TY  -  JOUR
TI  -  Stephen Hawking’s superspace and supergravity blackboard: an iconic artefact in the making
  AU -Juan-Andres Leon
PY  -  2024
VL  - 
IS  - Spring 2024
KW - astrophysics
KW - blackboards
KW - charismatic objects
KW - cosmology
KW - physics
KW - post-empiricism
KW - scientific collaboration
KW - Stephen Hawking
KW - string theory
KW - supergravity
KW - superstrings
KW - supersymmetry
KW - unification of physics

AB - Among about a thousand objects obtained by the Science Museum from Stephen Hawking’s office is a blackboard full of cartoons and puns, both childishly silly and deeply scientifically meaningful. This blackboard is now one of the Museum’s most popular objects thanks to its playful imagery and perhaps also its perceived fragility. But it is also one of the objects that best illustrates the scientific life of Stephen Hawking and his generation, and more broadly, it is an exemplar of the social and material culture of the postmodern epoch of theoretical physics in the decades around the turn of the twenty-first century.
In this article, the curator of the Hawking Collection explains the importance of this blackboard, first through an account of its unexpected trajectory to becoming the Hawking Collection’s most charismatic object, followed by a discussion of the general historical role of blackboards: their iconography, material culture, and value as historical sources and how their conservation requirements contribute to their perceived value. The author then delves deeper into the specific content of this blackboard, showing how it constitutes a window into the highs and lows of a generation of physicists inspired by Hawking’s work, as they attempted, and ultimately failed, to unify the two great theories of the twentieth century: general relativity and quantum mechanics.
What we now call the superspace and supergravity blackboard is a microcosm of one of those moments in physics when theory broke away from what was empirically verifiable. The scribblings on the blackboard were collectively drawn by an up-and-coming generation of supersymmetry theorists. It immortalises the promising early years of supergravity, one of the hopeful candidates at the time for the long-wished-for Theory of Everything. Preserved in chalk are the seeds of one of the most brilliant theoretical discoveries of the turn of the century: what is now called the holographic principle. But also, seen with the benefit of hindsight, supersymmetric approaches seeded the identity crisis that theoretical physics is experiencing today, especially around the role of empirical anchoring of proposed fundamental theories. The contested status of the blackboard’s content and its humorous, self-ironic style, make it a key piece of a unique zeitgeist of physics at the turn of the twenty-first century, which one could call the era of postmodern physics.
In addition to its significance to the history of specific ideas, this paper also argues that the blackboard reflects the collective, social nature of theoretical research, while also inviting reflection on what constitutes success and failure in the physical sciences.

N1 - Stephen Hawking at Work was in London February–December 2022, Bradford January–May 2023, and Manchester May 2023–September 2025 https://www.sciencemuseum.org.uk/stephen-hawkings-office (accessed 7 May 2024).
N1 - In anticipation of the permanent display of Stephen Hawking’s office, the Science Museum is setting up a programme specifically to address disability in a sensitive way, while still addressing this crucial aspect of Hawking’s identity – a necessary prototype for how to deal with disability outside of our medicine galleries. It is possible that the current fascination with Hawking’s scientific work, as described in this article, is a consequence of new sensitivities, with our audience more comfortable taking selfies in front of a blackboard than a wheelchair. We must take care not to over-indulge in this avoidance, as any Stephen Hawking exhibitions should continue to provide opportunities to discuss disability as an integral part of human experience. 
N1 - Ian Sample: ‘Stephen Hawking exhibition hopes to unravel the mysteries of his blackboard’, the Guardian, 10 February 2023. https://www.theguardian.com/science/2022/feb/10/stephen-hawking-exhibition-hopes-to-unravel-the-mysteries-of-his-blackboard (accessed 7 May 2024). 
N1 - Adela Suliman, ‘Stephen Hawking’s doodle-filled blackboard, a window into the theoretical physicist’s mind, goes on display’, Washington Post, 10 February 2022. https://www.washingtonpost.com/world/2022/02/10/stephen-hawking-exhibition-science-museum/
N1 - On ‘charismatic objects’ see Schaffer, S, ‘Chronometers, charts, charisma: on histories of longitude’, Science Museum Group Journal, autumn 2014 https://dx.doi.org/10.15180/140203/001. I especially want to emphasise Schaffer’s view that the charisma of an object is historically contingent and socially constructed. 
N1 - For a recent reflection on the effect of museum showpieces being photographable, see: Gareth Harris, ‘Photo ban lifted on Picasso’s Guernica after 30 years’, The Art Newspaper, 11 September 2023. https://www.theartnewspaper.com/2023/09/11/photo-ban-lifted-picassos-guernica-after-30-years-museo-reina-sofia-madrid
N1 - http://www.mhs.ox.ac.uk/blackboard/introduction.htm. See also Jean-François Gauvin’s 2009 interpretation of the blackboard, ‘Einstein’s blackboard as a mutant object’ [https://jfgauvin2008.wordpress.com/2009/03/09/einsteins-blackboard/]. For further discussion of the career of the late Jim Bennett see Stephen Johnston’s article in this issue. 
N1 - As most recently in Interstellar, blackboards seem to be the popular way for time travellers to communicate, sometimes to their younger selves, the solution that allows the time travel to happen in the first place.
N1 - See also Kaiser’s ‘From blackboards to bombs’ (Nature, Vol 523, 523-25, 2015) on the deliberate mythmaking of the Manhattan project being an accomplishment of theoretical physics, diverting the public’s attention away from its vast industrial infrastructure.  
N1 - https://digital.archives.caltech.edu/collections/Photographs/1.10-3/. Feynman’s blackboards were legendary and, for example, one story says Feynman had casually formulated what came to be known as ‘Hawking radiation’ a year before Hawking, but this was wiped off from the blackboard overnight by a Caltech cleaner. https://nautil.us/the-day-feynman-worked-out-black_hole-radiation-on-my-blackboard-237372/ (accessed 7 May 2024). The ‘playboy’ image of figures like Feynman was recognised at the time and was sometimes even literal. In the postwar era, for example, articles promoting physics as an attractive career featured in men’s ‘lifestyle’ magazines. Kaiser, ‘The Postwar Suburbanization of American Physics’, American Quarterly, Vol 56, No 4 (2004). 
N1 - As did Hawking’s own graduate students: their collective work space in the old Silver Street building was their coffee room, and it was there, with markers on the laminate tables, that much of the theory ‘magic’ took place. ‘Bruce, arbeite nicht zu hart’, Der Spiegel 14 March 2018. https://www.spiegel.de/wissenschaft/natur/stephen-hawking-so-war-die-arbeit-als-sein-doktorand-a-1128567.html (Interview with Hawking’s former student Bruce Allen, now director at the Max Planck Institute for Gravitational Physics in Hannover.)
N1 - Originally a Second World War graffiti indicating the previous presence of American soldiers in an area, Kilroy was soon appropriated in Britain with the catchphrase “Wot, no…” to mock postwar scarcity and rationing, and saw periodic revivals in popularity through the century, to the point of being considered one of the first ‘memes’. For much more detail and references, see: https://en.wikipedia.org/wiki/Kilroy_was_here 
N1 - SUNYSB is located right next to Brookhaven, the national laboratory on which CERN was originally modelled. Many crucial discoveries leading to the Standard Model originated there, as well as experiments that challenged it such as Ray Davis’s underground neutrino detection experiments (see, for example, Galison, 1997; and Bonolis and Leon, 2022). 
N1 - Hawking was noted for placing a great value on casual interactions over coffee, and his students remember the most important space in his old Silver Street location to be the joint kitchen and graduate student area, where his students, together with carers and technical assistants, practically ‘lived’ through their studies. This was later evoked, on a much larger scale, in the new Centre for Mathematical Sciences (CMS) with its common room, its 11am coffee break endowed in perpetuity by Hawking. (Conversation with Paul Shellard, April 2022.) 
N1 - Documentary Hawking: Can you Hear Me?, Sky, 2021 
N1 - Such was Hawking’s fame in the late 1980s that his Silver Street office had already been reconstructed in Hollywood, by the great documentary filmmaker Errol Morris, for the film version of A Brief History of Time.
N1 - While writing her book, Hélène Mialet (2014) reflected on this blackboard and what it tells us regarding Hawking’s efforts to ‘archive’ his own work while he was still alive. When office movers attempted to put the blackboard in storage against his wishes, Hawking insisted it be installed again in his new office.
N1 - The blackboard was the striking first impression when Thomas Hertog entered Hawking’s office, as he described in the introduction to his book (Hertog, 2023). 
N1 - A position supported by Dennis Avery and his wife Sally Tsui Wong-Avery, who had known and supported Hawking since the 1990s. Avery died in 2012 and photographs of his friendship with Hawking are on the office walls; the holder of the new position of Stephen Hawking Professor at Cambridge, again funded by a Wong-Avery endowment, will be the new inhabitant of this office.
N1 - In media appearances, plenty of use is made instead of the green ‘working’ chalkboard in the office, generally populated not with current cutting-edge research but with media-friendly scribblings. The current content on that green chalkboard was actually drawn after Hawking’s death for a documentary (see the article by Blyth and Boyle in this issue). 
N1 - On Hawking’s love of travel specifically, see Almeida, 2021, footnote 28. 
N1 - For the best account of Hawking’s scientific trajectory, as well as some of his personal quirks, see Carr et al (2019).
N1 - It was again through a Nuffield workshop that Hawking made his mark fostering the theory of cosmic inflation, bringing together scientists from around the world, including key Soviet contributors (Gibbons, Hawking and Siklos, 1983).
N1 - See, for example: Jacome Armas (ed), 2021, Conversations on Quantum Gravity (CUP). Dowker’s interview is on pages 194–209. For a more detailed account of Dowker’s role within the causal-set framework, see S Surya, 2019, ‘The causal set approach to quantum gravity’, Living Reviews in Relativity 22, No 1. This article mentions how Hawking had an early role inspiring this theory in the 1970s with: Hawking, S, King, A and McCarthy, P, 1976, ‘A new topology for curved space-time which incorporates the causal, differential, and conformal structures’, J Math Phys 17: 174–181 https://doi.org/10.1063/1.522874
N1 - Mialet, 2014. The interview was conducted for her chapter in From Newton to Hawking A History of Cambridge University’s Lucasian Professors of Mathematics (Cambridge University Press), 2003.
N1 - For some of the best examples, see Helge Kragh, 2011, Higher Speculations: Grand Theories and Failed Revolutions in Physics and Cosmology (Oxford University Press). This work is discussed again later in this article. 
N1 - Conversation with Neil Turok, March 2023. 
N1 - Witten’s contributions are best described in the documentation from the Breakthrough Prize in fundamental physics.[ https://breakthroughprize.org/Laureates/1/L9]. See also an interview describing his contributions upon receiving the Hamburg Prize: https://www.joachim-herz-stiftung.de/en/about-us/prices/hamburg-prize-for-theoretical-physics/edward-witten. And for his latest views on superstrings, the interview in Armas (2021). 
N1 - Hawking would joke that the M of the theory was for ‘Marika’. Joke aside, it’s widely considered to refer to Witten’s upside-down initial.
N1 - Juan Maldacena, ‘The Large N Limit of Superconformal field theories and supergravity’. Maldacena’s is the most cited paper in the history of high energy physics to date. It not only demonstrated this equivalence exactly (non-perturbatively) leading to the holographic principle, but, relevant for Hawking, did so aided by the use of black holes and black hole radiation as calculational entities. For a textbook interpretation if its significance see Martin Ammon and Johanna Erdmenger, 2015, Gauge/Gravity Duality: Foundations and Applications (Cambridge University Press). For a more intuitive account, see: Jean-Pierre Luminet, 2016, ‘The Holographic Universe’, Inference Review Vol 2, No.1. Online at https://inference-review.com/article/the-holographic-universe
N1 - This was the approach followed by Hawking, his former student and collaborator Malcolm Perry, and Harvard University’s Andrew Ströminger, in their proposal for ‘soft hair’ as means for encoding the information that has fallen into a black hole. See: S Saco, S W Hawking, M J Perry and A Ströminger, ‘Black Hole Entropy and Soft Hair’, Journal of High Energy Physics, 2018(2). https://arxiv.org/abs/1810.01847
N1 - This final quest is best described in Hertog (2023). 
N1 - Almeida (2021). Bekenstein’s key contribution is best described in Jakob Bekenstein, 2007, ‘Information in the Holographic Universe’, Scientific American, 289(2): 61. Online at: https://www.scientificamerican.com/article/information-in-the-holographic-univ/
N1 - M Isi, W M Farr, M Giesler, M A Scheel, S A Teukolsky, ‘Testing the Black Hole Area Law With GW20150914’, Phys. Rev. Lett. 127, 011103 (2021). For an intuitive description of this research, see: Jenniffer Chu, ‘Physicists observationally confirm Hawking’s black hole theorem for the first time’, MIT News, 1 July 2021. Online at: https://news.mit.edu/2021/hawkings-black-hole-theorem-confirm-0701
N1 - On Dirac, see the biographies by Helge Kragh (1990), and Graham Farmelo (2009).
N1 - The ‘black hole explosions’ predicted by Hawking’s theory have never been detected. But Hawking radiation is so fundamentally established that the non-detection of such explosions rather provides clues of our early universe: it has to be consistent with a scarcity of the small primordial black holes that would otherwise have been detected. 
N1 - On the link between postmodernity and post-empiricism see: Cathryn Carson, ‘Who Wants a Postmodern Physics?’, Science in Context, 8, 4 (1995). Online at: https://doi.org/10.1017/S0269889700002222. 
N1 - The Standard Model will probably remain valid but incomplete, as the experimentally observed behaviour of neutrinos, indicating that they have a mass, is not explained by it (Bonolis and Leon, 2022). 
N1 - So much so that new theoretical pathways towards a unification of physics and the origin and fate of the universe are starting to consider the Standard Model among its axiomatic starting points. See, for example, Latham Boyle, Kieran Flynn and Neil Turok, ‘CPT-Symmetric Universe’, Physical Review Letters 121, 251301 (2018); Neil Turok and Latham Boyle, ‘A Minimal Explanation of Primordial Cosmological Perturbations’ (Preprint), https://doi.org/10.48550/arXiv.2302.00344
N1 - See the interview with Witten in Armas, 2021. A more colourful description at the time of the discovery can be seen in: https://www.math.columbia.edu/~woit/wordpress/?p=6601 comment by DrDave: ‘In the absolute worst case scenario, where no evidence ever turns up, one could certainly claim that an LHC in another universe could detect something, and that ripples from this event could be seen in yet another universe, just not ours.’ 
N1 - Kragh, Higher Speculations, and especially the article Kragh, Helge, 2002, ‘The vortex atom: A Victorian theory of everything’, Centaurus 44, 32–114. I thank Bernadette Lessel, and the scholars attending the gathering of the Consortium of the History of Science, Technology and Medicine (CHSTM), February 2024, for pointing out these parallels and their relevance on the contemporary debates on the scientific status of supersymmetric theories. They also suggest the following: Barrow, John D, 2007, New Theories of Everything (Oxford: Oxford University Press); Gardner, Martin, 2007, ‘M for messy’, The New Criterion 25 (April), 90.
N1 - One of our priorities in the coming decade is to more maturely address whatever failure is, in all its complexity. And this blackboard, a relic of an entire generation of physicists pursuing a ‘wrong’ idea (while still obtaining some unexpected theoretical insights from it), is one of the most promising new exhibits for the Science Museum to address this. Richard Dunn et al (forthcoming).
PB - The Science Museum Group
 
SN -  2054-5770
LA -  eng
DO -  10.15180/242109
UR -  https://journal.sciencemuseum.ac.uk/article/stephen-hawkings-superspace-and-supergravity-blackboard-an-iconic-artefact-in-the-making/
T2 -  Science Museum Group Journal