By Hamish Johnston
When the film Angels and Demons was released last month, physicists around the world were inspired to give lectures about the “science” behind the film.
Now, someone has gathered a selection of videos and slides of these lectures in one place for your viewing pleasure.
My favourite title is The Science Behind ‘Angels and Demons’ is No Laughing Antimatter by Rolf Heuer, Boris Kayser and Leon Lederman.
Grab some popcorn and enjoy!
One of the UK’s leading research councils has announced today that it is to slash funding for a number of key national facilities. The Science and Technology Facilities Council (STFC) says that its £491m programme for 2009–10 will include a cut in support for the Diamond Light Source as well as “reductions in facility operations” at the ISIS neutron source and the Central Laser Facility. STFC chief executive Keith Mason blames the cuts on “the impact of the international financial situation”, which has led to a 15.1% rise in its subscriptions to CERN and other international facilities from £214.9m last year to £247.3m in 2009–10.
The STFC says it will make “significant internal savings” to re-invest in the science programme, including cuts in staff numbers by restricting recruitment, travel and use of external consultants. The council also plans to review its five neutron and light-source facilities that it funds “to ensure maximum cost effectiveness of these investments for UK science”. Mason promises, however, that funding for standard and rolling grants will be maintained at the level previously forecast.
Two other projects will see funding reduced: the Cambridge Astronomical Survey Unit (CASU) and the Wide-Field Astronomy Unit (WAFU) at Edinburgh. Meanwhile, the UK’s contribution to the Nuclear Structure, Astrophysics and Reaction (Nustar) project at the FAIR facility in Germany, and a research effort, dubbed SPIDER, into a generic particle-physics detector, will not now get any cash until April 2010 — a year later than planned. An upgrade to the VULCAN laser at the Rutherford Appleton Laboratory will also be deferred by a year.
Neutron scatterers in the UK will be particularly affected by the £2.3m cut to the ISIS facility, which has only just opened a £148m “second target station”. Uschi Steigenberger, ISIS operations director, told physicsworld.com that ISIS can now only be used for a maximum 120 days this year — a fifth fewer than last year. Indeed, a similar budget cut last year had already reduced the number of days that ISIS is used from 180 to 150.
“Other neutron-scattering labs, such as the Institut Laue-Langevin in France, typically operate for 220 days per year, which is the level recommended by the National Audit Office for an optimum operation and usage of ISIS,” she says. “ISIS serves over 1100 scientists and nearly half of the science programme carried out here is in areas like energy, environment, health and IT that map directly onto the UK government’s research priorities and have a strong economic impact. These programmes will be directly affected by the drastic reduction in operating time.”
The problems at ISIS and elsewhere stem from the 15.1% rise in the STFC’s international subscriptions. These have forced the council to fork out an extra £19.3m for its subscription to the European Space Agency, which has risen by 23% to £103.2m, as well an extra £5.5m for CERN, which has gone up by 6.9% to £85.6m. There are also increases to the membership fees of the European Southern Observatory (up 13.9% to £29.3m), the ILL (up 10.7% to £18.4m) and the European Synchrotron Radiation Facility (up 25.7% to £10.7m).
Robert Kirby-Harris, chief executive of the Institute of Physics, which publishes physicsworld.com, calls the STFC cuts “an ill omen”. Although he blames the problems on the “unique structure of STFC and the effects of a falling pound”, he thinks that the newly created Department for Business, Innovation and Skills, which sets the STFC’s budget, needs to do more to protect science.
“We would like to see the government match its verbal commitment to science and technology with funding to maintain the UK’s scientific stature, at the very least,” says Kirby-Harris. “Given President Obama has significantly increased the US science budget and the big Asian economies are doing likewise, our strategy appears very short term and penny-pinching. Further threats to the amount of scientific research being undertaken next year by STFC raise alarm bells and there appears to be no end of bad news in sight for this particular research council.”
Brian Foster, a particle physicist at Oxford University, who was highly critical of an earlier £80m STFC funding shortfall that opened up in late 2007, says that the council’s reaction this time has been “generally very sensible in that they have managed to avoid any more ‘blood on the floor'”. However, Foster is worried about next year, when he thinks the STFC will face a major shortfall unless the government steps in to help by protecting the STFC from currency fluctuations. “Otherwise it will be impossible for STFC to engage in sensible long-term planning,” he says.
Some physicists believe that changes to the Earth’s climate can be explained in large part by variations in the flux of cosmic rays reaching the Earth. These occur as the solar system pass in and out of our galaxy’s spiral arms — passages that seem to correlate closely with the timing of ice ages. However, new research based on a recent model of the structure and motion of the spiral arms finds there is no such correlation.
In 2003 physicists Nir Shaviv and Ján Veizer reported a close correlation between the motion of the solar system through the Milky Way and changes to the Earth’s climate. They found that the solar system passes through one of the galaxy’s four spiral arms about once every 140 million years, and these intersections correspond with both the peaks of successive ice ages and fluctuations in the abundance of oxygen-18 in fossils — which is related to temperature. Both climatic variables also vary with a period of about 140 million years.
To explain such a link, the researchers note that higher rates of local supernovae should lead to greater fluxes of cosmic rays as the solar system passes through the Milky Way’s spiral arms, which are higher-density regions of stars and gas within the galaxy. Physicist Henrik Svensmark has proposed that the secondary particles created by these cosmic rays as they pass through the atmosphere can help the formation of condensation nuclei for clouds, with the increased formation of low clouds blocking more sunlight and hence cooling the Earth. This hypothesis has proved controversial, given its implications for our understanding of global warming.
Now, physicists Adrian Melott and Andrew Overholt of the University of Kansas and Martin Pohl of Iowa State University in the US have carried out a new study of the supposed link between the solar system’s galactic motion and climate change and have found that the correlation does not exist.
They base their work on a new model of the galaxy produced last year by astronomer Peter Englmaier, who used the distribution of carbon monoxide molecules throughout the Milky Way, as revealed in infrared data collected by NASA’s Spitzer mission, to trace out the structure of the spiral arms. Englmaier found that the arms branch off at varying angles to one another and that the galaxy therefore has quite an asymmetrical shape.
In using this model to work out when the Sun intersects the galactic arms, Melott’s group also needed to know how quickly the spirals move (the speed of the solar system itself is well known). The spiral pattern propagates through the galactic material much as a sound wave propagates through air, and its speed of propagation is found out by measuring the speed with which newly born star clusters move away from the spiral arms where they are created.
Combining this speed data with the asymmetric position of the spirals in Englmaier’s model, the researchers found that the distance and therefore time between successive intersections of the solar system with spirals was not constant, and that there was therefore no correlation with ice ages on Earth. They discovered that this result held up across a wide range of pattern propagation speeds.
Pohl points out that, strictly speaking, this research only rules out a correlation between climate and spiral-arm passages, and that there has been speculation that the motion of the Sun in and out of the galactic plane could have effects on Earth.
Svensmark, however, believes the spiral–arm correlation itself still stands. He says the analysis by Melott and co-workers has problems in determining the location of spiral arms and also wrongly assumes that the whole spiral-arm pattern moves with a single speed. ““This latest work does not make me reconsider the link between galactic dynamics and the climate on Earth,” he added.
The research is reported on arXiv.
By Hamish Johnston
“Gina is very curious about science blogs”, writes Gil Kalai in his book Gina Says: Adventures in the Blogsphere String War .
“Can they be useful for learning about, or discussing science? What happens in these blogs and who participates in them?
Kalai, who is a mathematician at the Hebrew University of Jerusalem, tried to answer these questions by entering the fray of the “String Wars” — a sometimes heated online debate about the scientific merits of string theory that kicked off in 2006.
His first post as the fictional “Gina” was on Not Even Wrong — the blog of Peter Woit, an outspoken critic of string theory who has written a book with the same title.
“Peter, is it possible to state the main points for the case against string theory — with 4-5 sentences on each? This will be very helpful. Please consider doing it…”
50 days and many postings later, Gina was “expelled” from the discussion for apparently contributing to the “noise” on Woit’s blog. Fair dues, you might think, because she wasn’t exactly up front about her intentions. However, I couldn’t help feeling sorry for Gina as she tried to ingratiate herself back into the conversation.
Gina also conversed online with Lee Smolin — who, like Woit, had just published a book highly critical of string theory. She asked Smolin to address 16 specific objections to his book The Trouble With Physics and the ensuing discussion accounts for a large chunk of the book.
String theorists Clifford Johnson (Gina’s favourite blogger) and Jacques Distler also put in appearances via their respective blogs
So what did Kalai learn from his undercover adventure? He told me that he was disappointed by what he thought was the low scientific content of the debate — he believes that it quickly turned into a political argument. “90% of the issues discussed had nothing to do with string theory”, he said.
And what about the bloggers — are they upset to discover the real identity of Gina? Peter Woit seemed rather pleased, you can read his comments here.
Two of Canada’s best known physics facilities are expanding thanks in part to separate grants from the Canada Foundation for Innovation (CFI). The Sudbury Neutrino Observatory Laboratory (SNOLAB) in Ontario has bagged C$10.6m, to be spent on the ongoing expansion of its underground facilities. Meanwhile, the Perimeter Institute for Theoretical Physics in Waterloo, Ontario has received C$10.0m to double the size of its facility.
Located in a former nickel mine more than 2 km underground, SNOLAB is undergoing a facelift, with two new underground chambers completed earlier this year. Securing the CFI money will allow the lab to start building two new experiments — DEAP-3600 and SNO+ — which could be up and running in about two years.
SNO+ will study the properties of neutrinos as well as search for neutrinos from supernovas. It is a major refurbishment of the original SNO experiment, which stopped taking data in 2006. Switched on a decade ago, SNO was source of a major physics breakthrough in 2001, when data from its underground detectors confirmed that neutrinos have mass.
DEAP-3600, meanwhile, will use a 3.6 tonne liquid-argon detector to search for weakly interacting massive particles, or WIMPS. These hypothetical particles interact only via the weak nuclear force and gravity, and are a prominent candidate for dark matter.
The Perimeter Institute was founded in 1999 by Mike Lazaridis, chief executive of Research in Motion — the company that makes Blackberry wireless handheld devices. Home to more than 60 resident researchers, the Institute focuses on areas such as cosmology, particle physics, quantum gravity and quantum computing. Residents include quantum gravity specialist Lee Smolin and cosmologist Neil Turok — who is also director.
Built in 2002, the institute’s existing building has won several architectural awards and is now fully occupied. As well as boosting individual and group research spaces, the new CFI cash will also be spent on new teaching facilities — the institute will join forces with the University of Waterloo and take on 25 students in August when its Perimeter Scholars International MSc programme begins.
Plans for the expansion have been drawn up and the institute’s communications coordinator Angela Robinson told physicsworld.com, “The groundbreaking is expected soon, with construction taking about two years”.
Fire a squirt-gun skywards and the liquid stream will start to break up into smaller droplets due to surface tension. Intriguingly, this same behaviour is also observed in flows of sand even though granular matter is thought to be collection of grains that exert no forces on each other. Now — with the help of their $80,000 video camera — physicists in the US have developed an explanation for this puzzling similarity.
John Royer and colleagues at the University of Chicago attribute this behaviour to the roughness of individual grains of sand. They propose that coarse surfaces lead to a combination of van der Waals interactions and capillary forces, causing grains to become attracted. Although this corresponds to a surface tension that is 100, 000 times weaker than in liquid, these interactions closely resemble droplet formation in water jets, say the researchers.
Recent studies have revealed instabilities in the flow of granular materials but the minuteness of the forces involved have rendered the clusters too short-lived to observe. Royer and his team avoided this problem by combining high-speed photography with sensitive measuring of forces. By “dropping” the camera alongside a stream of sand, they were able to capture high-quality images at 1000 frames per second and record the sand dynamics as it fell a metre in less than a second. “We now have a magnetic release, though at first I literally held it up by and then let go,” John Royer told physicsworld.com.
In the experiment, glass spheres were fed through a funnel and began to accelerate under gravity. Almost immediately, the stream began to elongate and, after a metre of free fall, thin bridges of just a few grains wide begin to appear in the stream. By two and a half metres, these bridges had started to rupture as the clusters continue to separate.
To determine the strength of this cohesion, the researchers recorded the forces between individual grains by bringing them into contact and pulling them apart with an atomic force microscope. The grains were typically 150 µm in diameter and forces were of the order µN, or 100, 000 times smaller than an equivalent surface tension in water droplets.
These findings constitute the latest in a series of fluid experiments by Royer and his colleagues using their high-speed camera. Some other recent examples include the splashing of liquid droplets impacting a solid surface and the pinch-off of a bubble underwater.
The University of Chicago physicists intend to now develop this research by studying the flow of different materials including highly charged grains. They hope that an improved understanding of clustering dynamics and how it varies between materials could eventually lead to a sensitive tool to study cohesive interactions in grains and powders. “These findings could be very relevant to numerous industries that handle powders and grains, including the pharmaceutical and chemical processing industries,” said Royer.
These findings are published in the latest edition of Nature (Nature 459 1110).
Researchers at General Electric claim to have made a key breakthrough in optical data storage that could lead to commercial discs holding the equivalent of 100 DVDs within three years. The new technology is based on the physics of holograms, which enable information to be packed far more densely than with established recording formats. A new device will be needed to play these discs but this will be compatible with established formats like CDs, DVDs and Blu-ray discs, say the US-based team.
Invented over 50 years ago, holograms are now widely deployed as authentication tags, and can be found everywhere from credit cards and passports to cosmetics and pharmaceuticals. These futuristic surfaces can be generated in photosensitive materials by applying two coherent light beams: an “object” beam carrying information about a material’s structure; and a reference beam that records the desired pattern on the hologram. The resulting 3D interference pattern is usually stored as changes in refractive index of the recording material, which can be viewed when the material is illuminated by daylight.
In recent years, holography has also been proposed as an attractive technique for storing large quantities of data. Unlike “conventional” storage technologies that record one data bit at a time, holography could record and read more than a million bits of data with a single flash of light. The idea is to represent data bits as microscopic-sized holograms dispersed throughout the body of a suitable optical material.
Early attempts at creating these storage devices have used linear materials such as photopolymers, but these materials have shown significant limitations. Firstly, the micro-holograms tend to have larger dimensions than the beam that is producing them and this leads to errors in data transfer. Secondly, in recording multiple layers of holograms, the earlier layers suffer degradation due to repeated exposure to the recording beam and this again reduces the quality of recording.
Now, Victor Ostroverkhov and his colleagues at the General Electric Global Research Center near Albany, New York have overcome this problem by crafting a bespoke recording medium. The researchers use a special “thermoplastic” that can be “melted” and “frozen” numerous times without significant damage to its internal structure. In this way, they create a material that only alters its refractive index near the waist of the focussed writing beam and doesn’t inflict damage on the plastic above and below where the bit is being stored.
“We’re focused on introducing them to professional archival storage market in 2012, followed soon after to consumers,” said Todd Alhart, media relation manager at General Electric. “GE has been working in holographic storage for the last 6 years and would be interested in seeing the broadest possible adoption across the industry. To help drive that, we would look to partner across the value chain to enable manufacturers from materials and media to drives and manufacturing equipment.”
The research is described in the Japanese Journal of Applied Physics
By Michael Banks
What do street house numbers, death rates and election results have in common?
They all follow a law, devised by physicist Frank Benford in 1938, which states that in a list of numbers from real-life data there are more entries that start with the digit “1” than any other number.
According to Benford’s law, numbers that begin with “1” occur almost 30% of the time in a list of numbers that are distributed logarithmically, such as house numbers. The higher the number the less it occurs, to the point where numbers that begin with “9” occur less than 5% of the time.
This law also turns out to be useful for checking fraudulent behaviour, for example, finding out if people have made up number on their tax return forms.
Now, however, cosmologist Boudewijn Roukema, from the Nicolas Copernicus University in Poland, has used this law to test the results from the recent Iranian election.
On 12 June it was announced that Mahmoud Ahmadinejad, the current Iranian president, had won the election beating main rival Mir-Hossein Mousavi. Protests then broke out in Iran disputing the results.
Then on 14 June the Iranian Ministry of the Interior released the results of the 2009 Iranian election for 366 voting areas giving Mahmoud Ahmadinejad over 24 million votes and Mir-Hossein Mousavi around 13 million votes.
Roukema noticed a strange anomaly in the votes for Mehdi Karroubi from the National Trust Party, who came in third place. He found that the number seven occurs as a first digit more often than would be expected by Benford’s law.
He found that this anomaly occurs in three of the six largest voting areas and, moreover, that Mahmoud Ahmadinejad had a greater proportion of votes in these three areas than the others.
Roukema concludes that this could suggest an error in the official count of around one million votes.
However, he says that applying Benford’s law may not be able to find every “anomaly” in the election results – meaning the difference could be more significant.
“The fact that use of the first digit detected a significant anomaly in this particular case only indicates that this anomaly somehow failed to be hidden,” says Roukema. “It certainly doesn’t guarantee it’s the only anomaly.”
Meanwhile, Elham Kashefi and Vincent Danos from Edinburgh University have started collecting signatures for an appeal to call for fresh elections and to oppose violence against protesters.
Scientists in the US have built a tiny device that can separate some types of cancerous and non-cancerous cells. Resembling a ratchet, the device exploits the fact that different cells use different strategies to squeeze their way through narrow passages. The team believes that similar ratchets could be used to trap “metastatic” cancer cells, which can spread the disease throughout the body.
Metastasis is the process by which cancer cells break away from a tumour and move through the body — creating more tumours and often decreasing a patient’s chance of survival. Understanding how these cells move could lead to new medical treatments that stop metastasis — or even the development of “cancer traps” that remove cancer cells from circulation.
Now the physical chemist Bartosz Grzybowski and his colleagues at Northwestern University in Chicago have shown that it is possible to sort different types of cells according to how the cells move through tiny ratchet-like structures.
The team created the ratchets by etching channels into a flat gold surface. Their first design resembled a series of triangles, each about 50 μm across. One triangle funnels into the next and so on (see Moving along a ratchet).
The team studied the behaviour of three different types of cells — two that are involved in cancer metastasis, and one that is not. In all cases they found that the cells moved through the ratchet in the direction of the funnels but not in the opposite direction.
To understand this unidirectional behaviour, the team studied a series of microscope images that revealed how a cell’s cytoskeleton — internal filaments that define the shape of the cell — changes as it moves along the ratchet. A cell introduced into a triangle first adopts the triangular shape of its surroundings by pushing filaments of the protein actin into the three corners. The cell then “realizes” that it can squeeze through only one corner of the triangle, and does so by stretching an actin protrusion into the next triangle.
The protrusion “anchors” against the back side and corners of the next triangle and pulls the rest of the cell along with it. The process, which can take several hours to complete, then repeats itself. While cells did occasionally send out protrusions in the opposite direction along the ratchet, these found nowhere to anchor.
Although all three types of cell used this technique to move thought the ratchet, the team noticed that the non-cancerous cells tended to send out much longer protrusions than the cancer cells — often extending two triangles forward. With this in mind, the team designed a second ratchet that sends cancer cells in one direction and non-cancerous cells in the other direction.
This second ratchet contains a series of barbs (each about 30 μm long) on alternating sides of a channel (see Grabbing hold of a barb). The broad and relatively short protrusions of the cancer cells cannot “grab and pull” as they did in the triangular ratchet. Instead, the cells simply squeeze through the ratchet in one direction. The longer and thinner protrusions of the non-cancerous cells extend further along the ratchet — allowing them to anchor onto a barb and pull these cells in the opposite direction.
We could have a very new and very powerful tool for fighting metastasizing cancer — with a physical principle Bartosz Grzybowski, Northwestern University
The team believes that this effect could be exploited in devices they have dubbed “cancer traps” — concentric arrangements of ratchets that draw cancer cells to a central region where they are trapped permanently. Grzybowski told physicsworld.com that someday such ratchets could be implanted close to tumours to selectively fish out and trap metastatic cells. “We could have a very new and very powerful tool for fighting metastasizing cancer — with a physical principle”, he says.
Jane Hill, who studies the mobility of single-cell organisms at the University of Vermont, welcomed the research. “Cell mobility in confined geometries was not an area most biologists considered important — mostly because in the past our biochemical point of view has not considered the influence of a cell’s physical environment,” she says. Hill also points out the work could provide insight into whether there are geometries in the body that favour the migration of one cell type over another.
The research is reported in Nature Physics
By James Dacey
How does one compare the achievements of Nobel Prize winning physicists?
Well, a couple of researchers at University of California, Los Angeles (UCLA) believe it can be done – look a physicist’s cyber-presence.
Mikhail Simkin and Vwani Roychowdhury open their arXiv paper by dismissing the two “standard” measures of scientific achievement:
Number of published papers – journals publish all sorts of nonsense.
Number of citations – “multiplicate by mere copying”.
They go on to propose a third way based on a previous study of theirs…
Back in 2006, these two electrical engineers published a paper demonstrating that fame of German World War I fighter pilots (measured as number of Google hits) grows exponentially with their achievement (number of victories).
In this latest arXiv paper Simkin and Roychowdhury have turned their method on its head by measuring scientific ‘achievement’ by the number of Google hits a physicist receives.
They ran Google searches for all 45 pre-WWII Nobel Laureates in Physics, and translated this into achievement using a simple logarithm.
Unsurprisingly, Einstein is the biggest cyber celeb – his 22,700,000 Google hits give him an achievement score of “1 Einstein”. Second was Max Planck whose 10,600,000 rate his achievement as 0.911 Einsteins. Third was Marie Curie scoring 0.850 Einsteins.
Just missing out on the top ten is the UK’s Paul Dirac whose 255,000 hits give him a web presence just 1% that of Einstein’s but this rates his achievement as 0.48 Einsteins.
To round things up, Simkin and Raychowbury argue that their findings are backed up by the “recent attention given to studies where very many non-expert opinions lead to estimates agreeing with reality as good or better than expert opinions”.
Hmmm… that’s a little bit vague isn’t it! And aren’t they assuming that there is an absolute measure of scientific achievement?
So, readers of physicsworld.com, a question for you to ponder:
Can you think of a better / fairer / more useful way of comparing physicists’ achievements?
