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Test match physics

A cricket ball sitting in grass


A cricket ball at rest

By Margaret Harris

Late yesterday afternoon, I was pottering around with the BBC’s Test Match Special on in the background when something in the cricket commentary caught my attention. In-between the usual chatter about English bowling (good), Indian batting (bad) and the latest cakes delivered to the TMS commentary box (excellent), the conversation suddenly turned to physics – specifically, to the question of whether a ball could gain speed after nicking the edge of a bat.

The matter was raised after an Indian batsman, V V S Laxman, edged a delivery from Jimmy Anderson, an English bowler. The ball spurted off towards England’s captain, Andrew Strauss, who couldn’t quite catch it. After lamenting the missed opportunity, one of the TMS commentators suggested that Strauss might have mistimed his catch because the ball gained speed after glancing off Laxman’s bat. The commentators then spent the next several minutes talking a load of old rubbish about whether this was physically possible.

Then, shortly after 6 p.m., a secondary-school physics student, Laurence Copson, sent a message to the BBC’s online commentary team claiming that no, it wasn’t possible. “Removing all external forces on the ball, under no circumstance would the ball gain speed after a nick…as [the] bat would be slightly hitting the ball in the opposite direction,” he wrote. However, he did add a caveat: “What may be deceiving is if the batsmen swipes, catches an edge and then the ball gains top-spin and seems to reach the ground quicker than usual.”

This analysis was quickly contradicted by Rob, a university astrophysics student, who pointed out that Copson was neglecting both the elastic coefficients of ball and bat, and (more importantly) “the spin on the ball before it hits the bat which, if very fine, may accelerate the ball…in the direction of spin (like a car with its wheels spinning hitting the ground goes forward)”.

This seemed fair enough, but Rob’s parting shot – ”this is the real world, external forces on the ball can’t be discounted!” – struck me as rather snide, so I decided to do some analysis of my own.

(more…)

Vacuum chief looks to new horizons

IUVSTA provides a global platform for the promotion, proliferation and education of vacuum science, techniques and applications. As an international federation of 30 national vacuum societies, it represents some 15,000 scientists, engineers and technicians worldwide. J J Pireaux was elected president of IUVSTA in 2010 for a tenure of three years. He is a surface scientist who for the last decade has been director of the Interdisciplinary Laboratory of Electron Spectroscopy (LISE) at the University of Namur in Belgium.

What is IUVSTA’s role within the international vacuum community?

IUVSTA aims to stimulate international collaboration in vacuum science, including related multidisciplinary topics such as the solid–vacuum interface. It focuses on educational activities (organizing technical training courses and publishing educational material), on scientific activities (organizing thematic workshops and international conferences) and on awarding prizes and scholarships. Its actions are all related to one of the research themes covered by its divisions, namely applied surface science, electronic materials and processing, nanometre structures, plasma science and techniques, surface engineering, surface science, thin films, vacuum science and technology, and the newly created biointerfaces section. IUVSTA focuses a significant part of its activities in developing countries, helping to educate technicians and scientists in those areas of the world about the modern technologies relevant to materials science.

How would you assess the current state of vacuum science and technology?

It is obvious that the areas of research covered by IUVSTA are extremely broad, from very fundamental science to applied science to research and development. Indeed, these fields are much broader than just vacuum science and technology. This includes the development of methods of fabricating new materials, and the techniques to characterize them. Without vacuum science and technology, there would be no transistors, microprocessors, mobile phones, hybrid cars or alternative-energy devices. As it is so intimately connected to materials science, vacuum science and technology is a central pillar of modern academic and industrial research.

What do you see as the main challenges facing IUVSTA?

The challenges are to keep abreast of research and development, and to help focus enough energy and resources on fundamental research in the mid to long term while devoting expertise to new applications and production processes based on existing knowledge. A significant amount of quality research, together with the production of materials and devices, is now carried out in Asia and the Far East, so contact and communication have to be improved with these scientists and engineers.

How is IUVSTA addressing those challenges?

IUVSTA has set up a working scheme with a dual approach: working (or better, thinking) groups organized in different committees and a scientific body based on the work of its thematic divisions. The committees strive to adapt and improve the work of the union. For example, we recently revisited our educational materials. We also created a task force to initiate schemes for contacting non-member societies in developing countries. We have worked on the (still ongoing) creation of a new field of interest – namely a biointerfaces group – to address the emerging research and technologies of this area. We also try to ensure that we organize our scientific events across different parts of the globe.

How does IUVSTA plan to develop?

There are a few actions in the pipeline. First is attracting new membership from developing nations. We also aim to provide better expertise for training and learning via our educational materials and technical training courses, while there is a plan to refocus on excellence within the selection of our thematic workshops. Soon we hope to launch the World Transfer Program. This will be a new grant scheme to help early-career scientists work in another laboratory for a short period of time.

What aspects of basic science will impact most on vacuum science and technology over the next 20 years?

In my opinion, there are at least three areas of research, each with a significant fraction of very basic science, that have the potential to influence our everyday lives in the near future. The first is biotechnology, including genetic engineering. Physics, chemistry and mathematics will all have a significant role to play in the development of this field. The second is energy, including the materials and processes for solar-energy capture and conversion, fuel cells and the materials required for fission and fusion reactors. Finally, humankind will resume exploration and begin the exploitation of space. There are still huge problems to solve for those working in vacuum science and technology.

Yale defends procedures after student death

Yale University has defended its safety record after the US government’s Occupational Safety and Health Administration (OSHA) criticized the university’s safety procedures following the death of a student in April. A letter from OSHA area director, Robert Kowalski, to the university on 15 August accused it of several safety violations involving the high-speed metal lathe that killed physics student Michele Dufault. However, Yale spokesperson Tom Conroy has dismissed the charges, saying that the OSHA’s assessment contains “a number of significant inaccuracies”.

Dufault was working alone on a research project in a chemistry building on campus late at night when her hair caught in the lathe. The postmortem showed that she died from “asphyxiation due to neck compression”. The OSHA says that it has identified several safety issues in the machine shop where Dufault died. The lathe, Kowalski’s letter states, lacked any physical guarding, emergency stops or personal-protection equipment. The OSHA also notes that safety inspections and audits did not recommend safeguards for the machine and that rules and regulations regarding its use were not posted in the machine shop.

Kowalski gives several recommendations for the university, including the development of an inspection programme, written rules and regulations for working in all university facilities with industrial equipment, and a formal training programme that meets the requirements of all American National Standard Institute (ANSI) standards.

Defending its actions

In a statement, Yale University disputes the OSHA’s findings, saying that the lathe did meet ANSI standards and that the university provided both training and personal-protective equipment for the machines. The statement adds that professional staff inspected and maintained the machines regularly.

“Machine-tool training provided by Yale was extensive, consistently reinforced by professional staff and confirmed by Yale’s expert to be exemplary,” the statement reads. “Personal protective equipment was provided in the shop. The machine shop had room-access controls and students were repeatedly instructed not to use machinery without a buddy present.”

Conroy says that any implication that the university allowed students to work alone is false. He adds that the university set up a committee to review its safety policies immediately after the incident. “By the time the school year begins next month, we’ll have the policies and precautions in place,” Conroy tells physicsworld.com. “In particular, undergraduates will always have a monitor present when they work in the lab.”

Early-warning system for sunspots

Sunspots can trigger major eruptive events on the solar surface, which can lead to widespread power outages on Earth as well as wreaking havoc on telecommunication and navigation systems. But researchers in the US say that they have developed a technique that could detect emerging sunspots a full day or two before they appear.

Although scientists have been observing and documenting sunspots for more than 400 years, the origin of these cool, dark regions of strong magnetism on the solar surface have remained largely mysterious. Theories suggest that they are formed from complex motions of hot plasma inside the Sun. The idea is that acoustic waves that form near the surface propagate deep inside the Sun before returning to the surface at a different location because of refraction.

Emerging storms

Now, Stathis Llonidis and colleagues at Stanford University have taken this theory as the basis for a technique to locate the emergence of sunspots within the interior of the Sun. Llonidis’ team uses a specific helioseismology technique – called time–distance helioseismology – to analyse the time taken for these acoustic waves to propagate through the solar interior.

The technique involves selecting a pair of points on the solar surface separated by a specific distance between 100,000–200,000 km. Some of the acoustic waves excited near the location of one of these points will propagate 60,000 km into the Sun before returning to the surface near the location of the corresponding point. It usually takes about one hour for the acoustic waves to make this journey. However, if the waves pass through an emerging sunspot, then they speed up and the journey time is reduced slightly – for a large sunspot region this effect is about 12–16 s.

“In reality, we don’t select only one pair of points on the surface but thousands of pairs of points,” explains Llondis. From these data the researchers compute the travel times and then produce a travel-time map that identifies locations in the solar interior where the travel time is shorter. “We know that at these locations there is an emerging sunspot region.”

Up to two days’ warning

To test the technique, Llondis’ team used data collected by the Heliospheric Observatory (SOHO) and the Solar Dynamics Observatory (SDO) missions. They looked at four regions with emerging sunspots and nine quiet regions with no sunspots. Large sunspots were usually detected a day in advance and smaller sunspots detected up to two days in advance – because large sunspots are more buoyant and move to the surface faster. In contrast, the regions with no sunspots did not show significant travel-time anomalies.

The researchers believe that these findings prove that the detection of emerging sunspots is now possible, although they caution that they still need to analyse a large number of regions to test the robustness of their model. “Only after we do this, we will be able to know if we can predict the emergence of sunspots and how reliable our predictions are,” says IIonidis.

Llondis feels that the research could lead to a better understanding of the properties of the magnetic field in the deep solar interior, as well as having practical implications related to space-weather forecasting. “The Sun is a magnetized star. Much of the solar activity is related to the properties of the magnetic field, so we want to learn more about these properties,” he adds. “That’s why we study sunspots, because sunspots are the most prominent manifestation of solar magnetism in the photosphere [the solar surface].”

The research is published in Science.

Physics is popular again, sort of

By Margaret Harris

hands smll.jpg

Today is the day when hundreds of thousands of students across England, Wales and Northern Ireland receive the results of their A-level exams, which will determine where (and whether) they go to university in the coming academic year. The subsequent flood of exam statistics will keep education-policy experts busy for the next few days, but it’s already emerged that the number of students taking the physics A-level exam has gone up, rising 6.1% since 2010 and 19.6% over the past five years.

This is welcome news, and it’s the inspiration behind this week’s Facebook poll, which asks:

What is the main benefit of studying physics at university?

As usual, you can cast your vote on our Facebook page.

Now, as for the reasons behind the increase in physics A-level students, several commentators have cited the improving image of physics in pop culture, as evidenced by television shows like Brian Cox’s Wonders of the Universe and the US comedy The Big Bang Theory. Even the IOP’s president, Peter Knight, has suggested that the “Brian Cox effect” and publicity surrounding CERN’s Large Hadron Collider (LHC) may have helped propel physics back into the list of the 10 most popular A-level subjects for the first time since 2002.

But with all due respect to Knight, I’m personally dubious about the influence of pop culture in this case. The UK’s education system forces students to specialize early, so the current crop of A-level students will have begun narrowing down their options at least three years ago. Back then, The Big Bang Theory had only been on UK television for a few months, the LHC was still under construction and the two Wonders programmes were but gleams in Cox’s eye. So it’ll be a few years before we’ll know the true extent of their impact.

I’d place more weight on the second half of Knight’s statement, in which he noted that “Many students are also responding to calls from university leaders, businesses and the government to choose subjects which will provide the skills our country needs.” Campaigns by all these groups to boost science have been going on for years, and economic uncertainty (which, in the UK, dates back to 2007, when the bank Northern Rock collapsed) has probably made students more receptive to them. It’s worth noting that the last time the UK had so many physics students was in 2002, when the world economy was still recovering from the dot-com bust.

Anyway, regardless of the reasons behind physics’ new-found semi-popularity, we wish all students luck with their results – and those who plan to continue their physics education at university should watch this space next week, when we’ll discuss your views on the benefits of studying physics.

What physicists do

By Margaret Harris

hands smll.jpg

Last week’s Facebook poll asked a pretty straightforward question:

If you have a physics degree, what do you do for a living?

The options we offered were engineering, finance, IT, research and teaching, and voters could also add their own choices. Among the 161 people who voted, “research” was by far the most popular category, accounting for 45% of the total (N.B. we went ahead and classed the three people who said they were graduate students under “research”). The runner-up was engineering, with 16% of the vote, closely followed by teaching (15%) and IT (13%).

The only user-generated option to attract more than two votes was “science communication”, which picked up six – just shy of 4%. That’s more than finance got, but maybe most physicists in finance are too busy dealing with the financial crisis to vote in Facebook polls.

One final note: could the person who said they were an “inflatable entertainment company owner” please e-mail us at pwld@iop.org? We publish a column in Physics World called Once a physicist that profiles physicists with unusual jobs and, frankly, you’re a shoo-in for a future edition.

Space Shuttle rap

By Michael Banks

It had to come didn’t it? With the launch of the last and final flight of the Space Shuttle Programme last month when NASA’s Atlantis shuttle landed back on Earth after an 11-day mission to the International Space Station, the rap video couldn’t be too far off.

So yesterday a tweet from @NASAKennedy – the official Twitter stream of NASA’s Kennedy Space Flight Center – allayed any fears that the rap wouldn’t emerge when it posted a link to the video saying “You know your curiosity will get the better of you so you might as well click.”

Featuring a group of youths dressed in NASA jump suits rapping about the history of the Space Shuttle Programme, I will leave it up to you to decide whether the rap beats the likes of the Climate Change Rap, the Hubble Rap or the Large Hadron Rap.

Cubic neutrons might find it hip to be square

Neutrons and protons may appear quite spherical here on Earth, but two physicists in Spain and Germany have suggested that, if squeezed under enough pressure, these subatomic particles might squish themselves into cubic shapes. Although no evidence for such cubic neutrons has yet been obtained, an unprecedentedly heavy neutron star that was discovered last year could potentially house these unusually shaped particles. The star in question, which inspired the study, is a rotating neutron star – or “pulsar” – with a mass twice that of our Sun.

Neutron stars are created when a star explodes in a violent supernova, shedding most of its matter and forcing the remaining 80–90% of the star’s mass to collapse in on itself. If that remaining star is more than 2.5 times the Sun’s mass, then it can collapse completely, forming a black hole. But lighter stars instead stabilize, crushing 1.3–2 times the mass of the Sun into a city-sized sphere with a radius of just 11–12 km. These stars are so dense that gravitational pressure forces the electrons in atoms to merge with protons – forming neutrons. The inside of the star ends up being composed almost entirely of neutrons, hence the name “neutron star”.

However, Felipe Llanes-Estrada, who is on leave at the Technical University of Munich, and Gaspar Moreno Navarro of the Complutense University of Madrid say that if the interior pressures are high enough, the neutrons could be squeezed into cubes. They could then pack more tightly, further reducing their total volume by about 24%. “It’s like stacking oranges in a supermarket – the oranges at the bottom of the stack are a little distorted because of the weight of the ones on top,” says Llanes-Estrada.

Cubic movement

According to the two physicists’ calculations, neutrons would become fully cubic at a density of some 1015 grams per cubic centimetre, which is equivalent to an energy density of 500 megaelectronvolts per cubic femtometre (10–15 metres) (MeV/fm3). Although the cores of most neutron stars are just less than that density, a new, heavy pulsar discovered last year has a central region that exceeds that density by a factor of two, according to Llanes-Estrada – meaning that it could potentially harbour cubic neutrons.

The discovery of the pulsar came as a surprise to astronomers, who had previously not thought that neutron stars could be so big. Yet, even “ordinary” neutron stars could contain partially cubic neutrons, starting at an energy density of 140 MeV/fm3. Paul Demorest of the National Radio Astronomy Observatory in Charlottesville, Virginia, who was a member of the team that discovered the heavy pulsar, says that the extra compressibility would allow heavy neutron stars to achieve higher densities. The snag, says Demorest, is that this “tends to lower the maximum allowed neutron-star mass”.

Llanes-Estrada acknowledges this problem; namely that the increase in density would turn the new pulsar into a black hole unless something else is pushing outward. However, he suggests that poorly understood interactions between the neutrons may be strong enough to counter gravity and stave off collapse.

Squaring up

Kai Hebeler of Ohio State University in Columbus offers a note of caution about the simulation. He points out that rather than fleshing out the complex interplay of the quarks and gluons inside it, the study instead models the neutron as if it were a bag of quarks. Still, while this estimation is limited, Hebeler still finds the team’s model to be reasonable. However, the extreme environment of a neutron star’s interior could make the quantum-mechanical identities of the neutrons bleed into one another, so he wonders whether identifying their geometric shapes is relevant, although he admits that he cannot make a “solid statement” about the problem.

The researchers have a couple of ideas about how astronomers could possibly look for evidence of cubic neutrons in the new pulsar. As segments of a neutron star that have settled into a crystalline lattice of cubes will be stiffer than expected, stellar seismologists could look for star quakes that produce types of waves that run through solids but not fluids. Another option is based on the fact that rotating neutron stars sometimes slow down or speed up abruptly, in an event known as a “glitch”. The researchers say that such glitches might indicate a change in the way that different layers of the star interact – possibly hinting at neutrons entering or leaving cubic configurations if they occur in the heavy pulsar.

Why philosophy matters to physics

“Philosophy is dead.” So say the venerable physicists Stephen Hawking and Leonard Mlodinow on the first page of their recent bestselling book, The Grand Design.

Physicists declaring philosophy to be lifeless is nothing new. In his 2010 book In Praise of Science: Curiosity, Understanding, and Progress, Sander Bias likened philosophers’ discussions of science to doctors who diagnose patients before considering symptoms. In a 2004 New Scientist article, Simon Singh said that scientists do not need philosophers any more than birds need ornithologists. Steven Weinberg’s chapter “Against philosophy”, in his classic 1992 book Dreams of a Final Theory, needs no explanation.

Why do physicists so often, and confidently, condemn a field that is not their own? Where are their instincts to be inquisitive, resist overstepping what they know, withhold judgment until certain and accompany claims with error bars?

The evidence that Hawking (using his name as shorthand) cites is essentially the following. Questions such as, “How can we understand the world in which we find ourselves?” and “How does the universe behave?” are traditionally considered to be philosophical. But because philosophers have not kept up with scientists in their answers, therefore “Scientists have become the bearers of the torch of discovery in our quest for knowledge.”

No. Philosophers (including myself) approach such questions differently.

What philosophy does

For philosophers, the world includes more than physical matter. As the Harvard University philosopher Steven Shapin writes in his book, Never Pure, “Plants photosynthesize, plant biochemists are experts in knowing how plants photosynthesize, [while] reflective and informed students of science are experts in knowing how plant biochemists know how plants photosynthesize.” In other words, the world studied by science researchers includes not just objects, but also connections between scientists and objects.

Human beings, after all, engage with the world in different ways. They seek wealth, fame, pleasure, companionship, happiness and other “good” things. They do this as children, adolescents, parents, merchants, athletes, teachers and administrators. All these methods arise through modifications of a matrix of ways by which human beings practically connect to the world that precedes any cognitive understanding. The technical term philosophers use for this matrix is the “lifeworld”. But scientists are not like plants whose product is knowledge. Plants do not plan to follow laws of nature and do not interpret themselves. Human beings, however, do interpret both the world and themselves. The technical term philosophers use for human self-interpretation is “hermeneutics”.

Understanding photosynthesis, for instance, is only one – rare – way for human beings to interact with plants. Hawking’s theoretical stance as an observer of fundamental structures, too, is only one way for humans to engage with the world, and not the default setting either. Humans are not automatic information absorbers; they must be trained to approach the world as he does. They have to pay a special kind of attention, pursue a special kind of inquiry and find that inquiry valuable.

The lifeworld is the domain to which philosophers bring their torch of discovery. They study similarities and differences between various modes of being in the world – their group structures, if you will – and how each arises out of the lifeworld. To study this is not to undermine or critique these activities, but to understand and help cultivate them.

But the lifeworld – a kind of horizon structured by powerful metaphors, images and deeply embedded habits of thought – has its own character that changes over time. Philosophers – and here they differ from other students of science – do not and cannot adopt a “view from nowhere”, in a phrase popularized by New York University philosopher Thomas Nagel, but seek to be reflective. When philosophers think about science, they struggle to be self-aware of that horizon and how it affects human self-interpretation. This is why the humanities matter, for they study and help reshape the lifeworld. Without ornithologists, wrote one astute respondent to Singh’s New Scientist article, many bird species, in these ecologically troubled times, are heading for extinction.

Why it’s misunderstood

It is easy to misunderstand what philosophy does, for several reasons.

First, like much of physics, philosophy often has a narrow focus and is concerned with special topics or technical issues, whose place in the big picture may not be easy for an outsider to see. Much philosophy of science is thin or even anorexic and does not flesh out all of the ways in which science is embodied in the world.

Second, the lifeworld – like any horizon – tends to drop out of view. It is overlooked in favour of the objects, plans and goals that appear in and thanks to that horizon. That is perfectly understandable; detecting the horizon and its impact on our lives is the philosopher’s special task.

Finally, the particular character of the modern world is that the very successes of science lead us to think that only the measurable is worthwhile. The messy, often inchoate lifeworld is bound to seem not only less distinct and valuable, but also less tangible and real, than the grandeur of the designs uncovered by Hawking and others.

The critical point

On the first page of his book Subtle is the Lord…, the physicist Abraham Pais reports a discussion with Einstein in which the latter asked Pais if he “really believed that the Moon exists only if I look at it”. One could hardly think of a deeper, more challenging question about the concept “to exist”. Yet Pais smoothly characterizes the conversation as “not particularly metaphysical”. Discussing the meaning of reality is okay, evidently, so long as it is done in an amateur way.

So is philosophy dead? No; it will live as long as science does. When will physicists stop misunderstanding it? Probably never. But those who are ignorant of philosophy are destined to commit a bad version of it.

The inside track on simulation software

It has been a busy summer for the folks at COMSOL. For those who do not know, COMSOL is the company behind the COMSOL Multiphysics software platform for modelling and simulation of all manner of physics-based systems – in fact, everything from optimization of wound treatment through energy-efficient lighting to the creation of award-winning fish dishes, and plenty more besides.

Along with preparations for its annual series of user conferences (being held in Boston, Stuttgart and Bangalore in October and November) and a packed schedule of tutorial webinars, the firm has begun shipping the latest iteration of COMSOL Multiphysics. Version 4.2 of the software is billed as a “major release”, combining three new application modules (microfluidics, geomechanics and electrodeposition), greater CAD interoperability, as well as enhanced geometry, mesh and solver functionality.

Clearly lots to talk about – and this special video feature lets COMSOL staffers do just that. In the first instalment (above), David Kan, COMSOL’s vice-president of sales, explains that while “simulation has become an integral part of what we do as scientists and engineers”, the key to success lies in simulations that mimic what happens in the real world. “The [whole] point”, he adds, “is to have a simulation that gets as close to reality as possible.”

In part two, Daniel Smith, lead developer of the COMSOL Multiphysics plasma module, provides an application-specific take on simulation, explaining why a multiphysics modelling approach is essential for the simulation of complex plasma processes in semiconductor manufacturing. “Plasmas are perfect examples of a multiphysics problem,” he says. “They’re conductive assemblies of charged particles, neutrals and electromagnetic fields – all [of which] interact with each other in a nonlinear and very complicated way.”

As for the bigger picture, it seems inevitable that as simulation software becomes ever-more sophisticated, the natural progression will see increasing numbers of scientists and engineers using it to shed light on real-world problems, as Kan describes in the final segment.

“We’re already seeing the benefits to our customers,” claims Kan. “People have discovered new physics phenomena. [They] have been able to innovate new medical treatments, make better products faster, and students have even been able to grasp theory faster using simulation.”

As he concludes, “The future’s bright for this technology. Our community [of users] is growing and we’re headed in the right direction.”

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