̽��ֱ�� of Cambridge - Science and Technologies Facilities Council

Earth’s earliest forest revealed in Somerset fossils

sc604 — Thu, 07 Mar 2024 10:27:02 +0000

̽��ֱ��oldest fossilised forest known on Earth – dating from 390 million years ago – has been found in the high sandstone cliffs along the Devon and Somerset coast of South West England.

Astronomers spot oldest ‘dead’ galaxy yet observed

sc604 — Wed, 06 Mar 2024 16:00:10 +0000

Using the James Webb Space Telescope, an international team of astronomers led by the ̽��ֱ�� of Cambridge have spotted a ‘dead’ galaxy when the universe was just 700 million years old, the oldest such galaxy ever observed.

This galaxy appears to have lived fast and died young: star formation happened quickly and stopped almost as quickly, which is unexpected for so early in the universe’s evolution. However, it is unclear whether this galaxy’s ‘quenched’ state is temporary or permanent, and what caused it to stop forming new stars.

̽��ֱ��results, reported in the journal Nature, could be important to help astronomers understand how and why galaxies stop forming new stars, and whether the factors affecting star formation have changed over billions of years.

“ ̽��ֱ��first few hundred million years of the universe was a very active phase, with lots of gas clouds collapsing to form new stars,” said Tobias Looser from the Kavli Institute for Cosmology, the paper’s first author. “Galaxies need a rich supply of gas to form new stars, and the early universe was like an all-you-can-eat buffet.”

“It’s only later in the universe that we start to see galaxies stop forming stars, whether that’s due to a black hole or something else,” said co-author Dr Francesco D’Eugenio, also from the Kavli Institute for Cosmology.

Astronomers believe that star formation can be slowed or stopped by different factors, all of which will starve a galaxy of the gas it needs to form new stars. Internal factors, such as a supermassive black hole or feedback from star formation, can push gas out of the galaxy, causing star formation to stop rapidly. Alternatively, gas can be consumed very quickly by star formation, without being promptly replenished by fresh gas from the surroundings of the galaxy, resulting in galaxy starvation.

“We’re not sure if any of those scenarios can explain what we’ve now seen with Webb,” said co-author Professor Roberto Maiolino. “Until now, to understand the early universe, we’ve used models based on the modern universe. But now that we can see so much further back in time, and observe that the star formation was quenched so rapidly in this galaxy, models based on the modern universe may need to be revisited.”

Using data from JADES (JWST Advanced Deep Extragalactic Survey), the astronomers determined that this galaxy experienced a short and intense period of star formation over a period between 30 and 90 million years. But between 10 and 20 million years before the point in time where it was observed with Webb, star formation suddenly stopped.

“Everything seems to happen faster and more dramatically in the early universe, and that might include galaxies moving from a star-forming phase to dormant or quenched,” said Looser.

Astronomers have previously observed dead galaxies in the early universe, but this galaxy is the oldest yet – just 700 million years after the big bang, more than 13 billion years ago. This observation is one of the deepest yet made with Webb.

In addition to the oldest, this galaxy is also relatively low mass – about the same as the Small Magellanic Cloud (SMC), a dwarf galaxy near the Milky Way, although the SMC is still forming new stars. Other quenched galaxies in the early universe have been far more massive, but Webb’s improved sensitivity allows smaller and fainter galaxies to be observed and analysed.

̽��ֱ��astronomers say that although it appears dead at the time of observation, it’s possible that in the roughly 13 billion years since, this galaxy may have come back to life and started forming new stars again.

“We’re looking for other galaxies like this one in the early universe, which will help us place some constraints on how and why galaxies stop forming new stars,” said D’Eugenio. “It could be the case that galaxies in the early universe ‘die’ and then burst back to life – we’ll need more observations to help us figure that out.”

̽��ֱ��research was supported in part by the European Research Council, the Royal Society, and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).

Reference:
Tobias J Looser et al. ‘A recently quenched galaxy 700 million years after the Big Bang.’ Nature (2024). DOI: 10.1038/s41586-024-07227-0

A galaxy that suddenly stopped forming new stars more than 13 billion years ago has been observed by astronomers.

JADES Collaboration

False-colour JWST image of a small fraction of the GOODS South field, with JADES-GS-z7-01-QU highlighted

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

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Astronomers detect oldest black hole ever observed

sc604 — Wed, 17 Jan 2024 15:59:26 +0000

̽��ֱ��international team, led by the ̽��ֱ�� of Cambridge, used the NASA/ESA/CSA James Webb Space Telescope (JWST) to detect the black hole, which dates from 400 million years after the big bang, more than 13 billion years ago. ̽��ֱ��results, which lead author Professor Roberto Maiolino says are “a giant leap forward”, are reported in the journal Nature.

That this surprisingly massive black hole – a few million times the mass of our Sun – even exists so early in the universe challenges our assumptions about how black holes form and grow. Astronomers believe that the supermassive black holes found at the centre of galaxies like the Milky Way grew to their current size over billions of years. But the size of this newly-discovered black hole suggests that they might form in other ways: they might be ‘born big’ or they can eat matter at a rate that’s five times higher than had been thought possible.

According to standard models, supermassive black holes form from the remnants of dead stars, which collapse and may form a black hole about a hundred times the mass of the Sun. If it grew in an expected way, this newly-detected black hole would take about a billion years to grow to its observed size. However, the universe was not yet a billion years old when this black hole was detected.

“It’s very early in the universe to see a black hole this massive, so we’ve got to consider other ways they might form,” said Maiolino, from Cambridge’s Cavendish Laboratory and Kavli Institute for Cosmology. “Very early galaxies were extremely gas-rich, so they would have been like a buffet for black holes.”

Like all black holes, this young black hole is devouring material from its host galaxy to fuel its growth. Yet, this ancient black hole is found to gobble matter much more vigorously than its siblings at later epochs.

̽��ֱ��young host galaxy, called GN-z11, glows from such an energetic black hole at its centre. 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 edges of a black hole. ̽��ֱ��gas in the accretion disc becomes extremely hot and starts to glow and radiate energy in the ultraviolet range. This strong glow is how astronomers are able to detect black holes.

GN-z11 is a compact galaxy, about one hundred times smaller than the Milky Way, but the black hole is likely harming its development. When black holes consume too much gas, it pushes the gas away like an ultra-fast wind. This ‘wind’ could stop the process of star formation, slowly killing the galaxy, but it will also kill the black hole itself, as it would also cut off the black hole’s source of ‘food’.

Maiolino says that the gigantic leap forward provided by JWST makes this the most exciting time in his career. “It’s a new era: the giant leap in sensitivity, especially in the infrared, is like upgrading from Galileo’s telescope to a modern telescope overnight,” he said. “Before Webb came online, I thought maybe the universe isn’t so interesting when you go beyond what we could see with the Hubble Space Telescope. But that hasn’t been the case at all: the universe has been quite generous in what it’s showing us, and this is just the beginning.”

Maiolino says that the sensitivity of JWST means that even older black holes may be found in the coming months and years. Maiolino and his team are hoping to use future observations from JWST to try to find smaller ‘seeds’ of black holes, which may help them untangle the different ways that black holes might form: whether they start out large or they grow fast.

Reference:
Roberto Maiolino et al. ‘A small and vigorous black hole in the early Universe.’ Nature (2024). DOI: 10.1038/s41586-024-07052-5

Researchers have discovered the oldest black hole ever observed, dating from the dawn of the universe, and found that it is ‘eating’ its host galaxy to death.

It’s a new era: the giant leap in sensitivity, especially in the infrared, is like upgrading from Galileo’s telescope to a modern telescope overnight

Roberto Maiolino

NASA, ESA, and P. Oesch (Yale ̽��ֱ��)

̽��ֱ��GN-z11 galaxy, taken by the Hubble Space Telescope

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‘Bouncing’ comets could deliver building blocks for life to exoplanets

sc604 — Wed, 15 Nov 2023 00:10:19 +0000

In order to deliver organic material, comets need to be travelling relatively slowly – at speeds below 15 kilometres per second. At higher speeds, the essential molecules would not survive – the speed and temperature of impact would cause them to break apart.

̽��ֱ��most likely place where comets can travel at the right speed are ‘peas in a pod’ systems, where a group of planets orbit closely together. In such a system, the comet could essentially be passed or ‘bounced’ from the orbit of one planet to another, slowing it down.

At slow enough speeds, the comet would crash on a planet’s surface, delivering the intact molecules that researchers believe are the precursors for life. ̽��ֱ��results, reported in the Proceedings of the Royal Society A, suggest that such systems would be promising places to search for life outside our Solar System if cometary delivery is important for the origins of life.

Comets are known to contain a range of the building blocks for life, known as prebiotic molecules. For example, samples from the Ryugu asteroid, analysed in 2022, showed that it carried intact amino acids and vitamin B3. Comets also contain large amounts of hydrogen cyanide (HCN), another important prebiotic molecule. ̽��ֱ��strong carbon-nitrogen bonds of HCN make it more durable to high temperatures, meaning it could potentially survive atmospheric entry and remain intact.

“We’re learning more about the atmospheres of exoplanets all the time, so we wanted to see if there are planets where complex molecules could also be delivered by comets,” said first author Richard Anslow from Cambridge’s Institute of Astronomy. “It’s possible that the molecules that led to life on Earth came from comets, so the same could be true for planets elsewhere in the galaxy.”

̽��ֱ��researchers do not claim that comets are necessary to the origin of life on Earth or any other planet, but instead they wanted to place some limits on the types of planets where complex molecules, such as HCN, could be successfully delivered by comets.

Most of the comets in our Solar System sit beyond the orbit of Neptune, in what is known as the Kuiper Belt. When comets or other Kuiper Belt objects (KBOs) collide, they can be pushed by Neptune’s gravity toward the Sun, eventually getting pulled in by Jupiter’s gravity. Some of these comets make their way past the Asteroid Belt and into the inner Solar System.

“We wanted to test our theories on planets that are similar to our own, as Earth is currently our only example of a planet that supports life,” said Anslow. “What kinds of comets, travelling at what kinds of speed, could deliver intact prebiotic molecules?”

Using a variety of mathematical modelling techniques, the researchers determined that it is possible for comets to deliver the precursor molecules for life, but only in certain scenarios. For planets orbiting a star similar to our own Sun, the planet needs to be low mass and it is helpful for the planet to be in close orbit to other planets in the system. ̽��ֱ��researchers found that nearby planets on close orbits are much more important for planets around lower-mass stars, where the typical speeds are much higher.

In such a system, a comet could be pulled in by the gravitational pull of one planet, then passed to another planet before impact. If this ‘comet-passing’ happened enough times, the comet would slow down enough so that some prebiotic molecules could survive atmospheric entry.

“In these tightly-packed systems, each planet has a chance to interact with and trap a comet,” said Anslow. “It’s possible that this mechanism could be how prebiotic molecules end up on planets.”

For planets in orbit around lower-mass stars, such as M-dwarfs, it would be more difficult for complex molecules to be delivered by comets, especially if the planets are loosely packed. Rocky planets in these systems also suffer significantly more high-velocity impacts, potentially posing unique challenges for life on these planets.

̽��ֱ��researchers say their results could be useful when determining where to look for life outside the Solar System.

“It’s exciting that we can start identifying the type of systems we can use to test different origin scenarios,” said Anslow. “It’s a different way to look at the great work that’s already been done on Earth. What molecular pathways led to the enormous variety of life we see around us? Are there other planets where the same pathways exist? It’s an exciting time, being able to combine advances in astronomy and chemistry to study some of the most fundamental questions of all.”

̽��ֱ��research was supported in part by the Royal Society and the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI). Richard Anslow is a Member of Wolfson College, Cambridge.

Reference:
R J Anslow, A Bonsor and P B Rimmer. ‘Can comets deliver prebiotic molecules to rocky exoplanets?’ Proceedings of the Royal Society A (2023). DOI: 10.1098/rspa.2023.0434

How did the molecular building blocks for life end up on Earth? One long-standing theory is that they could have been delivered by comets. Now, researchers from the ̽��ֱ�� of Cambridge have shown how comets could deposit similar building blocks to other planets in the galaxy.

It’s possible that the molecules that led to life on Earth came from comets, so the same could be true for planets elsewhere in the galaxy

Richard Anslow

solarseven via Getty Images

Artist's impression of a meteor hitting Earth

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Webb sees carbon-rich dust grains in the first billion years of cosmic time

sc604 — Wed, 19 Jul 2023 15:00:48 +0000

Similar observational signatures have been observed in the much more recent universe, and have been attributed to complex, carbon-based molecules known as polycyclic aromatic hydrocarbons (PAHs). It is not thought likely, however, that PAHs would have developed within the first billion years of cosmic time.

̽��ֱ��international team, including researchers from the ̽��ֱ�� of Cambridge, say that Webb may have observed a different species of carbon-based molecule: possibly minuscule graphite- or diamond-like grains produced by the earliest stars or supernovas. Their results, which suggest that infant galaxies in the early universe developed much faster than anticipated, are reported in the journal Nature.

̽��ֱ��seemingly empty spaces in our universe are in reality often not empty at all, but are filled by clouds of gas and cosmic dust. This dust consists of grains of various sizes and compositions that are formed and ejected into space in a variety of ways, including by supernova events.

This material is crucial to the evolution of the universe, as dust clouds ultimately form the birthplaces for new stars and planets. However, the dust absorbs stellar light at certain wavelengths, making some regions of space challenging to observe.

An upside is that certain molecules will consistently absorb or otherwise interact with specific wavelengths of light. This means that astronomers can get information about the cosmic dust’s composition by observing the wavelengths of light that it blocks.

̽��ֱ��Cambridge-led team of astronomers used this technique, combined with Webb’s extraordinary sensitivity, to detect the presence of carbon-rich dust grains only a billion years after the birth of the universe.

“Carbon-rich dust grains can be particularly efficient at absorbing ultraviolet light with a wavelength around 217.5 nanometres, which for the first time we have directly observed in the spectra of very early galaxies,” said lead author Dr Joris Witstok from Cambridge’s Kavli Institute for Cosmology.

This 217.5-nanometre feature has previously been observed in the much more recent and local Universe, including within our own Milky Way galaxy, and has been attributed to two different types of carbon-based molecules: polycyclic aromatic hydrocarbons (PAHs) or nano-sized graphitic grains.

According to most models, it should take several hundreds of millions of years before PAHs form, so it would be surprising if the team had observed the chemical signature of molecules that shouldn’t have formed yet. However, according to the researchers, this result is the earliest and most distant direct signature for this carbon-rich dust grain.

̽��ֱ��answer may lie in the details of what was observed. ̽��ֱ��feature observed by the team peaked at 226.3 nanometres, not the 217.5-nanometre wavelength associated with PAHs and tiny graphitic grains. A discrepancy of less than ten nanometres could be accounted for by measurement error. Equally, it could also indicate a difference in the composition of the early universe cosmic dust mixture that the team detected.

“This slight shift in wavelength of where the absorption is strongest suggests we may be seeing a different mix of grains, for example, graphite- or diamond-like grains,” said Witstok, who is also a Postdoctoral Research Associate at Sidney Sussex College. “This could also potentially be produced on short timescales by Wolf-Rayet stars or by material ejected from a supernova.”

Models have previously suggested that nano-diamonds could be formed in the material ejected from supernovas; and huge, hot Wolf-Rayet stars, which live fast and die young, would give enough time for generations of stars to have been born, lived, and died, to distribute carbon-rich grains into the surrounding cosmic dust in under a billion years.

However, it is still a challenge to fully explain these results with the existing understanding of the early formation of cosmic dust. These results will go on to inform the development of improved models and future observations.

With the advent of Webb, astronomers are now able to make detailed observations of the light from individual dwarf galaxies, seen in the first billion years of cosmic time. Webb finally permits the study of the origin of cosmic dust and its role in the crucial first stages of galaxy evolution.

“This discovery was made possible by the unparalleled sensitivity improvement in near-infrared spectroscopy provided by Webb, and specifically its Near-Infrared Spectrograph (NIRSpec),” said co-author Professor Roberto Maiolino, who is based in the Cavendish Laboratory and the Kavli Institute for Cosmology. “ ̽��ֱ��increase in sensitivity provided by Webb is equivalent, in the visible, to instantaneously upgrading Galileo’s 37-millimetre telescope to the 8-metre Very Large Telescope, one of the most powerful modern optical telescopes.”

̽��ֱ��team is planning further research into the data and this result. “We are planning to work with theorists who model dust production and growth in galaxies,” said co-author Irene Shivaei of the ̽��ֱ�� of Arizona/Centro de Astrobiología (CAB). “This will shed light on the origin of dust and heavy elements in the early universe.”

These observations were made as part of the JWST Advanced Deep Extragalactic Survey, or JADES. This programme has facilitated the discovery of hundreds of galaxies that existed when the universe was less than 600 million years old, including some of the farthest galaxies known to date.

“I’ve studied galaxies in the first billion years of cosmic time my entire career and never did we expect to find such a clear signature of cosmic dust in such distant galaxies,” said co-author Dr Renske Smit from Liverpool John Moores ̽��ֱ��. “ ̽��ֱ��ultradeep data from JWST is showing us that grains made up of diamond-like dust can form in the most primordial of systems. This is completely overthrowing models of dust formation and opening up a whole new way of studying the chemical enrichment of the very first galaxies.”

Webb is an international partnership between NASA, ESA and the Canadian Space Agency (CSA). This research was supported in part by the Science and Technology Facilities Council (STFC), part of UK Research and Innovation (UKRI).

Reference:
Joris Witstok et al. ‘Carbonaceous dust grains seen in the first billion years of cosmic time.’ Nature (2023). DOI: 10.1038/s41586-023-06413-w

Adapted from an ESA press release.

For the first time, the James Webb Space Telescope has observed the chemical signature of carbon-rich dust grains in the early universe.

ESA/Webb, NASA, ESA, CSA

Galaxy JADES-GS-z6 in the GOODS-S field: JADES (NIRCam image)

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Existing infrastructure will be unable to support demand for high-speed internet

sc604 — Tue, 26 Apr 2022 15:00:00 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge and BT, have established the maximum speed at which data can be transmitted through existing copper cables. This limit would allow for faster internet compared to the speeds currently achievable using standard infrastructure, however it will not be able to support high-speed internet in the longer term.

̽��ֱ��team found that the ‘twisted pair’ copper cables that reach every house and business in the UK are physically limited in their ability to support higher frequencies, which in turn support higher data rates.

While full-fibre internet is currently available to around one in four households, it is expected to take at least two decades before it reaches every home in the UK. In the meantime, however, existing infrastructure can be improved to temporarily support high-speed internet.

̽��ֱ��results, reported in the journal Nature Communications, both establish a physical limit on the UK’s ubiquitous copper cables, and emphasise the importance of immediate investment in future technologies.

̽��ֱ��Cambridge-led team used a combination of computer modelling and experiments to determine whether it was possible to get higher speeds out of existing copper infrastructure and found that it can carry a maximum frequency of about 5 GHz, above the currently used spectrum, which is lower than 1 GHz. Above 5 GHz however, the copper cables start to behave like antennas.

Using this extra bandwidth can push data rates on the copper cables above several Gigabits per second on short ranges, while fibre cables can carry hundreds of Terabits per second or more.

“Any investment in existing copper infrastructure would only be an interim solution,” said co-author Dr Anas Al Rawi from Cambridge’s Cavendish Laboratory. “Our findings show that eventual migration to optical fibre is inevitable.”

̽��ֱ��twisted pair– where two conductors are twisted together to improve immunity against noise and to reduce electromagnetic radiation and interference – was invented by Alexander Graham Bell in 1881. Twisted pair cables replaced grounded lines by the end of the 19th century and have been highly reliable ever since. Today, twisted pair cables are standardised to carry 424 MHz bandwidth over shorter cable lengths owing to deeper fibre penetration and advancement in digital signal processing.

These cables are now reaching the end of their life as they cannot compete with the speed of fibre-optic cables, but it’s not possible to get rid of all the copper cables due to fibre’s high cost. ̽��ֱ��fibre network is continuously getting closer to users, but the connection between the fibre network and houses will continue to rely on the existing copper infrastructure. Therefore, it is vital to invest in technologies that can support the fibre networks on the last mile to make the best use of them.

“High-speed internet is a necessity of 21st century life,” said first author Dr Ergin Dinc, who carried out the research while he was based at Cambridge’s Cavendish Laboratory. “Internet service providers have been switching existing copper wires to high-speed fibre-optic cables, but it will take between 15 and 20 years for these to reach every house in the UK and will cost billions of pounds. While this change is happening, we’ve shown that existing copper infrastructure can support higher speeds as an intermediate solution.”

̽��ֱ��Cambridge researchers, working with industry collaborators, have been investigating whether it’s possible to squeeze faster internet speeds out of existing infrastructure as a potential stopgap measure, particularly for rural and remote areas.

“No one had really looked into the physical limitations driving the maximum internet speed for twisted pair cables before,” said Dinc. “If we used these cables in a different way, would it be possible to get them to carry data at higher speeds?”

Using a mix of theoretical modelling and experimentation, the researchers found that twisted pair cables are limited in the frequency they can carry, a limit that’s defined by the geometry of the cable. Above this limit, around 5 GHz, the twisted pair cables start to radiate and behave like an antenna.

“ ̽��ֱ��way that the cables are twisted together defines how high a frequency they can carry,” said Dr Eloy de Lera Acedo, also from the Cavendish, who led the research. “To enable higher data rates, we’d need the cables to carry a higher frequency, but this can’t happen indefinitely because of physical limitations. We can improve speeds a little bit, but not nearly enough to be future-proof.”

̽��ֱ��researchers say their results underline just how important it is that government and industry work together to build the UK’s future digital infrastructure, since existing infrastructure can handle higher data rates in the near future, while the move to a future-proof full-fibre network continues.

̽��ֱ��work is part of an ongoing collaboration between the Cavendish, the Department of Engineering, BT and Huawei in a project led by Professor Mike Payne, also of the Cavendish Laboratory. ̽��ֱ��research was also supported by the Royal Society, and the Science and Technology Facilities Council, part of UK Research and Innovation.

Reference:
Ergin Dinc et al. ‘High-Frequency Electromagnetic Waves on Unshielded Twisted Pairs: Upper Bound on Carrier Frequency.’ Nature Communications (2022). DOI: 10.1038/s41467-022-29631-8

Researchers have shown that the UK’s existing copper network cables can support faster internet speeds, but only to a limit. They say additional investment is urgently needed if the government is serious about its commitment to making high-speed internet available to all.

We can improve speeds a little bit, but not nearly enough to be future-proof

Eloy de Lera Acedo

Miroslaw Nozka/EyeEm via Getty Images

Copper wires

̽��ֱ��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.

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New result from LHCb experiment challenges leading theory in physics

sc604 — Tue, 23 Mar 2021 09:42:57 +0000

Results from the LHCb Collaboration at CERN suggests particles are not behaving the way they should according to the guiding theory of particle physics – suggesting gaps in our understanding of the Universe.

Physicists from the Universities of Cambridge, Bristol, and Imperial College London led the analysis of the data to produce this result, with funding from the Science and Technology Facilities Council. ̽��ֱ��result - which has not yet been peer-reviewed - was announced today at the Moriond Electroweak Physics conference and published as a preprint.

Beyond the Standard Model

Scientists across the world will be paying close attention to this announcement as it hints at the existence of new particles not explained by the Standard Model.

̽��ֱ��Standard Model is the current best theory of particle physics, describing all the known fundamental particles that make up our Universe and the forces that they interact with. However, the Standard Model cannot explain some of the deepest mysteries in modern physics, including what dark matter is made of and the imbalance of matter and antimatter in the Universe.

Dr Mitesh Patel of Imperial College London, and one of the leading physicists behind the measurement, said: “We were actually shaking when we first looked at the results, we were that excited. Our hearts did beat a bit faster.

“It’s too early to say if this genuinely is a deviation from the Standard Model but the potential implications are such that these results are the most exciting thing I’ve done in 20 years in the field. It has been a long journey to get here.”

Building blocks of nature

Today’s results were produced by the LHCb experiment, one of four huge particle detectors at CERN’s Large Hadron Collider (LHC).

̽��ֱ��LHC is the world’s largest and most powerful particle collider – it accelerates subatomic particles to almost the speed of light, before smashing them into each other.

These collisions produces a burst of new particles, which physicists then record and study in order to better understand the basic building blocks of nature.

̽��ֱ��LHCb experiment is designed to study particles called ‘beauty quarks’, an exotic type of fundamental particle not usually found in nature but produced in huge numbers at the LHC.

Once the beauty quarks are produced in the collision, they should then decay in a certain way, but the LHCb team now has evidence to suggest these quarks decay in a way not explained by the Standard Model.

Questioning the laws of physics

̽��ֱ��updated measurement could question the laws of nature that treat electrons and their heavier cousins, muons, identically, except for small differences due to their different masses.

According to the Standard Model, muons and electrons interact with all forces in the same way, so beauty quarks created at LHCb should decay into muons just as often as they do to electrons.

But these new measurements suggest this is not happening.

One way these decays could be happening at different rates is if never-before-seen particles were involved in the decay and tipped the scales in favour of electrons.

Dr Paula Alvarez Cartelle from Cambridge’s Cavendish Laboratory, was one of the leaders of the team that found the result, said: “This new result offers tantalising hints of the presence of a new fundamental particle or force that interacts differently with these different types of particles.

“ ̽��ֱ��more data we have, the stronger this result has become. This measurement is the most significant in a series of LHCb results from the past decade that all seem to line up – and could all point towards a common explanation.

“ ̽��ֱ��results have not changed, but their uncertainties have shrunk, increasing our ability to see possible differences with the Standard Model.”

Not a foregone conclusion

In particle physics, the gold standard for discovery is five standard deviations – which means there is a 1 in 3.5 million chance of the result being a fluke. This result is three deviations – meaning there is still a 1 in 1000 chance that the measurement is a statistical coincidence.

It is therefore too soon to make any firm conclusions. However, while they are still cautious, the team members are nevertheless excited by this apparent deviation and its potentially far-reaching implications.

̽��ֱ��LHCb scientists say there has been a breadcrumb trail of clues leading up to this result – with a number of other, less significant results over the past seven years also challenging the Standard Model in a similar way, though with less certainty.

If this result is what scientists think it is – and hope it is – there may be a whole new area of physics to be explored.

Dr Konstantinos Petridis of the ̽��ֱ�� of Bristol, who also played a lead role in the measurement, said: “ ̽��ֱ��discovery of a new force in nature is the holy grail of particle physics. Our current understanding of the constituents of the Universe falls remarkably short – we do not know what 95% of the Universe is made of or why there is such a large imbalance between matter and anti-matter.

“ ̽��ֱ��discovery of a new fundamental force or particle, as hinted at by the evidence of differences in these measurements could provide the breakthrough required to start to answer these fundamental questions.”

Dr Harry Cliff, LHCb Outreach Co-Convener, from Cambridge’s Cavendish Laboratory, said: “This result is sure to set physicists’ hearts beating a little faster today. We’re in for a terrifically exciting few years as we try to figure out whether we’ve finally caught a glimpse of something altogether new.”

It is now for the LHCb collaboration to further verify their results by collating and analysing more data, to see if the evidence for some new phenomena remains.

Additional information – about the result

̽��ֱ��results compare the decay rates of Beauty mesons into final states with electrons with those into muons.

̽��ֱ��LHCb experiment is one of the four large experiments at the Large Hadron Collider (LHC) at CERN in Geneva, and is designed to study decays of particles containing a beauty quark

This is the quark with the highest mass forming bound states. ̽��ֱ��resulting precision measurements of matter-antimatter differences and rare decays of particles containing a beauty quark allow sensitive tests of the Standard Model of particle physics.

Rather than flying out in all directions, beauty quarks that are created in the collisions of the proton beams at LHC stay close to the beam pipe.

̽��ֱ��UK team studied a large number of beauty or b quarks decaying into a strange-quark and two oppositely charged leptons. By measuring how often the b-quark decays into a final state containing a pair of muons or a pair of electrons, they found evidence that the laws of physics might be different, depending on whether the final state contains electrons or muons.

Since the b-quark is heavy compared to the masses of the electron and muon it is expected that the b-quark decays with the same probability into a final state with electrons and muons. ̽��ֱ��ratio between the two decay probabilities is hence predicted to be one.

However analysis of the UK team found evidence that the decay probability is less than one.

UK particle physicists have today announced ‘intriguing’ results that potentially cannot be explained by the current laws of nature.

This new result offers tantalising hints of the presence of a new fundamental particle or force that interacts differently with these different types of particles.

Paula Alvarez Cartelle

CERN

LHCb experiment

Yes

New class of materials could be used to make batteries that charge faster

sc604 — Wed, 25 Jul 2018 17:03:59 +0000

Although these materials, known as niobium tungsten oxides, do not result in higher energy densities when used under typical cycling rates, they come into their own for fast charging applications. Additionally, their physical structure and chemical behaviour give researchers a valuable insight into how a safe, super-fast charging battery could be constructed, and suggest that the solution to next-generation batteries may come from unconventional materials. ̽��ֱ��results are reported in the journal Nature.

Many of the technologies we use every day have been getting smaller, faster and cheaper each year – with the notable exception of batteries. Apart from the possibility of a smartphone which could be fully charged in minutes, the challenges associated with making a better battery are holding back the widespread adoption of two major clean technologies: electric cars and grid-scale storage for solar power.

“We’re always looking for materials with high-rate battery performance, which would result in a much faster charge and could also deliver high power output,” said Dr Kent Griffith, a postdoctoral researcher in Cambridge’s Department of Chemistry and the paper’s first author.

In their simplest form, batteries are made of three components: a positive electrode, a negative electrode and an electrolyte. When a battery is charging, lithium ions are extracted from the positive electrode and move through the crystal structure and electrolyte to the negative electrode, where they are stored. ̽��ֱ��faster this process occurs, the faster the battery can be charged.

In the search for new electrode materials, researchers normally try to make the particles smaller. “ ̽��ֱ��idea is that if you make the distance the lithium ions have to travel shorter, it should give you higher rate performance,” said Griffith. “But it’s difficult to make a practical battery with nanoparticles: you get a lot more unwanted chemical reactions with the electrolyte, so the battery doesn’t last as long, plus it’s expensive to make.”

“Nanoparticles can be tricky to make, which is why we’re searching for materials that inherently have the properties we’re looking for even when they are used as comparatively large micron-sized particles. This means that you don’t have to go through a complicated process to make them, which keeps costs low,” said Professor Clare Grey, also from the Department of Chemistry and the paper’s senior author. “Nanoparticles are also challenging to work with on a practical level, as they tend to be quite ‘fluffy’, so it’s difficult to pack them tightly together, which is key for a battery’s volumetric energy density.”

̽��ֱ��niobium tungsten oxides used in the current work have a rigid, open structure that does not trap the inserted lithium, and have larger particle sizes than many other electrode materials. Griffith speculates that the reason these materials have not received attention previously is related to their complex atomic arrangements. However, he suggests that the structural complexity and mixed-metal composition are the very reasons the materials exhibit unique transport properties.

“Many battery materials are based on the same two or three crystal structures, but these niobium tungsten oxides are fundamentally different,” said Griffith. ̽��ֱ��oxides are held open by ‘pillars’ of oxygen, which enables lithium ions to move through them in three dimensions. “ ̽��ֱ��oxygen pillars, or shear planes, make these materials more rigid than other battery compounds, so that, plus their open structures means that more lithium ions can move through them, and far more quickly.”

Using a technique called pulsed field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy, which is not readily applied to battery electrode materials, the researchers measured the movement of lithium ions through the oxides, and found that they moved at rates several orders of magnitude higher than typical electrode materials.

Most negative electrodes in current lithium-ion batteries are made of graphite, which has a high energy density, but when charged at high rates, tends to form spindly lithium metal fibres known as dendrites, which can create a short-circuit and cause the batteries to catch fire and possibly explode.

“In high-rate applications, safety is a bigger concern than under any other operating circumstances,” said Grey. “These materials, and potentially others like them, would definitely be worth looking at for fast–charging applications where you need a safer alternative to graphite.”

In addition to their high lithium transport rates, the niobium tungsten oxides are also simple to make. “A lot of the nanoparticle structures take multiple steps to synthesise, and you only end up with a tiny amount of material, so scalability is a real issue,” said Griffith. “But these oxides are so easy to make, and don’t require additional chemicals or solvents.”

Although the oxides have excellent lithium transport rates, they do lead to a lower cell voltage than some electrode materials. However, the operating voltage is beneficial for safety and the high lithium transport rates mean that when cycling fast, the practical (usable) energy density of these materials remains high.

While the oxides may only be suited for certain applications, Grey says that the important thing is to keep looking for new chemistries and new materials. “Fields stagnate if you don’t keep looking for new compounds,” she says. “These interesting materials give us a good insight into how we might design higher rate electrode materials.”

̽��ֱ��research was funded in part by the European Union, the Science and Technology Facilities Council, and the Engineering and Physical Sciences Research Council.

Reference:
Kent J. Griffith et al. ‘Niobium tungsten oxides for high-rate lithium-ion energy storage.’ Nature (2018). DOI: 10.1038/s41586-018-0347-0

Researchers have identified a group of materials that could be used to make even higher power batteries. ̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, used materials with a complex crystalline structure and found that lithium ions move through them at rates that far exceed those of typical electrode materials, which equates to a much faster-charging battery.

Fields stagnate if you don’t keep looking for new compounds.

Clare Grey

Ella Maru Studio

Impression of rapidly flowing ionic diffusion within a niobium tungsten oxide

Yes