̽��ֱ�� of Cambridge - MIT

Flight path to net zero

plc32 — Sun, 22 Sep 2024 22:18:18 +0000

Global aviation could be on a flight path to net zero if industry and governments reach just four goals by 2030, according to a new report from the ̽��ֱ�� of Cambridge.

Researchers devise a new path toward ‘quantum light’

sc604 — Thu, 02 Feb 2023 16:00:00 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, along with colleagues from the US, Israel and Austria, developed a theory describing a new state of light, which has controllable quantum properties over a broad range of frequencies, up as high as X-ray frequencies. Their results are reported in the journal Nature Physics.

̽��ֱ��world we observe around us can be described according to the laws of classical physics, but once we observe things at an atomic scale, the strange world of quantum physics takes over. Imagine a basketball: observing it with the naked eye, the basketball behaves according to the laws of classical physics. But the atoms that make up the basketball behave according to quantum physics instead.

“Light is no exception: from sunlight to radio waves, it can mostly be described using classical physics,” said lead author Dr Andrea Pizzi, who carried out the research while based at Cambridge’s Cavendish Laboratory. “But at the micro and nanoscale so-called quantum fluctuations start playing a role and classical physics cannot account for them.”

Pizzi, who is currently based at Harvard ̽��ֱ��, worked with Ido Kaminer’s group at the Technion-Israel Institute of Technology and colleagues at MIT and the ̽��ֱ�� of Vienna to develop a theory that predicts a new way of controlling the quantum nature of light.

“Quantum fluctuations make quantum light harder to study, but also more interesting: if correctly engineered, quantum fluctuations can be a resource,” said Pizzi. “Controlling the state of quantum light could enable new techniques in microscopy and quantum computation.”

One of the main techniques for generating light uses strong lasers. When a strong enough laser is pointed at a collection of emitters, it can rip some electrons away from the emitters and energise them. Eventually, some of these electrons recombine with the emitters they were extracted from, and the excess energy they absorbed is released as light. This process turns the low-frequency input light into high-frequency output radiation.

“ ̽��ֱ��assumption has been that all these emitters are independent from one another, resulting in output light in which quantum fluctuations are pretty featureless,” said Pizzi. “We wanted to study a system where the emitters are not independent, but correlated: the state of one particle tells you something about the state of another. In this case, the output light starts behaving very differently, and its quantum fluctuations become highly structured, and potentially more useful.”

To solve this type of problem, known as a many body problem, the researchers used a combination of theoretical analysis and computer simulations, where the output light from a group of correlated emitters could be described using quantum physics.

̽��ֱ��theory, whose development was led by Pizzi and Alexey Gorlach from the Technion, demonstrates that controllable quantum light can be generated by correlated emitters with a strong laser. ̽��ֱ��method generates high-energy output light, and could be used to engineer the quantum-optical structure of X-rays.

“We worked for months to get the equations cleaner and cleaner until we got to the point where we could describe the connection between the output light and the input correlations with just one compact equation. As a physicist, I find this beautiful,” said Pizzi. “Looking forward, we would like to collaborate with experimentalists to provide a validation of our predictions. On the theory side of things, our work suggests many-body systems as a resource for generating quantum light, a concept that we want to investigate more broadly, beyond the setup considered in this work.”

̽��ֱ��research was supported in part by the Royal Society. Andrea Pizzi is a Junior Research Fellow at Trinity College, Cambridge.

Reference:
Andrea Pizzi et al. ‘Light emission from strongly driven many-body systems.’ Nature Physics (2023). DOI: 10.1038/s41567-022-01910-7

Researchers have theorised a new mechanism to generate high-energy ‘quantum light’, which could be used to investigate new properties of matter at the atomic scale.

David Wall via Getty Images

Design of a glowing fractal pattern with stars floating on a black background

̽��ֱ��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

Could acid-neutralising life-forms make habitable pockets in Venus’ clouds?

sc604 — Mon, 20 Dec 2021 20:00:00 +0000

It’s hard to imagine a more inhospitable world than our closest planetary neighbour. With an atmosphere thick with carbon dioxide, and a surface hot enough to melt lead, Venus is a scorched and suffocating wasteland where life as we know it could not survive. ̽��ֱ��planet’s clouds are similarly hostile, blanketing the planet in droplets of sulphuric acid caustic enough to burn a hole through human skin.

And yet, a new study, published in the Proceedings of the National Academy of Sciences, supports the long-held theory that, if life exists, it might make a home in Venus’ clouds. ̽��ֱ��study’s authors, from MIT, Cardiff ̽��ֱ��, and the ̽��ֱ�� of Cambridge, have identified a chemical pathway by which life could neutralise Venus’ acidic environment, creating a self-sustaining, habitable pocket in the clouds.

Within Venus’ atmosphere, scientists have long observed puzzling anomalies — chemical signatures that are hard to explain, such as small concentrations of oxygen and nonspherical particles unlike sulphuric acid’s round droplets. Perhaps most puzzling is the presence of ammonia, a gas that was tentatively detected in the 1970s, and that by all accounts should not be produced through any chemical process known on Venus.

In their new study, the researchers modelled a set of chemical processes to show that if ammonia is indeed present, the gas would set off a cascade of chemical reactions that not only neutralises surrounding droplets of sulphuric acid, but also would explain most of the anomalies observed in Venus’ clouds. As for the source of ammonia itself, the authors propose the most plausible explanation is of biological origin, rather than an non-biological source such as lightning or volcanic eruptions.

̽��ֱ��chemistry suggests that life could be making its own environment on Venus.

This hypothesis is testable, and the researchers provide a list of chemical signatures for future missions to measure in Venus’ clouds, to either confirm or contradict their idea.

“No life that we know of could survive in the Venus droplets,” said study co-author Sara Seager, from MIT. “But the point is, maybe some life is there, and is modifying its environment so that it is livable.”

‘Life on Venus’ was a trending phrase last year, when scientists including Seager and her co-authors reported the detection of phosphine in the planet’s clouds. On Earth, phosphine is a gas that is produced mainly through biological interactions. ̽��ֱ��discovery of phosphine on Venus leaves room for the possibility of life. Since then, however, the discovery has been widely contested.

“ ̽��ֱ��phosphine detection ended up becoming incredibly controversial,” said Seager. “But phosphine was like a gateway, and there’s been this resurgence in people studying Venus.”

Inspired to look more closely, co-author Dr Paul Rimmer from Cambridge’s Department of Earth Sciences began combing through data from past missions to Venus. In these data, he identified anomalies, or chemical signatures, in the clouds that had gone unexplained for decades. In addition to the presence of oxygen and nonspherical particles, anomalies included unexpected levels of water vapor and sulphur dioxide.

Rimmer proposed the anomalies might be explained by dust. He argued that minerals, swept up from Venus’ surface and into the clouds, could interact with sulphuric acid to produce some, but not all of the observed anomalies. He showed the chemistry checked out. But the physical requirements were unfeasible: A massive amount of dust would have to loft into the clouds to produce the observed anomalies. “ ̽��ֱ��hypothesis requires either large amounts of water-rich volcanism or transport of a lot of dust rich in hydroxide salts,” he said. “So far, I have been unable to identify a plausible mineralogy for this mechanism.”

̽��ֱ��researchers wondered if the anomalies could be explained by ammonia. In the 1970s, the gas was tentatively detected in the planet’s clouds by the Venera 8 and Pioneer Venus probes. ̽��ֱ��presence of ammonia, or NH3, was an unsolved mystery.

“Ammonia shouldn’t be on Venus,” said Seager. “It has hydrogen attached to it, and there’s very little hydrogen around. Any gas that doesn’t belong in the context of its environment is automatically suspicious for being made by life.”

If the team were to assume that life was the source of ammonia, could this explain the other anomalies in Venus’ clouds? ̽��ֱ��researchers modeled a series of chemical processes in search of an answer.

They found that if life were producing ammonia in the most efficient way possible, the associated chemical reactions would naturally yield oxygen. Once present in the clouds, ammonia would dissolve in droplets of sulphuric acid, effectively neutralising the acid to make the droplets relatively habitable. ̽��ֱ��introduction of ammonia into the droplets would transform their formerly round, liquid shape into more of a nonspherical, salt-like slurry. Once ammonia dissolved in sulphuric acid, the reaction would trigger any surrounding sulphur dioxide to dissolve as well.

̽��ֱ��presence of ammonia could explain most of the major anomalies seen in Venus’ clouds. ̽��ֱ��researchers also show that sources such as lightning, volcanic eruptions, and even a meteorite strike could not chemically produce the amount of ammonia required to explain the anomalies. Life, however, might.

In fact, the team notes that there are life-forms on Earth — particuarly in our own stomachs — that produce ammonia to neutralise and make livable an otherwise highly acidic environment.

“This hypothesis predicts that the tentative detection of oxygen and ammonia in Venus’s clouds by probes will be confirmed by future missions, and that both life and ammonium sulphite and sulphate are present in the largest droplets in the lower part of the cloud,” said Rimmer, who is also affiliated with the Cavendish Laboratory and the MRC Laboratory for Molecular Biology. “There are also several remaining mysteries: if life is there, how does it propagate in an environment as dry as the clouds of Venus? If it is making water when neutralising the droplets, what happens to that water? If life is not in the clouds of Venus, what alternative abiotic chemistry is taking place to explain this depletion of sulphur dioxide and water? Future lab experiments and missions will be able to test these predictions and may shed light on these outstanding mysteries.”

Scientists may have a chance to check for the presence of ammonia, and signs of life, in the next several years with the Venus Life Finder Missions, a set of proposed privately funded missions that plan to send spacecraft to Venus to measure its clouds for ammonia and other signatures of life.

This research was supported in part by the Simons Foundation, the Change Happens Foundation, and the Breakthrough Initiatives.

Reference:
William Bains et al. ‘Production of ammonia makes Venusian clouds habitable and explains observed cloud-level chemical anomalies.’ Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2110889118

Adapted from an MIT news story.

A new study shows it’s theoretically possible. ̽��ֱ��hypothesis could be tested soon with proposed Venus-bound missions.

If life is there, how does it propagate in an environment as dry as the clouds of Venus?

Paul Rimmer

NASA/JPL-Caltech

Venus from Mariner 10

Yes

Licence type:

Public Domain

Gravitational waves detected 100 years after Einstein’s prediction

sc604 — Thu, 11 Feb 2016 15:30:00 +0000

An international team of scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos.

̽��ֱ��gravitational waves were detected on 14 September 2015 at 09:51 UK time by both LIGO (Laser Interferometer Gravitational-wave Observatory) detectors in Louisiana and Washington State in the US. They originated from two black holes, each around 30 times the mass of the Sun and located more than 1.3 billion light years from Earth, coalescing to form a single, even more massive black hole.

̽��ֱ��LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. ̽��ֱ��discovery, published in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

“ ̽��ֱ��discovery of gravitational waves by the LIGO team is an incredible achievement,” said Professor Stephen Hawking, the Dennis Stanton Avery and Sally Tsui Wong-Avery Director of Research at the Department of Applied Mathematics and Theoretical Physics at the ̽��ֱ�� of Cambridge. “It is the first observation of gravitational waves as predicted by Einstein and will allow us new insights into our universe. ̽��ֱ��gravitational waves were released from the collision of two black holes, the properties of which are consistent with predictions I made in Cambridge in the 1970s, such as the black hole area and uniqueness theorems. We can expect this observation to be the first of many as LIGO sensitivity increases, keeping us all busy with many further surprises.”

Gravitational waves carry unique information about the origins of our Universe and studying them is expected to provide important insights into the evolution of stars, supernovae, gamma-ray bursts, neutron stars and black holes. However, they interact very weakly with particles and require incredibly sensitive equipment to detect. British and German teams, including researchers from the ̽��ֱ�� of Cambridge, working with US, Australian, Italian and French colleagues as part of the LIGO Scientific Collaboration and the Virgo Collaboration, are using a technique called laser interferometry.

Each LIGO site comprises two tubes, each four kilometres long, arranged in an L-shape. A laser is beamed down each tube to very precisely monitor the distance between mirrors at each end. According to Einstein’s theory, the distance between the mirrors will change by a tiny amount when a gravitational wave passes by the detector. A change in the lengths of the arms of close to 10^-19 metres (just one-ten-thousandth the diameter of a proton) can be detected.

According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitational waves, causing them to gradually approach each other over billions of years, and then much more quickly in the final minutes. During the final fraction of a second, the two black holes collide into each other at nearly one-half the speed of light and form a single more massive black hole, converting a portion of the combined black holes’ mass to energy, according to Einstein’s formula E=mc². This energy is emitted as a final strong burst of gravitational waves. It is these gravitational waves that LIGO has observed.

Independent and widely separated observatories are necessary to verify the direction of the event causing the gravitational waves, and also to determine that the signals come from space and are not from some other local phenomenon.

To ensure absolute accuracy, the consortium of nearly 1,000 scientists from 16 countries spent several months carefully checking and re-checking the data before submitting their findings for publication.

Christopher Moore, a PhD student from Cambridge’s Institute of Astronomy, was part of the discovery team who worked on the data analysis.

“Since September, we’ve known that something was detected, but it took months of checking to confirm that it was actually gravitational waves,” he said. “This team has been looking for evidence of gravitational waves for decades – a huge amount of work has gone into it, and I feel incredibly lucky to be part of the team. This discovery will change the way we do astronomy.”

Over coming years, the Advanced LIGO detectors will be ramped up to full power, increasing their sensitivity to gravitational waves, and in particular allowing more distant events to be measured. With the addition of further detectors, initially in Italy and later in other locations around the world, this first detection is surely just the beginning. UK scientists continue to contribute to the design and development of future generations of gravitational wave detectors.

̽��ֱ��UK Minister for Universities and Science, Jo Johnson MP, said: “Einstein’s theories from over a century ago are still helping us to understand our universe. Now that we have the technological capability to test his theories with the LIGO detectors his scientific brilliance becomes all the more apparent. ̽��ֱ��Government is increasing support for international research collaborations, and these scientists from across the UK have played a vital part in this discovery.”

LIGO was originally proposed as a means of detecting these gravitational waves in the 1980s by Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, Emeritus; Ronald Drever, professor of physics, emeritus also from Caltech; and Rainer Weiss, professor of physics, emeritus, from MIT.

“ ̽��ֱ��description of this observation is beautifully described in the Einstein theory of General Relativity formulated 100 years ago and comprises the first test of the theory in strong gravitation. It would have been wonderful to watch Einstein’s face had we been able to tell him,” said Weiss.

“With this discovery, we humans are embarking on a marvelous new quest: the quest to explore the warped side of the universe—objects and phenomena that are made from warped spacetime. Colliding black holes and gravitational waves are our first beautiful examples,” said Thorne.

̽��ֱ��discovery was made possible by the enhanced capabilities of Advanced LIGO, a major upgrade that increases the sensitivity of the instruments compared to the first generation LIGO detectors, enabling a large increase in the volume of the universe probed—and the discovery of gravitational waves during its first observation run.

̽��ֱ��US National Science Foundation leads in financial support for Advanced LIGO. Funding organisations in Germany (Max Planck Society), the UK (Science and Technology Facilities Council, STFC) and Australia (Australian Research Council) also have made significant commitments to the project.

Several of the key technologies that made Advanced LIGO so much more sensitive have been developed and tested by the German UK GEO collaboration. Significant computer resources have been contributed by the AEI Hannover Atlas Cluster, the LIGO Laboratory, Syracuse ̽��ֱ��, and the ̽��ֱ�� of Wisconsin-Milwaukee.

Several universities designed, built, and tested key components for Advanced LIGO: ̽��ֱ��Australian National ̽��ֱ��, the ̽��ֱ�� of Adelaide, the ̽��ֱ�� of Florida, Stanford ̽��ֱ��, Columbia ̽��ֱ�� of New York, and Louisiana State ̽��ֱ��.

Cambridge has a long-standing involvement in the field of gravitational wave science, and specifically with the LIGO experiment. Until recently these efforts were spearheaded by Dr Jonathan Gair, who left last year for a post at the ̽��ֱ�� of Edinburgh and who has made significant contributions to a wide range of gravitational wave and LIGO science; he is one of the authors on the new paper. Several scientists in Cambridge are current members of the collaboration, including PhD students Christopher Moore and Alvin Chua from the Institute of Astronomy; Professor Anthony Lasenby and PhD student Sonke Hee from the Cavendish Laboratory and the Kavli Institute of Cosmology; and Professor Mike Hobson from the Cavendish Laboratory.

Further members of the collaboration until recently based at Cambridge, include Dr Philip Graff (author on the detection paper) and Dr Farhan Feroz, who, jointly with Mike Hobson and Anthony Lasenby, developed a machine learning method of analysis used currently within LIGO, as well as Dr Christopher Berry (author) and Dr Priscilla Canizares.

These findings will be discussed at next month's Cambridge Science Festival during the open afternoon at the Institute of Astronomy.

Reference:
B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration) 'Observation of Gravitational Waves from a Binary Black Hole Merger.' Physical Review Letters (2016). DOI: 10.1103/PhysRevLett.116.061102.

New window on the universe is opened with the observation of gravitational waves – ripples in spacetime – caused by the collision of two black holes.

I feel incredibly lucky to be part of the team - this discovery will change the way we do astronomy.

Christopher Moore

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

Yes

Science Live

dwc34 — Mon, 22 Dec 2014 14:52:07 +0000

From intimate science cafes to massive science festivals, the public science events sector encompasses an enormous diversity of activity involving a huge range of practitioners and target audiences. As unique as each event is, public science events are all live, in-person programs, designed to engage the public with science in a social context that is at least as meaningful as the content and messages delivered. This activity is already taking place on a grand scale in both the US and UK, and having a direct impact in a variety of ways. ̽��ֱ��Science Live project is a first significant step forward in a long-term effort to widen access to the beneficial impacts of public science events, better understand these impacts and how they are produced, and uncover new opportunities for engaging society with science.

Researchers at Cornell ̽��ֱ�� and the ̽��ֱ�� of the West of England (UWE), Bristol will work with science festival managers at MIT and the ̽��ֱ�� of Cambridge to tackle several issues across the science events sectors in the UK and US. Ben Wiehe from the Science Festival Alliance office at the MIT Museum said:

“We know that millions of people are participating in live public science events every year in both the US and UK, but the contributions of these events are only just coming to be acknowledged as distinct, and there is little overall tracking of or advocacy for such activity. ̽��ֱ��organizers of these events are often not aware of each other’s efforts. We have a lot to learn from each other, but right now there is no straightforward way to share findings with the full range of event practitioners.”

̽��ֱ��Science Live pilot study is funded by the Science Learning+ initiative of the Wellcome Trust, the US-based National Science Foundation, and the UK-based Economic and Social Research Council. It aims to lead to a longer term effort to establish a set of key facts related to live science activities, and use those facts to build a coherent narrative explaining the role that live events play in the larger science learning ecosystem.

Laura Fogg Rogers, Science Communication Research Fellow at UWE said:

“This is an exciting time to drill down and find out what works best in communicating research to benefit society. This consortium has access to some of the best networks of public science events, including science festival networks in the UK and US, grass-roots activities, and government level initiatives. ̽��ֱ��potential to make an impact on the researcher and practitioner landscape is massive.”

NOTES FOR EDITORS

Science Live is a collaborative project of the MIT Museum and the ̽��ֱ�� of Cambridge, administered by the Science Festival Alliance office at the MIT Museum, and is led by Dr John Durant from Massachusetts Institute of Technology. Research partners include

Professor Bruce Lewenstein from Cornell ̽��ֱ��, Laura Fogg Rogers from ̽��ֱ�� of the West of England, and Dr Wai Yi Feng from the ̽��ֱ�� of Cambridge.

Science Live is funded through the Science Learning+ scheme, an international initiative established by the Wellcome Trust, the US National Science Foundation (NSF), and the UK Economic and Social Research Council (ESRC) and in collaboration with the MacArthur Foundation, the Gordon and Betty Moore Foundation, and the Noyce Foundation. ̽��ֱ��scheme was launched in April 2014 after a review of informal learning commissioned by the Wellcome Trust indicated a need for further research to be undertaken in this area.

̽��ֱ��UK contact is Dane Comerford, from the ̽��ֱ�� of Cambridge Public Engagement Team and the US contact is Ben Wiehe from the Science Festival Alliance office at the MIT Museum.

Dane Comerford

Public Engagement Manager, ̽��ֱ�� of Cambridge

Phone: +44 (0)1223 764069

E-mail: dane.comerford@admin.cam.ac.uk

Ben Wiehe

Manager, Science Festival Alliance

Phone: +1 617.806.6369

E-mail: wiehe@mit.edu

A new transatlantic pilot study aims to better understand what makes science events tick.

These activities range from festivals, science busking and trips to nature reserves, and involve about half of the UK population. ̽��ֱ��project, called Science Live, will explore the differences between the huge varieties of live science events and will develop research questions about how they affect their audiences.

This consortium has access to some of the best networks of public science events, including science festival networks in the UK and US, grass-roots activities, and government level initiatives. ̽��ֱ��potential to make an impact on the researcher and practitioner landscape is massive.

Laura Fogg Rogers, Science Communication Research Fellow at UWE, Bristol

Around half the UK population access science activities every year.

̽��ֱ��text in this work is licensed under a Creative Commons Licence. If you use this content on your site please link back to this page. For image rights, please see the credits associated with each individual image.

Yes