physicsworld--2020-12-29--Physics World review of 2020: a year we’re glad to say goodbye to - Physics World

I remember receiving one of those “ hilarious ” WhatsApp messages in mid-March just as the coronavirus pandemic was taking hold and everyone was going slightly mad .
Signed by “ The Management ” , it declared that it was no longer in anyone ’ s best interests to proceed with 2020 and that “ after careful consideration ” , this year had been cancelled .
“ While we recognize that a lot of hard work has gone into preparing for 2020 , it has turned into a bit of a shitshow and we feel it is best to just @ @ @ @ @ @ @ thinking that 2020 couldn ’ t possibly end up being that bad .
Surely COVID-19 would be quickly forgotten and we ’ d all be back to “ normal ” in short measure .
In fact , 2020 has been an absolute stinker .
It ’ s ranged from the seriously bad – death , illness , lockdown and economic disruption – to the merely frustrating : social distancing , face masks and copious amounts of hand gel .
As if the pandemic wasn ’ t bad enough , 2020 saw the loss @ @ @ @ @ @ @ long and successful careers , including the Nobel laureates Philip Anderson ( 96 ) , Masatoshi Koshiba ( 94 ) , Arthur Ashkin ( 98 ) and Jack Steinberger ( 99 ) , as well as the eminent mathematical physicist Freeman Dyson ( 96 ) .
We mourned too the destruction of the iconic Arecibo Observatory in Puerto Rico , which dramatically collapsed following structural damage .
It ’ s hard to put a positive spin on the year that ’ s mercifully drawing to a close ( and I haven ’ t @ @ @ @ @ @ @ was some last-minute good news in the form of the withdrawal deal agreed by the EU with the UK on Christmas Eve , which means that Britain will fortunately remain part of the vital Horizon Europe research programme ) .
Still , I ’ ll try to look on the bright side .
First off , as we ’ ve reported on the Physics World website in our “ Physics in the pandemic ” blog series , physicists have shown enormous resilience .
Conferences , lectures and events have gone online , opening @ @ @ @ @ @ @ mix of people .
Kits for lab classes have been posted to students .
Old data have been analysed while plans for future experiments have been drawn up .
Hi-tech businesses have innovated with a renewed green focus , while medical and biophysicists have taken centre stage .
Second , the importance of making physics more attractive and welcoming to people of all backgrounds has , rightly , been in the spotlight as never before .
It was great to see Andrea Ghez ’ s work on black holes making her the second @ @ @ @ @ @ @ Nobel Prize for Physics , while October saw the first # BlackInPhysics week followed soon after by BlackInNano week .
Here at Physics World we were delighted to welcome a new pool of contributing columnists from across the international physics community , bringing fresh voices to Physics World .
We should also celebrate the fact that plenty of amazing physics has continued , as made clear through the variety of exciting research featured in the Physics World top 10 Breakthroughs of the Year , Our picks this year ranged from the first room-temperature @ @ @ @ @ @ @ to a super-sensitive X-ray detector .
The overall prize went to physicists in the Netherlands and Germany , who created a silicon-based material with a direct band gap that emits light at wavelengths used for optical telecommunications .
There was also the exciting news of the potential discovery of phosphine – a signature of life – in the clouds of Venus .
Finding life elsewhere in the cosmos would be a massive development , although we decided not to include the phosphine story in our Breakthroughs of the Year simply because the evidence @ @ @ @ @ @ @ with some astronomers suggesting the signal was from sulphur dioxide instead .
Beyond physics , the science story of the year was of course the development of vaccines against COVID-19 and the role that modellers and bioscientists played in understanding the spread of the SARS-COV-2 virus .
The pandemic was not the stage that researchers would have wanted to remind the world of the value of science , but scientists have certainly been in the spotlight as never before .
And we shouldn ’ t forget either the historic launch in May of @ @ @ @ @ @ @ was the first privately built rocket to carry people into space , ferrying two NASA astronauts to the International Space Station .
Finally , closer to home , you may remember the special issue of Physics World magazine back in May , which looked at how to reduce , track and recycle all the plastic waste the world uses and discards each year .
After a delay due to COVID-19 , it was a pleasure and a relief earlier this month that that we were finally able to switch our print magazine from @ @ @ @ @ @ @ Paper ’ s more expensive than the old “ polywrap ” , but it ’ s better on environmental grounds and I was pleased we could make the switch .
So as 2020 draws to its undignified close , I ’ ll end by saying a big “ thank you ” to all Physics World readers and advertisers for sticking with us this year .
We ’ ve appreciated all your thoughts and contributions – after all , without the work of physicists around the world , there would be no Physics World @ @ @ @ @ @ @ a better 2021 !

Physicists worldwide showed spirit and innovation, but 2020 can’t end soon enough. Physics World editor-in-chief Matin Durrani looks back at the year that’s coming to an end.
I remember receiving one of those “hilarious” WhatsApp messages in mid-March just as the coronavirus pandemic was taking hold and everyone was going slightly mad. Signed by “The Management”, it declared that it was no longer in anyone’s best interests to proceed with 2020 and that “after careful consideration”, this year had been cancelled. “While we recognize that a lot of hard work has gone into preparing for 2020, it has turned into a bit of a shitshow and we feel it is best to just call it off.”
I laughed, thinking that 2020 couldn’t possibly end up being that bad. Surely COVID-19 would be quickly forgotten and we’d all be back to “normal” in short measure. In fact, 2020 has been an absolute stinker. It’s ranged from the seriously bad – death, illness, lockdown and economic disruption – to the merely frustrating: social distancing, face masks and copious amounts of hand gel.
As if the pandemic wasn’t bad enough, 2020 saw the loss of several distinguished physicists who had had long and successful careers, including the Nobel laureates Philip Anderson (96), Masatoshi Koshiba (94), Arthur Ashkin (98) and Jack Steinberger (99), as well as the eminent mathematical physicist Freeman Dyson (96). We mourned too the destruction of the iconic Arecibo Observatory in Puerto Rico, which dramatically collapsed following structural damage.
It’s hard to put a positive spin on the year that’s mercifully drawing to a close (and I haven’t even mentioned Brexit yet, though there was some last-minute good news in the form of the withdrawal deal agreed by the EU with the UK on Christmas Eve, which means that Britain will fortunately remain part of the vital Horizon Europe research programme).
Positive spin
Still, I’ll try to look on the bright side. First off, as we’ve reported on the Physics World website in our “Physics in the pandemic” blog series, physicists have shown enormous resilience. Conferences, lectures and events have gone online, opening up such occasions for a more diverse mix of people. Kits for lab classes have been posted to students. Old data have been analysed while plans for future experiments have been drawn up. Hi-tech businesses have innovated with a renewed green focus, while medical and biophysicists have taken centre stage.
The importance of making physics more attractive and welcoming to people of all backgrounds has, rightly, been in the spotlight as never before.
Second, the importance of making physics more attractive and welcoming to people of all backgrounds has, rightly, been in the spotlight as never before. It was great to see Andrea Ghez’s work on black holes making her the second woman in three years to win the Nobel Prize for Physics, while October saw the first #BlackInPhysics week followed soon after by BlackInNano week. Here at Physics World we were delighted to welcome a new pool of contributing columnists from across the international physics community, bringing fresh voices to Physics World.
Great physics
We should also celebrate the fact that plenty of amazing physics has continued, as made clear through the variety of exciting research featured in the Physics World top 10 Breakthroughs of the Year, Our picks this year ranged from the first room-temperature superconductor (albeit at high pressure) to a super-sensitive X-ray detector. The overall prize went to physicists in the Netherlands and Germany, who created a silicon-based material with a direct band gap that emits light at wavelengths used for optical telecommunications.
There was also the exciting news of the potential discovery of phosphine – a signature of life – in the clouds of Venus. Finding life elsewhere in the cosmos would be a massive development, although we decided not to include the phosphine story in our Breakthroughs of the Year simply because the evidence doesn’t yet seem cast-iron, with some astronomers suggesting the signal was from sulphur dioxide instead.
Beyond physics, the science story of the year was of course the development of vaccines against COVID-19 and the role that modellers and bioscientists played in understanding the spread of the SARS-COV-2 virus. The pandemic was not the stage that researchers would have wanted to remind the world of the value of science, but scientists have certainly been in the spotlight as never before. And we shouldn’t forget either the historic launch in May of SpaceX’s Dragon rocketship, which was the first privately built rocket to carry people into space, ferrying two NASA astronauts to the International Space Station.
Finally, closer to home, you may remember the special issue of Physics World magazine back in May, which looked at how to reduce, track and recycle all the plastic waste the world uses and discards each year. After a delay due to COVID-19, it was a pleasure and a relief earlier this month that that we were finally able to switch our print magazine from a plastic to a paper wrapper. Paper’s more expensive than the old “polywrap”, but it’s better on environmental grounds and I was pleased we could make the switch.
So as 2020 draws to its undignified close, I’ll end by saying a big “thank you” to all Physics World readers and advertisers for sticking with us this year. We’ve appreciated all your thoughts and contributions – after all, without the work of physicists around the world, there would be no Physics World.
Let’s just hope for a better 2021!


physicsworld--2020-12-30--Medical physics highlights of the year - Physics World

This year has been a year like no other .
In 2020 , many physicists turned their research efforts towards tackling the pandemic .
Within medical physics , researchers worked to develop improved diagnostics and potential treatments for COVID-19 , as well as coming up with innovative technologies and devices to help healthcare workers .
Alongside , the medical physics community continued to innovate in the more traditional areas of research – from new approaches to delivering radiotherapy to novel diagnostic imaging devices and techniques .
Here are a few of the highlights that caught my eye .
Hypoxia , @ @ @ @ @ @ @ tumour can make it resistant to radiotherapy .
But currently , there ’ s no method to monitor tumour oxygenation noninvasively or without averaging across the whole lesion .
In January , a team headed up at Dartmouth-Hitchcock ’ s Norris Cotton Cancer Center demonstrated that Cherenkov excited luminescence imaging ( CELI ) could be used to non-invasively image oxygen distribution in tumours during radiation delivery .
Brian Pogue and his team irradiated tumours in mice with X-rays , generating Cherenkov light that served as an internal source to excite a phosphorescent probe @ @ @ @ @ @ @ one that ’ s responsive to radiation and one that ’ s radioresistant , and saw differences in tumour oxygenation that reflected their differences in response .
The researchers concluded that time-resolved CELI offers high spatial resolution and could be easily added to clinical protocols to evaluate tumour oxygenation at the time of radiation delivery – a long-sought goal in cancer therapy .
Ultrahigh dose rate radiation therapy ( FLASH ) is a hot topics in radiotherapy research .
Animal studies have shown that FLASH can destroy tumours while vastly reducing damage to @ @ @ @ @ @ @ just beginning .
But with such high dose rates , it is vital to continuously monitor dose deposition in the patient .
Researchers at the University of Michigan have proposed a new technique , ionizing radiation acoustic imaging , that can measure dose while simultaneously obtaining images of the radiation target and surrounding tissue .
The method is based on a thermoacoustic effect : as ionizing radiation deposits energy in the patient , the tissue temperature increases , causing expansion and a propagating pressure wave .
In conventional radiotherapy , these waves are @ @ @ @ @ @ @ rates ( 40 Gy/s or more ) , the signals can be detected by ultrasound probes on the patient ’ s skin .
First author Ibrahim Oraiqat and colleagues showed that this acoustic imaging signal increased linearly with the dose-per-pulse and that measurements at different depths agreed with those from commercial film dosimeters .
They also demonstrated simultaneous acoustic dosimetry and ultrasound imaging in a moving rabbit liver phantom .
Cystic fibrosis ( CF ) is a hereditary disease that causes sticky mucus to build up in the lungs , hindering breathing and @ @ @ @ @ @ @ damage caused by CF is often non-uniform , and treating the patches of damaged tissue can slow disease progression .
To quantify and localize such damaged regions , researchers in Australia have developed a novel tool to measure regional lung function .
The team , led by Freda Werdiger from Monash University , used X-ray velocimetry ( XV ) to non-invasively generate high-definition images of real-time airflow through the lungs of mice .
XV combines high-speed imaging – in this case , propagation-based phase-contrast X-ray imaging – and post-processing analysis to produce a @ @ @ @ @ @ @ The researchers tested the technique in mice with CF-like lung disease and their healthy littermates .
Maps of regional lung expansion clearly showed the presence and locations of areas of airflow deficits in the diseased animals .
Following its recent commercialization , this technology could help improve the length and quality-of-lives of people with CF and other respiratory diseases .
Suspicious skin lesions are usually identified by dermatologists using a handheld optical magnifier , and subsequently diagnosed via pathological analysis of a tissue biopsy .
This process , however , is invasive , @ @ @ @ @ @ @ skill of the physician .
To address these shortfalls , Abraham Katzir of Tel Aviv University and co-researchers are creating an accurate , affordable clinical system that can identify skin cancers in near-real-time .
The team has developed a fibre-optic evanescent wave spectroscopy system based on a long , U-shaped , mid-IR transmitting fibre connected to a mid-IR spectrometer .
By simply touching suspicious regions for 30 s with centre of the fibre , the system could identify cancerous lesions – including melanoma , basal cell carcinoma and squamous cell carcinoma – on @ @ @ @ @ @ @ in the future , this non-invasive “ spectroscopic pathology ” could replace standard invasive biopsies .
As 2020 drew to a close , we reported on a low-cost , portable brain MRI scanner being developed by researchers at Massachusetts General Hospital/Harvard Medical School .
MRI is the standard modality for assessing neurological disorders , but conventional high-field scanners are expensive , immobile and require dedicated power and cooling infrastructure .
As such , MRI is unavailable to critically ill patients who can not be safely transported to the scanner or patients in low-resource @ @ @ @ @ @ @ Cooley and colleagues used an array of neodymium rare-earth magnets to generate an 80 mT static field .
This permanent magnet does not require external power or cryogenic cooling , allowing the researchers to build a truly portable MRI brain scanner that can be wheeled around on a cart and operated from a standard power outlet .
They demonstrated that the system could perform standard brain scans employed for diagnosing and monitoring clinically important brain pathology .
Such a portable scanner could be used in many locations , such as a patient ’ @ @ @ @ @ @ @ an accident or in a rural clinic – expanding access to MR neuroimaging .

Maps of regional lung expansion in (left) a mouse with cystic fibrosis-like disease and (right) a healthy littermate. (Courtesy: Monash University)
This year has been a year like no other. In 2020, many physicists turned their research efforts towards tackling the pandemic. Within medical physics, researchers worked to develop improved diagnostics and potential treatments for COVID-19, as well as coming up with innovative technologies and devices to help healthcare workers.
Alongside, the medical physics community continued to innovate in the more traditional areas of research – from new approaches to delivering radiotherapy to novel diagnostic imaging devices and techniques. Here are a few of the highlights that caught my eye.
Hypoxia, or lack of oxygen, in a tumour can make it resistant to radiotherapy. But currently, there’s no method to monitor tumour oxygenation noninvasively or without averaging across the whole lesion. In January, a team headed up at Dartmouth-Hitchcock’s Norris Cotton Cancer Center demonstrated that Cherenkov excited luminescence imaging (CELI) could be used to non-invasively image oxygen distribution in tumours during radiation delivery.
Oxygen partial pressure in radiosensitive (top row) and radioresistant (bottom row) tumours during radiotherapy. (Courtesy: CC BY 4.0/Nature Commun. 10.1038/s41467-020-14415-9).
Brian Pogue and his team irradiated tumours in mice with X-rays, generating Cherenkov light that served as an internal source to excite a phosphorescent probe. They examined two tumour lines, one that’s responsive to radiation and one that’s radioresistant, and saw differences in tumour oxygenation that reflected their differences in response.
The researchers concluded that time-resolved CELI offers high spatial resolution and could be easily added to clinical protocols to evaluate tumour oxygenation at the time of radiation delivery – a long-sought goal in cancer therapy.
Ultrahigh dose rate radiation therapy (FLASH) is a hot topics in radiotherapy research. Animal studies have shown that FLASH can destroy tumours while vastly reducing damage to normal tissue, and clinical trials are just beginning. But with such high dose rates, it is vital to continuously monitor dose deposition in the patient. Researchers at the University of Michigan have proposed a new technique, ionizing radiation acoustic imaging, that can measure dose while simultaneously obtaining images of the radiation target and surrounding tissue.
Combined ultrasound and ionizing radiation acoustic images of a rabbit liver phantom. (Courtesy: Med. Phys. 10.1002/MP.14358)
The method is based on a thermoacoustic effect: as ionizing radiation deposits energy in the patient, the tissue temperature increases, causing expansion and a propagating pressure wave. In conventional radiotherapy, these waves are extremely weak. But with FLASH dose rates (40 Gy/s or more), the signals can be detected by ultrasound probes on the patient’s skin.
First author Ibrahim Oraiqat and colleagues showed that this acoustic imaging signal increased linearly with the dose-per-pulse and that measurements at different depths agreed with those from commercial film dosimeters. They also demonstrated simultaneous acoustic dosimetry and ultrasound imaging in a moving rabbit liver phantom.
Cystic fibrosis (CF) is a hereditary disease that causes sticky mucus to build up in the lungs, hindering breathing and leading to lung infections. The lung damage caused by CF is often non-uniform, and treating the patches of damaged tissue can slow disease progression. To quantify and localize such damaged regions, researchers in Australia have developed a novel tool to measure regional lung function.
The team, led by Freda Werdiger from Monash University, used X-ray velocimetry (XV) to non-invasively generate high-definition images of real-time airflow through the lungs of mice. XV combines high-speed imaging – in this case, propagation-based phase-contrast X-ray imaging – and post-processing analysis to produce a detailed ventilation map of the lungs. The researchers tested the technique in mice with CF-like lung disease and their healthy littermates. Maps of regional lung expansion clearly showed the presence and locations of areas of airflow deficits in the diseased animals. Following its recent commercialization, this technology could help improve the length and quality-of-lives of people with CF and other respiratory diseases.
Suspicious skin lesions are usually identified by dermatologists using a handheld optical magnifier, and subsequently diagnosed via pathological analysis of a tissue biopsy. This process, however, is invasive, costly, time-consuming and dependent upon the skill of the physician. To address these shortfalls, Abraham Katzir of Tel Aviv University and co-researchers are creating an accurate, affordable clinical system that can identify skin cancers in near-real-time.
When the U-shape in the centre of the fibre touches a skin lesion, the system measures its characteristic mid-IR absorption spectrum. (Courtesy: Abraham Katzir)
The team has developed a fibre-optic evanescent wave spectroscopy system based on a long, U-shaped, mid-IR transmitting fibre connected to a mid-IR spectrometer. By simply touching suspicious regions for 30 s with centre of the fibre, the system could identify cancerous lesions – including melanoma, basal cell carcinoma and squamous cell carcinoma – on patients’ skin.
Katzir suggests that in the future, this non-invasive “spectroscopic pathology” could replace standard invasive biopsies.
As 2020 drew to a close, we reported on a low-cost, portable brain MRI scanner being developed by researchers at Massachusetts General Hospital/Harvard Medical School. MRI is the standard modality for assessing neurological disorders, but conventional high-field scanners are expensive, immobile and require dedicated power and cooling infrastructure. As such, MRI is unavailable to critically ill patients who cannot be safely transported to the scanner or patients in low-resource settings.
A low-cost, portable brain MRI scanner could be mounted in an ambulance or installed in small clinics around the world. (Courtesy: Massachusetts General Hospital)
To address this, Clarissa Cooley and colleagues used an array of neodymium rare-earth magnets to generate an 80 mT static field. This permanent magnet does not require external power or cryogenic cooling, allowing the researchers to build a truly portable MRI brain scanner that can be wheeled around on a cart and operated from a standard power outlet. They demonstrated that the system could perform standard brain scans employed for diagnosing and monitoring clinically important brain pathology. Such a portable scanner could be used in many locations, such as a patient’s bedside, at the scene of an accident or in a rural clinic – expanding access to MR neuroimaging.


physicsworld--2020-12-31--The 10 quirkiest physics stories of 2020 - Physics World

Despite the impact of the COVID-19 pandemic , physicists have still found time to carry out research that touches on the quirkier side of science .
Here is our pick of the 10 best , not in any particular order .
Condensed-matter physicists like to put materials under extreme conditions to tease out their interesting properties .
So why not see if anything interesting happens with everyday objects ?
That is exactly what physicists at Lancaster University did when they put four LEGO bricks into their dilution refrigerator and cooled them to a chilly 70 mK .
LEGO bricks are @ @ @ @ @ @ @ Styrene ( ABS ) .
The team found that this acts as a better insulator than many well-known bulk-insulator materials such as the glass-ceramic Macor or the plastic-based Vespel .
Given that ABS is relatively cheap , the team says that 3D-printed scaffolds of the material could be an alternative to current materials used to build low-temperature equipment .
Being a playful group of physicists , they also put a LEGO minifigure into the refrigerator , which not only survived the deep freeze but has also become the “ world ’ s first @ @ @ @ @ @ @ long perplexed physicists due to its tendency to break into three pieces when bent , rather than two .
Nathaniel Goldberg and Oliver O ’ Reilly of the University of California , Berkeley , tackled another puzzle related to the stringy pasta .
When placed in a pot of boiling water , a spaghetti strand will first sag and then settle on the pot ’ s bottom before finally curving in on itself into a U-shape .
The researchers identify these three separate states as sagging , settling and curling , with Goldberg @ @ @ @ @ @ @ that could predict the mechanical behaviour of the pasta as it cooks .
The duo says that the model could be useful for the food-production industry and that future research could focus on the deformation of other types of pasta such as rigatoni or lasagne .
It seems like the pasta-bilities are endless .
You ’ d think that making an espresso is easy – just force hot , high-pressure water through a bed of coffee grounds .
Some of us have become coffee connoisseurs during lockdown , but even for skilled baristas @ @ @ @ @ @ @ of espresso that taste consistent from one to the next is tricky .
So to discover the secret of the perfect espresso , a team of researchers led by mathematician Jamie Foster from the University of Portsmouth created a model to describe the espresso-making process .
Espresso coffee normally comes in a fine grind , which maximizes the surface area of coffee that is in contact with the water .
That , in theory , should result in a strong cup of coffee that gets the most flavour out of the grounds .
@ @ @ @ @ @ @ , Foster and pals discovered that if the coffee is too fine , the water can be prevented from reaching all of the coffee grounds .
The researchers ’ theory is currently being tested at a coffee shop in Eugene , Oregon – which makes a mocha-ry of the notion that Americans aren ’ t interested in a decent brew .
Finding the best place to park your car might be the least of your worries during the current global COVID-19 pandemic .
But when life does finally return to normal and you @ @ @ @ @ @ @ spot , US physicists Paul Krapivsky and Sidney Redner have some advice .
Last year they examined whether it ’ s better to park far from your destination ( which should be easy but then require a long walk ) or to park nearby ( which should be harder but require only a short walk ) .
Their conclusion was that a “ prudent ” strategy is best , in which you park in the first gap of cars you come across but take the spot nearest to the venue .
This year @ @ @ @ @ @ @ this prudent strategy .
According to Krapivsky and Redner , drivers who observe a particular rule will have a probability of finding the best spot that can be as high as 25 % .
Trouble is , their calculation depends on every driver observing the rules , which as we know isn ’ t guaranteed .
And it assumes a 1D parking lot , which is the kind of place that only exists in a physicist ’ s imagination .
With video-conference services like Zoom all the rage this year , you still @ @ @ @ @ @ @ colleagues with a background from the Perimeter Institute for Theoretical Physics ( PI ) in Canada .
As one of the world ’ s top centres for physics research , it released nine science-themed images for use as a backdrop when you don ’ t want colleagues seeing the dirty-laundry basket , rioting kids or peeling wallpaper behind you .
The images include an artist ’ s impression of two colliding black holes , a dark-matter map of the cosmos as well as an exterior shot of the PI building in Waterloo , @ @ @ @ @ @ @ ’ t alone – other Zoom backgrounds are available too , including images of the ATLAS detector at the CERN particle-physics lab and shots taken by the Hubble Space Telescope .
Come Dine with Me is the brilliant British TV show in which amateur home cooks take turns hosting a dinner party for each other throughout the course of a week .
Each dinner is scored in private by the other contestants on the evening it ’ s served and whoever racks up the highest score at the end of the week wins @ @ @ @ @ @ @ the University of Hamburg analysed results from 2268 episodes of the German version of the show – Das Perfekte Dinner – and concluded that you have more chance of winning if you host a dinner later in the week .
Cook on a Monday and you might as well just open a jar of sauerkraut .
Peter Blum and Marc Wenskat say that their finding is an example of the “ secretary problem ” , which arises when things are rated consecutively using the same criteria .
Apparently , the application of those @ @ @ @ @ @ @ skewing the results .
“ When competing , one should always carefully choose when to compete , ” the authors write .
So if you want perfection , go last .
Researchers revisited a classic problem in the animal kingdom this year : why can penguins poo such large distances ?
In 2003 researchers from Germany , Finland and Hungary – who bagged an IgNobel prize in 2005 for their efforts – found that some penguins can fire their excreta as far as 40 cm , allowing these aquatic birds to continue to @ @ @ @ @ @ @ sea of faeces .
Researchers in Japan modified this pooping model to calculate the maximum distance that a penguin could manage to fling their dung when at a certain height .
Thanks to the penguins ’ “ strong rectal pressure ” , which they calculate to be higher than previous work , the team finds that the maximum distance is 1.34 m. The team says this information could be “ useful ” for zookeepers , who would know just how far away to stand to avoid getting hit by the firing faeces .
@ @ @ @ @ @ @ enclosure – do keep your faecal distancing .
We ’ ve long dismissed the notion developed by the Greek philosopher Plato that the universe is made of five types of matter : earth , air , fire , water and the cosmos .
Each was described with a particular geometry : a cube in the case of earth .
However , new research shows that Plato might have been onto something after scientists in the US and Hungary measured and analysed fragmentation patterns in around 100 rocks that they collected as well as @ @ @ @ @ @ @ To their surprise , they found that the resulting shape of the fragments is indeed a cube .
“ It turns out that Plato ’ s conception about the element earth being made up of cubes is , literally , the statistical average model for real earth , ” says geophysicist Douglas Jerolmack from University of Pennsylvania .
“ And that is just mind-blowing.
” What ’ s the fairest way to slice up a watermelon ?
Physicists in Belgium , France and Italy tackled the problem using geometry and calculus .
After @ @ @ @ @ @ @ its length and then in the middle to yield four equal quarters , the researchers discovered that this “ half rule ” fell away when then trying to slice the watermelon up into equal thin portions .
Instead , they found a “ 2/3 rule ” .
So for a spheroid of length 10 cm , for two slices , the first slice should be made at 3.5 cm along the length but for three slices , the first slice should be 2.1 cm and the second 4.2 cm .
After doing the @ @ @ @ @ @ @ a 4 kg watermelon and used Archimedes ’ principle to confirm that the slice volumes were equal .
Eureka !
And finally , in 1977 the Nobel-prize-winning physicist Leon Lederman published a tongue-in-cheek proposal to build a collider using existing subway tunnels in New York .
The city was then in financial crisis and Lederman , who died in 2018 , reckoned that physicists could acquire the tunnels for a knock-down price .
It never happened , of course , but his proposal has now inspired Caltech physicist David Hitlin to propose building @ @ @ @ @ @ @ wall along the US–Mexican border .
In a preprint paper , Hitlin describes how long , straight sections of the border between the states of Sonora and Arizona could be blocked by a huge linear particle collider .
Stretching some 300 km long , he reckons the machine could achieve a centre-of-mass energy of 5 TeV .
The proposed International Linear Collider ( ILC ) in Japan , in contrast , would be a mere 20 km long and have an initial energy of just 250 GeV .
And what would Hitlin call @ @ @ @ @ @ @ The TrumpILC , of course .
You can be sure that next year will throw up its fair share of quirky stories from the world of physics .
See you in 2021 !

Joshua Chawner (left) and Dmitry Zmeev with the world's first LEGO cryonaut (Courtesy: Joshua Chawner)
Despite the impact of the COVID-19 pandemic, physicists have still found time to carry out research that touches on the quirkier side of science. Here is our pick of the 10 best, not in any particular order.
Low-temperature LEGO
Condensed-matter physicists like to put materials under extreme conditions to tease out their interesting properties. So why not see if anything interesting happens with everyday objects? That is exactly what physicists at Lancaster University did when they put four LEGO bricks into their dilution refrigerator and cooled them to a chilly 70 mK. LEGO bricks are made from a material called Acrylonitrile Butadiene Styrene (ABS). The team found that this acts as a better insulator than many well-known bulk-insulator materials such as the glass-ceramic Macor or the plastic-based Vespel . Given that ABS is relatively cheap, the team says that 3D-printed scaffolds of the material could be an alternative to current materials used to build low-temperature equipment. Being a playful group of physicists, they also put a LEGO minifigure into the refrigerator, which not only survived the deep freeze but has also become the “world’s first LEGO cryonaut”.
Sag, settle, curl
Dried spaghetti has long perplexed physicists due to its tendency to break into three pieces when bent, rather than two. Nathaniel Goldberg and Oliver O’Reilly of the University of California, Berkeley, tackled another puzzle related to the stringy pasta. When placed in a pot of boiling water, a spaghetti strand will first sag and then settle on the pot’s bottom before finally curving in on itself into a U-shape. The researchers identify these three separate states as sagging, settling and curling, with Goldberg and O’Reilly creating a model that could predict the mechanical behaviour of the pasta as it cooks. The duo says that the model could be useful for the food-production industry and that future research could focus on the deformation of other types of pasta such as rigatoni or lasagne. It seems like the pasta-bilities are endless.
Grinding it out
You’d think that making an espresso is easy – just force hot, high-pressure water through a bed of coffee grounds. Some of us have become coffee connoisseurs during lockdown, but even for skilled baristas operating top-of-the-range coffee machines, creating cups of espresso that taste consistent from one to the next is tricky. So to discover the secret of the perfect espresso, a team of researchers led by mathematician Jamie Foster from the University of Portsmouth created a model to describe the espresso-making process. Espresso coffee normally comes in a fine grind, which maximizes the surface area of coffee that is in contact with the water. That, in theory, should result in a strong cup of coffee that gets the most flavour out of the grounds. But by examining different grinds of coffee, Foster and pals discovered that if the coffee is too fine, the water can be prevented from reaching all of the coffee grounds. The researchers’ theory is currently being tested at a coffee shop in Eugene, Oregon – which makes a mocha-ry of the notion that Americans aren’t interested in a decent brew.
Parking theory, part 2
Finding the best place to park your car might be the least of your worries during the current global COVID-19 pandemic. But when life does finally return to normal and you’re searching for that perfect car-park spot, US physicists Paul Krapivsky and Sidney Redner have some advice. Last year they examined whether it’s better to park far from your destination (which should be easy but then require a long walk) or to park nearby (which should be harder but require only a short walk). Their conclusion was that a “prudent” strategy is best, in which you park in the first gap of cars you come across but take the spot nearest to the venue. This year the duo formulated a general rule for this prudent strategy. According to Krapivsky and Redner, drivers who observe a particular rule will have a probability of finding the best spot that can be as high as 25%. Trouble is, their calculation depends on every driver observing the rules, which as we know isn’t guaranteed. And it assumes a 1D parking lot, which is the kind of place that only exists in a physicist’s imagination.
(Courtesy: Perimeter Institute)
Backgrounds to the fore
With video-conference services like Zoom all the rage this year, you still might want to impress your friends and colleagues with a background from the Perimeter Institute for Theoretical Physics (PI) in Canada. As one of the world’s top centres for physics research, it released nine science-themed images for use as a backdrop when you don’t want colleagues seeing the dirty-laundry basket, rioting kids or peeling wallpaper behind you. The images include an artist’s impression of two colliding black holes, a dark-matter map of the cosmos as well as an exterior shot of the PI building in Waterloo, Ontario. Of course, PI isn’t alone – other Zoom backgrounds are available too, including images of the ATLAS detector at the CERN particle-physics lab and shots taken by the Hubble Space Telescope.
Friday on my mind
Come Dine with Me is the brilliant British TV show in which amateur home cooks take turns hosting a dinner party for each other throughout the course of a week. Each dinner is scored in private by the other contestants on the evening it’s served and whoever racks up the highest score at the end of the week wins a cash prize. Two physicists from the University of Hamburg analysed results from 2268 episodes of the German version of the show – Das Perfekte Dinner – and concluded that you have more chance of winning if you host a dinner later in the week. Cook on a Monday and you might as well just open a jar of sauerkraut. Peter Blum and Marc Wenskat say that their finding is an example of the “secretary problem”, which arises when things are rated consecutively using the same criteria. Apparently, the application of those criteria change as each scoring occurs, skewing the results. “When competing, one should always carefully choose when to compete,” the authors write. So if you want perfection, go last.
The bottom line
Researchers revisited a classic problem in the animal kingdom this year: why can penguins poo such large distances? In 2003 researchers from Germany, Finland and Hungary – who bagged an IgNobel prize in 2005 for their efforts – found that some penguins can fire their excreta as far as 40 cm, allowing these aquatic birds to continue to nurture their eggs without sitting in a sea of faeces. Researchers in Japan modified this pooping model to calculate the maximum distance that a penguin could manage to fling their dung when at a certain height. Thanks to the penguins’ “strong rectal pressure”, which they calculate to be higher than previous work, the team finds that the maximum distance is 1.34 m. The team says this information could be “useful” for zookeepers, who would know just how far away to stand to avoid getting hit by the firing faeces. So next time you visit the penguin enclosure – do keep your faecal distancing.
Cubic earth
We’ve long dismissed the notion developed by the Greek philosopher Plato that the universe is made of five types of matter: earth, air, fire, water and the cosmos. Each was described with a particular geometry: a cube in the case of earth. However, new research shows that Plato might have been onto something after scientists in the US and Hungary measured and analysed fragmentation patterns in around 100 rocks that they collected as well as thousands from datasets collected by others. To their surprise, they found that the resulting shape of the fragments is indeed a cube. “It turns out that Plato’s conception about the element earth being made up of cubes is, literally, the statistical average model for real earth,” says geophysicist Douglas Jerolmack from University of Pennsylvania. “And that is just mind-blowing.”
Fair slices
(Courtesy: Timoteo Carletti)
What’s the fairest way to slice up a watermelon? Physicists in Belgium, France and Italy tackled the problem using geometry and calculus. After cutting the whole watermelon in half along its length and then in the middle to yield four equal quarters, the researchers discovered that this “half rule” fell away when then trying to slice the watermelon up into equal thin portions. Instead, they found a “2/3 rule”. So for a spheroid of length 10 cm, for two slices, the first slice should be made at 3.5 cm along the length but for three slices, the first slice should be 2.1 cm and the second 4.2 cm. After doing the calculations, the researchers tested them on a 4 kg watermelon and used Archimedes’ principle to confirm that the slice volumes were equal. Eureka!
Borderline collider
And finally, in 1977 the Nobel-prize-winning physicist Leon Lederman published a tongue-in-cheek proposal to build a collider using existing subway tunnels in New York. The city was then in financial crisis and Lederman, who died in 2018, reckoned that physicists could acquire the tunnels for a knock-down price. It never happened, of course, but his proposal has now inspired Caltech physicist David Hitlin to propose building another collider to address the politically controversial wall along the US–Mexican border. In a preprint paper, Hitlin describes how long, straight sections of the border between the states of Sonora and Arizona could be blocked by a huge linear particle collider. Stretching some 300 km long, he reckons the machine could achieve a centre-of-mass energy of 5 TeV. The proposed International Linear Collider (ILC) in Japan, in contrast, would be a mere 20 km long and have an initial energy of just 250 GeV. And what would Hitlin call the facility if it was built? The TrumpILC, of course.
You can be sure that next year will throw up its fair share of quirky stories from the world of physics. See you in 2021!


physicsworld--2020-12-31--The 10 quirkiest physics stories of 2020


physicsworld--2020-12-30--Medical physics highlights of the year

Medical physics highlights of the year


physicsworld--2020-12-29--Global map of tiny ‘third-degree tides’ made using satellite observations

Third-degree tides – tiny sea-level fluctuations once known only locally from measurements made by tidal gauges – have been mapped out across the globe by geophysicist Richard Ray at NASA ’ s Goddard Space Flight Center in Maryland , US .
As well as helping to refine ocean tidal predictions , the work could find application in geodesy and in understanding the behaviour of the Earth ’ s crust and mantle , which tides affect .
In simple terms , tides occur because the Moon ’ s gravitational tug causes the oceans to bulge out in two places – one @ @ @ @ @ @ @ on the opposite side of the Earth .
The gravitational potential can be expressed mathematically in terms of latitude and longitude using spherical harmonic functions .
To model the Earth ’ s dominant tidal patterns , explains Ray , “ it suffices to use just the three spherical harmonic functions of degree two .
However , that is only a first approximation.
” In reality , the tidal bulges are ever-so-slightly asymmetrical , with one side larger than the other .
“ To express that mathematically , we need higher degree spherical harmonic @ @ @ @ @ @ @ functions of degree three , ” says Ray .
The “ third-degree ” tides that arise from the tiny asymmetry are very small and their signal is easily swamped in tidal data – both by measurement noise and genuine non-tidal oceanographic signals .
“ The tides are fairly obscure , because they are so small , but they can be detected in coastal tide gauges if the time series is long enough , say 10 years or longer , ” Ray explains .
“ Away from these isolated tide gauges , little information @ @ @ @ @ @ @ had ever seen a global map of these waves from direct measurements.
” Today , maps of second-degree tides on the open ocean are made today using satellite altimetry observations .
Records have been collected for some three decades , so researchers like Ray can search for third-degree tides .
“ The nice thing about going fishing for a time-coherent signal – like tides – is that after lots of averaging , even a tiny signal can eventually begin to emerge from the background noise.
” In his study , Ray worked with @ @ @ @ @ @ @ Jason satellites , which operated from 1992–2005 and 2001–present , respectively .
Ray used an averaging process that involved using a least-squares fit to sine waves of known frequency , which revealed the tidal amplitude and phase at each ocean location .
The findings revealed a pattern of third-degree tides that was quite distinct from their second-degree counterparts .
Ray says that this is a result of the spherical harmonic forcing being so different in each case .
“ Depending on the tidal forcing , its frequency , the ocean depth , and @ @ @ @ @ @ @ waves can have certain resonances , some with unusually large amplitudes , ” he adds .
The maps revealed that in the Atlantic Ocean , for example – where regular , second-degree diurnal ( daily ) tides are relatively suppressed – third-degree tides are relatively large .
They reached even greater amplitudes in the Indian Ocean .
In the South Pacific , meanwhile , third-degree tides were suppressed and barely reached 2 mm in height .
Philip Woodworth , a researcher at the UK ’ s National Oceanographic Centre in Liverpool says , @ @ @ @ @ @ @ M1 , has been mapped previously around parts of the global coastline and at islands using tide gauges , but this is the first time they have been mapped over the whole ocean ” .
Edward Zaron at Oregon State University adds , “ It is truly astounding when you consider that the millimetre signals are here being extracted using data from satellites flying above the Earth at about 1300 km elevation , and it is a testimony to the precision of the satellite orbit determinations and geodetic sciences in the current age @ @ @ @ @ @ @ is a master of these analysis techniques and their application to satellite altimetry ” .
With his initial study complete , Ray is now looking to refine the accuracy of his tidal maps .
“ The results are still fairly noisy , ” he says .
“ I ’ d like to apply formal data assimilation methods , which combine theory from fluid dynamics with measurements , to get the best of both.
” He adds that the collection of more altimetry data in the future will also yield better results .
The @ @ @ @ @ @ @

Eye in the sky: data from the Jason-3 satellite was used in the study. (Courtesy: NASA/JPL-Caltech)
Third-degree tides – tiny sea-level fluctuations once known only locally from measurements made by tidal gauges – have been mapped out across the globe by geophysicist Richard Ray at NASA’s Goddard Space Flight Center in Maryland, US. As well as helping to refine ocean tidal predictions, the work could find application in geodesy and in understanding the behaviour of the Earth’s crust and mantle, which tides affect.
In simple terms, tides occur because the Moon’s gravitational tug causes the oceans to bulge out in two places – one positioned beneath the Moon and the other on the opposite side of the Earth. The gravitational potential can be expressed mathematically in terms of latitude and longitude using spherical harmonic functions.
To model the Earth’s dominant tidal patterns, explains Ray, “it suffices to use just the three spherical harmonic functions of degree two. However, that is only a first approximation.” In reality, the tidal bulges are ever-so-slightly asymmetrical, with one side larger than the other. “To express that mathematically, we need higher degree spherical harmonic functions. Specifically, here we use functions of degree three,” says Ray.
Swamped in the data
The “third-degree” tides that arise from the tiny asymmetry are very small and their signal is easily swamped in tidal data – both by measurement noise and genuine non-tidal oceanographic signals.
“The tides are fairly obscure, because they are so small, but they can be detected in coastal tide gauges if the time series is long enough, say 10 years or longer,” Ray explains. “Away from these isolated tide gauges, little information about them has existed; no one had ever seen a global map of these waves from direct measurements.”
Today, maps of second-degree tides on the open ocean are made today using satellite altimetry observations. Records have been collected for some three decades, so researchers like Ray can search for third-degree tides. “The nice thing about going fishing for a time-coherent signal – like tides – is that after lots of averaging, even a tiny signal can eventually begin to emerge from the background noise.”
In his study, Ray worked with altimetry data collected by the TOPEX/Poseidon and Jason satellites, which operated from 1992–2005 and 2001–present, respectively. Ray used an averaging process that involved using a least-squares fit to sine waves of known frequency, which revealed the tidal amplitude and phase at each ocean location.
Distinctive pattern
The findings revealed a pattern of third-degree tides that was quite distinct from their second-degree counterparts. Ray says that this is a result of the spherical harmonic forcing being so different in each case. “Depending on the tidal forcing, its frequency, the ocean depth, and the shape of a basin, tidal waves can have certain resonances, some with unusually large amplitudes,” he adds.
The maps revealed that in the Atlantic Ocean, for example – where regular, second-degree diurnal (daily) tides are relatively suppressed – third-degree tides are relatively large. They reached even greater amplitudes in the Indian Ocean. In the South Pacific, meanwhile, third-degree tides were suppressed and barely reached 2 mm in height.
Philip Woodworth, a researcher at the UK’s National Oceanographic Centre in Liverpool says, “The largest third-degree tide, called M1, has been mapped previously around parts of the global coastline and at islands using tide gauges, but this is the first time they have been mapped over the whole ocean”.
Edward Zaron at Oregon State University adds, “It is truly astounding when you consider that the millimetre signals are here being extracted using data from satellites flying above the Earth at about 1300 km elevation, and it is a testimony to the precision of the satellite orbit determinations and geodetic sciences in the current age”. He concludes, “Richard is a master of these analysis techniques and their application to satellite altimetry”.
With his initial study complete, Ray is now looking to refine the accuracy of his tidal maps. “The results are still fairly noisy,” he says. “I’d like to apply formal data assimilation methods, which combine theory from fluid dynamics with measurements, to get the best of both.” He adds that the collection of more altimetry data in the future will also yield better results.
The research is described in Science Advances.


physicsworld--2020-12-29--Nanotechnology and materials highlights of 2020

Regular readers of Physics World know that we have a penchant for materials and nanotechnology research .
I developed my fondness for materials physics when I did a PhD many years ago on the magnetic properties of ultrathin films and my interest has never waned .
So here are five of my favourite materials and nanotechnology stories of 2020 .
Bioinspiration and biomimicry involve studying how living organisms do something and using that insight to develop new technologies .
Pit vipers have two special organs on their heads called loreal pits that allow them to “ see ” the infrared @ @ @ @ @ @ @ .
Now , Pradeep Sharma and colleagues have worked out that the snakes use cells that act as a soft pyroelectric material to convert infrared radiation into electrical signals that can be processed by their nervous systems .
As well as potentially solving a longstanding puzzle in snake biology , the work could also aid the development of thermoelectric transducers based on soft , flexible structures rather than stiff crystals .
Perovskites could be platforms for exciton condensates Is there anything that perovskites can not do ?
This family of crystalline materials is @ @ @ @ @ @ @ but perovskites are true wonder materials that are finding increasingly exotic applications .
Now , researchers have shown that certain perovskites could be ideal platforms for creating Bose–Einstein condensates ( BECs ) of excitons .
Excitons are quasiparticles that comprise an electron–hole pair ( and we do love a quasiparticle at Physics World ) .
BECs are normally made from atomic gases that must be chilled to near absolute zero .
However , Kai Chang and colleagues reckon that exciton BECs in perovskites could exist at a balmy 77 K. There is no @ @ @ @ @ @ @ a sheet of carbon just one atom thick – but research really fired my imagination this year .
The rippling thermal motion of a tiny piece of graphene has been harnessed by a special circuit that delivers low-voltage electrical energy .
The system was created by Paul Thibado and colleagues , who say that if it could be duplicated enough times on a chip , it could deliver “ clean , limitless , low-voltage power for small devices ” .
Supercurrent goes to the edge The topological properties of matter have been a @ @ @ @ @ @ @ years , so it is no surprise that in 2020 physicists have observed “ topological superconductivity ” for the first time .
Nai Phuan Ong and colleagues have measured a robust supercurrent at the edge of a superconductor that is very different to the supercurrent in the material ’ s bulk .
The team does not yet fully understand the reason for why the edge supercurrent remains independent of bulk supercurrent , but they believe it could come from the topologically protected edge states in the material .
Polymer strands are often described @ @ @ @ @ @ @ living worms to gain insights into polymer materials ?
And if you want to alter the behaviour of the worms , there is no better way than to give them a stiff drink .
That is exactly what Antoine Deblais and colleagues did – using worms to gain new insights into the properties of poorly understood “ active polymer ” materials by measuring the viscosity of clusters of sludge worms as they were subjected to shear forces .
The wriggling activity of the worms was controlled by adjusting their temperature , and the @ @ @ @ @ @ @ .

Heat sssssensorsss A large-eyed green pit viper. The pit organs are small depressions between the snake's nostrils and eyes. (Courtesy: iStock_TommyIX)
Regular readers of Physics World know that we have a penchant for materials and nanotechnology research. I developed my fondness for materials physics when I did a PhD many years ago on the magnetic properties of ultrathin films and my interest has never waned. So here are five of my favourite materials and nanotechnology stories of 2020.
Bioinspiration and biomimicry involve studying how living organisms do something and using that insight to develop new technologies. Pit vipers have two special organs on their heads called loreal pits that allow them to “see” the infrared radiation given off by their warm-blooded prey. Now, Pradeep Sharma and colleagues have worked out that the snakes use cells that act as a soft pyroelectric material to convert infrared radiation into electrical signals that can be processed by their nervous systems. As well as potentially solving a longstanding puzzle in snake biology, the work could also aid the development of thermoelectric transducers based on soft, flexible structures rather than stiff crystals.
Is there anything that perovskites cannot do? This family of crystalline materials is usually associated with high-performance solar cells, but perovskites are true wonder materials that are finding increasingly exotic applications. Now, researchers have shown that certain perovskites could be ideal platforms for creating Bose–Einstein condensates (BECs) of excitons. Excitons are quasiparticles that comprise an electron–hole pair (and we do love a quasiparticle at Physics World). BECs are normally made from atomic gases that must be chilled to near absolute zero. However, Kai Chang and colleagues reckon that exciton BECs in perovskites could exist at a balmy 77 K.
There is no shortage of clever applications for graphene – a sheet of carbon just one atom thick – but research really fired my imagination this year. The rippling thermal motion of a tiny piece of graphene has been harnessed by a special circuit that delivers low-voltage electrical energy. The system was created by Paul Thibado and colleagues, who say that if it could be duplicated enough times on a chip, it could deliver “clean, limitless, low-voltage power for small devices”.
The topological properties of matter have been a very hot topic over the past few years, so it is no surprise that in 2020 physicists have observed “topological superconductivity” for the first time. Nai Phuan Ong and colleagues have measured a robust supercurrent at the edge of a superconductor that is very different to the supercurrent in the material’s bulk. The team does not yet fully understand the reason for why the edge supercurrent remains independent of bulk supercurrent, but they believe it could come from the topologically protected edge states in the material.
Polymer strands are often described as worm-like, so why not use living worms to gain insights into polymer materials? And if you want to alter the behaviour of the worms, there is no better way than to give them a stiff drink. That is exactly what Antoine Deblais and colleagues did – using worms to gain new insights into the properties of poorly understood “active polymer” materials by measuring the viscosity of clusters of sludge worms as they were subjected to shear forces. The wriggling activity of the worms was controlled by adjusting their temperature, and the creatures were temporarily knocked out using alcohol.


physicsworld--2020-12-29--Physics World review of 2020: a year we’re glad to say goodbye to


physicsworld--2020-12-28--A year of quantum highlights

A year of quantum highlights

This pandemic-blighted year isn ’ t going to top anyone ’ s list of favourites , but looking on the bright side for a moment , 2020 has seen some remarkable advances in quantum science and technology .
Here are a few of the highlights from subfields ranging from quantum fundamentals to quantum computing .
The most precise thermometer possible How precise can a thermometer be ?
In January , Jukka Pekkola , Bayan Karimi and colleagues at the University of Aalto , Finland , and Lund University in Sweden found the answer by building a nanoscale device that can @ @ @ @ @ @ @ of a sample .
The noise level in their thermometer is so low that they could detect the energy change due to the emission of a single microwave photon – all without disturbing the system .
Being able to spot such tiny temperature changes could enable advances in fundamental physics , and this “ quantum calorimeter ” might also be used to make non-invasive measurements of quantum systems such as qubits in superconducting quantum computers .
“ Everybody knows ” that quantum entanglement is a delicate phenomenon that only survives in ultracold , @ @ @ @ @ @ @ everybody ” is correct .
But in June , physicists at the ICFO in Barcelona , Spain used a technique called a quantum non-demolition measurement to show that at least 1.52 × 1013 out of the 5.32 × 1013 rubidium atoms in their 450 K sample were , in fact , entangled .
The team , led by Morgan Mitchell and Jia Kong , also showed that this entanglement was non-local , meaning that it involved atoms that were not close to each other .
As well as challenging assumptions about what entanglement @ @ @ @ @ @ @ important for sensing technologies such as vapour-phase spin-exchange-relaxation-free ( SERF ) magnetometers that are based on hot , dense clouds of atoms .
As quantum circuits become more complex , so , too , do the elements within them .
In June , physicists at the NEST-CNR Nanoscience Institute in Pisa and the University of Salerno , Italy demonstrated the first quantum phase battery : a device that provides a persistent phase bias to the wavefunction of a quantum circuit , similar to the way that a conventional battery provides a persistent voltage @ @ @ @ @ @ @ device that Francesco Giazotto , Elia Strambini , Andrea Iorio and colleagues built out of InAs nanowires and superconducting Al leads was based on a theoretical concept developed only five years ago by physicists in Spain – a speedy turnaround that illustrates just how fast this field is progressing .
How long does a particle take to tunnel through an energy barrier ?
To the physicists in the first “ golden age ” of quantum mechanics , who stumbled across tunnelling while playing around with the Schrödinger equation in the mid-1920s , the @ @ @ @ @ @ @ is the progress in quantum fundamentals , however , that we now have an answer .
In July , physicists led by Aephraim Steinberg of the University of Toronto , Canada , found that ultracold rubidium-87 atoms spent 0.62 ms tunnelling through a barrier 10 000 times wider than their diameter .
While Steinberg acknowledges that his team ’ s definition of tunnelling time is not the only one available , their experiment sheds much-needed light on a phenomenon that remains poorly understood despite lying at the heart of practical technologies such as @ @ @ @ @ @ @ In September 2019 , quantum computing experts at Google announced that they had used their Sycamore processor to solve a problem more than a billion times faster than a classical supercomputer .
Within weeks , competing experts at IBM were pouring cold water over the claim , suggesting that the upgrade was more like a factor of 1000 ( still impressive ) .
Late in 2020 , the quest for “ quantum advantage ” hit the headlines again as researchers led by Jian-Wei Pan and Chao-Yang Lu at the University of Science and @ @ @ @ @ @ @ they had performed a quantum computation called Gaussian boson sampling 100 trillion times faster than a supercomputer could .
Notably , Pan and Lu constructed their quantum circuit using optical elements rather than superconducting ones .
The result is a work of art as well as science , with 100 inputs and 100 outputs generated by some 300 beam splitters and 75 mirrors arranged in a random manner .
Whether such a system can be scaled up is an open question , but it ’ s also a question that isn ’ t @ @ @ @ @ @ @ year that many of us would love to forget ( and certainly don ’ t want to relive ) , developments like this – like the others on our list – are worth cheering .

This pandemic-blighted year isn’t going to top anyone’s list of favourites, but looking on the bright side for a moment, 2020 has seen some remarkable advances in quantum science and technology. Here are a few of the highlights from subfields ranging from quantum fundamentals to quantum computing.
How precise can a thermometer be? In January, Jukka Pekkola, Bayan Karimi and colleagues at the University of Aalto, Finland, and Lund University in Sweden found the answer by building a nanoscale device that can detect fundamental fluctuations in the electron temperature of a sample. The noise level in their thermometer is so low that they could detect the energy change due to the emission of a single microwave photon – all without disturbing the system. Being able to spot such tiny temperature changes could enable advances in fundamental physics, and this “quantum calorimeter” might also be used to make non-invasive measurements of quantum systems such as qubits in superconducting quantum computers.
“Everybody knows” that quantum entanglement is a delicate phenomenon that only survives in ultracold, ultra-low-noise environments. And usually, “everybody” is correct. But in June, physicists at the ICFO in Barcelona, Spain used a technique called a quantum non-demolition measurement to show that at least 1.52 × 1013 out of the 5.32 × 1013 rubidium atoms in their 450 K sample were, in fact, entangled. The team, led by Morgan Mitchell and Jia Kong, also showed that this entanglement was non-local, meaning that it involved atoms that were not close to each other. As well as challenging assumptions about what entanglement looks like, the finding could be important for sensing technologies such as vapour-phase spin-exchange-relaxation-free (SERF) magnetometers that are based on hot, dense clouds of atoms.
The first quantum phase battery. (Courtesy: Andrea Iorio)
As quantum circuits become more complex, so, too, do the elements within them. In June, physicists at the NEST-CNR Nanoscience Institute in Pisa and the University of Salerno, Italy demonstrated the first quantum phase battery: a device that provides a persistent phase bias to the wavefunction of a quantum circuit, similar to the way that a conventional battery provides a persistent voltage bias to an electrical circuit. The device that Francesco Giazotto, Elia Strambini, Andrea Iorio and colleagues built out of InAs nanowires and superconducting Al leads was based on a theoretical concept developed only five years ago by physicists in Spain – a speedy turnaround that illustrates just how fast this field is progressing.
How long does a particle take to tunnel through an energy barrier? To the physicists in the first “golden age” of quantum mechanics, who stumbled across tunnelling while playing around with the Schrödinger equation in the mid-1920s, the question would have seemed outlandish. Such is the progress in quantum fundamentals, however, that we now have an answer. In July, physicists led by Aephraim Steinberg of the University of Toronto, Canada, found that ultracold rubidium-87 atoms spent 0.62 ms tunnelling through a barrier 10 000 times wider than their diameter. While Steinberg acknowledges that his team’s definition of tunnelling time is not the only one available, their experiment sheds much-needed light on a phenomenon that remains poorly understood despite lying at the heart of practical technologies such as scanning tunnelling microscopes and flash memories.
In September 2019, quantum computing experts at Google announced that they had used their Sycamore processor to solve a problem more than a billion times faster than a classical supercomputer. Within weeks, competing experts at IBM were pouring cold water over the claim, suggesting that the upgrade was more like a factor of 1000 (still impressive). Late in 2020, the quest for “quantum advantage” hit the headlines again as researchers led by Jian-Wei Pan and Chao-Yang Lu at the University of Science and Technology of China in Hefei announced that they had performed a quantum computation called Gaussian boson sampling 100 trillion times faster than a supercomputer could. Notably, Pan and Lu constructed their quantum circuit using optical elements rather than superconducting ones. The result is a work of art as well as science, with 100 inputs and 100 outputs generated by some 300 beam splitters and 75 mirrors arranged in a random manner.
Quantum advantage: the Gaussian boson sampling experiment at the University of Science and Technology of China. (Courtesy: Chao-Yang Lu)
Whether such a system can be scaled up is an open question, but it’s also a question that isn’t unique to optical technologies. In a year that many of us would love to forget (and certainly don’t want to relive), developments like this – like the others on our list – are worth cheering.


physicsworld--2020-12-27--Hydrogen sensor is inspired by butterfly wings

Photonic nanostructures found on the wings of some butterflies have inspired researchers in Australia to create a new and highly accurate sensor for measuring hydrogen gas .
The device operates at room temperature and was made by a team led by Yilas Sabri and Ahmad Kandjani at RMIT University in Melbourne .
The sensor could play a role in the safe industrial storage of hydrogen fuel and the research could also lead to the development of new techniques for non-invasive medical diagnoses .
As a promising source of renewable energy , increasing amounts of hydrogen gas are now being stored @ @ @ @ @ @ @ Because of the extreme flammability of this gas , there is a need for highly accurate sensors that can detect even the smallest traces of hydrogen that has leaked into the air .
Today ’ s commercially available sensors measure changes in electrical resistance in metal-oxide layers as they interact with hydrogen .
However , these devices require temperatures of over 150 °C to operate and are also sensitive to other types of gas – limiting their potential for industrial applications .
Sabri and Kandjani ’ s team took a more sophisticated approach @ @ @ @ @ @ @ heat , hydrogen detection in their sensors is assisted by light .
Their design employs photonic crystals : optical nanostructures that can be manufactured , but also appear in nature .
In this case , the team was inspired by the wings of some butterflies – which have orderly patterns of tiny bumps that make the wings extremely good at absorbing light .
To mimic this structure , the researchers fabricated a lattice of hollow titanium dioxide nanospheres , which they deposited onto an electronic chip .
They then coated the device with @ @ @ @ @ @ @ sensitivity .
When activated by light , the surface of this sensor reacts hydrogen gas with oxygen to create water .
The presence of water changes the sensor ’ s electrical resistance , providing a precise measure of the amount of hydrogen in the air .
Operating at room temperature , the sensor can measure concentrations in the 10-40,000 parts-per-million range .
It can therefore sound the alarm when the concentration of the gas is high enough to be an explosion risk .
The device can discriminate between hydrogen and other gases with @ @ @ @ @ @ @ The sensor was made using established fabrication processes so the team is confident that production could easily be scaled up for widespread using – including in hydrogen fuel cells .
Furthermore , the ability of the sensors to detect low levels of hydrogen make them suitable for medical applications .
By detecting the gas produced by gastrointestinal disorders in a patients ’ breath , clinicians could carry out non-invasive diagnoses and monitoring procedures far more easily .
The research is reported in ACS Sensors .

Little wing: the sensor is made from tiny hollow spheres that are deposited on the surface of a chip. The largest gap between spheres is about 2 microns in size. (Courtesy: RMIT University)
Photonic nanostructures found on the wings of some butterflies have inspired researchers in Australia to create a new and highly accurate sensor for measuring hydrogen gas. The device operates at room temperature and was made by a team led by Yilas Sabri and Ahmad Kandjani at RMIT University in Melbourne. The sensor could play a role in the safe industrial storage of hydrogen fuel and the research could also lead to the development of new techniques for non-invasive medical diagnoses.
As a promising source of renewable energy, increasing amounts of hydrogen gas are now being stored at large facilities around the world. Because of the extreme flammability of this gas, there is a need for highly accurate sensors that can detect even the smallest traces of hydrogen that has leaked into the air. Today’s commercially available sensors measure changes in electrical resistance in metal-oxide layers as they interact with hydrogen. However, these devices require temperatures of over 150 °C to operate and are also sensitive to other types of gas – limiting their potential for industrial applications.
Sabri and Kandjani’s team took a more sophisticated approach in their study; where instead of heat, hydrogen detection in their sensors is assisted by light. Their design employs photonic crystals: optical nanostructures that can be manufactured, but also appear in nature. In this case, the team was inspired by the wings of some butterflies – which have orderly patterns of tiny bumps that make the wings extremely good at absorbing light. To mimic this structure, the researchers fabricated a lattice of hollow titanium dioxide nanospheres, which they deposited onto an electronic chip. They then coated the device with a titanium palladium composite to enhance its sensitivity.
Explosion alarm
When activated by light, the surface of this sensor reacts hydrogen gas with oxygen to create water. The presence of water changes the sensor’s electrical resistance, providing a precise measure of the amount of hydrogen in the air. Operating at room temperature, the sensor can measure concentrations in the 10-40,000 parts-per-million range. It can therefore sound the alarm when the concentration of the gas is high enough to be an explosion risk. The device can discriminate between hydrogen and other gases with a selectivity that exceeds 93%.
The sensor was made using established fabrication processes so the team is confident that production could easily be scaled up for widespread using – including in hydrogen fuel cells. Furthermore, the ability of the sensors to detect low levels of hydrogen make them suitable for medical applications. By detecting the gas produced by gastrointestinal disorders in a patients’ breath, clinicians could carry out non-invasive diagnoses and monitoring procedures far more easily.
The research is reported in ACS Sensors.


physicsworld--2020-12-24--Midwinter looking bleak? Have some festive cheer with this physics quiz

1 .
It ’ s dark at the North Pole in winter .
Fortunately , Santa ’ s reindeer have exceptional eyesight .
Which wavelengths of light can they see ?
A Ultraviolet B Infrared C Microwave D All of the above 2 .
In 2019 , researchers at the University of Manchester calculated that these same reindeer would burn 5.4 x 1013 J of energy per second while pulling Santa ’ s sleigh on its all-night supersonic Christmas flight .
How many carrots would they need to consume to refuel ?
A 9.1 x 1012 B 1.2 x 1015 @ @ @ @ @ @ @ 1021 3 .
Speaking of amazing animal feats , in July this year , a team of researchers calculated that the rectal pressure of a certain snow-dwelling creature can be as much as 28.2 kPa – enabling it to fire off its faeces at nearly 8 km/hr .
What is it ?
A Polar bear B Penguin C Arctic fox D Partridge ( in a pear tree ) 4 .
The Jewish festival of Hanukkah ( celebrated this year from 10–18 December ) commemorates an occasion in the 2nd century BCE when a @ @ @ @ @ @ @ 38.3 L ) of sacred olive oil burned for eight days instead of one .
What was the approximate carbon footprint of this miracle ?
A 117 kg CO B 306 kg CO C 720 kg CO D 948 kg CO 5 .
Which famous physicist was ( according to the old Julian calendar ) born on Christmas Day ?
A Galileo Galilei B Johannes Kepler C Isaac Newton D Gottfried Wilhelm Leibniz 6 .
Physicists love to quantify things – six quarks , four fundamental forces , three flavours of neutrino , @ @ @ @ @ @ @ “ hallelujahs ” are there in Handel ’ s Hallelujah Chorus ?
A 18 B 23 C 54 D 72 7 .
If a holiday fruitcake were as dense as a white dwarf star , what would be its approximate mass ?
A 1 x 104 kg B 1 x 106 kg C 1 x 108 kg D 1 x 1010kg 8 .
If you ’ re dreaming of a white Christmas , but the ( dry bulb ) temperature outside is hovering around 2 °C , how low must the humidity fall @ @ @ @ @ @ @ A 5 % B 25 % C 40 % D 50 % 9 .
Which scientist was the first person to manufacture an artificial snowflake ?
A Wilson “ Snowflake ” Bentley B Nathan Myhrvold C Ukichiro Nakaya D Frank Zamboni 10 .
And finally , what was the diameter of the largest natural snowflake ever recorded ?
A 6 cm B 17 cm C 24 cm D 38 cm Stuck on the questions ?
We ’ ll provide the answers in the new year .
Update : As promised , here are @ @ @ @ @ @ @ 3 B 4 C 5 C 6 D 7 B 8 B 9 C 10 D

Let it snow: Brighten up your holiday season with some quizzing. (Courtesy: Shutterstock/ESB-Professional)
1. It’s dark at the North Pole in winter. Fortunately, Santa’s reindeer have exceptional eyesight. Which wavelengths of light can they see? A Ultraviolet B Infrared C Microwave D All of the above
2. In 2019, researchers at the University of Manchester calculated that these same reindeer would burn 5.4 x 1013 J of energy per second while pulling Santa’s sleigh on its all-night supersonic Christmas flight. How many carrots would they need to consume to refuel? A 9.1 x 1012 B 1.2 x 1015 C 7.5 x 1018 D 5.8 x 1021
3. Speaking of amazing animal feats, in July this year, a team of researchers calculated that the rectal pressure of a certain snow-dwelling creature can be as much as 28.2 kPa – enabling it to fire off its faeces at nearly 8 km/hr. What is it? A Polar bear B Penguin C Arctic fox D Partridge (in a pear tree)
4. The Jewish festival of Hanukkah (celebrated this year from 10–18 December) commemorates an occasion in the 2nd century BCE when a single jar (1 Greek amphora ~ 38.3 L) of sacred olive oil burned for eight days instead of one. What was the approximate carbon footprint of this miracle? A 117 kg CO 2 B 306 kg CO 2 C 720 kg CO 2 D 948 kg CO 2
5. Which famous physicist was (according to the old Julian calendar) born on Christmas Day? A Galileo Galilei B Johannes Kepler C Isaac Newton D Gottfried Wilhelm Leibniz
6. Physicists love to quantify things – six quarks, four fundamental forces, three flavours of neutrino, etc. etc. But how many “hallelujahs” are there in Handel’s Hallelujah Chorus? A 18 B 23 C 54 D 72
7. If a holiday fruitcake were as dense as a white dwarf star, what would be its approximate mass? A 1 x 104 kg B 1 x 106 kg C 1 x 108 kg D 1 x 1010kg
8. If you’re dreaming of a white Christmas, but the (dry bulb) temperature outside is hovering around 2 °C, how low must the humidity fall before snow can be made artificially? A 5% B 25% C 40% D 50%
9. Which scientist was the first person to manufacture an artificial snowflake? A Wilson “Snowflake” Bentley B Nathan Myhrvold C Ukichiro Nakaya D Frank Zamboni
10. And finally, what was the diameter of the largest natural snowflake ever recorded? A 6 cm B 17 cm C 24 cm D 38 cm
Stuck on the questions? We’ll provide the answers in the new year.
Update: As promised, here are the answers: 1 A 2 C 3 B 4 C 5 C 6 D 7 B 8 B 9 C 10 D


physicsworld--2020-12-23--The best of physics in books, TV and film in 2020

In this episode , Andrew Glester is joined by Physics World journalists to discuss some of 2020 ’ s best @ @ @ @ @ their favourite examples of physics featuring in television and film this year .
For more @ @ @ @ @ media discussed , you can revisit these reviews that have appeared in Physics World during @ @ @ @ @ Like a Thing and I Love You : How Artificial Intelligence Works and Why It @ @ @ @ @ a Weirder Place by Janelle Shane • Quantum Legacies : Dispatches from an Uncertain World @ @ @ @ @ : the Epic Quest to Understand the Quantum Nature of Cause and Effect by Paul @ @ @ @ @ in the Universe : a Memoir by Sara Seager • For Small Creatures Such As @ @ @ @ @ for Finding Wonder by Sasha Sagan

In this episode, Andrew Glester is joined by Physics World journalists to discuss some of 2020’s best physics books, along with their favourite examples of physics featuring in television and film this year. For more information about all of the media discussed, you can revisit these reviews that have appeared in Physics World during 2020.
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physicsworld--2020-12-23--Magnetic coating gives life to millirobots

It is thrilling to live at a time when robots the size of small insects , known as millirobots , can open up new avenues of research .
Such millirobots can be finely tuned to exhibit real-life locomotive behaviour , such as crawling and walking , and find use in biomedical applications .
The millirobots ’ existence is thanks to a joint effort between two research groups in China .
Their research , published in Science Robotics , took advantage of recent materials developments to employ magnetic fields as a driving mechanism .
This approach enabled the team to design @ @ @ @ @ @ @ three-dimensional objects that , when coated with a magnetically drivable film , can simply be actuated by a magnetic field .
More surprisingly , the novel millirobots can also be disintegrated upon command , using an oscillating magnetic field in an aqueous environment .
The two teams of researchers , led by Yajing Shen from the City University of Hong Kong and Xinyu Wu at the Shenzhen Institutes of Advanced Technology at the Chinese Academy of Sciences , created the millirobots by coating the surface of a target object with an adhesive agglutinate @ @ @ @ @ @ @ the required degree of control over the robots and their scale , the researchers thought that this adhesion strategy could efficiently overcome the millirobots ’ deformability constraints , irrespective of the size or shape of the targets .
The M-spray consists of polyvinyl alcohol ( PVA ) , gluten and iron particles .
The PVA and gluten provide the self-adhesive ability of the M-spray ( referred to as M-skin ) .
The iron particles , meanwhile , provide the magnetic component , responding to the direction and strength of an applied magnetic field @ @ @ @ @ @ @ The M-spray can create a film that ’ s thin enough ( 100 to 250 µm ) to not interfere with the target ’ s original size , structure or morphology .
The researchers tested their devices under different magnetic field strengths ( 0 to 200 mT ) , demonstrating that their inanimate designs could be transformed into walking , rolling , crawling and flipping millirobots .
What ’ s more , the researchers can reprogramme the millirobots ’ navigation ability on demand .
This reprogramming depends upon the direction and strength of @ @ @ @ @ @ @ the distribution and alignment direction of the magnetic particles .
Since all the components of M-spray , namely PVA , gluten and iron particles , are biocompatible , the researchers sought to test the feasibility of their millirobots for biomedical applications , such as drug delivery .
For this , the team performed in vivo experiments in anaesthetized rabbits , using radiology imaging to track the route of a drug encapsulated in an M-spray-coated capsule .
When the capsule reached the target site , the researchers disintegrated the M-spray coating by applying an @ @ @ @ @ @ @ materials are biocompatible , the disintegrated coating can be absorbed and excreted by the body with little consequence .
To increase the stability of the M-spray-coated drug-delivery capsule in highly acidic environments , the researchers plan to replace the iron particles with nickel particles in the future .
Preliminary findings have shown that this can prolong the stability of the capsule from eight to 30 minutes .
“ Our experiment results indicated that different millirobots could be constructed with the M-spray adapting to various environments , surface conditions and obstacles .
We hope @ @ @ @ @ @ @ and application of millirobots in different fields , such as active transportation , moveable sensor and devices , particularly for the tasks in limited space , ” says Shen .

From left to right: Rong Tan, Yajing Shen and Xiong Yang from City University of Hong Kong are developing magnetically driven millirobots. (Courtesy: Xiong Yang)
It is thrilling to live at a time when robots the size of small insects, known as millirobots, can open up new avenues of research. Such millirobots can be finely tuned to exhibit real-life locomotive behaviour, such as crawling and walking, and find use in biomedical applications.
The millirobots’ existence is thanks to a joint effort between two research groups in China. Their research, published in Science Robotics, took advantage of recent materials developments to employ magnetic fields as a driving mechanism. This approach enabled the team to design a variety of one-, two- and three-dimensional objects that, when coated with a magnetically drivable film, can simply be actuated by a magnetic field. More surprisingly, the novel millirobots can also be disintegrated upon command, using an oscillating magnetic field in an aqueous environment.
Millirobot composition
The two teams of researchers, led by Yajing Shen from the City University of Hong Kong and Xinyu Wu at the Shenzhen Institutes of Advanced Technology at the Chinese Academy of Sciences, created the millirobots by coating the surface of a target object with an adhesive agglutinate magnetic spray (M-spray). Considering the required degree of control over the robots and their scale, the researchers thought that this adhesion strategy could efficiently overcome the millirobots’ deformability constraints, irrespective of the size or shape of the targets.
The M-spray consists of polyvinyl alcohol (PVA), gluten and iron particles. The PVA and gluten provide the self-adhesive ability of the M-spray (referred to as M-skin). The iron particles, meanwhile, provide the magnetic component, responding to the direction and strength of an applied magnetic field that acts as the driving mechanism. The M-spray can create a film that’s thin enough (100 to 250 µm) to not interfere with the target’s original size, structure or morphology.
The researchers tested their devices under different magnetic field strengths (0 to 200 mT), demonstrating that their inanimate designs could be transformed into walking, rolling, crawling and flipping millirobots. What’s more, the researchers can reprogramme the millirobots’ navigation ability on demand. This reprogramming depends upon the direction and strength of the applied magnetic field, together with the distribution and alignment direction of the magnetic particles.
Potential for biomedical application
Since all the components of M-spray, namely PVA, gluten and iron particles, are biocompatible, the researchers sought to test the feasibility of their millirobots for biomedical applications, such as drug delivery. For this, the team performed in vivo experiments in anaesthetized rabbits, using radiology imaging to track the route of a drug encapsulated in an M-spray-coated capsule. When the capsule reached the target site, the researchers disintegrated the M-spray coating by applying an oscillating magnetic field. As its raw materials are biocompatible, the disintegrated coating can be absorbed and excreted by the body with little consequence.
To increase the stability of the M-spray-coated drug-delivery capsule in highly acidic environments, the researchers plan to replace the iron particles with nickel particles in the future. Preliminary findings have shown that this can prolong the stability of the capsule from eight to 30 minutes.
“Our experiment results indicated that different millirobots could be constructed with the M-spray adapting to various environments, surface conditions and obstacles. We hope this construction strategy contributes to the development and application of millirobots in different fields, such as active transportation, moveable sensor and devices, particularly for the tasks in limited space,” says Shen.