Welcome to the second Newsletter from FUSION, the Open University Physics Society. Since we formed earlier this year we have gained over 260 members and have received some very encouraging feedback from you all about how the society is progressing so far.

For this edition we have an excellent selection of contributions; David McGloin returns to give us a fascinating insight into the Science of See-through and Jorge Sanchez, an Accelerator Operator at CERN in Geneva gives us the low down on The Life Of An Elementary Particle.

Also we are fortunate to have two physicist profiles for this edition. Firstly of Professor Jocelyn Bell Burnell who, after nearly 30 years of teaching and research at the OU, is leaving us to be Dean of Science at Bath University. And, secondly, a profile of Brian Steadman, who achieved his PhD at the OU as a research student of General Relativity with the Department of Mathematics.

On top of all these goodies we have the next instalment of Science History, with a look at the achievements of Galileo and his struggle with the Roman Papacy; a word from Julia Maddock at the Institute of Physics; our regular Letters section and a couple of amusing anecdotes to give you a breather from the serious science!

Don't forget to take a look at the back page for our Event Horizon, and make a note in your diaries of our current events on offer to come along to.

Anyway, enjoy your read, and do give us your views and opinions on the articles you see. Also, if there is a way we can improve on our newsletters, or there is something additional you would like to see, let us know.

Oh, and we are still eagerly awaiting a volunteer to do a crossword for us! Come on!

Tina Heaton - Editor

Cool Fusion Available Now!

Yes, you can look cool too, with the first FUSION T-Shirt featuring Maxwell's famous equations. "If only I could have worn my FUSION T-Shirt," quipped Paul Ruffle, "I could have scored an extra 5% in the SMT356 Electromagnetism exam!"

Priced at £8.50 (incl. p&p) and available in black, in sizes M, L, XL and XXL.

Send your cheque, made out to FUSION, to the address below.

The FUSION committee model their new Maxwell T-Shirts at the Science Museum.

QUANTA AND CONTINUUM

Your Letters

Re: 'Wot - No Quarks' article.

I am in full support of lobbying the Open University for named degrees in Physics & Mathematics and Physics & Astronomy. But surely the OU can award a named degree in pure Physics.

The Institute of Physics recognises four current level 2 courses and eight level 3 courses as per Recognition Leaflet 3.8 (Scientific Institutions), as physics courses. Surely if the IoP will give Associate Membership, to OU students who take a combination of these courses, then the OU could award a named degree in Physics, to students who have done these courses.

I have the first year of an engineering degree, (120 points credit transfer), but as long as I do 240 points worth of courses, 120 at level two and 120 at level three, from the recognised courses, the IoP will give me Associate Membership. So why can't the OU give me a named degree in Physics?

Also the OU will save money by simply awarding one physics degree to students, instead of two named degrees in diluted physics subjects.

Matthew Gilbert

Barrie Jones, Head of the Physics & Astronomy Department, tells us that they are applying to the Faculty Board for such a degree. The named degree in Physics would require students to do both SM355 and SMT356.

News from the Institute of Physics

It occurred to me that since so many FUSION members have also joined Nexus, this might be a good place to answer some of the questions that regularly crop up that specifically relate to OU students.

I will start with an apology - some of you have, on occasion, felt excluded from Institute organised events labelled as being for Young Members. This is in no way our intention! The Young Members section consists of Nexus (student) and Young Professionals. The word 'Young' is used to reflect a career stage rather than your age. We do not exclude anyone from our events on grounds of age. So as long as you are interested, you are welcome to participate. I am sorry that we have used an age-associated word, but it is the best way to identify this group from the majority of our members.

Let me now explain how Institute membership works. We restructured in March of this year, so you have been told different things in the past. The Institute of Physics is aiming to broaden its membership and make it more inclusive, so our new structure is as follows:

Student Membership - for those studying their first physics related undergraduate degree. Any OU course containing physics is acceptable for this. Postgraduate students should apply for Associate Member.

Associate Membership - for those who have obtained a degree in physical science or engineering.

Member - full membership for those who meet the requirements of Associate Membership and have acquired three years of relevant professional experience. In certain cases, this experience can be gained prior to or during your OU studies.

Chartered Physicist - a professional qualification for Members working in physics and who must have followed one of our recommended degree schemes.

To help you ensure that your degree meets our requirements, we have published a scheme of acceptable courses. This is distributed by the OU in certain mailings for post level one courses. You can also find it on the FUSION website under Course Reviews or obtain a copy by writing to: Qualifications Officer, Institute of Physics, 76 Portland Place, London, W1B 1NT.

If you are a student member of the Institute of Physics, we record a date that we believe is when you are likely to graduate. Since student membership is subsidised, it is not possible to remain in student membership once you have achieved a physics related degree. Therefore we will write to you when we think you are due to graduate. If you did not specify a graduation date when you joined, we will have estimated one. If you are not going to graduate at that time, simply contact us with your new expected date.

Should you need any further details about the Institute or its services, please contact me, preferably, by email at julia.maddock@iop.org or by post at the Institute of Physics.

Julia Maddock

Heroes and Zeros

HEROES

In 1907, Harlow Shapley, a 22-year-old crime reporter on a Kansas newspaper, arrived at the University of Missouri to enrol on a journalism course, only to find that the course would not open for another year. Rather than hang about for a year, he decided to study something else - anything else - and picked astronomy because it began with the letter 'A', and so caught his eye near the top of the list of courses.

Seven years later, he emerged from Princeton with a PhD and a reputation as one of the brightest of the new generation of astronomers, and went on to do pioneering work, using the new 60-inch telescope at Mount Wilson, to establish the true scale of the galaxy.

ZEROS

We have finally had a reply from CERN, "We take note of your comments on the age limit to our Summer Student Programme. This is a firm limit which we apply, so at this stage you are not eligible. The CERN Management takes the view that the Summer Student Programme is designed to attract young people to the field of particle physics."

New S357 Year Book Available

A new course year book for S357 - Space, Time and Cosmology can be downloaded in PDF format from our web site's Course Reviews page.

Relativity passes the pulsar test

A key prediction of Einstein's general theory of relativity - the 'Shapiro delay' - has been observed following highly accurate radio studies of a nearby pulsar. The theory forecasts that pulses of radiation streaming across the Universe should be impeded by relativistic distortions of space. Willem van Straten of Swinburne University of Technology in Australia and colleagues detected this effect while mapping the motion of the pulsar at the Parkes Observatory (W van Straten et al 2001 Nature 412 158).

See http://physicsweb.org/article/ news/5/7/8 for more details.

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Prof Moves On

Professor Jocelyn Bell Burnell is to leave the OU after a 28 year association with the university, including seven years as Department Head and ten as Professor of Physics, and an 18 month secondment to Princeton University in the USA.

Jocelyn started with the OU as a tutor back in 1973, and has taught most of the physics courses in four different regions. She found this really enjoyable, and misses the face-to-face contact since moving to Walton Hall. Her academic interests are the astrophysics of neutron stars, passively cooled infrared space telescopes, and the teaching of, and public understanding of, physics and astronomy, as well as the management of science in the UK. But most people will know her as the discoverer of pulsars.

As a research student looking for quasars in 1967, Jocelyn detected regular radio pulses from an unknown source. Because of their regular and rapid repetition rate, it was thought at first that the signals might be from alien life-forms, and they were dubbed LGM, for 'Little Green Men'. However, a few months later, three more such signals were discovered, in different parts of the sky, and it became clear that they were being produced, not by intelligent beings, but by rapidly-rotating neutron stars.

As one of the authors of the new astronomy and planetary science course, S208 (the replacement for S281) she will be kept busy right up to the end. She takes up an appointment as Dean of Science at the University of Bath, where she will have an overview of all science subjects and will also be involved in university governance.

Jocelyn says she will miss the OU, but is looking forward to the challenge of her new job, and to being surrounded by "hills, valleys and tall trees!" And we will miss her too - although students of MST207 may catch a glimpse of her at their summer school, which is held in Bath.

Electromagnetically Induced Transparency - the Science of 'See-through'

by David McGloin

We all know that you can't see through walls. Much as we might like the idea of x-ray glasses, modern science has yet to come up with a way to optically examine what lies behind an opaque medium¹. Or has it? About twelve years ago, Stephen Harris of Stanford University proposed a method of rendering a normally opaque medium transparent by application of electromagnetic waves (in this case using lasers). This technique later became known as Electromagnetically Induced Transparency (EIT) and was ultimately be used to 'freeze' light, reducing its velocity to zero. To understand how this remarkable phenomenon works we must first have a brief understanding of how light is absorbed by matter.

Figure 1 (a) A two level atom with a laser beam applied (the arrow) between the levels. (b) The absorption profile (note by convention increasing absorption is shown as increasingly negative).

If we take a simple atomic system, consisting of two energy levels, shown in Fig. 1(a), then the atom can be made to move from the lower energy state |1> to the upper energy state |2> by absorbing a photon of energy, for example from a laser beam. To be absorbed the photon must have an energy equal to the energy difference between |1> and |2> (we call this difference E). So we would expect that if we scanned the energy of the photon from a little less to a little more than the energy difference, E, we would see a short absorption peak when the energy was coincident with the value of E. What we see, however, is shown in Fig. 1(b). This typical absorption curve is due to the Uncertainty Principle - we don't know exactly where the atomic energy levels are, so the absorption of the light is smeared out over a small energy range. All absorption in all materials is based on this effect.

Figure 2 (a) Three level atom with two laser beams applied. (b) A characteristic EIT absorption trace. The normal absorption in Fig. 1(b) is split into two components with a zero absorption point in the middle.

So how, and why, do we stop this from happening? The answer is interference, quantum interference to be exact. We know that light waves can interfere in free space, from phenomena such as Young's Slits experiment but it turns out that we can do similar things with light within atoms. If we examine the three level atom in Fig. 2 then we know that if we apply a laser with appropriate energy between levels |1> and |2> then it will be absorbed and the atom will move from level |1> to |2> as it absorbs the energy of the light. If we then apply a second, somewhat stronger, laser between levels |2> and |3> then we set up an alternative pathway for the atom to move from level |1> to |2>. This pathway involves absorption of a photon moving the atom from level |1> to |2> and then absorbing another photon from the second laser and moving from level |2> to level |3>. Then by a process known as stimulated emission the atom is moved by the laser from level |3> back to level |2> (this is illustrated in Fig. 2). Thus two pathways exist for the atom to move from level |1> to level |2> (the pathways are denoted |1> - |2> and |1> - |2> - |3> - |2>). The interaction of the light with the atom is such that the interference of these two paths causes the absorption of the light on the |1> - |2> transition to be cancelled. This interference effect, rendering an opaque medium transparent, is the essence behind EIT. Such effects can be observed in the laboratory - normally we use atomic gases as the absorbing medium e.g. sodium, or rubidium - and when we see EIT we expect the characteristic absorption profile of the atomic transition (shown in Fig. 1(b)) to change to that shown in Fig. 2(b). This absorption profile has a dip in the middle - the transparent part.

So why would we want to do this? Well part of it is the fun of manipulating the normal state of affairs², but there are many other applications, two of which I'll touch on here, and discuss more fully in a subsequent article. The first is Lasing Without Inversion (LWI). Normal lasers need what is known as a population inversion but LWI can circumvent this possibility and opens up the possibility of producing very short wavelength lasers such as x-ray and gamma-ray lasers. The second effect is known as 'slow light' ³.

It turns out that by altering the absorption of the medium in which we create EIT we also alter the refractive index of the medium. The refractive index of a medium determines how fast light travels within it and recent experiments have shown that the medium can be altered such that the light actual stops. Bearing in mind that light normally travels at 300,000 km per second - this is quite a dramatic effect! It is such effects that make the quantum manipulation of light and matter so fascinating.

¹ Some methods of 'x-ray' vision are possible using non-optical sources, e.g. mm-waves. ² I did my PhD on EIT, so yes, I do find it fun! ³ Excellent introductory articles on slow light can be found in July's (2001) Scientific American and September's (2001) Physics World.

I'm more than happy to answer any questions on this subject, or to provide people with more references for further study - email: dm11@genie.co.uk

A Nanosecond in the Life of an Elementary Particle

by Jorge Sanchez

Imagine you were a particle and you had a clear objective in life: to serve science. For that, you'll travel together with about 1013 friends, all confined in a tiny space; suffering huge accelerations as you go around a chain of particle accelerators until you hit a target at a speed very close to that of light. Well, it's not an easy life, I'd say. But you just want to do your job the best you can and not ending your life losing control and hitting a wall on the way. Don't worry, because that is exactly the job of accelerator operators, to look after you and to lead you safely to the target. If you, my dear particle, are working at CERN, your problems are even less since there are two main control rooms that take care of you, one for the Proton Synchrotron complex and one for the Super Proton Synchrotron complex. In those, there is always a team of people, 24 hours a day, during the whole run of the machines.

Proton Synchrotron Main Control Room at CERN

We have many different diagnostic tools to check the status of the beam of particles at any moment, and probably one of the most useful ones is the measurement of the trajectory, both in the horizontal and vertical planes. These give us right away a view of your position along the accelerator. Big deviations from an ideal orbit can be the source of instabilities that lead to the subsequent loss of the beam. A delicate moment in your trip will be extraction from one accelerator and injection into the next, bigger one. You can think of it as a taxi waiting for a person outside a hotel; this person rushes out of the hotel, expecting the taxi to be right in its place, ready to shoot towards the airport. If the taxi is not there, the person will end up with his face in the asphalt. Well, in accelerators, we don't really have taxis, but radio-frequency (RF) buckets. The receiving accelerator prepares the RF bucket just at the right position and at the right moment so that it captures correctly the incoming beam. There are many timings we have to take care of for a correct capture of the beam by the RF bucket, requiring precision of nanoseconds. But maybe the most stressing moment for an accelerator operator is when many power supplies, if not all, fail simultaneously due to external sources, like a glitch in the power line, rapid changes of ambient temperature or thunderstorms. All these affect the delicate electronics of the accelerators quite a lot. Then we need to restart the equipment as soon as possible, from bending magnets and quadrupole magnets to radio-frequency and vacuum systems.

But not everything in the life of an accelerator operator has to do with solving problems. Even when the machines work fine, there are always improvements that can be done, like getting a better efficiency in the ratio of particles injected/particles in target; or a better beam shape; or less oscillations in the beam trajectory. We also take some part in the preparation of new beam requirements, with new characteristics for future use. That is the case with the Large Hadron Collider proton beam (LHC), which will have, among others, the function of supplying a neutrino beam for the CNGS (CERN Neutrino to Gran Sasso) experiment. The CNGS facility aims at directly detecting the hypothesis of neutrino oscillations, i.e. the conversion of a given neutrino type into another during their travel from the source to the detector. But that, my friends, is a different story.

FUSION member Jorge Sanchez is an accelerator operator at CERN, and currently studying SM355 and M435.

The Science Museum, London

"Space", says The Hitch Hiker's Guide to the Galaxy, "is big. Really big. You just won't believe how vastly hugely mind bogglingly big it is..." This guy obviously never went to the Science Museum. In fact, the only way to explain how the Museum can possibly cram in all those fascinating exhibits is to postulate that, like Magrathea, Douglas Adams' fictional planet factory, it contains a vast tract of hyperspace. It would take several lifetimes to go through them all. But on September 1st, eleven intrepid explorers dared to scratch the surface of this scientific monolith.

Helped along by the Museum's classical physics curator, Dr Neil Brown, we saw (amongst many other things): orreries; microscopes; vacuum pumps; a model to explain the moon's role in producing the tides; spectroscopes; telescopes; a machine for making diffraction gratings with 15,000 lines per inch; the manufacture of fine quartz fibres using a crossbow (not demonstrated!); early particle accelerators; a scale model of Sizewell B nuclear power station...

Then we had to go and sit down and have a cup of tea, and try to take it all in. We thanked Dr Brown and presented him with a FUSION T-Shirt. Thanks also to Eleanor for organising the visit. See Event Horizon for other tempting opportunities to sample 'real physics'!

Left to right; Sally Griffin, Norette Moore, Frank Hollis, Rivka Shmueli, Eleanor Cowan, Jim Grozier, Darren Phillips, Tina Heaton, Kumiko Matsuoka, Dr Neil Brown and Kelly Graham.

From S101 to PhD

Like Norrette Moore (see her S357 course review in the Summer 2001 Newsletter), I studied S357, although that was way back in 1982 when it was called S354. I remember enjoying the course, though it was not always easy to see the wood for the trees, and my appetite for general relativity was whetted.

By the end of 1992, I had taken all the OU courses that would feed my fascination with relativity, and finished a part-time diploma course in astrophysics at the University of London. Then the OU accepted my application to become a research student. I think the success of my application was partly due to my enthusiasm for the subject and to a good research proposal. That year, I had read a review paper concerning solutions of Einstein's gravitational equations which stated that the physical meaning of many solutions is unknown, or only partially understood. Sorting the physics from the mathematics in some of those solutions became the core of my proposal.

The application was sent to the Departments of both Physics and Mathematics at the OU. No luck with the former, but the Professor of Applied Mathematics accepted me as a part-time external research student, starting in January 1993. A couple of years later, he arranged for a relativist to be the external supervisor. This was none other than the author of the aforementioned review paper, a world authority on classical general relativity. If you think all the high-powered supervision was a little daunting, you are right! But it was also inspirational. The OU had taught me the fundamentals of differential geometry and I had learned some tensor calculus elsewhere. Theoretical physics needs no laboratory, so work started just with pencil, paper and a large rubbish bin. Then I discovered mathematics software and everything changed! Soon I was developing computer routines to plot the paths of test particles and light in space-time. This enabled me to 'explore' the spacetimes of various solutions to look for interesting phenomena. Once found, they could, with luck, be described analytically in a way that was intelligible to others. That was the harder part, sometimes involving weeks of work.

Although help was at hand through regular contact with both supervisors, I was determined, perhaps too determined, to work as independently as possible. Much of one year's work lead nowhere, then a change of emphasis eventually resulted in the publication of a paper and the experience of giving one of the London Relativity Seminars at Queen Mary College in 1998. The following year saw the publication of two more papers, one in conjunction with my external supervisor. Then began the long haul of thesis writing. My PhD was awarded in 2000 but I waited until June 2001 for the splendid graduation ceremony in Ely Cathedral. A long way from S101!

Brian Steadman

See Brian's comments on S357 - Space, Time and Cosmology on the FUSION web site under Course Reviews.

Cocktail Party Physics ...

Imagine the scene: a cocktail party, a crowded room, hubbub of conversation, chink of glasses. Suddenly it all goes quiet. Someone standing near the door has spotted a famous person who is about to arrive. It's that chap who used to read the news on ITV. When he arrives, several people gather round him, slowing his progress across the room, but most have forgotten him and ignore him, and he soon gets to the bar and pours himself a drink.

The room settles down again to chink and hubbub. Then the door-person shouts out another name: this time it's Jocelyn Bell-Burnell, Professor of Physics at the OU. The place is full of OU physics students (it's that kind of party) and a huge wave of adulation hits her as she enters the room. It is several minutes before she and her new-found entourage manage to cross the room, but eventually she too gets a drink.

The party settles down again, but not for long; and when the next name is called out, no-one can believe their ears. There is a great surge towards the door - everyone wants to see for themselves. Into this seething knot of people walks none other than Douglas Adams, author of The Hitch-Hiker's Guide to the Galaxy. He is not dead after all, it seems, but was simply abducted by Vogons for questioning about a library book of Vogon poetry which is overdue. He finds it difficult to even get into the room; autograph books are being thrust at him from every corner. When he tries to move, he is prevented by the sheer mass of bodies around him; but by selectively signing only those autograph books between himself and the bar, he manages to create a pressure gradient in that direction and gets his first drink for fifteen million years.

What's this got to do with physics? Well, what you have been reading is a popular account of the functioning of the Higgs boson, that elusive particle that the world's top particle physicists are currently looking for. The party is the vacuum in its lowest-energy state; our three partygoers are the electron, the proton and the top quark respectively, arriving at the speed of light but slowing down, acquiring inertia (and hence mass) in accordance with the response of the crowd; and the person at the door is the Higgs boson itself, the original spin-doctor, which controls the amount of mass each particle receives by its selective excitation of the medium.

Jim Grozier - with thanks to John Ellis

... and Physics Cocktails!

The A-Bomb

Checkout ground zero by recreating Oppenheimer's famous experiment in your throat.

Ingredients:

• 4 shots of vodka (more if you can afford it)

• 4 shots of tequila

• Orange squash concentrate, to fill up the glass

The Black Hole

Drink this, then disappear into your own event horizon (bedroom or study), never to be seen again.

Ingredients:

• 2 shots of Jack Daniels

• 2 shots of Whisky

• 4 shots of Cointreau

• Some coke, just for colour

The Schrödinger

Make your wave function collapse with this one.

Ingredients:

• 3 shots of vodka

• 1 shot of Archers

• 1/2 bottle of Grolsch

• 1 shot of Baileys

By kind permission of the Warwick University Physics Society. (It is believed that shortly after reading this, the entire FUSION committee held an extended cocktail tasting session and were never heard of for days).

SCIENCE HISTORY

Galileo Galilei - Continuing Discovery In The Face Of Papal Suppression

by Tina Heaton

Galileo Galilei (1564-1642) was born in Pisa on February 15th 1564. His father Vincenzio was a well known musician and scholar of the time and from an early age Galileo was fascinated with the way the mathematical relationships between the positions of the planets reflected the mathematical relationships in music, what he called the Harmony Of The Spheres.

Educated privately, then studying at a monastery until 1581, Galileo returned to Pisa to study medicine, but never finished, turning his attention to his true interests of mathematics, physics and astronomy.

Here at Pisa he realized whilst watching a lamp swinging to and fro that the time taken for each swing was the same regardless of the amplitude of the swing. This discovery was the basis for the design of a clock, although this was not constructed until after his death.

In 1589 Galileo became Professor of Mathematics at the University of Pisa, making his first significant mark by refuting the classical idea of the Ancient Greeks, that a heavy object will fall faster than a light one. It is rumoured that he proved this by dropping a cannon ball and a musket ball from the leaning tower of Pisa, although there is no historical proof that he actually did this.

What is known for sure is that Galileo carried out a series of experiments on the effect of what we now know as gravity, by rolling balls down inclined planes. The inclination meant that their falling motion was slowed down and could be timed accurately. From this Galileo realized that motion was relative. This would later be recognised as how gravity accelerates a falling object and was the groundwork for Isaac Newton's studies of motion in the 17th century.

Galileo can be considered the first modern astronomer as, on learning of the Dutch invention of the telescope (circa 1609), he made his own instrument with a magnification of x30 and turned it on the Heavens. Here he made the first systematic observations of the night sky. He saw mountains on the Moon, the phases of Venus, four satellites of Jupiter (Ganymede, Callisto, Europa and Io - The Galileans), spots on the Sun's surface and thousands of stars in the Milky Way Galaxy. Everything Galileo saw convinced him that Copernicus was right about a Sun-centred Universe and he publicly declared this.

His notes and observations were published in his Starry Messenger in 1610 and made him a famous man throughout Europe. This fame gained him support both within and outside the universities, outraging the Aristotelian professors, who were firm believers of an Earth-centred Universe placing Mankind at the centre of God's creation. Fearing consequences and backlash Galileo travelled to Rome to speak to the ecclesiastical authorities, claiming the Bible was not intended to teach scientific theories.

However, the Catholic Church, concerned that an unchallenged acceptance of Copernicism would undermine an already struggling battle against Protestantism, in 1616 declared Galileo a heretic and forced him to retract his support for the Theory. Galileo succumbed to the Pope's demands. In 1624 Urban VIII became Pope - a long term friend of Galileo. Galileo hoped that the 1616 decree would be revoked. This failed but he was permitted to discuss both Aristotelian and Copernican theories provided that he was not biased towards one or the other, and that under no circumstances would he question God's work.

Dialogue Concerning The Two Worlds was published in 1632 but, unfortunately for Galileo, though widely praised in Europe as a whole, was seen as a direct commendation of Copernicus and was banned outright by the Catholic Church. Galileo found himself charged with heresy and brought before the Inquisition who sentenced him to house arrest for life and demanded once again that he publicly renounce the idea that the Earth moved around the Sun. Under duress Galileo once again obliged.

Galileo lived out the rest of his life in his villa near Florence, until he died, blind and disillusioned in 1642, just before his 78th birthday. Despite his blindness he managed to complete Discourses, a book summing up his life's work, with the help of his disciples Vivani and Toricelli. The manuscript was smuggled out of Italy and published in Holland in 1638.

Over three hundred years later, in October 1992, Pope John Paul II formally retracted the sentence passed on Galileo by the Inquisition of the Catholic Church.