ֱ̽ of Cambridge - Physics /taxonomy/subjects/physics en From family archive to stage: ֱ̽remarkable journey of ‘Not for a cat’ play at the Cambridge Festival /stories/rediscovered-cavendish-play <div class="field field-name-field-content-summary field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><p>A recently rediscovered play, Not for a Cat: A Play for the Nuclear Age, will be premiering at the Cambridge Festival. The play was originally written in the 1950s by Wallace R. Harper, a student at the Cavendish Laboratory at the ֱ̽ of Cambridge in the 1920.</p> </p></div></div></div> Mon, 31 Mar 2025 09:20:39 +0000 zs332 248814 at Massive black hole in the early universe spotted taking a ‘nap’ after overeating /research/news/massive-black-hole-in-the-early-universe-spotted-taking-a-nap-after-overeating <div class="field field-name-field-news-image field-type-image field-label-hidden"><div class="field-items"><div class="field-item even"><img class="cam-scale-with-grid" src="/sites/default/files/styles/content-580x288/public/news/research/news/credit-jiarong-gu_0.jpg?itok=ISXksgsE" alt="Artist’s impression of a black hole during one of its short periods of rapid growth" title="Artist’s impression of a black hole during one of its short periods of rapid growth, Credit: Jiarong Gu" /></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>Like a bear gorging itself on salmon before hibernating for the winter, or a much-needed nap after Christmas dinner, this black hole has overeaten to the point that it is lying dormant in its host galaxy.</p> <p>An international team of astronomers, led by the ֱ̽ of Cambridge, used the NASA/ESA/CSA James Webb Space Telescope to detect this black hole in the early universe, just 800 million years after the Big Bang.</p> <p> ֱ̽black hole is huge – 400 million times the mass of our Sun – making it one of the most massive black holes discovered by Webb at this point in the universe’s development. ֱ̽black hole is so enormous that it makes up roughly 40% of the total mass of its host galaxy: in comparison, most black holes in the local universe are roughly 0.1% of their host galaxy mass.</p> <p>However, despite its gigantic size, this black hole is eating, or accreting, the gas it needs to grow at a very low rate – about 100 times below its theoretical maximum limit – making it essentially dormant.</p> <p>Such an over-massive black hole so early in the universe, but one that isn’t growing, challenges existing models of how black holes develop. However, the researchers say that the most likely scenario is that black holes go through short periods of ultra-fast growth, followed by long periods of dormancy. Their <a href="https://www.nature.com/articles/s41586-024-08210-5">results</a> are reported in the journal <em>Nature</em>.</p> <p>When black holes are ‘napping’, they are far less luminous, making them more difficult to spot, even with highly sensitive telescopes such as Webb. Black holes cannot be directly observed, but instead they are detected by the tell-tale glow of a swirling accretion disc, which forms near the black hole’s edges. When black holes are actively growing, the gas in the accretion disc becomes extremely hot and starts to glow and radiate energy in the ultraviolet range.</p> <p>“Even though this black hole is dormant, its enormous size made it possible for us to detect,” said lead author Ignas Juodžbalis from Cambridge’s Kavli Institute for Cosmology. “Its dormant state allowed us to learn about the mass of the host galaxy as well. ֱ̽early universe managed to produce some absolute monsters, even in relatively tiny galaxies.”</p> <p>According to standard models, black holes form from the collapsed remnants of dead stars and accrete matter up to a predicted limit, known as the Eddington limit, where the pressure of radiation on matter overcomes the gravitational pull of the black hole. However, the sheer size of this black hole suggests that standard models may not adequately explain how these monsters form and grow.</p> <p>“It’s possible that black holes are ‘born big’, which could explain why Webb has spotted huge black holes in the early universe,” said co-author Professor Roberto Maiolino, from the Kavli Institute and Cambridge’s Cavendish Laboratory. “But another possibility is they go through periods of hyperactivity, followed by long periods of dormancy.”</p> <p>Working with colleagues from Italy, the Cambridge researchers conducted a range of computer simulations to model how this dormant black hole could have grown to such a massive size so early in the universe. They found that the most likely scenario is that black holes can exceed the Eddington limit for short periods, during which they grow very rapidly, followed by long periods of inactivity: the researchers say that black holes such as this one likely eat for five to ten million years, and sleep for about 100 million years.</p> <p>“It sounds counterintuitive to explain a dormant black hole with periods of hyperactivity, but these short bursts allow it to grow quickly while spending most of its time napping,” said Maiolino.</p> <p>Because the periods of dormancy are much longer than the periods of ultra-fast growth, it is in these periods that astronomers are most likely to detect black holes. “This was the first result I had as part of my PhD, and it took me a little while to appreciate just how remarkable it was,” said Juodžbalis. “It wasn’t until I started speaking with my colleagues on the theoretical side of astronomy that I was able to see the true significance of this black hole.”</p> <p>Due to their low luminosities, dormant black holes are more challenging for astronomers to detect, but the researchers say this black hole is almost certainly the tip of a much larger iceberg, if black holes in the early universe spend most of their time in a dormant state.</p> <p>“It’s likely that the vast majority of black holes out there are in this dormant state – I’m surprised we found this one, but I’m excited to think that there are so many more we could find,” said Maiolino.</p> <p> ֱ̽observations were obtained as part of the <a href="https://jades-survey.github.io/">JWST Advanced Deep Extragalactic Survey (JADES)</a>. ֱ̽research was supported in part by the European Research Council and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).</p> <p><em><strong>Reference:</strong><br /> Ignas Juodžbalis et al. ‘<a href="https://www.nature.com/articles/s41586-024-08210-5">A dormant overmassive black hole in the early Universe</a>.’ Nature (2024). DOI: 10.1038/s41586-024-08210-5</em></p> </div></div></div><div class="field field-name-field-content-summary field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><p>Scientists have spotted a massive black hole in the early universe that is ‘napping’ after stuffing itself with too much food.</p> </p></div></div></div><div class="field field-name-field-image-credit field-type-link-field field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/" target="_blank">Jiarong Gu</a></div></div></div><div class="field field-name-field-image-desctiprion field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Artist’s impression of a black hole during one of its short periods of rapid growth</div></div></div><div class="field field-name-field-cc-attribute-text field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p><a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" rel="license"><img alt="Creative Commons License." src="/sites/www.cam.ac.uk/files/inner-images/cc-by-nc-sa-4-license.png" style="border-width: 0px; width: 88px; height: 31px;" /></a><br /> ֱ̽text in this work is licensed under a <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>. 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 – on our <a href="/">main website</a> under its <a href="/about-this-site/terms-and-conditions">Terms and conditions</a>, and on a <a href="/about-this-site/connect-with-us">range of channels including social media</a> that permit your use and sharing of our content under their respective Terms.</p> </div></div></div><div class="field field-name-field-show-cc-text field-type-list-boolean field-label-hidden"><div class="field-items"><div class="field-item even">Yes</div></div></div> Wed, 18 Dec 2024 16:00:00 +0000 sc604 248610 at A peek inside the box that could help solve a quantum mystery /research/news/a-peek-inside-the-box-that-could-help-solve-a-quantum-mystery <div class="field field-name-field-news-image field-type-image field-label-hidden"><div class="field-items"><div class="field-item even"><img class="cam-scale-with-grid" src="/sites/default/files/styles/content-580x288/public/news/research/news/gettyimages-898633556-dp_1.jpg?itok=_loID1Wq" alt="Abstract colourful lines" title="Abstract colourful lines, Credit: gremlin via Getty Images" /></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>Appearing as ‘bumps’ in the data from high-energy experiments, these signals came to be known as short-lived ‘XYZ states.’ They defy the standard picture of particle behaviour and are a problem in contemporary physics, sparking several attempts to understand their mysterious nature.</p> <p>But theorists at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility in Virginia, with colleagues from the ֱ̽ of Cambridge, suggest the experimental data could be explained with fewer XYZ states, also called resonances, than currently claimed.</p> <p> ֱ̽team used a branch of quantum physics to compute the energy levels, or mass, of particles containing a specific ‘flavour’ of the subatomic building blocks known as quarks. Quarks, along with gluons, a force-carrying particle, make up the Strong Force, one of the four fundamental forces of nature.</p> <p> ֱ̽researchers found that multiple particle states sharing the same degree of spin – or angular momentum – are coupled, meaning only a single resonance exists at each spin channel. This new interpretation is contrary to several other theoretical and experimental studies.</p> <p> ֱ̽researchers have presented their results in a pair of companion papers published for the international Hadron Spectrum Collaboration (HadSpec) in <em><a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.241901">Physical Review Letters</a></em> and <em><a href="https://journals.aps.org/prd/abstract/10.1103/PhysRevD.109.114503">Physical Review D</a></em>. ֱ̽work could also provide clues about an enigmatic particle: X(3872).</p> <p> ֱ̽charm quark, one of six quark ‘flavours’, was first observed experimentally in 1974. It was discovered alongside its antimatter counterpart, the anticharm, and particles paired this way are part of an energy region called ‘charmonium.’</p> <p>In 2003, Japanese researchers discovered a new charmonium candidate dubbed X(3872): a short-lived particle state that appears to defy the present quark model.</p> <p>“X(3872) is now more than 20 years old, and we still haven’t obtained a clear, simple explanation that everyone can get behind,” said lead author Dr David Wilson from Cambridge’s Department of Applied Mathematics and Theoretical Physics (DAMTP).</p> <p>Thanks to the power of modern particle accelerators, scientists have detected a hodgepodge of exotic charmonium candidate states over the past two decades.</p> <p>“High-energy experiments started seeing bumps, interpreted as new particles, almost everywhere they looked,” said co-author Professor Jozef Dudek from William &amp; Mary. “And very few of these states agreed with the model that came before.”</p> <p>But now, by creating a tiny virtual ‘box’ to simulate quark behaviour, the researchers discovered that several supposed XYZ particles might actually be just one particle seen in different ways. This could help simplify the confusing jumble of data scientists have collected over the years.</p> <p>Despite the tiny volumes they were working with, the team required enormous computing power to simulate all the possible behaviours and masses of quarks.</p> <p> ֱ̽researchers used supercomputers at Cambridge and the Jefferson Lab to infer all the possible ways in which mesons – made of a quark and its antimatter counterpart – could decay. To do this, they had to relate the results from their tiny virtual box to what would happen in a nearly infinite volume – that is, the size of the universe.</p> <p>“In our calculations, unlike experiment, you can't just fire in two particles and measure two particles coming out,” said Wilson. “You have to simultaneously calculate all possible final states, because quantum mechanics will find those for you.”</p> <p> ֱ̽results can be understood in terms of just a single short-lived particle whose appearance could differ depending upon which possible decay state it is observed in.</p> <p>“We're trying to simplify the picture as much as possible, using fundamental theory with the best methods available,” said Wilson. “Our goal is to disentangle what has been seen in experiments.”</p> <p>Now that the team has proved this type of calculation is feasible, they are ready to apply it to the mysterious particle X(3872).</p> <p>“ ֱ̽origin of X(3872) is an open question,” said Wilson. “It appears very close to a threshold, which could be accidental or a key part of the story. This is one thing we will look at very soon."</p> <p>Professor Christopher Thomas, also from DAMTP, is a member of the Hadron Spectrum Collaboration, and is a co-author on the current studies. Wilson’s contribution was made possible in part by an eight-year fellowship with the Royal Society. ֱ̽research was also supported in part by the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI). Many of the calculations for this study were carried out with the support of the <a href="https://docs.hpc.cam.ac.uk/hpc/">Cambridge Centre for Data Driven Discovery (CSD3)</a> and <a href="https://dirac.ac.uk/">DiRAC</a> high-performance computing facilities in Cambridge, managed by Cambridge’s <a href="https://www.hpc.cam.ac.uk/">Research Computing Services</a> division.</p> <p><em><strong>Reference:</strong><br /> David J. Wilson et al. ‘<a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.241901">Scalar and Tensor Charmonium Resonances in Coupled-Channel Scattering from Lattice QCD</a>.’ Physical Review Letters (2024). DOI: 10.1103/PhysRevLett.132.241901</em></p> <p><em>David J. Wilson et al. ‘<a href="https://journals.aps.org/prd/abstract/10.1103/PhysRevD.109.114503">Charmonium xc0 and xc2 resonances in coupled-channel scattering from lattice QCD</a>.’ Physical Review D (2024). DOI: 10.1103/PhysRevD.109.114503</em></p> <p><em>Adapted from a <a href="https://www.jlab.org/news/releases/inside-box-look-excited-hadrons-could-help-solve-mystery-particle-x3872">Jefferson Lab story</a>.</em></p> </div></div></div><div class="field field-name-field-content-summary field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><p>An elusive particle that first formed in the hot, dense early universe has puzzled physicists for decades. Following its discovery in 2003, scientists began observing a slew of other strange objects tied to the millionths of a second after the Big Bang.</p> </p></div></div></div><div class="field field-name-field-image-credit field-type-link-field field-label-hidden"><div class="field-items"><div class="field-item even"><a href="https://www.gettyimages.co.uk/detail/photo/abstract-tendril-particles-royalty-free-image/898633556?phrase=particle physics&amp;searchscope=image,film&amp;adppopup=true" target="_blank">gremlin via Getty Images</a></div></div></div><div class="field field-name-field-image-desctiprion field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Abstract colourful lines</div></div></div><div class="field field-name-field-cc-attribute-text field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p><a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" rel="license"><img alt="Creative Commons License." src="/sites/www.cam.ac.uk/files/inner-images/cc-by-nc-sa-4-license.png" style="border-width: 0px; width: 88px; height: 31px;" /></a><br /> ֱ̽text in this work is licensed under a <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>. 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 – on our <a href="/">main website</a> under its <a href="/about-this-site/terms-and-conditions">Terms and conditions</a>, and on a <a href="/about-this-site/connect-with-us">range of channels including social media</a> that permit your use and sharing of our content under their respective Terms.</p> </div></div></div><div class="field field-name-field-show-cc-text field-type-list-boolean field-label-hidden"><div class="field-items"><div class="field-item even">Yes</div></div></div> Tue, 19 Nov 2024 15:22:24 +0000 sc604 248565 at Diamonds and rust help unveil ‘impossible’ quasi-particles /research/news/diamonds-and-rust-help-unveil-impossible-quasi-particles <div class="field field-name-field-news-image field-type-image field-label-hidden"><div class="field-items"><div class="field-item even"><img class="cam-scale-with-grid" src="/sites/default/files/styles/content-580x288/public/news/research/news/monopoleimage-2-b.jpg?itok=-vwwiJ6K" alt="Magnetic monopoles in hematite" title="Magnetic monopoles in hematite, Credit: Anthony Tan and Michael Hoegen" /></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>Researchers led by the ֱ̽ of Cambridge used a technique known as diamond quantum sensing to observe swirling textures and faint magnetic signals on the surface of hematite, a type of iron oxide.</p> <p> ֱ̽researchers observed that magnetic monopoles in hematite emerge through the collective behaviour of many spins (the angular momentum of a particle). These monopoles glide across the swirling textures on the surface of the hematite, like tiny hockey pucks of magnetic charge. This is the first time that naturally occurring emergent monopoles have been observed experimentally.</p> <p> ֱ̽research has also shown the direct connection between the previously hidden swirling textures and the magnetic charges of materials like hematite, as if there is a secret code linking them together. ֱ̽<a href="https://www.nature.com/articles/s41563-023-01737-4">results</a>, which could be useful in enabling next-generation logic and memory applications, are reported in the journal <em>Nature Materials</em>.</p> <p>According to the equations of James Clerk Maxwell, a giant of Cambridge physics, magnetic objects, whether a fridge magnet or the Earth itself, must always exist as a pair of magnetic poles that cannot be isolated.</p> <p>“ ֱ̽magnets we use every day have two poles: north and south,” said Professor Mete Atatüre, who led the research. “In the 19th century, it was hypothesised that monopoles could exist. But in one of his foundational equations for the study of electromagnetism, James Clerk Maxwell disagreed.”</p> <p>Atatüre is Head of Cambridge’s Cavendish Laboratory, a position once held by Maxwell himself. “If monopoles did exist, and we were able to isolate them, it would be like finding a missing puzzle piece that was assumed to be lost,” he said.</p> <p>About 15 years ago, scientists suggested how monopoles could exist in a magnetic material. This theoretical result relied on the extreme separation of north and south poles so that locally each pole appeared isolated in an exotic material called spin ice.</p> <p>However, there is an alternative strategy to find monopoles, involving the concept of emergence. ֱ̽idea of emergence is the combination of many physical entities can give rise to properties that are either more than or different to the sum of their parts.</p> <p>Working with colleagues from the ֱ̽ of Oxford and the National ֱ̽ of Singapore, the Cambridge researchers used emergence to uncover monopoles spread over two-dimensional space, gliding across the swirling textures on the surface of a magnetic material.</p> <p> ֱ̽swirling topological textures are found in two main types of materials: ferromagnets and antiferromagnets. Of the two, antiferromagnets are more stable than ferromagnets, but they are more difficult to study, as they don’t have a strong magnetic signature.</p> <p>To study the behaviour of antiferromagnets, Atatüre and his colleagues use an imaging technique known as diamond quantum magnetometry. This technique uses a single spin – the inherent angular momentum of an electron – in a diamond needle to precisely measure the magnetic field on the surface of a material, without affecting its behaviour.</p> <p>For the current study, the researchers used the technique to look at hematite, an antiferromagnetic iron oxide material. To their surprise, they found hidden patterns of magnetic charges within hematite, including monopoles, dipoles and quadrupoles.</p> <p>“Monopoles had been predicted theoretically, but this is the first time we’ve actually seen a two-dimensional monopole in a naturally occurring magnet,” said co-author Professor Paolo Radaelli, from the ֱ̽ of Oxford.</p> <p>“These monopoles are a collective state of many spins that twirl around a singularity rather than a single fixed particle, so they emerge through many-body interactions. ֱ̽result is a tiny, localised stable particle with diverging magnetic field coming out of it,” said co-first author Dr Hariom Jani, from the ֱ̽ of Oxford.</p> <p>“We’ve shown how diamond quantum magnetometry could be used to unravel the mysterious behaviour of magnetism in two-dimensional quantum materials, which could open up new fields of study in this area,” said co-first author Dr Anthony Tan, from the Cavendish Laboratory. “ ֱ̽challenge has always been direct imaging of these textures in antiferromagnets due to their weaker magnetic pull, but now we’re able to do so, with a nice combination of diamonds and rust.”</p> <p> ֱ̽study not only highlights the potential of diamond quantum magnetometry but also underscores its capacity to uncover and investigate hidden magnetic phenomena in quantum materials. If controlled, these swirling textures dressed in magnetic charges could power super-fast and energy-efficient computer memory logic.</p> <p> ֱ̽research was supported in part by the Royal Society, the Sir Henry Royce Institute, the European Union, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI).</p> <p><em><strong>Reference:</strong><br /> K C Tan, Hariom Jani, Michael Högen et al. ‘<a href="https://www.nature.com/articles/s41563-023-01737-4">Revealing Emergent Magnetic Charge in an Antiferromagnet with Diamond Quantum Magnetometry</a>.’ Nature Materials (2023). DOI: 10.1038/s41563-023-01737-4.</em></p> <p><strong><em>For more information on energy-related research in Cambridge, please visit the <a href="https://www.energy.cam.ac.uk/">Energy IRC</a>, which brings together Cambridge’s research knowledge and expertise, in collaboration with global partners, to create solutions for a sustainable and resilient energy landscape for generations to come. </em></strong></p> </div></div></div><div class="field field-name-field-content-summary field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><p>Researchers have discovered magnetic monopoles – isolated magnetic charges – in a material closely related to rust, a result that could be used to power greener and faster computing technologies.</p> </p></div></div></div><div class="field field-name-field-content-quote field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even">If monopoles did exist, and we were able to isolate them, it would be like finding a missing puzzle piece that was assumed to be lost</div></div></div><div class="field field-name-field-content-quote-name field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Mete Atatüre</div></div></div><div class="field field-name-field-image-credit field-type-link-field field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/" target="_blank">Anthony Tan and Michael Hoegen</a></div></div></div><div class="field field-name-field-image-desctiprion field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Magnetic monopoles in hematite</div></div></div><div class="field field-name-field-cc-attribute-text field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p><a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" rel="license"><img alt="Creative Commons License." src="/sites/www.cam.ac.uk/files/inner-images/cc-by-nc-sa-4-license.png" style="border-width: 0px; width: 88px; height: 31px;" /></a><br /> ֱ̽text in this work is licensed under a <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>. 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 <a href="/">main website</a> under its <a href="/about-this-site/terms-and-conditions">Terms and conditions</a>, and on a <a href="/about-this-site/connect-with-us">range of channels including social media</a> that permit your use and sharing of our content under their respective Terms.</p> </div></div></div><div class="field field-name-field-show-cc-text field-type-list-boolean field-label-hidden"><div class="field-items"><div class="field-item even">Yes</div></div></div> Tue, 05 Dec 2023 10:02:43 +0000 sc604 243551 at Simulations of ‘backwards time travel’ can improve scientific experiments /research/news/simulations-of-backwards-time-travel-can-improve-scientific-experiments <div class="field field-name-field-news-image field-type-image field-label-hidden"><div class="field-items"><div class="field-item even"><img class="cam-scale-with-grid" src="/sites/default/files/styles/content-580x288/public/news/research/news/gettyimages-1494236463-dp.jpg?itok=PwkI1y0P" alt="Digital generated image of abstract glowing tech data tunnel " title="Digital generated image of abstract glowing tech data tunnel , Credit: Yaroslav Kushta via Getty Images" /></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>If gamblers, investors and quantum experimentalists could bend the arrow of time, their advantage would be significantly higher, leading to significantly better outcomes. </p>&#13; &#13; <p>Researchers at the ֱ̽ of Cambridge have shown that by manipulating entanglement – a feature of quantum theory that causes particles to be intrinsically linked – they can simulate what could happen if one could travel backwards in time. So that gamblers, investors and quantum experimentalists could, in some cases, retroactively change their past actions and improve their outcomes in the present.</p>&#13; &#13; <p>Whether particles can travel backwards in time is a controversial topic among physicists, even though scientists have <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.106.040403">previously</a> simulated models of how such spacetime loops could behave if they did exist. By connecting their new theory to quantum metrology, which uses quantum theory to make highly sensitive measurements, the Cambridge team has shown that entanglement can solve problems that otherwise seem impossible. The<a href="https://journals.aps.org/prl/accepted/b4073Y92Jff1ed78e19d2f31ebf2656afca4a7e17"> study</a> appears in the journal <em>Physical Review Letters</em>.</p>&#13; &#13; <p>“Imagine that you want to send a gift to someone: you need to send it on day one to make sure it arrives on day three,” said lead author David Arvidsson-Shukur, from the Hitachi Cambridge Laboratory. “However, you only receive that person’s wish list on day two. So, in this chronology-respecting scenario, it’s impossible for you to know in advance what they will want as a gift and to make sure you send the right one.</p>&#13; &#13; <p>“Now imagine you can change what you send on day one with the information from the wish list received on day two. Our simulation uses quantum entanglement manipulation to show how you could retroactively change your previous actions to ensure the final outcome is the one you want.”</p>&#13; &#13; <p> ֱ̽simulation is based on quantum entanglement, which consists of strong correlations that quantum particles can share and classical particles—those governed by everyday physics—cannot.</p>&#13; &#13; <p> ֱ̽particularity of quantum physics is that if two particles are close enough to each other to interact, they can stay connected even when separated. This is the basis of quantum computing – the harnessing of connected particles to perform computations too complex for classical computers.</p>&#13; &#13; <p>“In our proposal, an experimentalist entangles two particles,” said co-author Nicole Yunger Halpern, researcher at the National Institute of Standards and Technology (NIST) and the ֱ̽ of Maryland. “ ֱ̽first particle is then sent to be used in an experiment. Upon gaining new information, the experimentalist manipulates the second particle to effectively alter the first particle’s past state, changing the outcome of the experiment.”</p>&#13; &#13; <p>“ ֱ̽effect is remarkable, but it happens only one time out of four!” said Arvidsson-Shukur. “In other words, the simulation has a 75% chance of failure. But the good news is that you know if you have failed. If we stay with our gift analogy, one out of four times, the gift will be the desired one (for example a pair of trousers), another time it will be a pair of trousers but in the wrong size, or the wrong colour, or it will be a jacket.”</p>&#13; &#13; <p>To give their model relevance to technologies, the theorists connected it to quantum metrology. In a common quantum metrology experiment, photons—small particles of light—are shone onto a sample of interest and then registered with a special type of camera. If this experiment is to be efficient, the photons must be prepared in a certain way before they reach the sample. ֱ̽researchers have shown that even if they learn how to best prepare the photons only after the photons have reached the sample, they can use simulations of time travel to retroactively change the original photons.</p>&#13; &#13; <p>To counteract the high chance of failure, the theorists propose to send a huge number of entangled photons, knowing that some will eventually carry the correct, updated information. Then they would use a filter to ensure that the right photons pass to the camera, while the filter rejects the rest of the ‘bad’ photons.</p>&#13; &#13; <p>“Consider our earlier analogy about gifts,” said co-author Aidan McConnell, who carried out this research during his master’s degree at the Cavendish Laboratory in Cambridge, and is now a PhD student at ETH, Zürich. “Let’s say sending gifts is inexpensive and we can send numerous parcels on day one. On day two we know which gift we should have sent. By the time the parcels arrive on day three, one out of every four gifts will be correct, and we select these by telling the recipient which deliveries to throw away.”</p>&#13; &#13; <p>“That we need to use a filter to make our experiment work is actually pretty reassuring,” said Arvidsson-Shukur. “ ֱ̽world would be very strange if our time-travel simulation worked every time. Relativity and all the theories that we are building our understanding of our universe on would be out of the window.</p>&#13; &#13; <p>“We are not proposing a time travel machine, but rather a deep dive into the fundamentals of quantum mechanics. These simulations do not allow you to go back and alter your past, but they do allow you to create a better tomorrow by fixing yesterday’s problems today.”</p>&#13; &#13; <p>This work was supported by the Sweden-America Foundation, the Lars Hierta Memorial Foundation, Girton College, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI).</p>&#13; &#13; <p><br />&#13; <em><strong>Reference:</strong><br />&#13; David R M Arvidsson-Shukur, Aidan G McConnell, and Nicole Yunger Halpern, ‘<a href="https://journals.aps.org/prl/accepted/b4073Y92Jff1ed78e19d2f31ebf2656afca4a7e17">Nonclassical advantage in metrology established via quantum simulations of hypothetical closed timelike curves</a>’, Phys. Rev. Lett. 2023. DOI: 10.1103/PhysRevLett.131.150202</em></p>&#13; </div></div></div><div class="field field-name-field-content-summary field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><p>Physicists have shown that simulating models of hypothetical time travel can solve experimental problems that appear impossible to solve using standard physics.</p>&#13; </p></div></div></div><div class="field field-name-field-content-quote field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even">We are not proposing a time travel machine, but rather a deep dive into the fundamentals of quantum mechanics</div></div></div><div class="field field-name-field-content-quote-name field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">David Arvidsson-Shukur</div></div></div><div class="field field-name-field-image-credit field-type-link-field field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/" target="_blank">Yaroslav Kushta via Getty Images</a></div></div></div><div class="field field-name-field-image-desctiprion field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Digital generated image of abstract glowing tech data tunnel </div></div></div><div class="field field-name-field-cc-attribute-text field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p><a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" rel="license"><img alt="Creative Commons License." src="/sites/www.cam.ac.uk/files/inner-images/cc-by-nc-sa-4-license.png" style="border-width: 0px; width: 88px; height: 31px;" /></a><br />&#13; ֱ̽text in this work is licensed under a <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>. 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 <a href="/">main website</a> under its <a href="/about-this-site/terms-and-conditions">Terms and conditions</a>, and on a <a href="/about-this-site/connect-with-us">range of channels including social media</a> that permit your use and sharing of our content under their respective Terms.</p>&#13; </div></div></div><div class="field field-name-field-show-cc-text field-type-list-boolean field-label-hidden"><div class="field-items"><div class="field-item even">Yes</div></div></div> Thu, 12 Oct 2023 15:00:00 +0000 vb425 242551 at Machine learning models can produce reliable results even with limited training data /research/news/machine-learning-models-can-produce-reliable-results-even-with-limited-training-data <div class="field field-name-field-news-image field-type-image field-label-hidden"><div class="field-items"><div class="field-item even"><img class="cam-scale-with-grid" src="/sites/default/files/styles/content-580x288/public/news/research/news/gettyimages-1421511938-dp.jpg?itok=q03E5_XB" alt="Digital generated image of multi coloured glowing data over landscape." title="Digital generated image of multi coloured glowing data over landscape., Credit: Andriy Onufriyenko via Getty Images" /></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p> ֱ̽researchers, from the ֱ̽ of Cambridge and Cornell ֱ̽, found that for partial differential equations – a class of physics equations that describe how things in the natural world evolve in space and time – machine learning models can produce reliable results even when they are provided with limited data.</p>&#13; &#13; <p>Their <a href="https://www.pnas.org/doi/10.1073/pnas.2303904120">results</a>, reported in the <em>Proceedings of the National Academy of Sciences</em>, could be useful for constructing more time- and cost-efficient machine learning models for applications such as engineering and climate modelling.</p>&#13; &#13; <p>Most machine learning models require large amounts of training data before they can begin returning accurate results. Traditionally, a human will annotate a large volume of data – such as a set of images, for example – to train the model.</p>&#13; &#13; <p>“Using humans to train machine learning models is effective, but it’s also time-consuming and expensive,” said first author Dr Nicolas Boullé, from the Isaac Newton Institute for Mathematical Sciences. “We’re interested to know exactly how little data we actually need to train these models and still get reliable results.”</p>&#13; &#13; <p>Other researchers have been able to train machine learning models with a small amount of data and get excellent results, but how this was achieved has not been well-explained. For their study, Boullé and his co-authors, Diana Halikias and Alex Townsend from Cornell ֱ̽, focused on partial differential equations (PDEs).</p>&#13; &#13; <p>“PDEs are like the building blocks of physics: they can help explain the physical laws of nature, such as how the steady state is held in a melting block of ice,” said Boullé, who is an INI-Simons Foundation Postdoctoral Fellow. “Since they are relatively simple models, we might be able to use them to make some generalisations about why these AI techniques have been so successful in physics.”</p>&#13; &#13; <p> ֱ̽researchers found that PDEs that model diffusion have a structure that is useful for designing AI models. “Using a simple model, you might be able to enforce some of the physics that you already know into the training data set to get better accuracy and performance,” said Boullé.</p>&#13; &#13; <p> ֱ̽researchers constructed an efficient algorithm for predicting the solutions of PDEs under different conditions by exploiting the short and long-range interactions happening. This allowed them to build some mathematical guarantees into the model and determine exactly how much training data was required to end up with a robust model.</p>&#13; &#13; <p>“It depends on the field, but for physics, we found that you can actually do a lot with a very limited amount of data,” said Boullé. “It’s surprising how little data you need to end up with a reliable model. Thanks to the mathematics of these equations, we can exploit their structure to make the models more efficient.”</p>&#13; &#13; <p> ֱ̽researchers say that their techniques will allow data scientists to open the ‘black box’ of many machine learning models and design new ones that can be interpreted by humans, although future research is still needed.</p>&#13; &#13; <p>“We need to make sure that models are learning the right things, but machine learning for physics is an exciting field – there are lots of interesting maths and physics questions that AI can help us answer,” said Boullé.</p>&#13; &#13; <p> </p>&#13; &#13; <h2>Reference</h2>&#13; &#13; <p><em>Nicolas Boullé, Diana Halikias, and Alex Townsend. ‘<a href="https://www.pnas.org/doi/10.1073/pnas.2303904120">Elliptic PDE learning is provably data-efficient</a>.’ PNAS (2023). DOI: 10.1073/pnas.2303904120</em></p>&#13; </div></div></div><div class="field field-name-field-content-summary field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><p>Researchers have determined how to build reliable machine learning models that can understand complex equations in real-world situations while using far less training data than is normally expected.</p>&#13; </p></div></div></div><div class="field field-name-field-content-quote field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even">It’s surprising how little data you need to end up with a reliable model</div></div></div><div class="field field-name-field-content-quote-name field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Nicolas Boullé</div></div></div><div class="field field-name-field-image-credit field-type-link-field field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/" target="_blank">Andriy Onufriyenko via Getty Images</a></div></div></div><div class="field field-name-field-image-desctiprion field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">Digital generated image of multi coloured glowing data over landscape.</div></div></div><div class="field field-name-field-cc-attribute-text field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p><a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" rel="license"><img alt="Creative Commons License." src="/sites/www.cam.ac.uk/files/inner-images/cc-by-nc-sa-4-license.png" style="border-width: 0px; width: 88px; height: 31px;" /></a><br />&#13; ֱ̽text in this work is licensed under a <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/">Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>. 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 <a href="/">main website</a> under its <a href="/about-this-site/terms-and-conditions">Terms and conditions</a>, and on a <a href="/about-this-site/connect-with-us">range of channels including social media</a> that permit your use and sharing of our content under their respective Terms.</p>&#13; </div></div></div><div class="field field-name-field-show-cc-text field-type-list-boolean field-label-hidden"><div class="field-items"><div class="field-item even">Yes</div></div></div> Tue, 19 Sep 2023 10:03:16 +0000 sc604 241771 at Photosynthesis ‘hack’ could lead to new ways of generating renewable energy /stories/hacking-photosynthesis <div class="field field-name-field-content-summary field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><p>Researchers have ‘hacked’ the earliest stages of photosynthesis, the natural machine that powers the vast majority of life on Earth, and discovered new ways to extract energy from the process, a finding that could lead to new ways of generating clean fuel and renewable energy.</p> </p></div></div></div> Wed, 22 Mar 2023 15:57:53 +0000 sc604 237931 at Humanity’s quest to discover the origins of life in the universe /research/news/humanitys-quest-to-discover-the-origins-of-life-in-the-universe <div class="field field-name-field-news-image field-type-image field-label-hidden"><div class="field-items"><div class="field-item even"><img class="cam-scale-with-grid" src="/sites/default/files/styles/content-580x288/public/news/research/news/eth-zurich-speakers-aaas2023-credit-eth-zurich-web.jpg?itok=7rGQkGjz" alt="Emily Mitchell, Didier Queloz, Kate Adamal, Carl Zimmer. Landscape with Milky way galaxy. Sunrise and Earth view from space with Milky way galaxy. (Elements of this image furnished by NASA)." title="L-R: Emily Mitchell, Didier Queloz, Kate Adamal, Carl Zimmer, Credit: ETH Zurich/NASA" /></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>For thousands of years, humanity and science have contemplated the origins of life in the Universe. While today’s scientists are well-equipped with innovative technologies, humanity has a long way to go before we fully understand the fundamental aspects of what life is and how it forms.</p>&#13; &#13; <p>“We are living in an extraordinary moment in history,” said Professor Didier Queloz, who directs the <a href="https://www.lclu.cam.ac.uk/">Leverhulme Centre for Life in the Universe</a> at Cambridge and ETH Zurich’s <a href="https://copl.ethz.ch/">Centre for Origin and Prevalence of Life</a>. While still a doctoral student, Queloz was the first to discover an exoplanet – a planet orbiting a star other than our Sun. ֱ̽discovery led to him being awarded the <a href="/research/news/professor-didier-queloz-wins-2019-nobel-prize-in-physics-for-first-discovery-of-an-exoplanet">2019 Nobel Prize in Physics</a>.</p>&#13; &#13; <p>In the three decades since Queloz’s discovery, scientists have discovered more than 5,000 exoplanets. Trillions more are predicted to exist within our Milky Way galaxy alone. Each exoplanet discovery raises more questions about how and why life emerged on Earth and whether it exists elsewhere in the universe.</p>&#13; &#13; <p>Technological advancements, such as the James Webb Space Telescope and interplanetary missions to Mars, give scientists access to huge volumes of new observations and data. Sifting through all this information to understand the emergence of life in the universe will take a big, multidisciplinary network.</p>&#13; &#13; <p>In collaboration with chemist and fellow Nobel Laureate Jack Szostak and astronomer Dimitar Sasselov, Queloz announced the formation of such a network at the American Association for the Advancement of Science (AAAS) meeting in Washington, DC. ֱ̽Origins Federation brings together researchers studying the origins of life at Cambridge, ETH Zurich, Harvard ֱ̽, and ֱ̽ ֱ̽ of Chicago.</p>&#13; &#13; <p>Together, Federation scientists will explore the chemical and physical processes of living organisms and environmental conditions hospitable to supporting life on other planets. “ ֱ̽Origins Federation builds upon a long-standing collegial relationship strengthened through a shared collaboration in a recently completed project with the Simons Foundation,” said Queloz.</p>&#13; &#13; <p>These collaborations support the work of researchers like Dr <a href="https://www.zoo.cam.ac.uk/directory/dr-emily-mitchell">Emily Mitchell</a> from Cambridge's Department of Zoology. Mitchell is co-director of Cambridge’s Leverhulme Centre for Life in the Universe and an ecological time traveller. She uses field-based laser-scanning and statistical mathematical ecology on 580-million-year-old fossils of deep-sea organisms to determine the driving factors that influence the macro-evolutionary patterns of life on Earth.</p>&#13; &#13; <p>Speaking at AAAS, Mitchell took participants back to four billion years ago when Earth’s early atmosphere - devoid of oxygen and steeped in methane – showed its first signs of microbial life. She spoke about how life survives in extreme environments and then evolves offering potential astrobiological insights into the origins of life elsewhere in the universe.</p>&#13; &#13; <p>“As we begin to investigate other planets through the Mars missions, biosignatures could reveal whether or not the origin of life itself and its evolution on Earth is just a happy accident or part of the fundamental nature of the universe, with all its biological and ecological complexities,” said Mitchell.</p>&#13; &#13; <p> ֱ̽founding centres of the Origins Federation are ֱ̽Origins of Life Initiative (Harvard ֱ̽), Centre for Origin and Prevalence of Life (ETH Zurich), the Center for the Origins of Life ( ֱ̽ of Chicago), and the Leverhulme Centre for Life in the Universe ( ֱ̽ of Cambridge).</p>&#13; &#13; <p> ֱ̽Origins Federation will pursue scientific research topics of interest to its founding centres with a long-term perspective and common milestones. It will strive to establish a stable funding platform to create opportunities for creative and innovative ideas, and to enable young scientists to make a career in this new field. ֱ̽Origins Federation is open to new members, both centres and individuals, and is committed to developing the mechanisms and structure to achieve that aim.</p>&#13; &#13; <p>“ ֱ̽pioneering work of Professor Queloz has allowed astronomers and physicists to make advances that were unthinkable only a few years ago, both in the discovery of planets which could host life and the development of techniques to study them,” said Professor Andy Parker, head of Cambridge's Cavendish Laboratory. “But now we need to bring the full range of our scientific understanding to bear in order to understand what life really is and whether it exists on these newly discovered planets. ֱ̽Cavendish Laboratory is proud to host the Leverhulme Centre for Life in the Universe and to partner with the Origins Federation to lead this quest.”</p>&#13; </div></div></div><div class="field field-name-field-content-summary field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><p>Scientists from the ֱ̽ of Cambridge, ETH Zurich, Harvard ֱ̽, and the ֱ̽ of Chicago have founded the Origins Federation, which will advance our understanding of the emergence and early evolution of life, and its place in the cosmos.</p>&#13; </p></div></div></div><div class="field field-name-field-image-credit field-type-link-field field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/" target="_blank">ETH Zurich/NASA</a></div></div></div><div class="field field-name-field-image-desctiprion field-type-text field-label-hidden"><div class="field-items"><div class="field-item even">L-R: Emily Mitchell, Didier Queloz, Kate Adamal, Carl Zimmer</div></div></div><div class="field field-name-field-cc-attribute-text field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p><a href="http://creativecommons.org/licenses/by/4.0/" rel="license"><img alt="Creative Commons License" src="https://i.creativecommons.org/l/by/4.0/88x31.png" style="border-width:0" /></a><br />&#13; ֱ̽text in this work is licensed under a <a href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>. 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 <a href="/">main website</a> under its <a href="/about-this-site/terms-and-conditions">Terms and conditions</a>, and on a <a href="/about-this-site/connect-with-us">range of channels including social media</a> that permit your use and sharing of our content under their respective Terms.</p>&#13; </div></div></div><div class="field field-name-field-show-cc-text field-type-list-boolean field-label-hidden"><div class="field-items"><div class="field-item even">Yes</div></div></div> Wed, 08 Mar 2023 17:10:32 +0000 sc604 237511 at