supersymmetry group consisting then of Victor Isaakovich Ogievetsky, Sasha Galperin, Emery
Sokatchev, me and some other colleagues. He was a permanent member of the Advisory Committee of our biennial workshops “Supersymmetries and Quantum Symmetries”. All bad events
of twenties did not influence this his membership, though hampered his further visits to Russia (it became impossible to prolong his Russian long-term visa which was few times arranged
for him by International Department of JINR). When he was in Dubna, our meetings and discussions were not restricted solely to science, and our friendly human contacts were rather extensive. Once I invited him to my modest apartment where I was living with my first wife Svetlana and the two-year old son Dmitry. My son was very impressed by Kelly and frequently asked me later, after Kelly has departed, when we will meet him again. Kelly taught him the first English lesson: he stretched out the open palm and said “give me five!”. And Dmitry gave.
Much later, in 1997, we with my second wife Larissa arranged a party in our new appartment for some participants of the SQS meeting dedicated to the memory of V.I. Ogievetsky who
passed away in 1996. Kelly was among the guests and I was very glad to welcome him in our place. So Kelly visited two my apartments in Dubna and was well acquainted with my both
wives.
Apart from Dubna, we met many times at various scientific events in CERN, Alushta, Moscow, Yerevan and Tomsk. Last time I met him seemingly in the end of tenths at the workshop in Tomsk organized by Ioseph Buchbinder. I also listened to his on-line talk at the
Conference in Steklov Institute dedicated to memory of Andrey Slavnov. It happened just two years ago.
One more bright reminiscence of Kelly is related to my three-month visit to CERN in 1987. Once Kelly said me that he is going to visit his fomer teacher of French in Martigny and invited
me to join him. It was a very exciting trip by Kelly’s car with looking at the Saint- Bernard pass, Mont-Blanc and all that. We spent two days in Martigny and I took part in preparing some alcohole from the local grapes, using a special manual wine-press. It was a rather hard work of us both and Kelly encouraged me by exclamations “Keep turning!” or something like that. The owner awarded me two bottles of nice local wine.
To make more clear the attitude of Kelly to our country and to his Dubna friends, I attach reference to his interesting contribution to the remembrance site of Victor Isaakovich Ogievetsky whom Kelly respected very high.
http : //theor.jinr.ru/people/Ogievetsky/Appreciation−Stelle.pdf
Dear Kelly, Rest In Peace! We will remember you always.
Evgeny Ivanov (Dubna)
2
The unexpected and untimely death of Kelly Stelle became a shock for all his friends andcolleagues. It is still difficult for me to realize that we will never meet again on the earth. We were on friendly terms with Kelly for approximately 40 years and I would like to present below some memories about my distinguished friend.
For the first time we came across in the middle of eighties, at the Winter School in Karpach (Poland) organized by Jurek Lukierski, though maybe I listened to his talks on auxiliary fields in
N=1 supergravity earlier, at some conferences in Moscow, not being yet personally acquainted with him. Besides his great knowledge in the most urgent problems of gravity and supergarvity, I was very surprised by Kelly’s fluent Russian in which we preferred to talk in view of my rather pure practice in the spoken English that time. We discussed not only the science, but also politics and especially the so-called “perestroika” which started in USSR approximately in
those years. It proved that our views of all that were rather close. I also remember that he was very interested in the history of inventing the harmonic superspace approach which was one of
the subjects of my lectures and which he frankly admired. Once we with him and Dima Sorokin decided to climb the highest summit of the Krkonoshe Mountains nearby Karpach, “Snezhka”
(“Snow Mountain”). It was situated just near the board of Poland and Czechia and the guard on the board carefully checked our passports, that caused a few ironical comments from Kelly’s
side (I should say that he disliked all these officials, especially the military ones). Anyway, we have crossed the board and successfully on the pick which rose approximately 1000 metres above Karpach. Dima Sorokin was a former mountaineer and of course seriously passed ahead us with Kelly, though we tried to do our best to keep pace of him. Finally, we drunk cups of coffee in the bar on the tip and just looked on the very steep wall by which the mountain
descended to the Czechian side. On the way back we passed by some yard with a big hound barking rather ferociously. Kelly told us that he knew how to make it quiet: he squatted and moved some distance along the fence, leaning on the hands and barking a way quite similar to the dog which was highly surprised by such a strange behavior of the human being and stopped any threats in our address.
Later on, Kelly frequently visited our Laboratory in Dubna and closely contacted our supersymmetry group consisting then of Victor Isaakovich Ogievetsky, Sasha Galperin, Emery
Sokatchev, me and some other colleagues. He was a permanent member of the Advisory Committee of our biennial workshops “Supersymmetries and Quantum Symmetries”. All bad events
of twenties did not influence this his membership, though hampered his further visits to Russia (it became impossible to prolong his Russian long-term visa which was few times arranged
for him by International Department of JINR). When he was in Dubna, our meetings and discussions were not restricted solely to science, and our friendly human contacts were rather extensive. Once I invited him to my modest apartment where I was living with my first wife Svetlana and the two-year old son Dmitry. My son was very impressed by Kelly and frequently asked me later, after Kelly has departed, when we will meet him again. Kelly taught him the first English lesson: he stretched out the open palm and said “give me five!”. And Dmitry gave.
Much later, in 1997, we with my second wife Larissa arranged a party in our new appartment for some participants of the SQS meeting dedicated to the memory of V.I. Ogievetsky who
passed away in 1996. Kelly was among the guests and I was very glad to welcome him in our place. So Kelly visited two my apartments in Dubna and was well acquainted with my both
wives.
Apart from Dubna, we met many times at various scientific events in CERN, Alushta, Moscow, Yerevan and Tomsk. Last time I met him seemingly in the end of tenths at the workshop in Tomsk organized by Ioseph Buchbinder. I also listened to his on-line talk at the
Conference in Steklov Institute dedicated to memory of Andrey Slavnov. It happened just two years ago.
One more bright reminiscence of Kelly is related to my three-month visit to CERN in 1987. Once Kelly said me that he is going to visit his fomer teacher of French in Martigny and invited
me to join him. It was a very exciting trip by Kelly’s car with looking at the Saint- Bernard pass, Mont-Blanc and all that. We spent two days in Martigny and I took part in preparing some alcohole from the local grapes, using a special manual wine-press. It was a rather hard work of us both and Kelly encouraged me by exclamations “Keep turning!” or something like that. The owner awarded me two bottles of nice local wine.
To make more clear the attitude of Kelly to our country and to his Dubna friends, I attach reference to his interesting contribution to the remembrance site of Victor Isaakovich Ogievetsky whom Kelly respected very high.
http : //theor.jinr.ru/people/Ogievetsky/Appreciation−Stelle.pdf
Dear Kelly, Rest In Peace! We will remember you always.
Evgeny Ivanov (Dubna)
2
December 16, 2025
Kelly was heading the theory group during my post-doctoral years at Imperial and I have only good memories from those times, thanks to him.
On a regular basis, quite late in the evenings, or early at night, Kelly was popping in the post-docs office asking us to stop working and inviting all of us for dinner. Group cohesion, social interactions, new science ideas were actually made there.
Thank you for those times Kelly, and have a nice trip into the 11 dimensions!
With sadness,
Chris.
On a regular basis, quite late in the evenings, or early at night, Kelly was popping in the post-docs office asking us to stop working and inviting all of us for dinner. Group cohesion, social interactions, new science ideas were actually made there.
Thank you for those times Kelly, and have a nice trip into the 11 dimensions!
With sadness,
Chris.
December 11, 2025
I met Kelly in 1983–84, and he was a co-author on my first two papers, together with Paul Howe. It is very hard to accept that there will be no more opportunities to talk with him, to go for a meal in town, or to hike together to an alpine hut, a park, or a forest.
He will be remembered for his scientific contributions—which influenced my own work—his infectious love of life, and the wonderful company he always was.
Rest in peace, Kelly. You are greatly missed.
He will be remembered for his scientific contributions—which influenced my own work—his infectious love of life, and the wonderful company he always was.
Rest in peace, Kelly. You are greatly missed.
December 11, 2025
I was deeply saddened to hear about the passing of the gracious and very kind person Kelly Stelle was. I was in the QFFF MSc program in 2011-2012 which he led and ever since he stood by me in my struggles and successes. He always had a kind word for me at the Holidays and was a mentor for me from the distance, ready to help, ready to come up with an illuminating idea. I will never forget his brilliance and his kindness. May he rest in peace!
December 7, 2025
I was deeply shocked and saddened by Kelly's passing. My heart goes out to all who held him dear.
Kelly was my PhD advisor and I am forever infinitely grateful for that.
When I think of him, I immediately think of the German word "Doktorvater", meaning doctoral father, as it signifies much better the close, mentor-like, and even familial relationship we had. Kelly was way more than a supervisor to me. He was a caring mentor, a wise counselor and most importantly, a very good friend!
My journey with Kelly began in the autumn of 2004. I came to Imperial as an ERASMUS undergrad exchange student and I took part in the Master's course. Kelly gave the course on string theory and I was particularly interested in it. Together with two other students, I would often ask questions after the end of his lecture and in his distinctive and characteristically sharp-witted manner, he soon devised a nickname for us: he called us "the three usual suspects". I did not do too bad in the end of year exams and Kelly asked me if I wanted to become his next PhD student. I did not have to think twice.
Through many conferences, schools, and workshops that Kelly generously supported me to attend, along with countless meetings in his Huxley office, we had the opportunity to truly get to know one another. I soon discovered that our biorhythms were remarkably in tune -- neither of us ever quite mastered the art of the early morning. By the end of my first year as a PhD student in 2006, he had converted me into an 'Apple guy.' I cherish the many afternoons spent in his office, immersed in physics discussions that often found their way to "Da Mario's," his favorite restaurant near Imperial. As a non-native speaker with a deep affection for the English language, I was continually fascinated by his extensive vocabulary and, as Chris Pope aptly described, his "memorable folksy expressions."
Honored with a Humboldt Research Award, he spent a sabbatical year at the AEI in Potsdam from 2007 to 2008. As a thoughtful advisor, he recognized the importance of this critical phase in my PhD journey and arranged for me to join him as a visiting student in Potsdam. During that time we spent many hours almost every workday trying to calculate the fermionic part of a supergravity dimensional reduction, including the four-fermi terms -- a painful but very insightful exercise. Oftentimes the day ended in one of Potsdam's restaurants. There were moments when I struggled, and he was always there -- offering unwavering support and deep understanding.
A memorable event was the "Kellyfest" in 2008, celebrating his 60th birthday. While it's customary to name such events after a professor's surname -- like Duff-Fest or Gibbons-Fest -- using his first name was a unique tribute that perfectly captures how beloved Kelly was within the theoretical physics community.
Having completed my PhD and a year-long postdoctoral fellowship, I left London in 2010. Yet, our paths continued to cross e.g. at conferences and workshops. Years later, we met again at the AEI in Potsdam during the summer of 2014, coinciding with the soccer World Cup. I found myself watching the World Cup final with Kelly and my girlfriend in a lively bar downtown -- naturally, he chose the spot. Surrounded by enthusiastic German soccer fans, we shared a truly memorable evening.
To Kelly: Thank you for all your support, guidance, encouragement, inspiration, time, as well as the countless enjoyable meetings and conversations. I miss you.
While we mourn Kelly's passing, his legacy endures in the profound contributions to theoretical physics and in the lives he touched. Farewell, dear friend -- your light remains with us.
Kelly was my PhD advisor and I am forever infinitely grateful for that.
When I think of him, I immediately think of the German word "Doktorvater", meaning doctoral father, as it signifies much better the close, mentor-like, and even familial relationship we had. Kelly was way more than a supervisor to me. He was a caring mentor, a wise counselor and most importantly, a very good friend!
My journey with Kelly began in the autumn of 2004. I came to Imperial as an ERASMUS undergrad exchange student and I took part in the Master's course. Kelly gave the course on string theory and I was particularly interested in it. Together with two other students, I would often ask questions after the end of his lecture and in his distinctive and characteristically sharp-witted manner, he soon devised a nickname for us: he called us "the three usual suspects". I did not do too bad in the end of year exams and Kelly asked me if I wanted to become his next PhD student. I did not have to think twice.
Through many conferences, schools, and workshops that Kelly generously supported me to attend, along with countless meetings in his Huxley office, we had the opportunity to truly get to know one another. I soon discovered that our biorhythms were remarkably in tune -- neither of us ever quite mastered the art of the early morning. By the end of my first year as a PhD student in 2006, he had converted me into an 'Apple guy.' I cherish the many afternoons spent in his office, immersed in physics discussions that often found their way to "Da Mario's," his favorite restaurant near Imperial. As a non-native speaker with a deep affection for the English language, I was continually fascinated by his extensive vocabulary and, as Chris Pope aptly described, his "memorable folksy expressions."
Honored with a Humboldt Research Award, he spent a sabbatical year at the AEI in Potsdam from 2007 to 2008. As a thoughtful advisor, he recognized the importance of this critical phase in my PhD journey and arranged for me to join him as a visiting student in Potsdam. During that time we spent many hours almost every workday trying to calculate the fermionic part of a supergravity dimensional reduction, including the four-fermi terms -- a painful but very insightful exercise. Oftentimes the day ended in one of Potsdam's restaurants. There were moments when I struggled, and he was always there -- offering unwavering support and deep understanding.
A memorable event was the "Kellyfest" in 2008, celebrating his 60th birthday. While it's customary to name such events after a professor's surname -- like Duff-Fest or Gibbons-Fest -- using his first name was a unique tribute that perfectly captures how beloved Kelly was within the theoretical physics community.
Having completed my PhD and a year-long postdoctoral fellowship, I left London in 2010. Yet, our paths continued to cross e.g. at conferences and workshops. Years later, we met again at the AEI in Potsdam during the summer of 2014, coinciding with the soccer World Cup. I found myself watching the World Cup final with Kelly and my girlfriend in a lively bar downtown -- naturally, he chose the spot. Surrounded by enthusiastic German soccer fans, we shared a truly memorable evening.
To Kelly: Thank you for all your support, guidance, encouragement, inspiration, time, as well as the countless enjoyable meetings and conversations. I miss you.
While we mourn Kelly's passing, his legacy endures in the profound contributions to theoretical physics and in the lives he touched. Farewell, dear friend -- your light remains with us.
December 7, 2025
I first met Kelly in 1982, when he visited Moscow. At the time I was a graduate student, but I had already read all of his papers on quantum gravity and supergravity, so we had several discussions, in both English and Russian. Kelly also gave a talk on the finiteness of N=4 SYM at a conference on Group Theoretical Methods in Physics held in Zvenigorod, near Moscow. He came to Moscow again in 1987 to participate in Quantum Gravity conference giving a talk about his work on quantum supermemberanes.
We met also in 1989, when I came to London as a visitor at King’s College. Later, in 1991, when I was a visiting fellow at Trinity College, Cambridge, Kelly hinted that he would not mind being invited to one of Trinity’s formal dinners. As I had the privilege of inviting a guest, Kelly drove up from London, bringing his black tie dress with him, and looked completely at home among the dons.
Kelly was a one of the main reasons I eventually came to Imperial College as a lecturer in the fall of 1992. We were then colleagues for 33 years, with many discussions on both physics and politics. One unusual memory I have of Kelly is his reaction to having his Audi stolen while he was visiting Berlin in the late 1990s: “I just need to get a new one—this is what a checking account is for.” Another is from 2008, during his 60th birthday conference, when we organized a football match in Hyde Park and Kelly volunteered to referee. He was a gentle one—running from one end of the pitch to the other, but hardly interfering with the game.
It is hard to come to grips with the fact that Kelly is no longer with us. Although we did not collaborate directly, I continue to use and cite his papers, so in that sense, through his work, he is still very much alive for me.
We met also in 1989, when I came to London as a visitor at King’s College. Later, in 1991, when I was a visiting fellow at Trinity College, Cambridge, Kelly hinted that he would not mind being invited to one of Trinity’s formal dinners. As I had the privilege of inviting a guest, Kelly drove up from London, bringing his black tie dress with him, and looked completely at home among the dons.
Kelly was a one of the main reasons I eventually came to Imperial College as a lecturer in the fall of 1992. We were then colleagues for 33 years, with many discussions on both physics and politics. One unusual memory I have of Kelly is his reaction to having his Audi stolen while he was visiting Berlin in the late 1990s: “I just need to get a new one—this is what a checking account is for.” Another is from 2008, during his 60th birthday conference, when we organized a football match in Hyde Park and Kelly volunteered to referee. He was a gentle one—running from one end of the pitch to the other, but hardly interfering with the game.
It is hard to come to grips with the fact that Kelly is no longer with us. Although we did not collaborate directly, I continue to use and cite his papers, so in that sense, through his work, he is still very much alive for me.
December 6, 2025
I first met Kelly in the common room of the Isaac Newton Institute in Cambridge, in the summer of 1994. In the course of the chat we had, he fatefully suggested I speak to Chris Hull, who happened to be scribbling on a blackboard across the room; Chris later supervised my PhD in London. Over the next 30 years or so, Kelly and I met regularly at seminars, conferences, or in his office at Imperial College, when I was a research fellow in the Theory Group. He had started leading the group a few months after I arrived, taking over from Chris Isham. There were always many friendly arguments -- over physics, Middle East politics, for which we shared a keen interest, or the choice of restaurant. One day in Paris, Kelly suggested I join a party consisting of much more senior physicists for lunch: he had booked a table at the Tour d'Argent, a venerable institution dating back to 1582 and specialising in a dish which I don't eat, "canard au sang", duck cooked in its own blood. Each duck served there since 1582 has a number; if I remember correctly, the king of France, Henri IV, ate duck number 1. Each guest receives a certificate with the number of her duck, except me I guess (I ate fish that day). Also, the restaurant has one of the most extensive wine list in Paris, which Kelly discussed at length with the sommelier, a very elegant man in a bow tie, before ordering a number of very expensive bottles. I don't drink wine, and I was exempted from contributing to the sommelier's separate bill, so this is not something Kelly and I argued about. Still, it was a memorable lunch in many ways for me, and it would never have happened without Kelly. I was very saddened when Graziela called to inform me that Kelly fell ill in my hometown of Alexandria, and later passed away there. We had many discussions about Egypt over the years; he had visited my country of birth several times I believe, and he was always curious and interested. It's not easy to accept that Kelly will not be organising a dinner on my next visit to London, and that we will not be arguing about the venue.
December 3, 2025
Kelly and I first met at Brandeis in 1972, as fellow grad students in the same cohort. The more I try to remember about my times with Kelly the more I do remember; so many things that the space here is insufficient. The period in which we spent most time together was when we both moved from CERN to the Ecole Normale Superieure in Paris in 1980. I was there for two years but Kelly came for six months. He had trouble finding an apartment for that length of time and the one he eventually took came with a feature that he had not previously encountered: a toilet with a ``broyeur'', which is best left untranslated. I had taken my VW Golf with its Swiss number plates to Paris and I was obliged, in principle, to change the plates to French ones. I had to go to some police station to do this and Kelly came along to help me, but when he realised that I was going to be charged a huge fee he dragged me out of the office. So I kept my Swiss plates and was occasionally regaled by angry Parisian drivers with ``Vous n'etes pas en Suisse maintenant! I had no idea that the Swiss were such bad drivers. Kelly and I often ate out together; sometimes at places recommended by John Iliopoulos, and other times at places that did not meet John's high standards. The chateaubriand at La Coupole was a favourite of Kelly, before he changed his diet to one of mussels and more mussels. In March of 1981 we had our birthdays a week apart; it was my 30th and Kelly's 33rd and we decided to celebrate together by having lunch at the Taillevent, a 3 star Michelin restaurant, and then a walk up the Eiffel tower. This was towards the end of Kelly's stay in Paris, and we were also celebrating the completion of our first paper together as a duo. Kelly had spent his time wondering what we would find if we were to do such and such a calculation while I was usually wondering how to do it; fortunately, this combination of approaches turned out to be suitable for the problem we had set ourselves.
I have many memories of travelling somewhere with Kelly in his various cars. I recounted a couple of these car anecdotes at his wedding. Another was a trip, to Italy I think, but of course we had to stop at a famous chateau to try the wine; Montrachet I think it was. There was a wine tasting going on in the cellar, with the appropriate utensil for sipping and a bucket for spitting it out. I thought that it was a shame not to drink it; it didn't seem like much but of course it all adds up. Kelly abstained entirely because he was driving, but he bought himself a case to imbibe later. On some similar occasion but with other companions, Kelly bought a case of a Margaux with the name``Le Baron de Brane'' and he gave me one of the bottles. I put the label on my office door in Cambridge for several years and now I have it on the door of my study at home as a reminder of Kelly.
Memories are notoriously unreliable, but they are what we have. In his autobiography ``Mon dernier soupir'' the film director Luis Bunuel writes ``You have to begin to lose your memory, if only in bits and pieces, to realise that memory is what makes our lives. Without it we are nothing.'' The more you think about it, and maybe the longer you live, the more you see how true that is. Kelly is no longer with us but our memories of him are part of what we are while we still live.
I have many memories of travelling somewhere with Kelly in his various cars. I recounted a couple of these car anecdotes at his wedding. Another was a trip, to Italy I think, but of course we had to stop at a famous chateau to try the wine; Montrachet I think it was. There was a wine tasting going on in the cellar, with the appropriate utensil for sipping and a bucket for spitting it out. I thought that it was a shame not to drink it; it didn't seem like much but of course it all adds up. Kelly abstained entirely because he was driving, but he bought himself a case to imbibe later. On some similar occasion but with other companions, Kelly bought a case of a Margaux with the name``Le Baron de Brane'' and he gave me one of the bottles. I put the label on my office door in Cambridge for several years and now I have it on the door of my study at home as a reminder of Kelly.
Memories are notoriously unreliable, but they are what we have. In his autobiography ``Mon dernier soupir'' the film director Luis Bunuel writes ``You have to begin to lose your memory, if only in bits and pieces, to realise that memory is what makes our lives. Without it we are nothing.'' The more you think about it, and maybe the longer you live, the more you see how true that is. Kelly is no longer with us but our memories of him are part of what we are while we still live.
December 2, 2025
I’d been avoiding writing this message, as it is too emotional.
I may not have known Kelly as long as Mike Duff and Chris Hull, but still—36 years for me!
Kelly sometimes made me a bit angry with his late or early calls when he wanted to spend some money on his college accounts or ask for a purchase order. How I wish he would still do that.
Three months into my contract here, I was about to hand in my notice when I decided to talk to Kelly and share my doubts about whether to take another job I had been offered. After a long dinner and chatting away he successfully convinced me not to resign. Only 36 years have passed, and I am still working for Imperial.
We both usually worked late. For me, it was often reassuring to be in College at, say, 8 p.m. and to know that he was still in his office next to mine.
I fondly remember the 1990s, when I mingled more with the students, as we were roughly the same age. Many times we would go out—not dining, but dancing in South American clubs. Kelly would always be the first to say yes to the adventure of dancing salsa, samba, or lambada.
It has truly been a pleasure to have worked with Kelly and to have had him as a friend.
I sincerely miss him now and will miss him for many years to come.
Bless his soul.
I may not have known Kelly as long as Mike Duff and Chris Hull, but still—36 years for me!
Kelly sometimes made me a bit angry with his late or early calls when he wanted to spend some money on his college accounts or ask for a purchase order. How I wish he would still do that.
Three months into my contract here, I was about to hand in my notice when I decided to talk to Kelly and share my doubts about whether to take another job I had been offered. After a long dinner and chatting away he successfully convinced me not to resign. Only 36 years have passed, and I am still working for Imperial.
We both usually worked late. For me, it was often reassuring to be in College at, say, 8 p.m. and to know that he was still in his office next to mine.
I fondly remember the 1990s, when I mingled more with the students, as we were roughly the same age. Many times we would go out—not dining, but dancing in South American clubs. Kelly would always be the first to say yes to the adventure of dancing salsa, samba, or lambada.
It has truly been a pleasure to have worked with Kelly and to have had him as a friend.
I sincerely miss him now and will miss him for many years to come.
Bless his soul.
November 30, 2025
I met Kelly when I arrived at the Max Planck Institute in Potsdam. I was extremely fortunate that he happened to be on sabbatical there just as I was starting my postdoc. He immediately suggested that we work together on non-renormalisation theorems in supergravity. My scientific life would have been very different if he hadn’t. I will be eternally grateful to him for that.
Almost every other day, we would spend the entire afternoon working together until quite late, and then go out to find a restaurant for dinner. He taught me an enormous amount of physics during the day, and in the evening he would share his knowledge of American politics and countless other topics. He was full of stories—among them the time he ran naked through the Antarctic snow from the sauna back to the station.
He was not only a collaborator, but also a friend. I will miss him deeply.
Almost every other day, we would spend the entire afternoon working together until quite late, and then go out to find a restaurant for dinner. He taught me an enormous amount of physics during the day, and in the evening he would share his knowledge of American politics and countless other topics. He was full of stories—among them the time he ran naked through the Antarctic snow from the sauna back to the station.
He was not only a collaborator, but also a friend. I will miss him deeply.
November 29, 2025
He was my tutor during the MSc. He was so supportive, I don’t know if I would have made it without him. Such great teacher and person!
November 26, 2025
This is a very sad loss.
Kelly was a great lecturer, who inspired me when I spent a year as an exchange student at Imperial College and learnt the basics of string theory from him. Later, he became a much-valued discussion partner, when he challenged (always in a very friendly manner) my ideas on quantum gravity, while I was a postdoc at Imperial College. We continued to discuss, whenever we met at conferences, and I always came away from these discussions with a new perspective or question to think about.
Kelly will be much missed!
Kelly was a great lecturer, who inspired me when I spent a year as an exchange student at Imperial College and learnt the basics of string theory from him. Later, he became a much-valued discussion partner, when he challenged (always in a very friendly manner) my ideas on quantum gravity, while I was a postdoc at Imperial College. We continued to discuss, whenever we met at conferences, and I always came away from these discussions with a new perspective or question to think about.
Kelly will be much missed!
November 25, 2025
This terrible news has deeply saddened me. I first met Kelly when I was an undergraduate at IC. He taught the group theory course...and it brilliant but tough! With his generous help, things finally came to make sense, and I finished up doing my PhD in the theory group at IC. Though not his student, Kelly was always very supportive and friendly. Over the years we often met up in different places around Europe, sharing wonderful dinners and conversations…and wines. He will be greatly missed.
November 23, 2025
I always associated Kelly with Phileas Fogg, one of my childhood heroes. He obviously loved traveling around the world and had so many fascinating stories about far-out places.
Funny enough, our first encounter was in the Royal Geographical Society, on Kensington Gore near Imperial, where Kelly had invited me for a talk in the 1996 annual meeting of Toine Van Proyen's European Network. We met many times thereafter in not-so-exotic places: At Ecole Normale (where Kelly was a frequent visitor), in Crete, and of course at Imperial where his door was always open for any visitor willing to chat about any subject: physics, politics, cuisine.. .
In recent years Kelly got interested in the question of gravity localisation, and we had numerous discussions and arguments. In all our encounters Kelly was his usual self: courteous, passionate, good-spirited, generous. It is ironic but bitterly fitting that he passed away while traveling in a distant land, the one where civilisation began. Like all his friends, I will miss him.
Funny enough, our first encounter was in the Royal Geographical Society, on Kensington Gore near Imperial, where Kelly had invited me for a talk in the 1996 annual meeting of Toine Van Proyen's European Network. We met many times thereafter in not-so-exotic places: At Ecole Normale (where Kelly was a frequent visitor), in Crete, and of course at Imperial where his door was always open for any visitor willing to chat about any subject: physics, politics, cuisine.. .
In recent years Kelly got interested in the question of gravity localisation, and we had numerous discussions and arguments. In all our encounters Kelly was his usual self: courteous, passionate, good-spirited, generous. It is ironic but bitterly fitting that he passed away while traveling in a distant land, the one where civilisation began. Like all his friends, I will miss him.
November 22, 2025
It is so sad to learn of Kelly’s death. He was a great source of wisdom. And he took all that wisdom with him. I came to know him better late as I started working on topics which he pioneered. It was always a pleasure to interact with him. A great loss.
November 21, 2025
A FEW KELLY STORIES
Les Houches
I first met Kelly at the 1975 Les Houches summer school in the French alps devoted to Quantum Field Theory. Many of that year's students were to become leaders in the field, for example Ed Witten. I drove my old Triumph Spitfire there but the Alps took their toll, and the driveshaft broke. Luckily there was someone who knew all about cars and could speak fluent French with the mechanics at the local garage....Kelly. We also found we had common interests: quantum gravity and good food and wine and we became great friends.
Balham
There is a novel by David Lodge called “Changing Places” about a British and an American academic crossing the Atlantic in opposite directions which Kelly and I were to imitate. In 1978 I was going from a postdoc at Queen Mary College London to one with Stan Deser, at Brandeis University near Boston, while Kelly was moving from Brandeis (where he was Stan's student) to King’s College London. We even swapped apartments; I to his in Cambridge Massachusetts and he to mine in Balham (arguably the most boring and unremarkable suburb of London, hailed as “gateway to the south” in a famous comedy satire.)
Moscow
About this time a series of annual conferences on Quantum Gravity started in Moscow. The likes of Stephen Hawking, Andrei Sakharov, and Yakov Zeldovich would be there. In those bleak days before Glasnost travelling behind the iron curtain still had an air of danger and mystique about it. I also seem to remember much more vodka and caviar being consumed. I met many Russian colleagues who were to become friends, thanks in no small part to Kelly who seemed to know everyone already and of course spoke perfect Russian. (If I am not mistaken the photo of Kelly and me was in the home of Viktor Ogievetsky in Dubna).
Aspen
The physics summer school in Aspen Colorado is close to the marquee that houses the music festival, attended by the millionaires and showbiz celebrities. One night, Dionne Warwick was the main attraction and members of the Kennedy family and the cast of the TV series Dynasty were in the audience. Needless to say the ticket prices were beyond what the physicists could afford but Kelly and I were able to “walk on by” to the back of the tent and enjoy the concert for free. (For a different Aspen event see the whitewater rafting photo).
Geneva
Kelly was one of the pioneers of supersymmetry. He and I were both enamored of supergravity in 11 dimensions, the maximum that supersymmetry allows. But this was knocked off its pedestal in 1984 by D=10 superstrings. Yet strings had there own problems: Why D=10? Why 5 different candidates? Why not non-perturbative calculations? Why not membranes or more generally p-branes? The Oxford English Dictionary attributes first usage of the word 'brane' to a 1987 CERN preprint that Kelly wrote with Takeo Inami, Chris Pope, Ergin Sezgin and me, published in NPB 1988.
Singapore
In 1990 Kelly and I attended a conference in Singapore. On the flight back to London we wondered whether such supermembranes could emerge as solutions of the D=11 supergravity field equations. By the time we landed at Heathrow we had not only found the solution, but had completed the paper which we dispatched to Physics Letters B. This so-called M2-brane solution (which when wrapped around the eleventh dimension described a string solution of D=10 Type IIA supergravity ) proved to be a cornerstone of M-theory, the non-perturbative D=11 theory developed in 1995 by Ed Witten, Chris Hull, and Paul Towsend, that subsumes all five D=10 string theories. The aeroplane paper with Kelly is one of my most cited publications.
Haute Cuisine
The Singapore conference was memorable not only for the physics but also the sumptuous meal Kelly and I enjoyed at the famous Raffles Hotel, washed down with several Singapore Slings. (Sling theory?) There was never a menu so grand that Kelly could not home in on its most expensive item. With Kelly you would dine like a king but go home a pauper. In one of the Michelin starred restaurants mentioned in Chris Pope’s message, I forget which, the world-famous chef came to our table after the meal, no doubt expecting to bask in the glory of our compliments. But Kelly, glancing over his shoulder, mistook the chef for the waiter and said ''deux cafés, s'il vous plait''.
Catania
Kelly was a remarkable human being, always willing to help others and with a keen sense of humour; he will be sorely missed. It was a privilege to have known him for these fifty years and especially to have attended his wonderful wedding in Sicily in September to Marise, to whom I extend my sincere condolences.
Les Houches
I first met Kelly at the 1975 Les Houches summer school in the French alps devoted to Quantum Field Theory. Many of that year's students were to become leaders in the field, for example Ed Witten. I drove my old Triumph Spitfire there but the Alps took their toll, and the driveshaft broke. Luckily there was someone who knew all about cars and could speak fluent French with the mechanics at the local garage....Kelly. We also found we had common interests: quantum gravity and good food and wine and we became great friends.
Balham
There is a novel by David Lodge called “Changing Places” about a British and an American academic crossing the Atlantic in opposite directions which Kelly and I were to imitate. In 1978 I was going from a postdoc at Queen Mary College London to one with Stan Deser, at Brandeis University near Boston, while Kelly was moving from Brandeis (where he was Stan's student) to King’s College London. We even swapped apartments; I to his in Cambridge Massachusetts and he to mine in Balham (arguably the most boring and unremarkable suburb of London, hailed as “gateway to the south” in a famous comedy satire.)
Moscow
About this time a series of annual conferences on Quantum Gravity started in Moscow. The likes of Stephen Hawking, Andrei Sakharov, and Yakov Zeldovich would be there. In those bleak days before Glasnost travelling behind the iron curtain still had an air of danger and mystique about it. I also seem to remember much more vodka and caviar being consumed. I met many Russian colleagues who were to become friends, thanks in no small part to Kelly who seemed to know everyone already and of course spoke perfect Russian. (If I am not mistaken the photo of Kelly and me was in the home of Viktor Ogievetsky in Dubna).
Aspen
The physics summer school in Aspen Colorado is close to the marquee that houses the music festival, attended by the millionaires and showbiz celebrities. One night, Dionne Warwick was the main attraction and members of the Kennedy family and the cast of the TV series Dynasty were in the audience. Needless to say the ticket prices were beyond what the physicists could afford but Kelly and I were able to “walk on by” to the back of the tent and enjoy the concert for free. (For a different Aspen event see the whitewater rafting photo).
Geneva
Kelly was one of the pioneers of supersymmetry. He and I were both enamored of supergravity in 11 dimensions, the maximum that supersymmetry allows. But this was knocked off its pedestal in 1984 by D=10 superstrings. Yet strings had there own problems: Why D=10? Why 5 different candidates? Why not non-perturbative calculations? Why not membranes or more generally p-branes? The Oxford English Dictionary attributes first usage of the word 'brane' to a 1987 CERN preprint that Kelly wrote with Takeo Inami, Chris Pope, Ergin Sezgin and me, published in NPB 1988.
Singapore
In 1990 Kelly and I attended a conference in Singapore. On the flight back to London we wondered whether such supermembranes could emerge as solutions of the D=11 supergravity field equations. By the time we landed at Heathrow we had not only found the solution, but had completed the paper which we dispatched to Physics Letters B. This so-called M2-brane solution (which when wrapped around the eleventh dimension described a string solution of D=10 Type IIA supergravity ) proved to be a cornerstone of M-theory, the non-perturbative D=11 theory developed in 1995 by Ed Witten, Chris Hull, and Paul Towsend, that subsumes all five D=10 string theories. The aeroplane paper with Kelly is one of my most cited publications.
Haute Cuisine
The Singapore conference was memorable not only for the physics but also the sumptuous meal Kelly and I enjoyed at the famous Raffles Hotel, washed down with several Singapore Slings. (Sling theory?) There was never a menu so grand that Kelly could not home in on its most expensive item. With Kelly you would dine like a king but go home a pauper. In one of the Michelin starred restaurants mentioned in Chris Pope’s message, I forget which, the world-famous chef came to our table after the meal, no doubt expecting to bask in the glory of our compliments. But Kelly, glancing over his shoulder, mistook the chef for the waiter and said ''deux cafés, s'il vous plait''.
Catania
Kelly was a remarkable human being, always willing to help others and with a keen sense of humour; he will be sorely missed. It was a privilege to have known him for these fifty years and especially to have attended his wonderful wedding in Sicily in September to Marise, to whom I extend my sincere condolences.
November 21, 2025
I met Kelly for the first time in Cargese, Corsica in 1978. Over the years we have had overlapping interests in supergravity counterterms,
although we only have one joint paper.
I was surprised when he did not show up for an announced talk at NTUA in Athens and did not reply to my emails. I feared something serious had happened. Unfortunately that was indeed the case.
I shall miss him and our pleasant encounters, lately most frequently at Imperial.
although we only have one joint paper.
I was surprised when he did not show up for an announced talk at NTUA in Athens and did not reply to my emails. I feared something serious had happened. Unfortunately that was indeed the case.
I shall miss him and our pleasant encounters, lately most frequently at Imperial.
November 20, 2025
I first met Kelly when he was the external examiner for my PhD, and he went on to become a wonderful colleague for more than twenty years. He cared deeply about theoretical physics at Imperial - and in London more broadly - seeing it as part of an international academy of scholars, an academy he loved being a part of. Urbane and kind, he possessed a natural charm and was always welcoming. Kelly was a connoisseur of the good things in life, with physics intertwined with engaging conversation and memorable meals (Kelly usually selecting the most extravagant items on the menu!). As Director of our QFFF MSc programme, I was always impressed with the care he devoted to the students facing particular challenges. Kelly was woven into the fabric of the Theory Group at Imperial, and he will be deeply missed.
November 20, 2025
Kelly has been a regular visitor, for decades, at the Laboratoire de Physique Théorique de l’Ecole Normale Supérieure in Paris. He participated in many of our Summer Institutes in August and also occupied more official positions as Visiting Professor for longer stays. Soon he was regarded as a member of our community and got engaged in fruitful collaborations with the members and students of our lab. Once he said he felt himself a part of that team. Personally, I remember long discussions with him about languages as we both had a passionate interest in “le mot juste”. He thus became for me a trustworthy resource during his stays. Years after years we continued that endless conversation. He came to my retirement event in 2006, I went to his fest in London in 2008. Fortunately, we met again last year for a drink with Marise and had dinner in London last January together with Curtis. All your messages evoke the same gentleman I have known. We all have lost a dear and unique friend. All my heartfelt thoughts and condolences to Marise.
Nicole Ribet-Callan
Nicole Ribet-Callan
November 19, 2025
I am very saddened by the passing of Kelly. I've known him well since the mid 90's when I came to London as post-doc. He has always been a key part of the London Physics community and there is now a palpable sense of loss. Looking back over our times together, which indeed included an uncountable number of dinners, I feel grateful for the all attention and support that he gave at various stages in my career. Having a senior friendly face to talk to about physics or life was a very empowering experience for an early career post-doc. And I have continued to benefit from his knowledge, kindness and crazy stories ever since.
November 19, 2025
It was a shock to hear about Kelly’s passing. He has been a constant presence in our London Theoretical Physics community, always kind and open-minded, up for a discussion and friendly chats. He was one of those increasingly rare people who had a clear vision of what academia was about and fought hard with the ever-increasing army of apparatchiks that unfortunately proliferate more and more at our universities to make sure that science and academic thinking won the day.
Like others, I have many fond memories of hikes and meals at conferences and after Triangle seminars with Kelly. Those charming and memorable stories - like the “Prowokacja!” story about bringing in diapers to socialist Poland - will stay with me for ever.
For me, it was his support and empathy towards the younger generations and those yet to become established that showed the true character of the man. He cared, he thought about others, he made sure to give the benefit of the doubt and think the best of people. Combined with his formidable physical instincts and knowledge, these qualities I will miss the most. We’ve lost a good one. RIP, Kelly.
Like others, I have many fond memories of hikes and meals at conferences and after Triangle seminars with Kelly. Those charming and memorable stories - like the “Prowokacja!” story about bringing in diapers to socialist Poland - will stay with me for ever.
For me, it was his support and empathy towards the younger generations and those yet to become established that showed the true character of the man. He cared, he thought about others, he made sure to give the benefit of the doubt and think the best of people. Combined with his formidable physical instincts and knowledge, these qualities I will miss the most. We’ve lost a good one. RIP, Kelly.
November 19, 2025
With great sorrow we have heard the mournful news about
untimely passing of Kelly Stelle. He was a distinguished scientist and a very friendly personality known world-wide by his classical seminal papers on gravity and supergravity. He kept long-lasting scientific and human contacts with our Laboratory and was a good friend of many of us. Kelly visited our Lab many times with the brilliant lectures on supergravity and related topics and served as a permanent member of the Advisory Committee of the biennial Workshops on "Supersymmeties and Quantum Symmetries" held in BLTP from the beginning of nineties and founded in those times by Victor Ogievetsky and Julius Wess. He also frequently participated in other conferences of similar trends organized in Moscow and Tomsk, where we enjoyed additional fortune opportunities to meet him and discuss with him the urgent problems, both in science and in life. It is very painful to realize that we will never meet again this great theorist and cheerful and fascinating man. In these days of turbulence the value of personal ties and friendship become invaluable. We will miss Kelly as you do.
We express our deepest condolences to all relations, friends and colleagues of dear Kelly Stelle!
Dmitry Kazakov, Evgeny Ivanov, Joseph Buchbinder, Alexey Isaev
and the other members of Particle Physics and Mathematical Physics divisions of the Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna
untimely passing of Kelly Stelle. He was a distinguished scientist and a very friendly personality known world-wide by his classical seminal papers on gravity and supergravity. He kept long-lasting scientific and human contacts with our Laboratory and was a good friend of many of us. Kelly visited our Lab many times with the brilliant lectures on supergravity and related topics and served as a permanent member of the Advisory Committee of the biennial Workshops on "Supersymmeties and Quantum Symmetries" held in BLTP from the beginning of nineties and founded in those times by Victor Ogievetsky and Julius Wess. He also frequently participated in other conferences of similar trends organized in Moscow and Tomsk, where we enjoyed additional fortune opportunities to meet him and discuss with him the urgent problems, both in science and in life. It is very painful to realize that we will never meet again this great theorist and cheerful and fascinating man. In these days of turbulence the value of personal ties and friendship become invaluable. We will miss Kelly as you do.
We express our deepest condolences to all relations, friends and colleagues of dear Kelly Stelle!
Dmitry Kazakov, Evgeny Ivanov, Joseph Buchbinder, Alexey Isaev
and the other members of Particle Physics and Mathematical Physics divisions of the Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna
November 18, 2025
Kelly was a brilliant scientist who was also a truly lovely person. I always enjoyed talking to with him, and never left a conversation without having learned something new and fascinating. I'm so sorry to hear of his passing.
November 18, 2025
I first met Kelly when I was a PhD student. He was frequently an external examiner for PhD vivas in DAMTP and I slowly got to know him then. His warmth and easy-going manner was immediately apparent, but I really got to know Kelly during the conferences and workshops that we attended all over the world.
Kelly was a real all-rounder. He was as comfortable talking about politics, world cultures, music, and art as he was discussing physics. I remember with fondness the stories of his many adventures from getting out of Georgia during an invasion of the country without his yellow jumper (which was saved later only to disappear in London!) to his childhood in Tehran.
Kelly was intellectually curious - above all about people. He cared about people and generously gave his time. No wonder he had friends in every corner of the world! I will miss him.
Kelly was a real all-rounder. He was as comfortable talking about politics, world cultures, music, and art as he was discussing physics. I remember with fondness the stories of his many adventures from getting out of Georgia during an invasion of the country without his yellow jumper (which was saved later only to disappear in London!) to his childhood in Tehran.
Kelly was intellectually curious - above all about people. He cared about people and generously gave his time. No wonder he had friends in every corner of the world! I will miss him.
November 18, 2025
I am so saddened to hear of Kelly's passing. He was my upstairs neighbor in Cambridge in the early 1970s. We hiked large parts of the Appalachian Trail together throughout the years and I visited him in London several times. He and my husband, Fred Cooper both did theoretical physics and I introduced them in the 1980's. Kelly was such a wonderful person, we had many great times together and I will deeply miss him. My condolences to Marise.
November 18, 2025
I was shocked and saddened to hear the news about Kelly. It’s hard to believe that he is no longer with us. Since hearing the sad news I have been reliving the many wonderful memories with him, almost always involving good food and wine as others have reminisced.
I first met Kelly in 2010 when he visited Cambridge as an external PhD examiner. His easy-going and kind nature meant that it felt like we’d known each other for years. Kelly never failed to surprise with his experiences, anecdotes, knowledge, and kindness. Chris Pope’s reference to Kelly’s “memorable folksy expressions“ reminded me of another expression of his: a “hands off the steering wheel calculation”; what a wonderful expression!
It was always an adventure when Kelly was around. I remember the time when a bunch of us were going up the valley for lunch in Benasque. Kelly suggested a direct route up; a couple of hours later, having fought through shrubs, streams, and fields, we arrived at the restaurant looking completely dishevelled (Chris Pope holding his torn shirt together with his hands). We laughed so much and the lunch was much better than it could ever have been without that adventure.
He was a very unique and wonderful man.
I first met Kelly in 2010 when he visited Cambridge as an external PhD examiner. His easy-going and kind nature meant that it felt like we’d known each other for years. Kelly never failed to surprise with his experiences, anecdotes, knowledge, and kindness. Chris Pope’s reference to Kelly’s “memorable folksy expressions“ reminded me of another expression of his: a “hands off the steering wheel calculation”; what a wonderful expression!
It was always an adventure when Kelly was around. I remember the time when a bunch of us were going up the valley for lunch in Benasque. Kelly suggested a direct route up; a couple of hours later, having fought through shrubs, streams, and fields, we arrived at the restaurant looking completely dishevelled (Chris Pope holding his torn shirt together with his hands). We laughed so much and the lunch was much better than it could ever have been without that adventure.
He was a very unique and wonderful man.
November 18, 2025
I was saddened to hear of Kelly’s passing. Kelly was my PhD advisor, having graciously taken me on when I wanted a change of subject after only a few months of my first year. I also had the chance to have him as an undergraduate tutor, and across both periods I remember his remarkable patience and care in explanation and calculation when he got to the whiteboard. He taught me the appreciation of good science and the art of a well-written paper. I remember his mild annoyance at a review of one of our papers - “Good, if pedagogical.” said reviewer 2; “But that’s the point.” retorted Kelly.
I will fondly remember Kelly's calmness, kindness and in particular his joie de vivre: those meals and the stories that went along with them, a jaunt around Geneva for car parts that became an impromptu history lesson (his and the city’s), excited advice about a particular library or museum to visit in some other destination, and his simple joy at hoping to fit the entire arXiv on an early iPod.
I will fondly remember Kelly's calmness, kindness and in particular his joie de vivre: those meals and the stories that went along with them, a jaunt around Geneva for car parts that became an impromptu history lesson (his and the city’s), excited advice about a particular library or museum to visit in some other destination, and his simple joy at hoping to fit the entire arXiv on an early iPod.
November 17, 2025
I am deeply shocked by Kelly’s sudden death. He was a great lecturer, a phenomenal raconteur, and a kind soul. I will miss him greatly.
November 17, 2025
I was shocked and saddened to hear that Kelly Stelle has passed away. Yes, Kelly was a phenomenal physicist, but as many people have been pointing out, he was equally remarkable for his diverse range of interests, experience and knowledge. For example, Kelly spoke fluent Russian, apparently without any accent. This allowed Kelly and I to navigate the truly convoluted path to the confluence of the Tom and Ob rivers in rural Siberia, to explore the harbor at Sebastopol in Crimea and so much more. A wonderful man who I will deeply miss.
November 17, 2025
I was very saddened to learn of Kelly's death. I've known him for something like 45 years, and I believe I can claim to have been Kelly's most frequent co-author. Where to begin in encapsulating my reminiscences of him? Two threads, I think, run through many of the wonderful stories and memories. One was already mentioned in the splendid review by Mike Duff and Chris Hull: Kelly was the consumate gourmet physicist. I have many happy memories of going with him to Michelin starred restaurants; the Auberge de Lille in Alsace, the Auberge de l'Eridan near Annecy, the Maison Lameloise in Chagny, the Restaurant de l'Hotel de Ville, in Crissier, the Fat Duck in Bray,... and the list goes on. And, of course, many less pretentious but nonetheless marvellous restaurants over the years. As Mike and Chris remarked in their reminiscences, these could tax the wallet, as well as the stomach. The rest of us used to have a rule of thumb for how one could estimate what the shared-out damage for one of these meals would be, before the bill actually arrived. If I recall correctly, it was something like "take the cost of Kelly's main course, and multiply by three."
Another memorable feature of almost every arrangement to meet up with Kelly was that he would arrive "fashionably later" than anyone else in the group. "Waiting for Kelly" was a constant theme over the years. It was a bit like "Waiting for Godot," except that Kelly did always show up...eventually. It could seem infuriating at times while we were waiting, but of course in retrospect it was just one of Kelly's most endearing traits.
Those were great days, and lest it seem as if it all centred around the dinner table, it was also wonderful to work with Kelly, to argue over fine points of physics (and sometimes grammar when writing the paper), and generally have a lot of fun discovering new things and then celebrating the achievements with fine food and fine wine. Kelly had a wonderful physical insight, and, of course, a deep understanding and intuition for all things "super." He also had a fine way with words, coming up with memorable folksy expressions, like "the letter to grandmother," to encapsulate the notion of an externally-supplied constraint over and above what was implied by the other equations. All in all, it was a great adventure; we shall not see his like again.
Another memorable feature of almost every arrangement to meet up with Kelly was that he would arrive "fashionably later" than anyone else in the group. "Waiting for Kelly" was a constant theme over the years. It was a bit like "Waiting for Godot," except that Kelly did always show up...eventually. It could seem infuriating at times while we were waiting, but of course in retrospect it was just one of Kelly's most endearing traits.
Those were great days, and lest it seem as if it all centred around the dinner table, it was also wonderful to work with Kelly, to argue over fine points of physics (and sometimes grammar when writing the paper), and generally have a lot of fun discovering new things and then celebrating the achievements with fine food and fine wine. Kelly had a wonderful physical insight, and, of course, a deep understanding and intuition for all things "super." He also had a fine way with words, coming up with memorable folksy expressions, like "the letter to grandmother," to encapsulate the notion of an externally-supplied constraint over and above what was implied by the other equations. All in all, it was a great adventure; we shall not see his like again.
November 17, 2025
I had the good fortune of having Kelly as my Ph.D. advisor. I imagine that being taught by Kelly was somewhat different from most people’s graduate school experiences. We rarely talked in the morning, the earliest moment in the day for a relevant conversion being the coffee after lunch. But often even this was far too early. On many days, Kelly would send me away and tell me to come and see him later. What this usually meant was that we would end up going for dinner together. Often this was to Da Mario on Gloucester Road, which Princess Di used to frequent, and which was one of Kelly’s favourite restaurants. There, he would tell me about supergravity, branes and M-theory - with a bottle of wine nearby, which he would invariably pay for.
But of course, as many have remarked, we did not talk only about physics. In fact, there was basically no topic that was off-limits, be it the repairs to his green Audi quattro, some castle in France, a jazz concert he had experienced, the fascination of men in the Kashmir for British cricket results, or the time his cat accidentally ate some hash and was stoned for two days…
In working with Kelly, the division of labour was always clear: he would talk and I would calculate. Kelly always had an idea of what the result should be, and I always had an idea of what a certain calculation showed. Then we would compare notes, and often he would update his expectation of the results, and I would update my premises in the calculations. We did this until we agreed, however long that took – it could be days, or it could be years. Kelly was never in a hurry, all that mattered was that we were happy with the result.
In this way, Kelly and I stayed in touch after my PhD, and we continued working together on regular occasions. What makes me happy is that in our most recent work, we came to appreciate a new facet of his starting theory in physics, quadratic gravity, because we realized that it may have useful implications for the early universe.
What a stroke of luck it was to have known Kelly. Every conversation with him was enriching and made me appreciate the world a little more. I will miss him deeply.
But of course, as many have remarked, we did not talk only about physics. In fact, there was basically no topic that was off-limits, be it the repairs to his green Audi quattro, some castle in France, a jazz concert he had experienced, the fascination of men in the Kashmir for British cricket results, or the time his cat accidentally ate some hash and was stoned for two days…
In working with Kelly, the division of labour was always clear: he would talk and I would calculate. Kelly always had an idea of what the result should be, and I always had an idea of what a certain calculation showed. Then we would compare notes, and often he would update his expectation of the results, and I would update my premises in the calculations. We did this until we agreed, however long that took – it could be days, or it could be years. Kelly was never in a hurry, all that mattered was that we were happy with the result.
In this way, Kelly and I stayed in touch after my PhD, and we continued working together on regular occasions. What makes me happy is that in our most recent work, we came to appreciate a new facet of his starting theory in physics, quadratic gravity, because we realized that it may have useful implications for the early universe.
What a stroke of luck it was to have known Kelly. Every conversation with him was enriching and made me appreciate the world a little more. I will miss him deeply.
November 17, 2025
I have many great memories of Kelly, mostly associated with meals. During my years in London, we had many memorable meals together. This continued for some time when Kelly was external examiner in Edinburgh. During that time we had less frequent but no less memorable meals together in Edinburgh. He was cultured and fun to be with.
Kelly was very kind to me personally when my late wife Sonia Stanciu was in hospital in London. I remember that Sonia's parents were having difficulty in getting their passports and visas to visit her in the UK. Kelly solved the problem in real time through a "close contact" at the Home Office and in the Romanian Embassy in London.
Rest in peace, my friend.
Kelly was very kind to me personally when my late wife Sonia Stanciu was in hospital in London. I remember that Sonia's parents were having difficulty in getting their passports and visas to visit her in the UK. Kelly solved the problem in real time through a "close contact" at the Home Office and in the Romanian Embassy in London.
Rest in peace, my friend.
November 17, 2025
Kelly was a pioneer of quantum gravity, string theory, and quantum field theory. A true giant of theoretical physics, with a passion for physics. His research inspired, and will continue to inspire for many years to come, generations of theoretical physicists.. He has also been a wonderful person. He will be greatly missed..
November 17, 2025
Such a loss to our community. Kelly was one of a kind.
I got to know him well when I was external examiner for the Imperial Master's course. Kelly was in charge. What struck me most was how deeply he cared. He cared about how the course was run and taught, and about keeping standards high. But more importantly he cared about the students -- that they were being treated fairly, that they had the chance to succeed, that each would ultimately thrive.
I got to know him well when I was external examiner for the Imperial Master's course. Kelly was in charge. What struck me most was how deeply he cared. He cared about how the course was run and taught, and about keeping standards high. But more importantly he cared about the students -- that they were being treated fairly, that they had the chance to succeed, that each would ultimately thrive.
November 16, 2025
So sorry at Kelly's passing . Besides his kind, calm personality and his wide interests, his openness and willingness to question made him unusual, and always a pleasure to spend time with. His loss is a huge one for us all.
November 16, 2025
Kelly was an absolutely wonderful person. He and I had long physics arguments, which were always a joy to have. The first time I met him, we did not overlap on physics, except vaguely that I was just starting to get interested in gravity. For reasons that were unclear to me at the time, he invited me to a Michelin-starred restaurant in Sardinia. He was really fun to be with. As it turned out, that invitation later led to some very nice physics. When I got interested in ultraviolet divergences in supergravity, I knew exactly who to consult. Little did I know that we would become friends, arguing endlessly over the fate of various supergravity counterterms. He will be sorely missed.
November 16, 2025
When I joined the theory group at Imperial close to ten years ago, Kelly was one of the most welcoming colleagues. He shared fresh insights into physics — whether his newly developed ideas on massive spin-2 or the most delicate Russian results from the 1950s that only he could connect to modern developments. But to me, he was the one who noticed the small, human details that so often escape many of us in physics.
Yet seeing him in the corridors, chatting with him at tea time, or attending his notorious examiner meetings, was nothing compared to bumping into him at conferences around the world. In the middle of the most agitated physics discussions, Kelly was always the most grounding presence. Instead of quizzing me about the latest scattering-amplitude subtleties, the relevance of any of our work, or the state of funding, he would lift everyone’s spirits (or at least mine) by talking about the history of whatever beautiful city we were in, the hidden streets worth wandering, or the best place to watch the sunset over an old castle.
Back at Imperial, as the intense scrutiny from my colleagues would still be buzzing in my ears, he would drop by my office with insightful stories — often about women scientists during the war or other overlooked figures in our field. Kelly will be deeply missed here, but it’s at my next conference, when I don’t see his calm, quietly profound presence — as if from another place in space and time — that I will feel his absence most.
Yet seeing him in the corridors, chatting with him at tea time, or attending his notorious examiner meetings, was nothing compared to bumping into him at conferences around the world. In the middle of the most agitated physics discussions, Kelly was always the most grounding presence. Instead of quizzing me about the latest scattering-amplitude subtleties, the relevance of any of our work, or the state of funding, he would lift everyone’s spirits (or at least mine) by talking about the history of whatever beautiful city we were in, the hidden streets worth wandering, or the best place to watch the sunset over an old castle.
Back at Imperial, as the intense scrutiny from my colleagues would still be buzzing in my ears, he would drop by my office with insightful stories — often about women scientists during the war or other overlooked figures in our field. Kelly will be deeply missed here, but it’s at my next conference, when I don’t see his calm, quietly profound presence — as if from another place in space and time — that I will feel his absence most.
November 15, 2025
I knew Kelly in the class of Black Hole and Standard Model (and Beyond). He often told us the story about the physicist during WWII, the “clever Japanese” who built neutrino detectors and many more than I can remember now. Often I found myself asleep, like near a cozy bonfire with a Santa telling us Christmas stories (not an excuse to justify my sleeping in the class). Later I became a PhD student in the group; the storytelling continued—his great-grandmother who played the role of interpreter between the Empress Dowager Cixi and the western guests, his father as a diplomat in Yan’an before the Chinese Civil War, and his cosmic gazing at the South Pole during the Vietnam War. He was a storyteller, until he became the story himself.
Last summer I took a train from Shanghai to Beijing. When I arrived at the station, I immediately spotted Kelly (you cannot miss that when he was the only white man among so many Chinese), who was going to visit the Luhe International School, which was founded by his great-grandfather Davelle Z. Sheffield as a missionary school (you can find a picture of Kelly, the school principal, and the sculpture of his great-grandfather in the gallery). We were both shocked (confused too) as we were in Shanghai and here in Beijing for completely different purposes, but ended up taking the same train. It was an interesting encounter. Though it was not a particularly meaningful encounter, but still felt somehow symbolic for me. I am sure in his life there were many more encounters much exciting than this one, with the people he used to know, the people he was about to know, and the people he would know, as if there was some sort of “gravity” bringing them (and us) together.
Last summer I took a train from Shanghai to Beijing. When I arrived at the station, I immediately spotted Kelly (you cannot miss that when he was the only white man among so many Chinese), who was going to visit the Luhe International School, which was founded by his great-grandfather Davelle Z. Sheffield as a missionary school (you can find a picture of Kelly, the school principal, and the sculpture of his great-grandfather in the gallery). We were both shocked (confused too) as we were in Shanghai and here in Beijing for completely different purposes, but ended up taking the same train. It was an interesting encounter. Though it was not a particularly meaningful encounter, but still felt somehow symbolic for me. I am sure in his life there were many more encounters much exciting than this one, with the people he used to know, the people he was about to know, and the people he would know, as if there was some sort of “gravity” bringing them (and us) together.
November 15, 2025
I am deeply saddened by Kelly's tragic and untimely passing.
Kelly was a kind and supportive friend. I have very fond memories of the times we spent together, collaborating and socializing in Trieste, CERN, Benasque and other places around the world.
His kindness to me and my family have left an indelible mark on my life. I will cherish memories of him.
Kelly was a kind and supportive friend. I have very fond memories of the times we spent together, collaborating and socializing in Trieste, CERN, Benasque and other places around the world.
His kindness to me and my family have left an indelible mark on my life. I will cherish memories of him.
November 14, 2025
The best decision I ever made was to do my first postdoc at Imperial and Kelly convinced me to do this after a phone call where he said that the group goes to the Queens Arms Pub, next to campus, to discuss physics. I intuited that Kelly would be "my dude". Once I got to imperial, Kelly invited me to a 3 month workshop (that he organized) in Paris and this is where my career took off. I would not acheive what little I did in my career without uncle Kelly. He was always available to discuss ideas no matter how crazy they were.. He encouraged, empowered, and protected me to pursue my ideas and also challenged me to grow technically. Kelly always had that twinkle in his eyes even when there were disagreements and boy what laughs and fine dinners we enjoyed over the years! He was a rare human being of the highest integrity, an iconic physicist and I consider him my Uncle Kelly. Rest in peace Uncle Kelly.. you will never be forgotten and will live in our hearts.
November 13, 2025
Kelly gave me the invaluable opportunity to begin a PhD with him. He was thoughtful, passionate and persistent as a physicist. I still remember one afternoon meeting that went on for nearly three hours. While I was getting tired, Kelly was still fully engaged, eager to go through every interesting question in detail.
Although our time working together was shorter than we had hoped, I feel very fortunate to have learned so much from him over the past two years. He was not only a great supervisor, but also a kind friend, almost like a grandfather figure to me.
We will miss him deeply.
Although our time working together was shorter than we had hoped, I feel very fortunate to have learned so much from him over the past two years. He was not only a great supervisor, but also a kind friend, almost like a grandfather figure to me.
We will miss him deeply.
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