The Reckoning is an intimate work of documentary theatre composed from a verified archive of witness testimonies chronicling Russia’s war of aggression. It is now playing at London’s Arcola Theatre to universal acclaim. We are too often tempted to turn our eyes away from Ukraine Rory Finnin The Guardian calls it “shattering.” The Stage heralds it as a “challenging, artfully constructed indictment of Russian war crimes in Ukraine.” Written by Anastasiia Kosodii and Josephine Burton, and directed by Burton, The Reckoning channels voices of Ukrainians across the country – a priest, a volunteer, a dentist, a security guard, a journalist – who are forced to confront the sudden horrors of invasion and occupation and to repair bonds of trust amid violence and fear. These voices are real, drawn from witness statements collected and conserved by the journalists and lawyers behind The Reckoning Project. Rory Finnin, Professor of Ukrainian Studies and a Fellow of Robinson College at Cambridge, collaborated with Burton to help shape the play. His decades of research into Ukraine’s culture and society formed the basis for a grant in support of The Reckoning from the University of Cambridge’s AHRC Impact Starter Fund account. “Our collaboration with Rory Finnin has been invaluable throughout the making of The Reckoning,” said Burton, who is also Artistic Director and Chief Executive of Dash Arts. “Rory’s insights into Ukraine’s past and present gave me deeper grounding as a director and co-writer and helped sharpen the questions the play asks of its audience.” The Reckoning blends dynamic storytelling with movement, music, and food to forge new routes of solidarity and understanding with the audience. As Everything Theatre notes in a glowing review, “We leave not as passive spectators but as an active part of the struggle.” Attendees share in a summer salad made over the course of the play by the Ukrainian and British cast – Tom Godwin, Simeon Kyslyi, Marianne Oldham, and Olga Safronova – who bring empathy, humour, and integrity to each scene. The conclusion of each performance features an invited speaker from the audience who comes to the stage to reckon with their own experience of the play from different ethical and intellectual perspectives. Professor Finnin spoke on the play’s first night at the Arcola Theatre. “Over three years into Russia’s full-scale invasion, we are too often tempted to turn our eyes away from Ukraine,” said Finnin. “But The Reckoning empowers us to look closely and to see with new purpose. It has been an incredible privilege to support a dynamic work of art that brings Ukrainian voices to the fore and challenges us to listen and respond to them, with urgency and moral clarity.” The Reckoning runs through 28 June at London’s Arcola Theatre. The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Cambridge researchers urge public health bodies like the NHS to provide trustworthy, research-driven alternatives to platforms driven by profit. Women deserve better than to have their menstrual tracking data treated as consumer data Prof Gina Neff Smartphone apps that track menstrual cycles are a “gold mine” for consumer profiling, collecting information on everything from exercise, diet and medication to sexual preferences, hormone levels and contraception use. This is according to a new report from the University of Cambridge’s Minderoo Centre for Technology and Democracy, which argues that the financial worth of this data is “vastly underestimated” by users who supply profit-driven companies with highly intimate details in a market lacking in regulation. The report’s authors caution that cycle tracking app (CTA) data in the wrong hands could result in risks to job prospects, workplace monitoring, health insurance discrimination and cyberstalking – and limit access to abortion. They call for better governance of the booming ‘femtech’ industry to protect users when their data is sold at scale, arguing that apps must provide clear consent options rather than all-or-nothing data collection, and urge public health bodies to launch alternatives to commercial CTAs. “Menstrual cycle tracking apps are presented as empowering women and addressing the gender health gap,” said Dr Stefanie Felsberger, lead author of the report from Cambridge’s Minderoo Centre. “Yet the business model behind their services rests on commercial use, selling user data and insights to third parties for profit.” “There are real and frightening privacy and safety risks to women as a result of the commodification of the data collected by cycle tracking app companies.” As most cycle tracking apps are targeted at women aiming to get pregnant, the download data alone is of huge commercial value, say researchers, as – other than home buying – no life event is linked to such dramatic shifts in consumer behaviour. In fact, data on pregnancy is believed to be over two hundred times more valuable than data on age, gender or location for targeted advertising. The report points out that period tracking could also be used to target women at different points in their cycle. For example, the oestrogen or ‘mating’ phase could see an increase in cosmetics adverts. Just the three most popular apps had estimated global download figures of a quarter of a billion in 2024. So-called femtech – digital products focused on women’s health and wellbeing – is estimated to reach over US$60 billion by 2027, with cycle tracking apps making up half of this market. With such intense demand for period tracking, the report argues that the UK’s National Health Service (NHS) should develop its own transparent and trustworthy app to rival those from private companies, with apps allowing permission for data to be used in valid medical research. “The UK is ideally positioned to solve the question of access to menstrual data for researchers, as well as privacy and data commodification concerns, by developing an NHS app to track menstrual cycles,” said Felsberger, who points out that Planned Parenthood in the US already has its own app, but the UK lacks an equivalent. “Apps that are situated within public healthcare systems, and not driven primarily by profit, will mitigate privacy violations, provide much-needed data on reproductive health, and give people more agency over how their menstrual data is used.” “The use of cycle tracking apps is at an all-time high,” said Prof Gina Neff, Executive Director of Cambridge’s Minderoo Centre. “Women deserve better than to have their menstrual tracking data treated as consumer data, but there is a different possible future.” “Researchers could use this data to help answer questions about women’s health. Care providers could use this data for important information about their patients’ health. Women could get meaningful insights that they are searching for,” Neff said. In the UK and EU, period tracking data is considered “special category”, as with that on genetics or ethnicity, and has more legal safeguarding. However, the report highlights how in the UK, apps designed for women's health have been used to charge women for illegally accessing abortion services In the US, data about menstrual cycles has been collected by officials in an attempt to undermine abortion access. Despite this, data from CTAs are regulated simply as “general wellness” and granted no special protections. “Menstrual tracking data is being used to control people’s reproductive lives,” said Felsberger. “It should not be left in the hands of private companies.” Investigations by media, non-profit, and consumer groups have revealed CTAs sharing data with third parties ranging from advertisers and data brokers to tech giants such as Facebook and Google. The report cites work published last month from Privacy International showing that, while the major CTA companies have updated their approach to data sharing, device information is still collected in the UK and US with “no meaningful consent”. Despite data protection improvements, the report suggests that user information is still shared with third parties such as cloud-based delivery networks that move the data around, and outside developers contracted to handle app functionalities. At the very least, commercial apps could include delete buttons, says Felsberger, allowing users to erase data in the app as well as the company servers, helping protect against situations – from legal to medical – where data could be used against them. “Menstrual tracking in the US should be classed as medical data,” said Felsberger. “In the UK and EU, where this data is already afforded special category status, more focus needs to be placed on enforcing existing regulation.” The report stresses the need to improve public awareness and digital literacy around period tracking. The researchers argue that schools should educate students on medical data apps and privacy, so young people are less vulnerable to health hoaxes. The report ‘The High Stakes of Tracking Menstruation’ is authored by Dr Stefanie Felsberger with a foreword by Professor Gina Neff and published by the Minderoo Centre for Technology and Democracy (MCTD). The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

NHS patients at Addenbrooke’s Hospital, Cambridge, will become the first in the UK and Europe to undergo incisionless ultrasound surgery using a cutting-edge ‘histotripsy machine’ as part of their cancer care. Through his longstanding support of cancer research at Cambridge, Sir Ka-shing Li continues to make a significant impact on outcomes for cancer patients Deborah Prentice, Vice-Chancellor The Edison Histotripsy System was purchased thanks to a generous donation to the University of Cambridge from Hong Kong-based philanthropist Sir Ka-shing Li, a longstanding supporter of cancer research at the University. Histotripsy uses pulsed sound waves to create ‘bubble clouds’ from gases present in targeted tissue. These bubble clouds form and collapse in microseconds, creating mechanical forces able to destroy tissue at cellular and sub-cellular levels while avoiding ionising energy of radiation, heat damage from thermal treatments, or the need for surgery. Treatment is delivered via a single short session – potentially taking no longer than 30 minutes – with limited or no pain, a quick recovery, and can be performed as a day case. The speed of delivery has the potential to reduce cancer treatment times, avoid disease progression and improve cancer survival. The system will be demonstrated today by Dr Teik Choon See, Consultant Interventional Radiologist at Cambridge University Hospitals NHS Foundation Trust (CUH). Guests will include Solina Chau, Director of the Li Ka Shing Foundation, and Baroness Merron, Parliamentary Under-Secretary of State at the Department of Health and Social Care (DHSC). The machine, manufactured by HistoSonics, is expected to be fully installed at CUH later this year, where it will be used initially to treat patients with primary and secondary liver tumours before being expanded to treat tumours in other organs. Previously, 23 patients from Europe were recruited in a histotripsy clinical trial that was completed in 2022. So far, over 1,500 patients worldwide have received treatment using histotripsy, mainly in the United States following approval by the US Food and Drug Administration in late 2023. The machine at Cambridge will be the first in the UK and Europe to treat patients as part of their clinical care pathway, outside the trial setting Professor Deborah Prentice, Vice-Chancellor of the University of Cambridge, said: “Through his longstanding support of cancer research at Cambridge, Sir Ka-shing Li continues to make a significant impact on outcomes for cancer patients. Cutting-edge technology such as this histotripsy machine allows Cambridge to remain at the forefront of understanding and treating cancer, a position we aim to strengthen further with Cambridge Cancer Research Hospital.” Roland Sinker, Chief Executive of CUH said: “Histotripsy is an exciting new technology that will make a huge difference to patients. By offering this non-invasive, more targeted treatment we can care for more people as outpatients and free up time for surgeons to treat more complex cases. The faster recovery times mean patients will be able to return to their normal lives more quickly, which will also reduce pressure on hospital beds, helping us ensure that patients are able to receive the right treatment at the right time. We are delighted to be receiving this new state of the art machine.” Fiona, who has lived with cancer for over two decades, is Co-Chair of the Patient Advisory Group for Cambridge Cancer Research Hospital, and has been involved in planning and designing the new hospital, said: “This is seriously good news. A new, non-invasive option to treat these cancers is very welcome indeed. For patients for whom ordinary surgery is no longer an option, this could make all the difference.” Health and Social Care Secretary Wes Streeting granted authorisation for controlled early access to the device via an unmet clinical need authorisation. Available through the UK’s Innovative Devices Access Pathway programme, this bypasses red tape to accelerate lengthy authorisation stages, so NHS patients benefit from it years earlier than planned. Wes Streeting said: “Bureaucracy has become a handbrake on ambition, stopping innovation in its tracks and holding our health service back. But through our Plan for Change, we are slashing red tape, so game-changing new treatments reach the NHS front line quicker – transforming healthcare. “Regulation is vital to protect patients. However, as the pace of innovation ramps up, our processes must be more agile to help speed the shift from analogue to digital. Our common-sense approach to regulation will streamline approval processes so countless more patients are liberated from life-limiting conditions.” Last year, an £11million donation was made in honour of Sir Ka-shing Li to support the now-renamed Li Ka Shing Early Cancer Institute. Sir Ka-shing Li has previously made generous donations to support cancer research at the University, including in 2007 to the Li Ka Shing Centre, which houses the CRUK Cambridge Institute. Cutting-edge technology such as the histotripsy machine will enable Cambridge Cancer Research Hospital, a partnership with Cambridge University Hospitals NHS Foundation Trust and the University of Cambridge, to change the story of cancer. The University and Addenbrooke's Charitable Trust (ACT) are fundraising for the new hospital, which will transform how we diagnose and treat cancer. The hospital will treat patients across the East of England, but the research that takes place there promises to change the lives of cancer patients across the UK and beyond. Find out more here. The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Whistleblowers can contact journalists more securely thanks to a new confidential and anonymous messaging technology co-developed by University of Cambridge researchers and software engineers at the Guardian. The Guardian has launched Secure Messaging as a module within its mobile news app to provide a secure and usable method of establishing initial contact between journalists and sources. It builds on a technology - CoverDrop –developed by Cambridge researchers and includes a wide range of security features. The code is available online and is open source, to encourage adoption by other news organisations. The app automatically generates regular decoy messages to the Guardian to create ‘air cover’ for genuine messages, even when they are passing through the cloud, preventing an adversary from finding out if any communication between a whistleblower and a journalist is taking place. “This provides whistleblowers with plausible deniability,” said Professor Alastair Beresford from Cambridge’s Department of Computer Science and Technology. “That’s important in a world of pervasive surveillance where it has become increasingly hazardous to be a whistleblower,” said Cambridge’s Dr Daniel Hugenroth, who co-led the development of CoverDrop with Beresford. The technology also provides digital ‘dead drops’ – like virtual bins or park benches – where messages are left for journalists to retrieve. These are just two of a suite of functions that protect a source from discovery even if their smartphone is seized or stolen. CoverDrop encrypts outgoing messages between the source and their named contact at the news organisation to ensure no other party can read their content. For this, it relies on cryptography using digital security key pairs consisting of a public and a secret key. The source is given the public key that instructs the existing encryption technology on their smartphone to encrypt their messages to the Guardian. This key only works one way, so it can lock – but not unlock – their messages. The only person able to decode them is the whistleblower’s named contact at the Guardian, who uses their secret key to retrieve and decode the messages left in the dead drop. CoverDrop also pads all messages to the same length, making it harder for adversaries – whether acting on their own behalf or for an organisation or state – to distinguish real messages from decoy ones. The system fulfils a need long identified by media organisations: providing a highly secure, yet easy-to-use, system for potential sources who want to contact them with sensitive information. “The Guardian is committed to public-interest journalism,” said Luke Hoyland, product manager for investigations and reporting at The Guardian. “Much of this is possible thanks to first-hand accounts from witnesses to wrongdoing. We believe whistleblowing is an important part of a functioning democracy and will always do our utmost to avoid putting sources at risk. So we're delighted to have worked with the University of Cambridge on turning their groundbreaking CoverDrop research into a reality.” The research began with workshops with UK news organisations to find out how potential sources first contacted them. The researchers learned that whistleblowers often reach out to them via platforms that are either insecure or hard to use. Beresford said that when they started looking for a practical solution to this problem, “we realised that news organisations already run a widely available platform from which they can offer a secure, usable method of initial contact – their mobile news app.” “When sources send messages, their confidentiality and integrity can be assured through the secure messaging protocols on their smartphone,” said Hugenroth. “CoverDrop goes one step further and also protects the communication patterns between sources and journalists by using decoy messages to provide cover and padding all messages to the same length.” Importantly, the researchers say, users of the new CoverDrop system won’t need to install any specialist software that chews up large amounts of battery power or slows down their phones. Its simple interface looks and works just like a typical messaging app. And there are no traces left on the device that the CoverDrop system has ever been used on that phone before. “When you open the app,” said Beresford, “even if you’ve already set up an account on it, the CoverDrop feature will look as though you haven’t used it. Its home screen will only offer two prompts – ‘Get started’ or ‘Check your message vault’. This is because if it’s stolen, or a user is under duress, we don’t want your phone to reveal to anyone that you’ve already used it.” The development of CoverDrop began in the years after the whistleblower Edward Snowden, a former US intelligence contractor, leaked classified documents revealing the existence of global surveillance programmes. This showed, the researchers said, the mass surveillance infrastructure available to nation states, which has profound implications for those who wish to expose wrongdoing within companies, organisations, and government. Work on CoverDrop was first unveiled at an international Symposium on Privacy-Enhancing Technologies in 2022 by the Cambridge researchers (who originally included the late Professor Ross Anderson, a leader in security engineering and privacy). When they published their peer-reviewed paper on the research at the conference, it attracted interest from the Guardian which, in collaboration with the researchers, subsequently helped develop CoverDrop from an academic prototype into a fully usable technology. “The free press fulfils an important function in a democracy,” said Beresford. “It can provide individuals with a mechanism through which they can hold powerful people and organisations to account. We’re delighted that the Guardian is the first media organisation to adopt CoverDrop and will use it to help protect their sources.” “All the CoverDrop code will be available online and open source,” said Hugenroth. “This transparency is essential for security-critical software and allows others to audit and improve it. Open-sourcing the code also means that other news organisations, particularly those with expertise in investigative journalism, could also use it. We would be excited to see them do so.” References: Mansoor Ahmed-Rengers et al. ‘CoverDrop: Blowing the Whistle Through A News App.’ Paper presented at the Privacy Enhancing Technologies Symposium. 12 July 2022, Sydney, Australia. DOI: 10.2478/popets-2022-0035 A new technical report on CoverDrop, describing its architecture and explaining how it works, is available at: www.coverdrop.org/coverdrop_guardian_implementation_june_2025.pdf The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Cambridge will join forces with Manchester as part of a pioneering collaboration to harness the combined strengths of both universities and cities – and boost innovation and growth for the whole of the UK This pioneering initiative brings together the combined strengths of Cambridge and Manchester to create something that is truly groundbreaking. Professor Deborah Prentice, Vice-Chancellor The Cambridge x Manchester Innovation Partnership – the first trans-UK innovation collaboration of its kind – will receive £4.8m of funding from Research England over three years, it has been announced. With further investment from the two universities, the total funding for the partnership will be £6m. The initiative aims to strengthen research networks, accelerate scale-up growth, drive private sector investment into R&D, and attract new foreign direct investment. Led by the universities of Cambridge and Manchester, ‘CBG×MCR’ is supported by two mayoral combined authorities, city councils, key businesses (such as AZ, ARM, ROKU, and Microsoft), venture capitalists (Northern Gritstone and CIC), and angel investors (Cambridge and Manchester Angels). As well as strengthening relations within and between the two cities, the partnership – fronted by Innovate Cambridge and Unit M – will pilot new approaches for delivering inclusive growth, providing insights to other cities, the wider higher education sector community, and local and national governments in the UK and internationally. In the UK, collaboration has traditionally been focused on geographically proximate areas, such as Manchester-Liverpool, or Edinburgh-Glasgow. This new model of hyper-connected, place-to-place partnering – similar to those developed in the US’ Northeast Corridor, Coastal California, and China’s Greater Bay Area – combines complementary innovation capabilities to create globally competitive connected ecosystems. Amplifying what each city can achieve independently, the model aims to drive national economic growth, responding directly to the UK government’s national industrial strategy. Professor Deborah Prentice, Vice-Chancellor of the University of Cambridge, said: “This pioneering initiative brings together the combined strengths of Cambridge and Manchester to create something that is truly groundbreaking. By connecting our cities, we’re helping to build a more collaborative and dynamic environment in which innovative research can connect with industry, venture capital, and entrepreneurs, to drive economic growth and deliver real benefits for people and places across the UK.” Paul Bristow, Mayor of Cambridgeshire and Peterborough, said: "This is exactly the kind of partnership working we need to fire up innovation-led growth in both our regions. I’m delighted to see it backed with new funding. By joining forces to drive the discoveries of tomorrow, we can bring in investment, support exciting new businesses, and deliver real jobs and opportunity for our communities." Professor Duncan Ivison, President and Vice-Chancellor at the University of Manchester, said: "Our partnership with Cambridge marks a new model of collaboration between UK universities. It brings together the distinctive strengths of each of our universities and cities, connecting two of the great innovation ecosystems to scale up what we can achieve. This new approach to innovation accelerates the time between discovery and impact, getting ideas into the real economy and our communities even more quickly to drive inclusive growth.” Jessica Corner, Executive Chair of Research England, said: “This investment underscores our commitment to fostering innovation and collaboration across England. By connecting the vibrant ecosystems of Cambridge and Manchester, we aim to drive significant economic growth and create a model for place-based innovation that can be replicated nationwide." The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

The Department for Science, Innovation and Technology (DSIT) has today announced the launch of the Spärck AI Scholarships, a major new initiative to nurture the next generation of AI leaders, with Cambridge University proud to join as a founding partner. We are delighted to be a founding partner in this ambitious initiative, which reflects a shared commitment to attracting exceptional talent and reinforcing the UK’s position as a home for world-class AI. Professor Deborah Prentice, University of Cambridge Vice-Chancellor, The scholarships, aimed at exceptionally high-potential domestic and international students, will support study towards AI-related Masters degrees and provide an unparalleled package of benefits. Students will receive full tuition fees, a living stipend, and access to priority work placements with leading UK AI companies and government institutions. The programme, which will open to its first cohort in the 2026/27 academic year, intends to enrol 100 scholars over its first four years. Scholars will be selected from the top 1% of AI talent worldwide, with applicants required to demonstrate academic excellence, leadership, and ambassadorial potential, alongside a STEM background. Uniquely, the Spärck AI Scholarships will provide its students with priority access to work placements within UK-based AI companies and organisations, including the UK government’s AI Security Institute (AISI) and i.AI, their in-house AI incubator. The scholarships are named in honour of Professor Karen Spärck Jones (1935–2007), a pioneering British computer scientist whose ground breaking work at Cambridge University laid the foundations for modern search engines and natural language processing. One of the most remarkable women in computer science, her seminal 1972 paper introduced the concept of inverse document frequency (IDF), a fundamental principle still central to information retrieval today. karen_sparck.jpg Professor Deborah Prentice, University of Cambridge Vice-Chancellor, said: “Cambridge combines academic excellence with a dynamic, interdisciplinary AI community, from foundational research to real-world impact. We are delighted to be a founding partner in this ambitious initiative, which reflects a shared commitment to attracting exceptional talent and reinforcing the UK’s position as a home for world-class AI. We are especially proud that these scholarships are named after Karen Spärck Jones, a brilliant Cambridge computer scientist.” A long-time valued member of the Cambridge community, Professor Spärck Jones was an undergraduate at Girton College (1953-1956), a Research Fellow at Newnham College (1965-1968), an Official Fellow of Darwin College (1968-1980) and a Fellow of Wolfson College (2000-2007). She began her research career at the Cambridge Language Research Unit in the late 1950s and later taught for the MPhil in Computer Speech and Language Processing, on language systems, and for the Computer Science Tripos on information retrieval. She supervised many Cambridge PhD students across a wide range of topics and was a tireless advocate for women in computing, famously declaring: “I think it's very important to get more women into computing. My slogan is: Computing is too important to be left to men.” Her international influence was recognised by numerous awards, including the ACM SIGIR Salton Award, the BCS Lovelace Medal, and election as a Fellow of the British Academy (of which she was also Vice-President from 2000 to 2002) and the American Association for Artificial Intelligence. The University of Cambridge is delighted to honour her legacy by co-founding this exciting new programme, which was formally announced today at London Tech Week. The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Professor George Efstathiou has been awarded the Shaw Prize in Astronomy, one of the biggest prizes in the field. Efstathiou, Emeritus Professor of Astrophysics (1909) at Cambridge’s Institute of Astronomy, shares the prize with Professor John Richard Bond from the Canadian Institute for Theoretical Astrophysics and the University of Toronto. They were recognised for their pioneering research in cosmology, in particular for their studies of fluctuations in the cosmic microwave background. Their predictions have been verified by an armada of ground-, balloon- and space-based instruments, leading to precise determinations of the age, geometry, and mass-energy content of the universe. Cosmology has undergone a revolution in the past two decades, driven mainly by increasingly precise measurements of the angular power spectrum of fluctuations in the temperature and polarisation fields of the cosmic microwave background, a relic of the early universe, most notably by NASA’s Wilkinson Microwave Anisotropy Probe spacecraft (2001–2010) and the European Space Agency’s Planck spacecraft (2009–2013). These fluctuations are small — the strength of the background radiation is the same in all directions to better than 0.01% and it is only slightly polarised — but they offer a glimpse of the universe when it was very young, a test of many aspects of fundamental physics, insights into the nature of dark matter and dark energy, and measurements of many fundamental cosmological parameters with accuracies unimaginable to cosmologists a few decades ago. Although many researchers contributed to the development of the theoretical framework that governs the behaviour of the cosmic microwave background, Bond and Efstathiou emphasised the importance of the background as a cosmological probe and took the crucial step of making precise predictions for what can be learned from specific models of the history and the composition of the mass and energy in the universe. Modern numerical codes used to interpret the experimental results are based almost entirely on the physics developed by Bond and Efstathiou. Their work exemplifies one of the rare cases in astrophysics where later experimental studies accurately confirmed unambiguous, powerful theoretical predictions. The interpretation of these experiments through Bond and Efstathiou’s theoretical models shows that the spatial geometry of the observable universe is nearly flat, and yields the age of the universe with a precision of 0.15%, the rate of expansion of the universe with a precision of 0.5%, the fraction of the critical density arising from dark energy to better than 1%, and so on. The measurements also strongly constrain theories of the early universe that might have provided the initial “seed” for all the cosmic structure we see today, and the nature of the dark matter and dark energy that dominate the mass-energy content of the universe. Both Bond and Efstathiou have worked closely with experimentalists to bring their predictions to the test: they have been heavily involved in the analysis of cosmic microwave background data arising from a wide variety of experiments of growing sophistication and accuracy. George Efstathiou received his BA in Physics from the University of Oxford and PhD in Astronomy from Durham University. He has held postdoctoral fellowships at the University of California, Berkeley, USA and the University of Cambridge. He was Savilian Professor of Astrophysics at Oxford, where he served as Head of Astrophysics until 1994. He returned to Cambridge in 1997 as Professor of Astrophysics, where he also served as Director of the Institute of Astronomy and the first Director of the Kavli Institute for Cosmology. He received the 2022 Gold Medal of the Royal Astronomical Society. He is a Fellow of the Royal Society of London and the Royal Astronomical Society, UK. He is a Fellow of King’s College, Cambridge. Originally published on the Shaw Prize website. The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.