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Aujourd’hui — 29 novembre 2024Flux principal

The mechanics of squirting cucumbers revealed

29 novembre 2024 à 17:00

The plant kingdom is full of intriguing ways to distribute seeds such as the dandelion pappus effortlessly drifting on air currents to the ballistic nature of fern sporangia.

Not to be outdone, the squirting cucumber (Ecballium elaterium), which is native to the Mediterranean and is often regarded as a weed, has its own unique way of ejecting seeds.

When ripe, the ovoid-shaped fruits detach from the stem and as it does so explosively ejects seeds in a high-pressure jet of mucilage.

The process, which lasts just 30 milliseconds, launches the seeds at more than 20 metres per second with some landing 10 metres away.

Researchers in the UK have, for the first time, revealed the mechanism behind the squirt by carrying out high-speed videography, computed tomography scans and mathematical modelling.

“The first time we inspected this plant in the Botanic Garden, the seed launch was so fast that we weren’t sure it had happened,” recalls Oxford University mathematical biologist Derek Moulton. “It was very exciting to dig in and uncover the mechanism of this unique plant.”

The researchers found that in the weeks leading up to the ejection, fluid builds up inside the fruits so they become pressurised. Then just before seed dispersal, some of this fluid moves from the fruit to the stem, making it longer and stiffer.

This process crucially causes the fruit to rotate from being vertical to close to an angle of 45 degrees, improving the launch angle for the seeds.

During the first milliseconds of ejection, the tip of the stem holding the fruit then recoils away causing the fruit to counter-rotate and detach. As it does so, the pressure inside the fruit causes the seeds to eject at high speed.

By changing certain parameters in the model, such as the stiffness of the stem, reveals that the mechanism has been fine-tuned to ensure optimal seed dispersal. For example, a thicker or stiffer stem would result in the seeds being launched horizontally and distributed over a narrower area.

According to Manchester University physicist Finn Box, the findings could be used for more effective drug delivery systems “where directional release is crucial”.

The post The mechanics of squirting cucumbers revealed appeared first on Physics World.

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À partir d’avant-hierFlux principal

Institute of Physics says physics ‘deep tech’ missing out on £4.5bn of extra investment

26 novembre 2024 à 14:40

UK physics “deep tech” could be missing out on almost a £1bn of investment each year. That is according to a new report by the Institute of Physics (IOP), which publishes Physics World. It finds that venture capital investors often struggle to invest in high-innovation physics industries given the lack of a “one-size-fits-all” commercialisation pathway that is seen in others areas such as biotech.

According to the report, physics-based businesses add about £230bn to the UK economy each year and employ more than 2.7 million full-time employees. The UK also has one of the largest venture-capital markets in Europe and the highest rates of spin-out activity, especially in biotech.

Despite this, however, venture capital investment in “deep tech” physics – start-ups whose business model is based on high-tech innovation or significant scientific advances – remains low, attracting £7.4bn or 30% of UK science venture-capital investment.

To find out the reasons for this discrepancy, the IOP interviewed science-led businesses as well as 32 leading venture capital investors. Based on these discussions, it was found that many investors are confused about certain aspects of physics-based start-ups, finding that they often do not follow the familiar lifecycle of development as seen other areas like biotech.

Physics businesses are not, for example, always able to transition from being tech focussed to being product-led in the early stages of development, which prevents venture capitalists from committing large amounts of money. Another issue is that venture capitalists are less familiar with the technologies, timescales and “returns profile” of physics deep tech.

The IOP report estimates that if the full investment potential of physics deep tech is unlocked then it could result in an extra £4.5bn of additional funding over the next five years. In a foreword to the report, Hermann Hauser, the tech entrepreneur and founder of Acorn Computers, highlights “uncovered issues within the system that are holding back UK venture capital investment” into physics-based tech. “Physics deep-tech businesses generate huge value and have unique characteristics – so our national approach to finance for these businesses must be articulated in ways that recognise their needs,” writes Hauser.

Physics deep tech is central to the UK’s future prosperity

Tom Grinyer

At the same time, investors see a lot of opportunity in subjects such as quantum and semiconductor physics as well as with artificial intelligences and nuclear fusion. Jo Slota-Newson, a managing partner at Almanac Ventures who co-wrote the report, says there is “huge potential” for physics deep-tech businesses but “venture capital funds are being held back from raising and deploying capital to support this crucial sector”.

The IOP is now calling for a coordinated effort from government, investors as well as the business and science communities to develop “investment pathways” to address the issues raised in the report.  For example, the UK government should ensure grant and debt-financing options are available to support physics tech at “all stages of development”.

Slota-Newson, who has a background in science including a PhD in chemistry from the University of Cambridge, says that such moves should be “at the heart” of the UK’s government’s plans for growth. “Investors, innovators and government need to work together to deliver an environment where at every stage in their development there are opportunities for our deep tech entrepreneurs to access funding and support,” adds Slota-Newson. “If we achieve that we can build the science-driven, innovative economy, which will provide a sustainable future of growth, security and prosperity.”

The report also says that the IOP should play a role by continuing to highlight successful physics deep-tech businesses and to help them attract investment from both the UK and international venture-capital firms. Indeed, Tom Grinyer, group chief executive officer of the IOP, says that getting the model right could “supercharge the UK economy as a global leader in the technologies that will define the next industrial revolution”.

“Physics deep tech is central to the UK’s future prosperity — the growth industries of the future lean very heavily on physics and will help both generate economic growth and help move us to a lower carbon, more sustainable economy,” says Grinyer. “By leveraging government support, sharing information better and designing our financial support of this key sector in a more intelligent way we can unlock billions in extra investment.”

That view is backed by Hauser. “Increased investment, economic growth, and solutions to some of our biggest societal challenges [will move] us towards a better world for future generations,” he writes. “The prize is too big to miss”.

The post Institute of Physics says physics ‘deep tech’ missing out on £4.5bn of extra investment appeared first on Physics World.

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Noodles of fun as UK researchers create the world’s thinnest spaghetti

22 novembre 2024 à 16:30

While spaghetti might have a diameter of a couple of millimetres and capelli d’angelo (angel hair) is around 0.8 mm, the thinnest known pasta to date is thought to be su filindeu (threads of God), which is made by hand in Sardinia, Italy, and is about 0.4 mm in diameter.

That is, however, until researchers in the UK created spaghetti coming in at a mindboggling 372 nanometres (0.000372 mm) across (Nanoscale Adv. 10.1039/D4NA00601A).

About 200 times thinner than a human hair, the “nanopasta” is made using a technique called electrospinning, in which the threads of flour and liquid were pulled through the tip of a needle by an electric charge.

“To make spaghetti, you push a mixture of water and flour through metal holes,” notes Adam Clancy from University College London (UCL). “In our study, we did the same except we pulled our flour mixture through with an electrical charge. It’s literally spaghetti but much smaller.”

While each individual strand is too thin to see directly with the human eye or with a visible light microscope, the team used the threads to form a mat of nanofibres about two centimetres across, creating in effect a mini lasagne sheet.

The researchers are now investigating how the starch-based nanofibres could be used for medical purposes such as wound dressing, for scaffolds in tissue regrowth and even in drug delivery. “We want to know, for instance, how quickly it disintegrates, how it interacts with cells, and if you could produce it at scale,” says UCL materials scientist Gareth Williams.

But don’t expect to see nanopasta hitting the supermarket shelves anytime soon. “I don’t think it’s useful as pasta, sadly, as it would overcook in less than a second, before you could take it out of the pan,” adds Williams. And no-one likes rubbery pasta.

The post Noodles of fun as UK researchers create the world’s thinnest spaghetti appeared first on Physics World.

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Martin Rees, Carlo Rovelli and Steven Weinberg tackle big questions to mark Oxford anniversary

22 novembre 2024 à 10:00

If you want to read about controversies in physics, a (brief) history of the speed of light or the quest for dark matter, then make sure to check out this collection of papers to mark the 10th anniversary of the St Cross Centre for the History and Philosophy of Physics (HAPP).

HAPP was co-founded in 2014 by Jo Ashbourn and James Dodd and since then the centre has run a series of one-day conferences as well as standalone lectures and seminars about big topics in physics and philosophy.

Based on these contributions, HAPP has now published a 10th anniversary commemorative volume in the open-access Journal of Physics: Conference Series, which is published by IOP Publishing.

The volume is structured around four themes: physicists across history; space and astronomy; philosophical perspectives; and concepts in physics.

The big names in physics to write for the volume include Martin Rees on the search for extraterrestrial intelligence across a century; Carlo Rovelli on scientific thinking across the centuries; and the late Steven Weinberg on the greatest physics discoveries of the 20th century.

I was delighted to also contribute to the volume based on a talk I gave in February 2020 for a one-day HAPP meeting about big science in physics.

The conference covered the past, present and future of big science and I spoke about the coming decade of new facilities in physics and the possible science that may result. I also included my “top 10 facilities to watch” for the coming decade.

In a preface to the volume, Ashbourn writes that HAPP was founded to provide “a forum in which the philosophy and methodologies that inform how current research in physics is undertaken would be included alongside the history of the discipline in an accessible way that could engage the general public as well as scientists, historians and philosophers,” adding that she is “looking forward” to HAPP’s second decade.

The post Martin Rees, Carlo Rovelli and Steven Weinberg tackle big questions to mark Oxford anniversary appeared first on Physics World.

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Timber! Japan launches world’s first wooden satellite into space

5 novembre 2024 à 18:31

Researchers in Japan have launched the world’s first wooden satellite to test the feasibility of using timber in space. Dubbed LignoSat2, the small “cubesat” was developed by Kyoto University and the logging firm Sumitomo Forestry. It was launched on 4 November to the International Space Station (ISS) from the Kennedy Space Center in Florida by a SpaceX Falcon 9 rocket.

Given the lack of water and oxygen in space, wood is potentially more durable in orbit than it is on Earth where it can rot or burn. This makes it an attractive and sustainable alternative to metals such as aluminium that can create aluminium oxide particles during re-entry into the Earth’s atmosphere.

Work began on LignoSat in 2020. In 2022 scientists at Kyoto sent samples of cherry, birch and magnolia wood to the ISS where the materials were exposed to the harsh environment of space for 240 days to test their durability.

While each specimen performed well with no clear deformation, the researchers settled on building LignoSat from magnolia – or Hoonoki in Japanese. This type of wood has traditionally been used for sword sheaths and is known for its strength and stability.

LignoSat2 is made without screws of glue and is equipped with external solar panels and encased in an aluminium frame. Next month the satellite is expected to be deployed in orbit around the Earth for about six months to measure how the wood withstands the environment and how well it protects the chips inside the satellite from cosmic radiation.

Data will be collected on the wood’s expansion and contraction, the internal temperature and the performance of the electronic components inside.

Researchers are hopeful that if LignoSat is successful it could pave the way for satellites to be made from wood. This would be more environmentally friendly given that each satellite would simply burn up when it re-enters the atmosphere at the end of its lifetime.

“With timber, a material we can produce by ourselves, we will be able to build houses, live and work in space forever,” astronaut Takao Doi who studies human space activities at Kyoto University told Reuters.

The post Timber! Japan launches world’s first wooden satellite into space appeared first on Physics World.

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Universe’s lifespan too short for monkeys to type out Shakespeare’s works, finds study

1 novembre 2024 à 16:00

According to the well-known thought experiment, the infinite monkeys theorem, a monkey randomly pressing keys on a typewriter for an infinite amount of time would eventually type out the complete works of William Shakespeare purely by chance.

Yet a new analysis by two mathematicians in Australia finds that even a troop might not have the time to do so within the supposed timeframe of the universe.

To find out, the duo created a model that includes 30 keys – all the letters in the English language plus punctuation marks. They assumed a constant chimpanzee population of 200,000 could be enlisted to the task, each typing at one key per second until the end of the universe in about 10100 years.

“We decided to look at the probability of a given string of letters being typed by a finite number of monkeys within a finite time period consistent with estimates for the lifespan of our universe,” notes mathematician Stephen Woodcock from the University of Technology Sydney.

The mathematicians found that there is only a 5% chance a single monkey would type “bananas” within its own lifetime of just over 30 years. Yet even with all the chimps feverishly typing away, they would not be able to produce Shakespeare’s entire works (coming in at over 850,000 words) before the universe ends. They would, however, be able to type “I chimp, therefore I am”.

“It is not plausible that, even with improved typing speeds or an increase in chimpanzee populations, monkey labour will ever be a viable tool for developing non-trivial written works,” the authors conclude, adding that while the infinite monkeys theorem is true, it is also “somewhat misleading”, or rather it’s “not to be” in reality.

The post Universe’s lifespan too short for monkeys to type out Shakespeare’s works, finds study appeared first on Physics World.

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Superconductivity theorist Leon Cooper dies aged 94

29 octobre 2024 à 15:09

The US condensed-matter physicist Leon Cooper, who shared the 1972 Nobel Prize for Physics, has died at the age of 94. In the late 1950s, Cooper, together with his colleagues Robert Schrieffer and John Bardeen, developed a theory of superconductivity that could explain why certain materials undergo an absolute absence of electrical resistance at low temperatures.

Born on 28 February 1930 in New York City, US, Cooper graduated from the Bronx High School of Science in 1947 before earning a degree from Columbia University, which he completed in 1951, and then a PhD in 1954.

Cooper then spent time at the Institute for Advanced Study in Princeton, the University of Illinois and Ohio State University before heading to Brown University in 1958 where he remained for the rest of his career.

It was in Illinois that Cooper began to work on a theoretical explanation of superconductivity – a phenomenon that was first seen by the Dutch physicist Heike Kamerlingh Onnes when he discovered in 1911 that the electrical resistance of mercury suddenly disappeared beneath a temperature of 4.2 K.

However, there was no microscopic theory of superconductivity until 1957, when Bardeen, Cooper and Schrieffer – all based at Illinois – came up with their “BCS” theory. This described how an electron can deform the atomic lattice through which it moves, thereby pairing with a neighbouring electron, which became known as a Cooper pair. Being paired allows all the electrons in a superconductor to move as a single cohort, known as a condensate, prevailing over thermal fluctuations that could cause the pairs to break.

Bardeen, Cooper and Schrieffer published their BCS theory in April 1957 (Phys. Rev. 106 162), which was then followed in December by a full-length paper (Phys. Rev. 108 1175). Cooper was in his late 20s when he made the breakthrough.

Not only did the BCS theory of superconductivity successfully account for the behaviour of “conventional” low-temperature superconductors such as mercury and tin but it also had application in particle physics by contributing to the notion of spontaneous symmetry breaking.

For their work the trio won the 1972 Nobel Prize for Physics “for their jointly developed theory of superconductivity, usually called the BCS-theory”.

From BCS to BCM

While Cooper continued to work in superconductivity, later in his career he turned to neuroscience. In 1973 he founded and directed Brown’s Institute for Brain and Neural Systems, which studied animal nervous systems and the human brain. In the 1980s he came up with a physical theory of learning in the visual cortex dubbed the “BCM” theory, named after Cooper and his colleagues Elie Bienenstock and Paul Munro.

He also founded the technology firm Nestor along with Charles Elbaum, which aimed to find commercial and military applications for artificial neural networks.

As well as the Nobel prize, Cooper was awarded the Comstock Prize from the US National Academy of Sciences in 1968 and the Descartes Medal from the Academie de Paris in 1977.

He also wrote numerous books including An Introduction to the Meaning and Structure of Physics in 1968 and Physics: Structure and Meaning in 1992. More recently, he published Science and Human Experience in 2014.

“Leon’s intellectual curiosity knew no boundaries,” notes Peter Bilderback, who worked with Cooper at Brown. “He was comfortable conversing on any subject, including art, which he loved greatly. He often compared the construction of physics to the building of a great cathedral, both beautiful human achievements accomplished by many hands over many years and perhaps never to be fully finished.”

The post Superconductivity theorist Leon Cooper dies aged 94 appeared first on Physics World.

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First look at prototype telescope for the LISA gravitational-wave mission

23 octobre 2024 à 12:30

NASA has released the first images of a full-scale prototype for the six telescopes that will be included in the €1.5bn Laser Interferometer Space Antenna (LISA) mission.

Expected to launch in 2035 and operate for at least four year, LISA is a space-based gravitational-wave mission led by the European Space Agency.

It will comprise of three identical satellites that will be placed in an equilateral triangle in space, with each side of the triangle being 2.5 million kilometers – more than six times the distance between the Earth and the Moon.

The three craft will send infrared laser beams to each other via twin telescopes in the satellites. The beams will be sent to free-floating golden cubes – each slightly smaller than a Rubik’s cube — that are placed inside the craft.

The system will be able to measure the separation between the cubes down to picometers, or trillionths of a meter. Such subtle changes in the distances between the measured laser beams will indicate the presence of a gravitational wave.

The prototype telescope, dubbed the Engineering Development Unit Telescope, was manufactured and assembled by L3Harris Technologies in Rochester, New York.

It is made entirely from an amber-coloured glass-ceramic called Zerodur, which has been manufactured by Schott in Mainz, Germany. The primary mirror of the telescopes is coated in gold to better reflect the infrared lasers and reduce heat loss.

On 25 January ESA’s Science Programme Committee formally approved the start of construction of LISA.

The post First look at prototype telescope for the LISA gravitational-wave mission appeared first on Physics World.

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How a next-generation particle collider could unravel the mysteries of the Higgs boson

22 octobre 2024 à 12:00

More than a decade following the discovery of the Higgs boson at the CERN particle-physics lab near Geneva in 2012, high-energy physics stands at a crossroads. While the Large Hadron Collider (LHC) is currently undergoing a major £1.1bn upgrade towards a High-Luminosity LHC (HL-LHC), the question facing particle physicists is what machine should be built next – and where – if we are to study the Higgs boson in unprecedented detail in the hope of revealing new physics.

Several designs exist, one of which is a huge 91 km circumference collider at CERN known as the Future Circular Collider (FCC). But new technologies are also offering tantalising alternatives to such large machines, notably a muon collider. As CERN celebrates its 70th anniversary this year, Michael Banks talks to Tulika Bose from the University of Wisconsin–Madison, Philip Burrows from the University of Oxford and Tara Shears from the University of Liverpool about the latest research on the Higgs boson, what the HL-LHC might discover and the range of proposals for the next big particle collider.

Tulika Bose, Philip Burrows and Tara Shears
Expert panel Tulika Bose, Philip Burrows and Tara Shears were speaking on a Physics World Live panel discussion about the future of particle physics held on 26 September 2024. (Courtesy: Tulika Bose; Philip Burrows; McCoy Wynne)

What have we learnt about the Higgs boson since it was discovered in 2012?

Tulika Bose (TB): The question we have been working towards in the past decade is whether it is a “Standard Model” Higgs boson or a sister, or a cousin or a brother of that Higgs. We’ve been working really hard to pin it down by measuring its properties. All we can say at this point is that it looks like the Higgs that was predicted by the Standard Model. However, there are so many questions we still don’t know. Does it decay into something more exotic? How does it interact with all of the other particles in the Standard Model? While we’ve understood some of these interactions, there are still many more particle interactions with the Higgs that we don’t quite understand. Then of course, there is a big open question about how the Higgs interacts with itself. Does it, and if so, what is its interaction strength? These are some of the exciting questions that we are currently trying to answer at the LHC.

So the Standard Model of particle physics is alive and well?

TB: The fact that we haven’t seen anything exotic that has not been predicted yet tells us that we need to be looking at a different energy scale. That’s one possibility – we just need to go much higher energies. The other alternative is that we’ve been looking in the standard places. Maybe there are particles that we haven’t yet been able to detect that couple incredibly lightly to the Higgs.

Has it been disappointing that the LHC hasn’t discovered particles beyond the Higgs?

Tara Shears (TS): Not at all. The Higgs alone is such a huge step forward in completing our picture and understanding of the Standard Model, providing, of course, it is a Standard Model Higgs. And there’s so much more that we’ve learned aside from the Higgs, such as understanding the behaviour of other particles such as differences between matter and antimatter charm quarks.

How will the HL-LHC take our understanding of the Higgs forward?

TS: One way to understand more about the Higgs is to amass enormous amounts of data to look for very rare processes and this is where the HL-LHC is really going to come into its own. It is going to allow us to extend those investigations beyond the particles we’ve been able to study so far making our first observations of how the Higgs interacts with lighter particles such as the muon and how the Higgs interacts with itself. We hope to see that with the HL-LHC.

What is involved with the £1.1bn HL-LHC upgrade?

Philip Burrows (PB): The LHC accelerator is 27 km long and about 90% of it is not going to be affected. One of the most critical aspects of the upgrade is to replace the magnets in the final focus systems of the two large experiments, ATLAS and CMS. These magnets will take the incoming beams and then focus them down to very small sizes of the order of 10 microns in cross section. This upgrade includes the installation of brand new state-of-the-art niobium-tin (Nb3Sn) superconducting focusing magnets.

Engineer working on the HL-LHC upgrade in the LHC tunnel
Super LHC The High-Luminosity Large Hadron Collider, to be completed by the end of the decade at a cost of £1.1bn, will result in a factor of 10 increase in luminosity over the original LHC. (Courtesy: CERN)

What is the current status of the project?

PB: The schedule involves shutting down the LHC for roughly three to four years to install the high-luminosity upgrade, which will then turn on towards the end of the decade. The current CERN schedule has the HL-LHC running until the end of 2041. So there’s another 10 years plus of running this upgraded collider and who knows what exciting discoveries are going to be made.

TS: One thing to think about concerning the cost is that the timescale of use is huge and so it is an investment for a considerable part of the future in terms of scientific exploitation. It’s also an investment in terms of potential spin-out technology.

In what way will the HL-LHC be better than the LHC?

PB: The measure of the performance of the accelerator is conventionally given in terms of luminosity and it’s defined as the number of particles that cross at these collision points per square centimetre per second. That number is roughly 1034 with the LHC. With the high-luminosity upgrade, however, we are talking about making roughly an order of magnitude increase in the total data sample that will be collected over the next decade or so. So in other words, we’ve only got 10% or so of the total data sample so far in the bag. After the upgrade, there’ll be another factor of 10 data that will be collected and that is a completely new ball game in terms of the statistical accuracy of the measurements that can be made and the sensitivity and reach for new physics

Looking beyond the HL-LHC, particle physicists seem to agree that the next particle collider should be a Higgs factory – but what would that involve?

TB: Even at the end of the HL-LHC, there will be certain things we won’t be able to do at the LHC and that’s for several reasons. One is that the LHC is a proton–proton machine and when you’re colliding protons, you end up with a rather messy environment in comparison to the clean collisions between electrons and positrons and this allows you to make certain measurements which will not be possible at the LHC.

So what sort of measurements could you do with a Higgs factory?

TS:  One is to find out how much the Higgs couples to the electron. There’s no way we will ever find that out with the HL-LHC, it’s just too rare a process to measure, but with a Higgs factory, it becomes a possibility. And this is important not because it’s stamp collecting, but because understanding why the mass of the electron, which the Higgs boson is responsible for, has that particular value is of huge importance to our understanding of the size of atoms, which underpins chemistry and materials science.

PB: Although we often call this future machine a Higgs factory, it has far more uses beyond making Higgs bosons. If you were to run it at higher energies, for example, you could make pairs of top quarks and anti-top quarks. And we desperately want to understand the top quark, given it is the heaviest fundamental particle that we are aware of – it’s roughly 180 times heavier than a proton. You could also run the Higgs factory at lower energies and carry out more precision measurements of the Z and W bosons. So it’s really more than a Higgs factory. Some people say it’s the “Higgs and the electroweak boson factory” but that doesn’t quite roll off the tongue in the same way.

Artist concept of the International Linear Collider
Balancing act A linear collider has the benefit that particles accelerated in it don’t lose energy due to synchrotron radiation, potentially making it cheaper to build. To collect the same number of Higgs bosons at the nominal energy of 250 GeV the linear machine would probably have to be run for longer than the circular one. (Courtesy: ILC)

While it seems there’s a consensus on a Higgs factory, there doesn’t appear to be one regarding building a linear or circular machine?

PB: There are two main designs on the table today – circular and linear. The motivation for linear colliders is due to the problem of sending electrons and positrons round in a circle – they radiate photons. So as you go to higher energies in a circular collider, electrons and positrons radiate that energy away in the form of synchrotron radiation. It was felt back in the late-1990s that it was the end of the road for circular electron–positron colliders because of the limitations of synchrotron radiation. But the discovery of the Higgs boson at 125 GeV was lighter than some had predicted. This meant that an electron–positron collider would only need a centre of mass energy of about 250 GeV. Circular electron–positron colliders then came back in vogue.

TS: The drawback with a linear collider is that the beams are not recirculated in the same way as they are in a circular collider. Instead, you have “shots”, so it’s difficult to reach the same volume of data in a linear collider. Yet it turns out that both of these solutions are really competitive with each other and that’s why they are still both on the table.

PB: Yes, while a circular machine may have two, or even four, main detectors in the ring, at a linear machine the beam can be sent to only one detector at a given time. So having two detectors means you have to share the luminosity, so each would get notionally half of the data. But to take an automobile analogy, it’s kind of like arguing about the merits of a Rolls-Royce versus a Bentley. Both linear and circular are absolutely superb, amazing options and some have got bells and whistles over here and others have got bells and whistles over there, but you’re really arguing about the fine details.

CERN seems to have put its weight behind the Future Circular Collider (FCC) – a huge 91 km circumference circular collider that would cost £12bn. What’s the thinking behind that?

TS: The cost is about one-and-a-half times that of the Channel Tunnel so it is really substantial infrastructure. But bear in mind it is for a facility that’s going to be used for the remainder of the century, for future physics, so you have to keep that longevity in mind when talking about the costs.

TB: I think the circular collider has become popular because it’s seen as a stepping stone towards a proton–proton machine operating at 100 TeV that would use the same infrastructure and the same large tunnel and begin operation after the Higgs factory element in the 2070s. That would allow us to really pin down the Higgs interaction with itself and it would also be the ultimate discovery machine, allowing us to discover particles at the 30–40 TeV scale, for example.

Artist concept of the Future Circular Collider
Let’s go round again The Future Circular Collider would involve constructing a huge 91 km-circumference ring near the existing LHC that would collide electrons with positrons to study the Higgs in unprecedented detail. (Courtesy: CERN)

What kind of technologies will be needed for this potential proton machine?

PB: The big issue is the magnets, because you have to build very strong bending magnets to keep the protons going round on their 91 km circumference trajectory. The magnets at the LHC are 8 T but some think the magnets you would need for the proton version of the FCC would be 16–20 T. And that is really pushing the boundaries of magnet technology. Today, nobody really knows how to build such magnets. There’s a huge R&D effort going on around the world and people are constantly making progress. But that is the big technological uncertainty. Yet if we follow the model of an electron–positron collider first, followed by a proton–proton machine, then we will have several decades in which to master the magnet technology.

With regard to novel technology, the influential US Particle Physics Project Prioritization Panel, known as “P5”, called for more research into a muon collider, calling it “our muon shot”. What would that involve?

TB: Yes, I sat on the P5 panel that published a report late last year that recommended a course of action for US particle physics for the coming 20 years. One of those recommendations involves carrying out more research and development into a muon collider. As we already discussed, an electron–positron collider in a circular configuration suffers from a lot of synchrotron radiation. The question is if we can instead use a fundamental elementary particle that is more massive than the electron. In that case a muon collider could offer the best of both worlds, the advantages of an electron machine in terms of clean collisions but also reaching larger energies like a proton machine. However, the challenge is that the muon is very unstable and decays quickly. This means you are going to have to create, focus and collide them before they decay. A lot of R&D is needed in the coming decades but perhaps a decision could be taken on whether to go ahead by the 2050s.

And potentially, if built, it would need a tunnel of similar size to the existing LHC?

TB: Yes. The nice thing about the muon collider is that you don’t need a massive 90 km tunnel so it could actually fit on the existing Fermilab campus. Perhaps we need to think about this project in a global way because this has to be a big global collaborative effort. But whatever happens it is exciting times ahead.

  • Tulika Bose, Philip Burrows and Tara Shears were speaking on a Physics World Live panel discussion about the future of particle physics held on 26 September 2024. This Q&A is an edited version of the event, which you can watch online now

The post How a next-generation particle collider could unravel the mysteries of the Higgs boson appeared first on Physics World.

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Semiconductor pioneer Richard Friend bags 2024 Isaac Newton Medal and Prize

15 octobre 2024 à 16:44

The semiconductor physicist Richard Friend from the University of Cambridge has won the 2024 Isaac Newton Medal and Prize “for pioneering and enduring work on the fundamental electronic properties of molecular semiconductors and in their engineering development”. Presented by the Institute of Physics (IOP), which publishes Physics World, the international award is given annually for “world-leading contributions to physics”.

Friend was born in 1953 in London, UK. He completed a PhD at the University of Cambridge in 1979 under the supervision of Abe Yoffe and remained at Cambridge becoming a full professor in 1995. Friend’s research has led to a deeper understanding of the electronic properties of molecular semiconductors having in the 1980s pioneered the fabrication of thin-film molecular semiconductor devices that were later developed to support field-effect transistor circuits.

When it was discovered that semiconducting polymers could be used for light-emitting diodes (LEDs), Friend founded Cambridge Display Technology in 1992 to develop polymer LED displays. In 2000 he also co-founded Plastic Logic to advance polymer transistor circuits for e-paper displays.

As well as the 2024 Newton Medal and Prize, Friend’s other honours include the IOP’s Katherine Burr Blodgett Medal and Prize in 2009 and in 2010 he shared the Millennium Technology Prize for the development of plastic electronics. He was also knighted for services to physics in the 2003 Queen’s Birthday Honours list.

“I am immensely proud of this award and the recognition of our work,” notes Friend. “Our Cambridge group helped set the framework for the field of molecular semiconductors, showing new ways to improve how these materials can separate charges and emit light.”

Friend notes that he is “not done just yet” and is currently working on molecular semiconductors to improve the efficiency of LEDs.

Innovating and inspiring

Friend’s honour formed part of the IOP’s wider 2024 awards, which recognize everyone from early-career scientists and teachers to technicians and subject specialists.

Other winners include Laura Herz from the University of Oxford, who receives the Faraday Prize “for pioneering advances in the photophysics of next-generation semiconductors, accomplished through innovative spectroscopic experiments”. Rebecca Dewey from the University of Nottingham, meanwhile, receives the Phillips Award “for contributions to equality, diversity and inclusion in Institute of Physics activities, including promoting, updating and improving the accessibility of the I am a Physicist Girlguiding Badge, and engaging with British Sign Language users”.

In a statement, IOP president Keith Burnett congratulated all the winners, adding that they represent “some of the most innovative and inspiring” work that is happening in physics.

“Today’s world faces many challenges which physics will play an absolutely fundamental part in addressing, whether its securing the future of our economy or the transition to sustainable energy production and net zero,” adds Burnett. “Our award winners are in the vanguard of that work and each one has made a significant and positive impact in their profession. Whether as a researcher, teacher, industrialist, technician or apprentice, I hope they are incredibly proud of their achievements.”

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Top-cited authors from China discuss the importance of citation metrics

11 octobre 2024 à 11:26

More than 90 papers from China have been recognized with a top-cited paper award for 2024 from IOP Publishing, which publishes Physics World. The prize is given to corresponding authors who have papers published in both IOP Publishing and its partners’ journals from 2021 to 2023 that are in the top 1% of the most cited papers.

Among them are quantum physicist Xin Wang from Xi’an Jiaotong University and environmental scientist Huijuan Cui from the Institute of Geographic Sciences and Natural Resources Research.

Cui, who carries out research into climate change, says that China’s carbon neutrality goal has attracted attention all over the world, which may be a reason why the paper, published in Environmental Research Letters, garnered so many citations. “As the Chinese government pays more attention on sustainability issues like climate change…we see growing activities and influence from Chinese researchers,” she says.

A similar impact can be seen in Wang’s work in “chiral quantum networks”, which is published in Quantum Science and Technology, and is equally seen as an area that is quickly gaining traction.

Citations have an important role in Chinese research, and they can also highlight a research topic’s growing impact. “They indicate that what we are studying is a mainstream research field,” Wang says. “Our peers agree with our results and judgement of the field’s future.” Cui, meanwhile, says that citations reflect a “a positive acceptance and recognition of the quality of the research”.

Wang, however, notes that citations and impact doesn’t necessarily happen overnight and that researchers must not base their work’s impact on instantly generating citations.

He adds that some pioneering papers are not well-cited initially with researchers only beginning to realize their value after several years. “If we are confident that our findings are important, we should not be upset with its bad citation but keep on working,” he says. “It is the role of the researcher to stick with their gut to uncover their key research questions. Citations will come afterwards.”

Language barriers

When it comes to Chinese researchers getting their research cited internationally, Wang says that the language barrier is one of the greatest challenges. “The readability of a paper has a close relation with its citation,” adds Wang. “Most highly cited papers not only have an insight into scientific problems, but also are well-written.”

He adds that non-native speakers tend to avoid using “snappy” expressions, which often leads to a conservative and uninspiring tone. “These expressions are grammatically correct but awkward to native speakers,” Wang states.

Despite the potential difficulties with slow citations and language barriers, Cui says that success can be achieved through determination and focussing on important research questions. “Constant effort yields success,” adds Cui. “Keep digging into interesting questions and keep writing high-quality papers.”

That view is backed by Wang. “If your research is well-cited, congratulations,” adds Wang. “However, please do not be upset with a paper with few citations – it still might be pioneering work in its field.”

  • For the full list of top-cited papers from China for 2024, see here. Xin Wang’s and Huijuan Cui’s award-winning research can be read here and here, respectively

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European Space Agency launches Hera mission to investigate asteroid ‘crash-scene’

7 octobre 2024 à 16:53

The European Space Agency (ESA) has launched a €360m mission to perform a close-up “crash-scene” investigation of the 150 m-diameter asteroid Dimorphos, which was purposely hit by a NASA probe in 2022. Hera took off aboard a SpaceX Falcon 9 rocket from Cape Canaveral at 10:52 local time. The mission should reach the asteroid in December 2026.

On 26 September 2022, NASA confirmed that its $330m Double Asteroid Redirection Test (DART) mission successfully demonstrated “kinetic impact” by hitting Dimorphos at a speed of 6.1 km/s. This resulted in the asteroid being put on a slightly different orbit around its companion body – a 780 m-diameter asteroid called “Didymos”.

A month later in October, NASA confirmed that DART had altered Dimorphos’ orbit by 33 minutes, shortening the 11 hour and 55-minute orbit to 11 hours and 23 minutes. This was some 25 times greater than the 73 seconds NASA had defined as a minimum successful orbit period change. Much of the momentum change came from the ejecta liberated by the impact including a plume of debris that extended more than 10 000 km into space.

Mars flyby

The Hera mission, which has 12 instruments including cameras and thermal-infrared imagers, will perform a detailed post-impact survey of Dimorphos. This will involve measuring its size, shape mass and orbit more precisely than has been carried out to date by follow-up measurements from ground- and space-based observatories including the Hubble Space Telescope.

It is hoped that Hera will be able to reach up to 200 m from the surface of Dimorphos to deliver 2 cm imaging resolution in certain sections.

Part of the Hera mission involves releasing two cubesats – each the size of a shoebox – that will also have imagers and radar onboard. They will examine Dimorphos’ internal structure to determine whether it is a rubble pile or has a solid core surrounding by layers of boulders.

The cubesats will also attempt to land on the asteroid with one measuring the asteroid’s gravitational field. The cubesats are also technology demonstrators, testing communication in deep space between them and Hera.

Once Hera’s mission is complete about six months after arrival at Dimorphos, it may also attempt to land on the asteroid, although a decision to do so has not yet been made.

On its way to Dimorphos, next year Hera will carry out a “swingby” of Mars and a flyby of the Martian moon Deimos.

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Study finds preschool children form ‘social droplets’ when moving around the classroom

5 octobre 2024 à 11:00

If you have ever experienced a preschool environment you will know how seemingly chaotic it can be. Now physicists in the US and Germany have examined the movement of preschool children in classroom and playground settings to determine if any rules can be gleaned from their dawdling.

To do so they put radio-frequency tags on the vests of more than 200 children aged between two and four and then monitored their position and trajectories via receivers placed around the environment.

The researchers found that the dynamics resembled two distinct phases. The first is a gas-like phase in which the children are moving freely while exploring their surroundings.

This was mostly seen in the playground where children could roam without restriction, with the researchers finding that toddlers’ movement is similar to that of pedestrian flow.

The second phase is a “liquid-vapour-like state”, in which the children act like molecules to form “droplets” of social groups. In other words, they coalesce into smaller, more clustered groups with some “free-moving” individuals entering and exiting these groups.

The team found that this phase was most evident in classrooms, in which the children are more constrained and social communication plays a bigger role. Indeed, this type of behaviour has not been observed in human movement before, with the findings offering new insights about the dynamics of low-speed movement.

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CERN celebrates 70 years at the helm of particle physics in lavish ceremony

2 octobre 2024 à 14:02

Officials gathered yesterday for an official ceremony to celebrate 70 years of the CERN particle-physics lab, which was founded in 1954 in Geneva less than a decade after the end of the Second World War.

The ceremony was attended by 38 national delegations including the heads of state and government from Bulgaria, Italy, Latvia, Serbia, Slovakia and Switzerland as well as Her Royal Highness Princess Astrid of Belgium and the president of the European Commission. It marked the culmination of a year of events that showcased the lab’s history and plans for the future as it looks beyond the Large Hadron Collider.

Created to foster peace between nations and bring scientists together, CERN’s origins can be traced back to 1949 when the French Nobel-prize-winning physicist Louis de Broglie first proposed the idea a European laboratory. A resolution to create the European Council for Nuclear Research (CERN) was adopted at a UNESO conference in Paris in 1951, with 11 countries signing an agreement to establish the CERN council the year after.

CERN Council met for the first time in May 1952 and in October of that year chose Geneva as the site for a 25–30 GeV proton synchrotron. The formal convention establishing CERN was signed at a meeting in Paris in 1953 by the lab’s 12 founding member states: Belgium, Denmark, France, West Germany, Greece, Italy, the Netherlands, Norway, Sweden, Switzerland, the UK and Yugoslavia.

On 29 September 1954 CERN was formed and the provisional CERN council was dissolved. That year also saw the start of construction of the lab in which the proton synchrotron, with a circumference of 628 m, accelerated protons for the first time on 24 November 1959 with an energy of 24 GeV, becoming the world’s highest-energy particle accelerator.

A proud moment

Today CERN has 23 member states with 10 associate member states. Some 17,000 people from 100 nationalities work at CERN, mostly on the LHC but the lab also does research into antimatter research and theory. CERN is now planning on building on that success through a Future Circular Collider, which if funded, would include a 91 km circumference collider to study the Higgs boson in unprecedented detail.

As part of the celebrations, this year has seen over 100 events organized in 63 cities in 28 countries. The first public event at CERN, held on 30 January, combined science, art and culture, and featured scientists discussing the evolution of particle physics and CERN’s significant contributions in advancing this field.

Other events over the past months have focused on open questions in physics and future directions; the link between fundamental science and technology; CERN’s role as a model for international collaboration; and training, education and accessibility.

The meeting yesterday, the culmination of this year-long celebration, was held in the auditorium of CERN’s Science Gateway, which was inaugurated in October 2023.

“CERN is a great success for Europe and its global partners, and our founders would be very proud to see what CERN has accomplished over the seven decades of its life,” noted CERN director general Fabiola Gianotti. “The aspirations and values that motivated those founders remain firmly anchored in our organization today: the pursuit of scientific knowledge and technological developments for the benefit of humanity; training and education; collaboration across borders, diversity and inclusion; knowledge, technology and education accessible to society at no cost; and a great dose of boldness and determination to pursue paths that border on the impossible.”

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Physicists reveal the mechanics of tea scum

28 septembre 2024 à 11:00

If you have ever brewed a cup of black tea with hard water you will be familiar with the oily film that can form on the surface of the tea after just a few minutes.

Known as “tea scum” the film consists of calcium carbonate crystals within an organic matrix. Yet it can be easily broken apart with a quick stir of a teaspoon.

Physicists in France and the UK have now examined how this film forms and also what happens when it breaks apart through stirring.

They did so by first sprinkling graphite powder into a water tank. Thanks to capillary forces, the particles gradually clump together to form rafts. The researchers then generated waves in the tank that broke apart the rafts and filmed the process with a camera.

Through these experiments and theoretical modelling, they found that the rafts break up when diagonal cracks form at the raft’s centre. This causes them to fracture into larger chunks before the waves eventually eroded them away.

They found that the polygonal shapes created when the rafts split up is the same as that seen in ice floes.

Despite the visual similarities, however, sea ice and tea scum break up through different physical mechanisms. While ice is brittle, bending and snapping under the weight of crushing waves, the graphite rafts come apart when the viscous stress exerted by the waves overcome the capillary forces that hold the individual particles together.

Buoyed by their findings, the researchers now plan to use their model to explain the behaviour of other thin biofilms, such as pond scum.

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The physics of cycling’s ‘Everesting’ challenge revealed

20 septembre 2024 à 17:00

“Everesting” involves a cyclist riding up and down a given hill multiple times until the ascent totals the elevation of Mount Everest – or 8848 m.

The challenge became popular during the COVID-19 lockdowns and in 2021 the Irish cyclist Ronan McLaughlin was reported to have set a new “Everesting” record of 6:40:54. This was almost 20 minutes faster than the previous world record of 6:59:38 set by the US’s Sean Gardner in 2020.

Yet a debate soon ensued on social media concerning the significant tailwind that day of 5.5 meters per second, which they claimed would have helped McLaughlin to climb the hill multiple times.

But did it? To investigate, Martin Bier, a physicist at East Carolina University in North Carolina, has now analysed what effect air resistance might have when cycling up and down a hill.

“Cycling uses ‘rolling’, which is much smoother and faster, and more efficient [than running],” notes Bier. “All of the work is purely against gravity and friction.”

Bier calculated that a tailwind does help slightly when going uphill, but most of the work when doing so is generating enough power to overcome gravity rather than air resistance.

When coming downhill, however, any headwind becomes significant given that the force of air resistance increases with the square of the cyclist’s speed. The headwind can then have a huge effect, causing a significant reduction in speed.

So, while a tailwind going up is negligible the headwind coming down certainly won’t be. “There are no easy tricks,” Bier adds. “If you want to be a better Everester, you need to lose weight and generate more [power]. This is what matters — there’s no way around it.”

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The free-to-read Physics World Big Science Briefing 2024 is out now

19 septembre 2024 à 14:00

Over the past decades, “big science” has become bigger than ever be it planning larger particle colliders, fusion tokamaks or space observatories. That development is reflected in the growth of the Big Science Business Forum (BSBF), which has been going from strength to strength following its first meeting in 2018 in Copenhagen.

This year, more than 1000 delegates from 500 organizations and 30 countries will descend on Trieste from 1 to 4 October for BSBF 2024. The meeting will see European businesses and organizations such as the European Southern Observatory, the CERN particle-physics laboratory and Fusion 4 Energy come together to discuss the latest developments and business trends in big science.

A key component of the event – as it was at the previous BSBF in Granada, Spain, in 2022 – is the Women in Big Science group, who will be giving a plenary session about initiatives to boost and help women in big science.

In this year’s Physics World Big Science Briefing, Elizabeth Pollitzer – co-founder and director of Portia, which seeks to improve gender equality in science, technology, engineering and mathematics.

She explains why we need gender equality in big science and what measures must be taken to tackle the gender imbalance among staff and users of large research infrastructures.

One prime example of big science is particle physics. Some 70 years since the founding of CERN and a decade following the discovery of the Higgs boson at the lab’s Large Hadron Collider (LHC) in 2012, particle physics stands at a crossroads. While the consensus is that a “Higgs factory” should come next after the LHC, there is disagreement over what kind of machine it should be – a large circular collider some 91 km in circumference or a linear machine just a few kilometres long.

As the wrangling goes on, other proposals are also being mooted such as a muon collider. Despite needing new technologies, a muon collider has the advantage that it would only require a circular collider in a tunnel roughly the size of the LHC.

Another huge multinational project is the ITER fusion tokamak currently under construction in Cadarache, France. Hit by cost hikes and delays for decades, there was more bad news earlier this year when ITER said the tokamak will now not fire up until 2035. ”Full power” mode with deuterium and tritium won’t happen until 2039 some 50 years since the facility was first mooted.

Backers hope that ITER will lay the way towards fusion power plants delivering electricity to the grid, but huge technical challenges lie in store. After all, those reactors will have to breed their own tritium so they become fuel independent, as John Evans explains.

Big science also involves dedicated user facilities. In this briefing we talk to Gianluigi Botton from the Diamond Light Source in the UK and Mike Witherell from the Lawrence Berkeley National Laboratory on managing such large scale research infrastructures and their plans for the future.

We hope you enjoy the briefing and let us know your feedback on the issue.

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