̽��ֱ�� of Cambridge - Centre for Theoretical Cosmology

New findings that map the universe’s cosmic growth support Einstein’s theory of gravity

sc604 — Tue, 11 Apr 2023 14:00:00 +0000

̽��ֱ��findings, from the Atacama Cosmology Telescope collaboration involving researchers from the ̽��ֱ�� of Cambridge, provide further support to Einstein’s theory of general relativity, which has been the foundation of the standard model of cosmology for more than a century. ̽��ֱ��results offer new methods to demystify dark matter, the unseen mass thought to account for 85% of the matter in the universe.

For millennia, humans have been fascinated by the mysteries of the cosmos. From ancient civilisations such as the Babylonians, Greeks, and Egyptians to modern-day astronomers, the allure of the starry sky has inspired countless quests to unravel the secrets of the universe.

And although models that explain the cosmos have existed for centuries, the field of cosmology, where scientists use quantitative methods to understand the evolution and structure of the universe, is relatively new—having only formed in the early 20th century with the development of Albert Einstein’s theory of general relativity.

Now, a set of papers submitted to ̽��ֱ��Astrophysical Journal by researchers from the Atacama Cosmology Telescope (ACT) collaboration has produced a new image that reveals the most detailed map of matter distributed across a quarter of the entire sky, reaching deep into the cosmos. It confirms Einstein’s theory about how massive structures grow and bend light, with a test that spans the entire age of the universe.

“We have mapped the invisible dark matter across the sky to the largest distances, and clearly see features of this invisible world that are hundreds of millions of light-years across,” said co-author Professor Blake Sherwin from Cambridge’s Department of Applied Mathematics and Theoretical Physics, where he leads a group of ACT researchers. “It looks just as our theories predict.”

Although dark matter makes up a large chunk of the universe and shaped its evolution, it has remained hard to detect because it doesn’t interact with light or other forms of electromagnetic radiation. As far as we know, dark matter only interacts with gravity.

To track it down, the more than 160 collaborators who have built and gathered data from the National Science Foundation’s Atacama Cosmology Telescope in the high Chilean Andes observe light emanating following the dawn of the universe’s formation, the Big Bang—when the universe was only 380,000 years old. Cosmologists often refer to this diffuse light that fills our entire universe as the “baby picture of the universe,” but formally, it is known as the cosmic microwave background radiation (CMB).

̽��ֱ��team tracks how the gravitational pull of large, heavy structures including dark matter warps the CMB on its 14-billion year journey to us, like how a magnifying glass bends light as it passes through its lens.

“We’ve made a new mass map using distortions of light left over from the Big Bang,” said Mathew Madhavacheril from the ̽��ֱ�� of Pennsylvania, lead author of one of the papers. “Remarkably, it provides measurements that show that both the ‘lumpiness’ of the universe, and the rate at which it is growing after 14 billion years of evolution, are just what you’d expect from our standard model of cosmology based on Einstein's theory of gravity.”

“Our results also provide new insights into an ongoing debate some have called ‘ ̽��ֱ��Crisis in Cosmology’,” said Sherwin. This crisis stems from recent measurements that use a different background light, one emitted from stars in galaxies rather than the CMB. These have produced results that suggest the dark matter was not lumpy enough under the standard model of cosmology and led to concerns that the model may be broken. However, the team’s latest results from ACT were able to precisely assess that the vast lumps seen in this image are the exact right size.

“When I first saw them, our measurements were in such good agreement with the underlying theory that it took me a moment to process the results,” said Cambridge PhD candidate Frank Qu, lead author of one of the new papers. “But we still don’t know what the dark matter is, so it will be interesting to see how this possible discrepancy between different measurements will be resolved.”

“ ̽��ֱ��CMB lensing data rivals more conventional surveys of the visible light from galaxies in their ability to trace the sum of what is out there,” said Suzanne Staggs from Princeton ̽��ֱ��, Director of ACT. “Together, the CMB lensing and the best optical surveys are clarifying the evolution of all the mass in the universe.”

“When we proposed this experiment in 2003, this measurement wasn’t even on our agenda; we had no idea the full extent of information that could be extracted from our telescope,” said Mark Devlin, from the ̽��ֱ�� of Pennsylvania, Deputy Director of ACT. “We owe this to the cleverness of the theorists, the many people who built new instruments to make our telescope more sensitive, and the new analysis techniques our team came up with.”

With ACT having been decommissioned in late 2022, further papers highlighting some of the other final results are slated for submission in the coming year. Observations will continue at the site with the Simons Observatory, including a new telescope due to begin in 2024 that can map the sky almost ten times faster.

̽��ֱ��pre-print articles highlighted in this release are available on act.princeton.edu and will appear on the open-access arXiv.org. They have been submitted to ̽��ֱ��Astrophysical Journal.

This work was supported by the U.S. National Science Foundation, Princeton ̽��ֱ��, the ̽��ֱ�� of Pennsylvania, and a Canada Foundation for Innovation award. Team members at the ̽��ֱ�� of Cambridge were supported by the European Research Council.

A new image reveals the most detailed map of dark matter distributed across a quarter of the entire sky, reaching deep into the cosmos.

We have mapped the invisible dark matter across the sky to the largest distances, and clearly see features of this invisible world that are hundreds of millions of light-years across

Blake Sherwin

ACT Collaboration

A new map of the dark matter made by the Atacama Cosmology Telescope. ̽��ֱ��orange regions show where there is more mass; purple where there is less.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, 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.

Yes

Hawking Centre for Theoretical Cosmology named Intel oneAPI Center of Excellence

Anonymous — Tue, 26 Oct 2021 04:00:00 +0000

̽��ֱ��oneAPI Center of Excellence will focus on advancing cosmological research, open-source code development, and in situ compute and visualisation, as well as teaching computational and visualisation coding techniques.

̽��ֱ��Centre for Theoretical Cosmology was established by Professor Stephen Hawking in 2007 within the Department of Applied Mathematics and Theoretical Physics. It exists to advance the scientific understanding of our universe, developing and testing mathematical theories for cosmology and black holes.

Over the past six years, Hawking CTC Director Professor Paul Shellard and the COSMOS computing team have collaborated with Intel on developing and optimising several codes with many simulations and visualization results for cosmology study. This includes areas such as the analysis of the Cosmic Microwave Background (CMB), simulations of Einstein’s General Relativity and the creation of gravitational waves during black hole or boson star collisions, and by cosmic string networks.

̽��ֱ��COSMOS team, its work and computational and visualisation discoveries together with Intel were documented in the Discovery+ “UNIVERSE UNRAVELED” series currently available in select countries, including the UK.

A major goal of the Hawking CTC is to continue Professor Hawking’s vision of confronting our models of the Universe with the latest observations to reveal deep connections between quantum and galactic scales, while explaining such discoveries in ways understandable by everyone. Hawking recognised that this high-precision data and our complex theories can only touch each other using powerful computers.

“We are honoured to be among the vanguard of institutions chosen to be an Intel oneAPI Center of Excellence, ensuring we build on our longstanding collaboration on in situ visualisation and code modernisation as we prepare to study the Universe at exascale,” said Shellard. “We’re committed to flexible platform-independent programming paradigms so that we can do more with fewer people, focusing on trying out new ideas and new algorithms for our cosmology workflows. ̽��ֱ��oneAPI development tools offer us a fast pathway on to the widest range of HPC architectures, especially the latest GPU accelerators, so we can respond to the flood of new cosmological data sooner.”

“Intel is pleased to extend the highly impactful work done by the Hawking CTC Intel Graphics and Visualization Institute by adding the centre to our growing family of Intel oneAPI Centers of Excellence,” said Jim Jeffers, senior principal engineer and senior director of Intel Advanced Rendering and Visualization. “As part of this program, the Hawking CTC can take full advantage of state-of-the-art software development tools and advanced CPUs and GPUs to break new ground in understanding our universe. This honours the legacy of Stephen Hawking and his passion, vision, and goal to answer the ultimate questions of our existence, our past and our future.”

̽��ֱ��Stephen Hawking Centre for Theoretical Cosmology (Hawking CTC) at the ̽��ֱ�� of Cambridge is expanding its Intel Graphics and Visualization Institute of Xellence (Intel GVI) to an Intel oneAPI Center of Excellence, which will help expand our understanding of the universe.

Amelia Drew (CTC, ̽��ֱ�� of Cambridge) and Carson Brownlee (Intel Advanced Visualisation and Rendering)

Visualisation of radiation from a cosmic string network created with the help of the Intel oneAPI Rendering Toolkit.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, 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.

Yes

Universe unravelled: Stephen Hawking Centre collaborates on new streaming series

sc604 — Fri, 13 Nov 2020 10:51:13 +0000

̽��ֱ��Universe Unravelled series premieres on Discovery+ in November 2020, coinciding with the UK launch of this new digital platform. ̽��ֱ��series is aimed at anyone who is curious about the Universe we live in, with no previous knowledge of cosmology required. Across more than 20 short episodes, the series explores what we already know about the Universe, what cosmologists and relativists are working on right now, and where new observations may lead in the future.

̽��ֱ��programme is inspired by the late Stephen Hawking’s ground-breaking work on cosmology, black holes and gravitational waves, and features researchers from the Hawking Centre for Theoretical Cosmology (CTC) and the Kavli Institute for Cosmology at the ̽��ֱ�� of Cambridge.

̽��ֱ��series explores the big questions in contemporary research which are being driven by new observations, such as the recent discovery of gravitational waves. It starts with Einstein’s general theory of relativity, describing how massive objects warp the fabric of spacetime and how they can collapse under their own gravity to form black holes. It explores how these black holes can send gravitational waves rippling across spacetime, and what happens if you were to fall into a black hole.

̽��ֱ��series also describes the violent explosion that marked the beginning of our Universe, and how the Universe expanded from this initial Big Bang, forming all the structures we observe today – galaxies, stars and planets. It then probes the mysteries that still puzzle cosmologists, such as dark energy and dark matter. ̽��ֱ��series ends with a future outlook of what we might expect to learn from ambitious new observational programmes. All the basic concepts underlying are presented in an easily accessible manner, and it features stunning graphics, some produced in collaboration with Intel’s Advanced Visualization team.

̽��ֱ��series features CTC and Kavli researchers explaining these remarkable concepts. It offers a glimpse of what it’s like to work at the cutting edge of cosmology: confronting sophisticated mathematics with observational data, employing some of the world’s fastest supercomputers, and even daring to challenge Einstein's highly successful theory in an attempt to explain what has so far defied explanation. Viewers not only learn about the deepest secrets of our Universe, but also find out about the everyday life of students and staff at a world-leading research centre.

̽��ֱ��collaboration between Discovery and the CTC started in 2010. A highlight was Discovery live-streaming Stephen Hawking's 75th birthday symposium which was a huge success watched by millions, especially among younger members of their audience.

̽��ֱ��series was filmed at the Centre for Mathematical Sciences and the Institute of Astronomy and produced with the help of science editors from Plus magazine, part of the ̽��ֱ��’s Millennium Mathematics Project outreach programme.

̽��ֱ��CTC team worked closely with Navada Studios, who were responsible for the video production, with editorial oversight from Discovery producers. Funding for the project was provided by the Kavli Foundation, an organisation dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research, and supporting scientists and their work.

“We are grateful to Discovery and the Kavli Foundation for supporting this unique opportunity to continue Stephen Hawking’s vision of reaching out, especially to younger audiences, to inspire curiosity about our Universe and the huge progress currently being made to unveil its secrets,” said Paul Shellard, CTC Director. “This was a remarkable collaboration in which we were able to work closely with the production team, ensuring both viewer interest and scientific accuracy, which we hope provides a great model for future science outreach.”

̽��ֱ��series is available on the new Discovery+ service that can be found at discoveryplus.co.uk, together with a short trailer. To find out more about the Hawking Centre, visit ctc.cam.ac.uk.

̽��ֱ��Stephen Hawking Centre for Theoretical Cosmology has teamed up with Discovery on a documentary series exploring new windows on our Universe.

We are grateful for this unique opportunity to continue Stephen Hawking’s vision of reaching out, especially to younger audiences, to inspire curiosity about our Universe and the huge progress currently being made to unveil its secrets

Paul Shellard

Discovery+

Universe Unravelled

Yes

Women in STEM: Amelia Drew

sc604 — Thu, 10 Oct 2019 06:00:00 +0000

My parents are lawyers, and as far as I know there aren’t any other scientists in my family. I was really interested in maths, physics and biology at school, so I applied to Cambridge intending to study biology within the Natural Sciences Tripos. However, when I arrived I decided I preferred the physics course, so I switched!

My research sets out to determine potential observational signatures from cosmic and axion strings. Cosmic and axion strings are hypothetical cosmological objects that may have formed as a result of a phase transition in the early universe. An example of a phase transition in more familiar terms is the example of water freezing to ice. ̽��ֱ��so-called 'axions' emitted by axion strings are also a hypothetical dark matter candidate, where dark matter is a theoretical type of matter that makes up around 85% of the total matter in the universe. ̽��ֱ��detection of these strings would significantly enhance our understanding of the universe and fundamental physics.

On a daily basis, I am usually coding up and running simulations in my office. This involves developing and compiling highly parallelised code, which I run on powerful supercomputers. I then analyse my results to see if they fit with expected theoretical models. Outside my PhD work, I attend several seminars per week and also supervise undergraduate Natural Science students.

One of the most exciting things about working in my department has been meeting so many distinguished physicists and mathematicians. Working in such close proximity to Stephen Hawking was definitely a highlight, as he was such an inspiration to me and so many other students and scientists. ̽��ֱ��most rewarding aspect of studying theoretical physics at Cambridge is the high standard of the research. Cambridge has a prestigious reputation, and the quality of the research is world-class. In my department, the Centre for Theoretical Cosmology, there is a lot of technical support available, as well as funding to enable students to travel to schools and conferences abroad. ̽��ֱ��department also has around 30-40 PhD students, making it a very sociable place to study.

It can be easy in the early days of a PhD to feel isolated from others working in your field, or not to be aware of them at all. Towards the end of my first year, I attended a two-week summer school in Spain on gravitational radiation. This really opened my eyes to the research being carried out by students all over Europe and allowed me to put my research into a wider context.

Pursue your passion, regardless of whether others in the field intimidate you or try to put you off. It can often be overwhelming being in an environment that is so male-dominated, which is especially the case in maths, physics and computing. Make sure to remind yourself that you have as much right to be there as anybody else. If science is what you want to do, go for it!

Amelia Drew is a PhD candidate in the Department of Applied Mathematics and Theoretical Physics. Here, she tells us about dark matter, being the only scientist in the family, and how to avoid feeling isolated during a PhD.

Tobias Baldauf

Amelia Drew

Yes

Women in STEM: Dr Cora Uhlemann

sc604 — Thu, 27 Jun 2019 07:00:00 +0000

I am fascinated by the physics of the Universe across the largest scales. I am a theoretical physicist by training and specialise in theoretical and mathematical physics. I was awarded a PhD in Theoretical Cosmology from LMU Munich. I spent two years as a Research Associate at Utrecht ̽��ֱ�� before moving to Cambridge, and am now a Research Associate at the Stephen Hawking Centre for Theoretical Cosmology and a Junior Research Fellow at Fitzwilliam College.

I am embedded in an active and diverse community - from applied mathematics to astrophysics and astronomy. Since I am applying methods from different fields of physics and mathematics to problems in cosmology, it’s invaluable to be among experts in all kind of areas. I also find it quite stimulating to be surrounded by so many smart and motivated young researchers.

My research aims at understanding the cosmic web - the skeleton of matter in our Universe. With large telescopes, we can see this cosmic web as an intricate pattern of galaxies on the sky. I’m trying to describe how those structures were formed. This is particularly interesting because we know that there were virtually no structures in the early universe. If we look at the afterglow of the Big Bang, the so-called cosmic microwave background, we observe that the matter was evenly distributed across the universe with tiny deviations of 10 parts in a million.

My research can feel a bit like detective work. We are trying to unveil what drives the evolution of our universe and determines its fate from a couple of key observations. I find it fascinating to look for models that can describe almost 13 billion years of cosmic history. Since I am a theorist, I spend a large part of my day thinking, reading and calculating. Thanks to the active scientific life at DAMTP, almost all of my days include listening to seminars or colloquia talks and chatting to my colleagues from a lot of different fields of theoretical physics. When I am not travelling, I usually work either in the Centre for Mathematical Sciences or in Fitzwilliam College.

My favourite project is describing galaxy clustering using number counts. What I find so fascinating is that there are certain clustering statistics that contain a lot of information and can still be predicted accurately. This situation is quite remarkable because in general, it is hard to make good predictions for gravitational clustering where initially small deviations from mean density are amplified (making the system highly nonlinear). As a theoretical physicist, I love to look for ’smart’ observables that can be calculated from first principles and provide an accurate description of observations in the real world.

In 2016 I spent an incredibly inspiring week with more than 30 Nobel Laureates. This was the Lindau Nobel Laureate Meeting in Physics, attended by more than 400 young participants. And as if that wasn't thrilling enough, I also had the opportunity to present part of my PhD research in a plenary talk at the Bavarian evening. It was certainly a dare to give a scientific talk in a dirndl in front of so many people, but it sparked great discussions and I am happy I got this chance.

My advice to everyone is to follow your interests and strive to achieve your own goals. Find people who don’t push you around but push you forward. Seize the opportunities and don’t give up too easily. Explore, enjoy and try to make yourself comfortable outside your current comfort zone.

Dr Cora Uhlemann is a postdoctoral researcher in the Department of Applied Mathematics and Theoretical Physics, where she studies the cosmic web: the 'skeleton' of matter in our Universe. Here, she talks about the Big Bang, spending time with Nobel Laureates, and presenting her research in a dirndl.

Yes

Taming the multiverse: Stephen Hawking’s final theory about the big bang

sc604 — Wed, 02 May 2018 10:47:29 +0000

̽��ֱ��theory, which was submitted for publication before Hawking’s death earlier this year, is based on string theory and predicts the universe is finite and far simpler than many current theories about the big bang say.

Professor Hertog, whose work has been supported by the European Research Council, first announced the new theory at a conference at the ̽��ֱ�� of Cambridge in July of last year, organised on the occasion of Professor Hawking’s 75^th birthday.

Modern theories of the big bang predict that our local universe came into existence with a brief burst of inflation – in other words, a tiny fraction of a second after the big bang itself, the universe expanded at an exponential rate. It is widely believed, however, that once inflation starts, there are regions where it never stops. It is thought that quantum effects can keep inflation going forever in some regions of the universe so that globally, inflation is eternal. ̽��ֱ��observable part of our universe would then be just a hospitable pocket universe, a region in which inflation has ended and stars and galaxies formed.

“ ̽��ֱ��usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes, separated by an inflating ocean,” said Hawking in an interview last autumn. “ ̽��ֱ��local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse. But I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory can’t be tested. ”

In their new paper, Hawking and Hertog say this account of eternal inflation as a theory of the big bang is wrong. “ ̽��ֱ��problem with the usual account of eternal inflation is that it assumes an existing background universe that evolves according to Einstein’s theory of general relativity and treats the quantum effects as small fluctuations around this,” said Hertog. “However, the dynamics of eternal inflation wipes out the separation between classical and quantum physics. As a consequence, Einstein’s theory breaks down in eternal inflation.”

“We predict that our universe, on the largest scales, is reasonably smooth and globally finite. So it is not a fractal structure,” said Hawking.

̽��ֱ��theory of eternal inflation that Hawking and Hertog put forward is based on string theory: a branch of theoretical physics that attempts to reconcile gravity and general relativity with quantum physics, in part by describing the fundamental constituents of the universe as tiny vibrating strings. Their approach uses the string theory concept of holography, which postulates that the universe is a large and complex hologram: physical reality in certain 3D spaces can be mathematically reduced to 2D projections on a surface.

Hawking and Hertog developed a variation of this concept of holography to project out the time dimension in eternal inflation. This enabled them to describe eternal inflation without having to rely on Einstein’ theory. In the new theory, eternal inflation is reduced to a timeless state defined on a spatial surface at the beginning of time.

“When we trace the evolution of our universe backwards in time, at some point we arrive at the threshold of eternal inflation, where our familiar notion of time ceases to have any meaning,” said Hertog.

Hawking’s earlier ‘no boundary theory’ predicted that if you go back in time to the beginning of the universe, the universe shrinks and closes off like a sphere, but this new theory represents a step away from the earlier work. “Now we’re saying that there is a boundary in our past,” said Hertog.

Hertog and Hawking used their new theory to derive more reliable predictions about the global structure of the universe. They predicted the universe that emerges from eternal inflation on the past boundary is finite and far simpler than the infinite fractal structure predicted by the old theory of eternal inflation.

Their results, if confirmed by further work, would have far-reaching implications for the multiverse paradigm. “We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes,” said Hawking.

This makes the theory more predictive and testable.

Hertog now plans to study the implications of the new theory on smaller scales that are within reach of our space telescopes. He believes that primordial gravitational waves – ripples in spacetime – generated at the exit from eternal inflation constitute the most promising “smoking gun” to test the model. ̽��ֱ��expansion of our universe since the beginning means such gravitational waves would have very long wavelengths, outside the range of the current LIGO detectors. But they might be heard by the planned European space-based gravitational wave observatory, LISA, or seen in future experiments measuring the cosmic microwave background.

Reference:
S.W. Hawking and Thomas Hertog. ‘A Smooth Exit from Eternal Inflation?’’ Journal of High-Energy Physics (2018). DOI: 10.1007/JHEP04(2018)147

Professor Stephen Hawking’s final theory on the origin of the universe, which he worked on in collaboration with Professor Thomas Hertog from KU Leuven, has been published in the Journal of High Energy Physics.

We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes.

Stephen Hawking

Andre Pattenden

Stephen Hawking

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Professor Stephen Hawking 1942-2018

sc604 — Wed, 14 Mar 2018 04:57:48 +0000

Widely regarded as one of the world’s most brilliant minds, he was known throughout the world for his contributions to science, his books, his television appearances, his lectures and through biographical films. He leaves three children and three grandchildren.

Professor Hawking broke new ground on the basic laws which govern the universe, including the revelation that black holes have a temperature and produce radiation, now known as Hawking radiation. At the same time, he also sought to explain many of these complex scientific ideas to a wider audience through popular books, most notably his bestseller A Brief History of Time.

He was awarded the CBE in 1982, was made a Companion of Honour in 1989, and was awarded the US Presidential Medal of Freedom in 2009. He was the recipient of numerous awards, medals and prizes, including the Copley Medal of the Royal Society, the Albert Einstein Award, the Gold Medal of the Royal Astronomical Society, the Fundamental Physics Prize, and the BBVA Foundation Frontiers of Knowledge Award for Basic Sciences. He was a Fellow of ̽��ֱ��Royal Society, a Member of the Pontifical Academy of Sciences, and a Member of the US National Academy of Sciences.

He achieved all this despite a decades-long battle motor neurone disease, with which he was diagnosed while a student, and eventually led to him being confined to a wheelchair and to communicating via his instantly recognisable computerised voice. His determination in battling with his condition made him a champion for those with a disability around the world.

Professor Hawking came to Cambridge in 1962 as a PhD student and rose to become the Lucasian Professor of Mathematics, a position once held by Isaac Newton, in 1979. In 2009, he retired from this position and was the Dennis Stanton Avery and Sally Tsui Wong-Avery Director of Research in the Department of Applied Mathematics and Theoretical Physics until his death - he was also a member of the ̽��ֱ��'s Centre for Theoretical Cosmology, which he founded in 2007. He was active scientifically and in the media until the end of his life.

Professor Stephen Toope, Vice-Chancellor of the ̽��ֱ�� of Cambridge, paid tribute, saying, “Professor Hawking was a unique individual who will be remembered with warmth and affection not only in Cambridge but all over the world. His exceptional contributions to scientific knowledge and the popularisation of science and mathematics have left an indelible legacy. His character was an inspiration to millions. He will be much missed.”

Stephen William Hawking was born on January 8, 1942 in Oxford although his family was living in north London at the time. In 1959, the family moved to St Albans where he attended St Albans School. Despite the fact that he was always ranked at the lower end of his class by teachers, his school friends nicknamed him ‘Einstein’ and seemed to have encouraged his interest in science. In his own words, “physics and astronomy offered the hope of understanding where we came from and why we are here. I wanted to fathom the depths of the Universe.”

His ambition brought him a scholarship to ̽��ֱ�� College Oxford to read Natural Science.There he studied physics and graduated with a first class honours degree.

He then moved to Trinity Hall Cambridge and was supervised by Dennis Sciama at the Department of Applied Mathematics and Theoretical Physics for his PhD; his thesis was titled ‘Properties of Expanding Universes.’ In 2017, he made his PhD thesis freely available online via the ̽��ֱ�� of Cambridge’s Open Access repository. There have been over a million attempts to download the thesis, demonstrating the enduring popularity of Professor Hawking and his academic legacy.

On completion of his PhD, he became a research fellow at Gonville and Caius College where he remained a fellow for the rest of his life. During his early years at Cambridge, he was influenced by Roger Penrose and developed the singularity theorems which show that the Universe began with the Big Bang.

An interest in singularities naturally led to an interest in black holes and his subsequent work in this area laid the foundations for the modern understanding of black holes. He proved that when black holes merge, the surface area of the final black hole must exceed the sum of the areas of the initial black holes, and he showed that this places limits on the amount of energy that can be carried away by gravitational waves in such a merger. He found that there were parallels to be drawn between the laws of thermodynamics and the behaviour of black holes. This eventually led, in 1974, to the revelation that black holes have a temperature and produce radiation, now known as Hawking radiation, a discovery which revolutionised theoretical physics.

He also realised that black holes must have an entropy – often described as a measure of how much disorder is present in a given system – equal to one quarter of the area of their event horizon: – the ‘point of no return’, where the gravitational pull of a black hole becomes so strong that escape is impossible. Some forty-odd years later, the precise nature of this entropy is still a puzzle. However, these discoveries led to Hawking formulating the ‘information paradox’ which illustrates a fundamental conflict between quantum mechanics and our understanding of gravitational physics. This is probably the greatest mystery facing theoretical physicists today.

To understand black holes and cosmology requires one to develop a theory of quantum gravity. Quantum gravity is an unfinished project which is attempting to unify general relativity, the theory of gravitation and of space and time with the ideas of quantum mechanics. Hawking’s work on black holes started a new chapter in this quest and most of his subsequent achievements centred on these ideas. Hawking recognised that quantum mechanical effects in the very early universe might provide the primordial gravitational seeds around which galaxies and other large-scale structures could later form. This theory of inflationary fluctuations, developed along with others in the early 1980’s, is now supported by strong experimental evidence from the COBE, WMAP and Planck satellite observations of the cosmic microwave sky. Another influential idea was Hawking’s ‘no boundary’ proposal which resulted from the application of quantum mechanics to the entire universe. This idea allows one to explain the creation of the universe in a way that is compatible with laws of physics as we currently understand them.

Professor Hawking’s influential books included ̽��ֱ��Large Scale Structure of Spacetime, with G F R Ellis; General Relativity: an Einstein centenary survey, with W Israel; Superspace and Supergravity, with M Rocek (1981); ̽��ֱ��Very Early Universe, with G Gibbons and S Siklos, and 300 Years of Gravitation, with W Israel.

However, it was his popular science books which took Professor Hawking beyond the academic world and made him a household name. ̽��ֱ��first of these, A Brief History of Time, was published in 1988 and became a surprise bestseller, remaining on the Sunday Times best-seller list for a record-breaking 237 weeks. Later popular books included Black Holes and Baby Universes, ̽��ֱ��Universe in a Nutshell, A Briefer History of Time, and My Brief History. He also collaborated with his daughter Lucy on a series of books for children about a character named George who has adventures in space.

In 2014, a film of his life, ̽��ֱ��Theory of Everything, was released. Based on the book by his first wife Jane, the film follows the story of their life together, from first meeting in Cambridge in 1964, with his subsequent academic successes and his increasing disability. ̽��ֱ��film was met with worldwide acclaim and Eddie Redmayne, who played Stephen Hawking, won the Academy Award for Best Actor at the 2015 ceremony.

Travel was one of Professor Hawking’s pastimes. One of his first adventures was to be caught up in the 7.1 magnitude Bou-in-Zahra earthquake in Iran in 1962. In 1997 he visited the Antarctic. He has plumbed the depths in a submarine and in 2007 he experienced weightlessness during a zero-gravity flight, routine training for astronauts. On his return, he quipped “Space, here I come.”

Writing years later on his website, Professor Hawking said: “I have had motor neurone disease for practically all my adult life. Yet it has not prevented me from having a very attractive family and being successful in my work. I have been lucky that my condition has progressed more slowly than is often the case. But it shows that one need not lose hope.”

At a conference In Cambridge held in celebration of his 75th birthday in 2017, Professor Hawking said “It has been a glorious time to be alive and doing research into theoretical physics. Our picture of the Universe has changed a great deal in the last 50 years, and I’m happy if I’ve made a small contribution.”

And he said he wanted others to feel the passion he has for understanding the universal laws that govern us all. “I want to share my excitement and enthusiasm about this quest. So remember to look up at the stars and not down at your feet. Try to make sense of what you see and wonder about what makes the universe exist. Be curious, and however difficult life may seem, there is always something you can do, and succeed at. It matters that you don’t just give up.”

Friends and colleagues from the ̽��ֱ�� of Cambridge have paid tribute to Professor Stephen Hawking, who died on 14 March 2018 at the age of 76.

Professor Stephen Hawking 1942 - 2018

Graham CopeKoga/Cambridge ̽��ֱ�� Library

Stephen Hawking pictured with Newton's own annotated copy Principia Mathematica as part of Cambridge ̽��ֱ�� Library's 600th anniversary.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Cambridge celebrates Stephen Hawking’s 75th birthday

sc604 — Mon, 03 Jul 2017 12:11:41 +0000

̽��ֱ��event, on the theme of Gravity and Black Holes and organised by the Centre for Theoretical Cosmology where Professor Hawking is based, featured public lectures from Professors Brian Cox, Gabriela González, Martin Rees and Professor Hawking himself. Many of Professor Hawking’s current and former students and colleagues were in attendance to celebrate his life and career in science.

Professor Cox, from CERN and the ̽��ֱ�� of Manchester, is well-known for his popular science series on the BBC, including Wonders of the Universe. He spoke of Professor Hawking’s great contributions to the public understanding of physics, and how he was inspired by Hawking’s 1988 bestseller A Brief History of Time as a teenager.

“Physics challenges us to think very carefully about our place in the Universe,” he said during his lecture on Our Place in the Universe. And echoing another great science communicator, the physicist Richard Feynman, he said, “ ̽��ֱ��most valuable thing about science is not what it teaches us about nature, or the spin-off technologies, it’s a state of mind. ̽��ֱ��state of mind is that not knowing is a powerful thing.”

Professor González from Louisiana State ̽��ֱ�� is a former spokesperson for LIGO, and updated the conference on the latest research at LIGO, which announced the first detection of gravitational waves – ripples in spacetime – in early 2016. Since then, there have been two more detections. She outlined a planned network of gravitational wave detectors, which would allow scientists to detect gravitational waves with ever-greater precision.

In his lecture From Mars to the Multiverse, Professor Martin Rees, Emeritus Professor in Cambridge’s Institute of Astronomy, discussed the likelihood of finding life on other planets, and of the eternal allure of outer space. “It’s a dangerous illusion to think that space offers a solution to Earth’s problems – we’ve got to solve them right here,” he said. “We are stewards at an incredibly important time in the Earth’s history.”

(click to enlarge)

In his lecture, Professor Hawking reflected on his life and career, and discussed his current research. He talked about when he was diagnosed with motor neurone disease when he was a PhD student at Cambridge, and was give just two years to live.

“At first I became depressed. There didn’t seem any point in finishing my PhD, because I didn’t know if I’d be alive long enough to finish it,” he said. “But after my expectations had been reduced to zero, every new day became a bonus, and I began to appreciate everything I did have. Where there is life, there is hope.”

Professor Hawking also discussed his academic work, which broke new ground on the basic laws which govern the universe, including the revelation that black holes have a temperature and produce radiation, now known as Hawking radiation. At the same time, he also sought to explain many of these complex scientific ideas to a wider audience through popular books, most notably his bestseller A Brief History of Time.

“I thought I might make a modest amount, to help support my children at school, and help with the rising costs of my care,” he said. “But the main reason is I enjoyed it. I think it’s important for scientists to explain their work, especially in cosmology. I never expected A Brief History of Time to do as well as it did. Not everyone may have finished it, or understood everything they read. But at least they would have gotten the idea that we live in a Universe governed by rational laws that we can discover and understand.

“It has been a glorious time to be alive and doing research into theoretical physics. Our picture of the Universe has changed a great deal in the last 50 years, and I’m happy if I’ve made a small contribution. Remember to look up at the stars and not down at your feet. Be curious. And however difficult life may seem, there is always something you can do and succeed at. It matters that you just don’t give up.”

All of the lectures are available to watch online.

Some of the biggest names in science took part in a special public event yesterday (2 July) to celebrate the life and work of Stephen Hawking, on the occasion of his 75th birthday.

It has been a glorious time to be alive and doing research into theoretical physics.

Stephen Hawking

Sir Cam

Stephen Hawking

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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