Category Archives: Physics

astronomy, Biography, Book reviews, Books, Engineering, History, Physics

Book Review: Collider – the search for the world’s smallest particles, by Paul Halpern

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  • Hardcover: 272 pages
  • Publisher: John Wiley & Sons (28 July 2009)
  • Language English
  • ISBN-10: 0470286202
  • ISBN-13: 978-0470286203
  • Product Dimensions: 23.6 x 16.3 x 3.3 cm

 

Good luck I say to anyone setting out to write a popular science book on particle physics.  The concepts are weird, the math is hard; and on publishing timescales there’s not a whole lot of new stuff worth talking about.

Moreover, it’s a tall order that’s less about content and more about the way you tell it.  Happily, in Collider: The Search for the World’s Smallest Particles– Paul Halpern tells it well.

Anchoring the core physics around a theme is helpful: whether it’s Brian Greene on string theory or Paul Davies on the search for extra terrestrial life or,  as in Halpern’s case, the physics, technology and people that have advanced our understanding of the subatomic world.

Collider is a story of impressive people building big machines to smash small particles together to reveal big truths.  With CERN’s Large Hadron Collider (LHC) limbering up under the Franco-Swiss countryside, the timing couldn’t be better.

At 232 pages before the notes, Collider is manageable without being superficial, and has sufficient pace and variety to engage even those for whom memories of high-school science induce a cold sweat (and for whom leptons is just another brand of tea).

Tracts of quantum weirdness interspersed with biographical vignettes and discussions on collider engineering should ensure a broad spectrum of readers stay the distance.  Those led out of their depth, however gently, will find delightful pangs of (at least partial) understanding along the way.   Personally, the engineer in me found particular joy in the mix of ethereal concept and enabling technology that particle physics, perhaps more than any other field, embodies.  Halpern as a physicist clearly enjoys and respects all aspects of the endeavour.  Indeed, Collider stylistically is quite polymathic, even poetic in a Saganish sort of way:

“Alas, summer’s heat sometimes shapes cruel mirages.  After modifying its equipment and retesting its data, the HPWF team’s findings vanished amid the desert sands of statistical insignificance. Skeptics wondered if electroweak unity was simply a beautiful illusion.”

Poetry aside, the physics kicks in early with unification, theories of everything (TOE), and the limitations of an incomplete Standard Model.

The better known particles are introduced via their discoverers’ stories: Thompson’s electron, Roentgen’s X-Rays, Becquerel and the decomposition products of uranium, Rutherford’s proton, and Chadwick’s neutron.

By describing relatively simple experiments from the early era, like the measurement of alpha and beta particle size, Halpern gives his subject a tangibility, a graspable air that prepares  the mental ground for later complexities.

Following the evolution of particle sources, accelerators, and detectors, Collider takes us through a chronology starting with unaccelerated decay products striking stationary targets, to linear accelerators, to the various circular synchrotron variants like Ernest Lawrence’s Bevatron and Cosmotron, ending with the contra-rotating particle streams and super-cooled magnets of the LHC.

As beam energies increased, detectors became more complex, sensitive, and selective, allowing the existence of myriad new particles to be confirmed or discovered.  Cloud and bubble chambers joined hand-held scintillation detectors and Geiger counters in the particle physicists’ armory, and as the forerunners of the giant counters, traps and calorimeters stacked up today in CERN’s ATLAS and ALICE experiments.

Halpern devotes the last three chapters to a discussion of dark matter, dark energy and the possibility of higher dimensions in the context of string, brane and M-theory, where he underlines the mutuality of physics and cosmology in understanding the bang, whimper, crunch or (somewhat depressing) rip possibilities of an uncertain multiverse.

Looking to the future, Halpern suggests the fate of particle physics itself is less certain than current LHC excitement might lead us to believe.  If the Higgs Boson, higher dimensions, or mini-blackholes show up, then fine; but if they don’t – where do we go next?’.  Larger machines might be an answer, but with costs that were never pocket money now truly enormous, stakeholders, including the physics community, will need to look to their priorities.  And as if to say ‘don’t say it will never happen’, Halpern dedicates a whole chapter to the last,  some would say terminal, back-step in American particle physics: the 1992 cancellation of the Reagan era Superconducting Super Collider (SSC).

Something Collider really brought home for me is how the nature of particle physics as a discipline and a career has changed.  Individual pioneers have been replaced by research groups working on projects staffed by thousands.  As Halpern says, if the Higgs were discovered, they’d be no obvious single candidate for the inevitable Nobel prize (except Higgs himself of course).   Data filtration and  computation as disciplines have become as important as the collider itself: the LHC is served by a global network of computers.  That creates the opportunity for remote distributed working and facilitates multi-national involvement, but also means young researchers need to think about the kind of experience, and resume, they’re building.  At PhD level already,  Halpern says the slow pace of fundamental revelations has required a force-put change in the definition of what qualifies for the degree in particle physics [we can’t all split the atom for the first time, right?].

I’ve one critical note on the history, and maybe I’ve just been reading too many Cold War biographies of late, but I felt Halpern’s analysis underplayed the military motivation and sponsorship behind the adolescent years of particle physics.  Given that the  topic’s already well covered in works like Gregg Herken’s Brotherhood of the Bomb, and that I walked away from Collider feeling inspired rather than cynical, it’s a choice of emphasis I’m inclined to forgive.

So quibbles aside, Collider is a bit of a page turner – which by the timbre of my opening statements isn’t a bad endorsement.   By presenting the obscure realities of particle physics in the context of the machines and people that revealed them, Halpern has for sure made an unfamiliar pill easier to swallow.

astronomy, nature, Physics, weather

Mountains and Moonbows

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What do aurora, noctilucent clouds, sun-dogs, and green flash have in common ?  Answer: they’re all examples of rare and interesting visual atmospheric phenomena I’ve totally failed to observe this summer.

Lunar corona and Lenticular Clouds, Jungfrau Massive (Photo: Tim Jones, Darkroommatter.com)

Conditions have often been right, even optimal.  I’ve made repeated observations with sophisticated equipment: my eyes and a camera, but no joy.  The only solace for standing in a field staring at the twilight horizon for nights on end has been the proximity of the local hostelry.  On reflection not such a bad deal.

I’ve had better luck in the past, but more so with the moon than the sun.  Take the example above of a lunar corona in the Swiss mountains.  Snapped between avalanches from an improvised snow-hole during my ascent of the Eiger from the window of the Beau Rivage Hotel in Interlaken.

Lunar coronae are in no way attached to the moon, but are an earthbound visual effect caused by moonlight passing through clouds of small particles.  As it’s a diffraction effect rather than a refraction effect, it works even with particles that don’t transmit light, like pollen grains for instance.   In this case the effect is most likely caused by water droplets in clouds.  The same thing happens with the sun sometimes, the visual ‘corona’ in that case not to be confused with the physical corona that is attached to the sun – so to speak.

Talking of confusion, lunar coronae, or moonbows, are not the same thing as Moon Rings.  I made that mistake when I started writing this piece and subsequently had to change the title.   A Moon Ring is just a name, but it’s a name specifically reserved for a ring of light caused by the refraction of moonlight through high altitude ice crystals.  Because ice crystals are hexagonal in shape, they all refract light at the same angle, which from an observer’s viewpoint produces a ring concentric with the moon at a fixed radius of 22 degrees (for fuller explanation see here).  Measured across the sky, that looks like 44 moons put next to each other (the moon takes up roughly half a degree of the 180 degrees of the sky we can see at any time).  The ring in my picture is at most ten moon diameters from the moon’s disc, or five degrees.  So it ain’t a Moon Ring.

A lunar corona can be more spectacular though, and if the conditions are right, a whole rainbow of colours can spread out from the inner ring, going from red to blue.

On a different tack now….

Apart from the moonbow, this scene includes an almost text-book perfect example of a mountain weather phenomenon known as Mountain Waves and Lenticular Cloud formation.

Lenticular clouds over the Jungfrau Massive by moonlight
Blow-up of the scene above showing moonlit lenticular clouds forming over the Jungfrau Massive (Photo:Tim Jones)

When air is forced to rise by flowing up the side of a mountain, it can cool down sufficiently, to the dewpoint temperature, where water vapour  condenses to form clouds. (That is adiabatic cooling and cloud formation as first explained by Erasmus Darwin. Just sayin’.)  When the air descends on the other side of the mountain, it warms up to above the dewpoint and the cloud disappears, the water drops vapourising again.   The isolated cap left on top of the mountain is a lenticular cloud.

That said, what I think we’re seeing in the photo here is a special circumstance for lenticular cloud formation that I first came across as a trainee private pilot.  In this case, air flowing over the mountains is trapped under a higher layer of stable air, causing standing waves to be set up, with lenticular clouds peeling off the cusps.

Reminiscent of a Katsushika Hokusai painting

The same conditions generate a series of turbulent rotating eddies lower down on the lee side of the mountain which can cause so-called ‘rotor clouds’ or ‘roll clouds’ to form.   It’s best not to fly anywhere near areas of rotating turbulence, so these clouds are good visual warnings for pilots to take special care (although as the mountain wave effect can extend 30 or forty miles downwind of a large range, you’re just as likely to feel the warning).

For a close-up view of a lenticular cloud, here is a lenticular altocumulus I snapped this summer floating off the leeward side of the San Gabriel Mountains in California.  The bulges are caused by rotating air under the cloud.

lenticular cloud formation off San Gabriel mountains in S.California
Lenticular cloud formation (Photo: Tim Jones)

That then about wraps it up for mountains and moonbows.  Just to leave you in the true spirit of transparent open-book research and a view of the laboratory where the Swiss studies were made, complete with proof of location.  And flowers.

Armchair atmospheric physics (Photo: Tim Jones)

Update November 2011 – Here’s another lunar corona; this time with Jupiter and taken from Kingston upon Thames:

Moon with lunar corona and Jupiter
Moon with lunar corona and Jupiter

Of related interest on external sites:

Rare Green Flashes Captured from the Moon (Universe Today)

http://www.sciencebase.com/science-blog/cloud-spotting.html

http://blogs.agu.org/wildwildscience/2011/12/17/magic-clouds-in-the-magic-city/

 

Biography, education, Physics

Of Physics, Firearms, and Fireworks

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Physics, Firearms, and Fireworks
(photo: Tim Jones)

I learnt only recently, while researching the early use of computers in schools, that my physics teacher from the late seventies, John Page, had died during 2009.

Better known by his nickname ‘Bumble’ (possibly after the Dickens character), he was certainly a character himself.  He was also a teacher who encouraged me to think.

Reproduced from the Gateway Magazine

For sure, Bumble covered the official syllabus: wheeling out worthy but ultimately plain vanilla physics kit like air pucks, weights, and springs.  But the most interesting discussions – the ones that have stuck with me –  followed some of his more off-the-wall demonstrations.

For example, as an introduction to Newton’s Laws of Motion and the Gas Laws, Bumble kicked off one lesson by discharging a black powder pistol at the front of the classroom.

The lesson started in the usual way, Bumble making his signature ponderous walk to the laboratory’s front desk, eyes looking at the floor.  

Entirely normal so far, except today he carried a long-barrelled  revolver in his hand, one chamber of which he proceeded to load, methodically inserting pieces of cloth, then gunpowder, then cloth again (no bullet thankfully), before compressing the package with a small ram rod.  We watched in stunned silence.

Gateway Grammar School Leicester
Gateway Grammar School, Leicester (Photo: Tim Jones)

Remember, this was all way before the Dunblane massacre or other school shootings, so I guess we felt a sense of intrigue rather than fear.  This was Bumble anyhow – he did weird stuff.   With a copper percussion cap in place, the gun was pointed in the general direction of the laboratory wall.  And fired.

Within seconds of the most enormous bang echoing through the now smoke-filled laboratory, the Head of Physics, Mr Gill, closely followed by the Head of Chemistry, Mr Scottow, tumbled into the lab looking suitably alarmed.  They’d clearly not been pre-briefed, and I still remember their expressions changing from shock to relief – and a glance of resignation between them – as the gunman stepped out of the smoke.

Stunts like Bumble’s Colt Navy revolver demo were attention grabbing and fun, but also an introduction to typically stretching discussions. 

In this case, Bumble got us thinking about how long a gun barrel would have to be before the bullet changed direction and went back the other way.  Imagine the thought processes needed for that.  First off, there’s the non-intuitive realisation that a projectile in a tube can change direction if the pressure behind it falls sufficiently relative to the pressure in front of it – which theoretically can happen in a long enough gun barrel.   Then there’s the skill of mentally extrapolating the familiar (relatively short barrel) to unfamiliar extremes (hugely long barrel).  Thinking in abstraction and at scales beyond normal experience is useful, for scientists and non-scientists alike, in appreciating the scales relevant to fields as diverse as evolutionary biology and cosmology (and presumably also super-gun design).

Sections of Big Babylon at Fort Nelson, Portsmouth
Sections of the ‘Big Babylon’ Iraqi super-gun at the Royal Armouries, Fort Nelson, Portsmouth (Photo: Tim Jones)

Then comes the actual physics and chemistry: mechanics, thermodynamics, kinetics, friction, shock-wave propagation – not to mention the mathematical tools needed (I don’t remember if we came up with an actual quantitative answer, and suspect an analytical solution is only possible with major simplification. )  The follow-on lesson might cover ballistics: catching up with the bullet after it leaves the gun.

In a similar vein, my introduction to fluid flow through constrictions and Bernoulli’s principle took the form of the largest firework rocket I’d ever seen being launched from the school playground.  In the lesson afterwards, we talked about rocket nozzle design.   It turned out Bumble was licensed to make fireworks and had designed and cast his own ceramic nozzles.  I still marvel that the thing came down ‘safely’ in the confines of the school yard.

So that’s how I remember Bumble.  We might at times have got distracted from the strict letter of the course syllabus; but that’s the nature of real-world problems if they’re studied with sufficient rigor.  And arguably as the antithesis of spoon-fed exam training, Bumble’s teaching style may not have suited all students.  But personally, I love the attitude and approach to education John Page represented, and very much hope we haven’t seen the last of the Bumbles.

Aviation, Physics, Television

A Brush with Base Jumping

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Base jumper in the Lauterbrunnen Valley, Switzerland (Photo: Tim Jones)

I see from the TV listings that Channel 4 (UK) will tomorrow be airing  The Men Who Jump off Buildings: a documentary about the extreme sport of base jumping.  Launching from Buildings, Antennas, Spans, Earth (hence BASE), base jumping practitioners have only seconds to control their descent  and deploy a parachute.   Jumps from buildings and cliffs are particularly demanding due to the danger of hitting something sideways on the way down.

Base jumper in Lauterbrunnen Valley (Photo:Tim Jones)
Base jumper in Lauterbrunnen Valley (Photo:Tim Jones,Darkroommatter.com)

While the Channel 4 show promises to focus more on jumps from buildings, it reminds me of a base jump from a cliff side I witnessed in 2007, in Switzerland’s Lauterbrunnen Valley.  The rapid-fire sequence of photos I took at the time should convince you that stamp collecting isn’t such a bad hobby after all.

I later discovered Lauterbrunnen is something of a base jumping hot-spot, famous for the quality of the jumps, but also for the number of related deaths in recent years.

The sequence of 16 pictures in the gallery below shows the various stages of the jump, including the free-fall glide and chute deployment; the main chute is activated by a smaller chute the jumper holds and throws out at the critical moment.

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dpp_0010
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dpp_0014
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dpp_0017
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Although the guy in the pictures landed safe and sound – I had a chat with him later – the sequence  shows him fighting to unravel a tangled harness.  Jumpers say every jump is different, so an ability to think quickly on the spot is as important as understanding the theory.

Lauterbrunnen valley (photo:Tim Jones)
Lauterbrunnen Valley (photo:Tim Jones, Darkroommatter.com)

The timing and manner of the chute’s release depends on many factors, including the jumper’s velocity, which in some cases may be below the terminal velocity of around 120 mph.  It goes without saying that the time available to avoid objects and adjust parachutes is severely limited.

Apart from one holiday paragliding experience in the Med., I’ve only worn a parachute while flying gliders – and thankfully never had to use it.  And for now, exhilarating as I’m sure base jumping is, I think I’ll stick to walking up mountains rather than jumping off them.

Art, Film, Physics, Politics

Dr Atomic – A Poignant Blast

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Yesterday evening I spent three hours in one of the 850 theatres in 28 countries that were screening John Adams’s opera Dr Atomic , live from the Metropolitan Opera in New York.

Gerald Finley as J.Robert Oppenheimer (Photo NY Met Opera)

I thoroughly enjoyed this modern opera. Set around the first U.S. atomic bomb tests in 1945, Dr Atomic explores the tensions, dilemmas, and decisions that occupied the minds of J.Robert Oppenheimer, his wife, and his project Trinity associates in the weeks, hours, and seconds leading up to the world’s first nuclear detonation.

Lines taken directly from declassified documents lent authenticity. As did a suitably sinister Atom Bomb, it’s crude complexity resembling a lash-up from a PhD lab, but radiating a pawl of edgy doom as it hung center stage.

Memorable moments along the way included the team’s sweepstake on expected explosive yield; Oppenheimer’s conservative estimate of 3kT (TNT equivalent) perhaps betraying a wishful regret that would later turn into his consuming guilt. And the other scientists, reluctant to put their money where their calculations had taken them – so massive, other, and beyond intuition were the predictions.

We also saw the quintessential moral dilemma that faces most if not all scientists at some point. When to speak up, protest, do-the-right-thing; take and act on the responsibility that knowledge has both blessed and damned you with.

Trinity

Predictably, the finale was charged with tension and poignancy. The begoggled cast stared into the audience/horizon for what seemed an eternity – as the minutes, then seconds, counted down to the detonation itself. In the final seconds, a translucent curtain descended between audience and stage with the typewritten words “give me some water” and we heard the stuttering voice of a Japanese child.

biology, News, Physics

Bum Genes Mean End Of The Line For Iceman

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(I ought to add up front that the following is the result of an exercise in a type of sensationalistic reporting characteristic of certain UK tabloids)

Remember the Iceman? Not Maverick’s nemesis from Top Gun, but the 5000 year old Neolithic mummy found in the German Alps back in 1991.

Cool

After 17 years of peaking and prodding, Frozen Fritz is out of the freezer and back in the news. This time, Italian scientists working with DNA taken from the Iceman’s rectum have figured out he has no living relatives. A team including Franco Rollo from Camerino University, and Luca Ermini working at Camerino and Leeds University, used the genes in Iceman’s DNA like an identity card; but it turns out nobody today carries anything even similar.

Books, education, Physics

Domestic Science – Not

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I’m not the first to ask why science has become less popular with school children and young people. It’s a fact, at least in the UK and the USA, that fewer students are selecting science subjects at school or making a college or professional career out of science.

While there are doubtless many complex reasons behind the decline, some of today’s thinkers put at least part of the blame on the reduction in first hand experience and active personal experimentation in science that young people engage in.

And could something as apparently innocent as the emasculation of the home chemistry set, or the retreat by schools from the more spectacular classroom science demonstrations, be a contributing cause?

While I’ve been musing over my own formative influences, which I put down to: inherent curiosity, parental support, inspiring teachers, a home culture of learning and DIY (do-it-yourself), and relatively unhindered experimentation; my latest reading is a warning of what can happen when home grown science goes too far.

David Hahn was an adolescent Boy Scout from Michigan when he built an operational model nuclear reactor in his parents’ garden shed. His improbable but true story is told by Ken Silverstein in The Radioactive Boyscout: The True Story of a Boy Who Built a Nuclear Reactor in His Shed.

Silverstein describes Hahn’s obsession with nuclear power and radioactivity, culminating in his own nuclear pile. It’s a frightening and fascinating study in single-minded ingenuity; the ultimate expression of ‘string and elastic bands’ resourcefulness. But it’s also a sad tale of misguided talent and lost opportunity, with Hahn’s informal career in science never blossoming beyond the confines of his backyard. I’ve just finished this book from 2004 – another volume from my latest ‘3 for £5’ trawl – and can heartily recommend it. It’s a good adult read, plus you won’t find a more mischievous gift for any young person with a maturing interest in home science experiments.

Hahn’s own inspiration was the doubly infamous Golden Book of Chemistry Experiments, a product of 1950s/60s US techno-optimism that was subsequently banned from most US libraries. Certainly, some of the children’s experiments described within its colourful covers are way beyond anything that today we would consider safe – for the child or the publisher.

There is of course nothing new under the sun, and, despite the recent plethora of mimic Victoriana ‘thing-to-do’ books, titled ‘The Dangerous Books for Boys, Girls,…Whatever’, nothing compares with the original bane of the enlightened Victorian parent – ‘The Young Man’s Book Of Amusement‘. Packed with all sorts of nonsense, ranging from

the harmless to the downright suicidal, my favourite wheeze from this 1850’s bible of curiosity is the Artificial Volcano. The experimental procedure, which results in a runaway exothermic reaction of iron filings and sulphur, specifies minimum quantities of both reactants such that, in the spirit of all good compost heap construction, a critical and sustaining thermal mass is achieved – in this case 28lbs of each. The 56lb of damp mixture is buried two feet below the ground, and left to do its stuff. Never having got up the nerve or the resources to try this, on any scale, I can only imagine the combined impact on the senses of vigourous suphur dioxide production, rivers of molten sulphur, showers of burning iron particles, all escaping through an earth bulging under the pressure of a man-made magma chamber. Environmentally friendly – not. Politically correct – not. Fun, thought provoking, and inspiring….? For more excerpts from this cheery manual visit Lateralscience (but don’t fall for the apochryphal stories surrounding the text – which is real).

I’m not endorsing the building of volcanoes or nuclear piles, in our back gardens or anywhere else, but we should consider what has happened over the last thirty or forty years with regard to our freedoms and restrictions in the home-science department. Are we to be trusted with only baking soda and citric acid? – apparently so.

I’ll wind up with a taste of how some of the ‘today’s thinkers’ I referred to earlier feel about the subject of scientific inspiration and freedom for self-experimentation. “Hands-on experience and experiments” was one of the ten categories highlighted by respondents to a 2006 study by the Spiked team who, working with Pfizer, asked some well-known scientists/thinkers (including Simon Singh whom I had the unexpected pleasure of meeting recently) – ‘”What inspired you to take up science?’” Many respondents emphasised the importance during their formative years of being able to do their own independent testing, experimentation, and indeed – risk taking. Here is the complete summary of responses.

cybernetics, News, Physics, technology

Robots – The Good, The Bad, and The Cuddly

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Military robots are in the news today, with the BBC reporting six deaths in Pakistan, allegedly caused by a missile strike from a US unmanned aircraft, or drone. We’re going to see a lot more of this. The military robot sector is booming and well funded through the USA’s $145bn Future Combat Systems (FCS) programme. Robots (the name derives from the Czech vobota, for forced labour) are seen as battlefield lifesavers, which doubtless they are for the side that controls them.

On a lighter robotic note, cuddly dinosaur robot Pleo continues to wow pundits with its cuteness and personality capability – tested here, while in Japan, this unicycle riding robot demonstrated state of the art balance. Balance, particularly in pseudo-human robots with legs, is one of the big challenges for robot engineers. Maybe the solution is to double up on the legs, as in this slightly disturbing clip of Boston Dynamics ‘Big Dog’.

Update Feb 2011 – Latest on Boston Dynamics

http://www.wired.co.uk/news/archive/2011-02/28/boston-dynamics-atlas-and-cheetah

Update 1 March 2013 – Big Dog gets an arm (BBC News)

 

Art, events, News, Physics

Dr Atomic

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“Science and art belong to the whole world, and before them vanish the barriers of nationality“

Johann Wolfgang Goethe

That sentiment will be endorsed when, on 8th November, John Adams’s opera Dr Atomic is broadcast live from the Metropolitan Opera in New York City to cinema venues across the world.

Trinity

Taking as its theme the first U.S. atomic bomb tests in 1945, Doctor Atomic draws on declassified documents to inform a production that explores the tensions, dilemmas, and decisions that occupied the minds of J.Robert Oppenheimer and his project associates in the weeks leading up to detonation.

In London, the 3hr 21m performance starts at 18.00 GMT, relayed to the BFI IMAX, Barbican, Curzon Mayfair, and Greenwich Picturehouse cinemas, amongst others.

Thanks to C and J for the tip-off.