Category Archives: APS March Meeting 2009

As close as I could get

By Hamish Johnston

Despite legging it across the convention centre, I left it a bit late to get anywhere near Hideo Hosono’s talk on “Materials and Physics in Pnictide Superconductors”. It looks like the pnictides — which burst on the scene during the last March Meeting — are a contender for this year’s hot topic.

You might recall that these materials comprise a completely new family of high-temperature superconductors. They could help physicists understand just exactly why some materials are superconducting at relatively high temperatures — something that has been a genuine mystery for over 20 years.

Of course, they might just add to the confusion by giving physicists more materials that they don’t understand.

But if the crowd at Hosono’s talk is any indication, there won’t be a lack of trying.

By Hamish Johnston

Here’s a question for you: how many physicists graduate each year from US universities?

The answer is about 4000 — a number that has been steady for about 40 years, which is why the APS and the AIP want to more than double this to 10,000 per annum.

But does the nation need more physicists? To try to answer that question, there is a session at the March Meeting called “Why do we need 10,000 physics majors”.

I got a preview of the issues at a press conference with two of the speakers — Theodore Hodapp of the APS and Roman Czujko of the AIP.

Hodapp explained one beneficiary of more physicists would be high school students because more of them would be taught physics by physicists. Indeed, today American universities produce just a third of the required physics teachers — and amongst those who teach physics, just a third have physics degrees.

And according to Hodapp, the current crisis in the shortage of physicists could be solved in one stroke if every teaching college in the US graduated just one extra physicist per year.

Hodapp places some of the blame on physics departments, who for years have set curricula with a focus on getting their undergraduates into graduate school — rather than into jobs like teaching.

This, according to Czujko is changing, with physics departments trying to improve how they prepare their graduates for lives outside of academia. Indeed, he thinks they should even tailor their programmes to deal with the economic realities facing graduates — in other words recognizing that physicists that graduate in a recession may need different skills that leave in boom times.

And just to stir things up a bit, Czujko pointed out that when it comes to pay, physics graduates do fair to middling — better than biology grads, but worse than engineers. So is the market lukewarm on physicists. Indeed, if you look a bit closer it seems that physics grads get paid more than others because many of them end up doing engineering jobs — whereas biologists do not.

So, does the US need 10,000 new physicists every year?

Marc Baldo shines light on phycobilisomes

By Hamish Johnston

It’s a dull morning here in Pittsburgh — and the view out the press room window is of a rusting railway viaduct, grey pavement, hills covered in leafless brown trees and a leaden sky.

However in a couple of months it will be hot and hazy here as the city basks under a Mediterranean-strength Sun. You might think this would make Pittsburgh a perfect place to deploy solar panels (at least in the summer) — but there is a problem, all that haze makes it difficult to focus sunlight onto high-performance photovoltaics.

This focussing is necessary because it is very difficult to make large-area photovoltaics from semiconductors. The materials and processing are expensive and it is tricky to make large devices without defects, which reduce their efficiency.

One solution is to simply use an optical system of lenses and/or reflectors to concentrate the light at a photovoltaic. The problem is that such systems must track the Sun precisely — which is tough to do when it is lurking in the haze.

A better way would be to take a hint from nature and capture diffuse light and then concentrate it on an efficient photovoltaic. However like most biomimicry, this is easier said than done.

This morning MIT’s Marc Baldo talked us through a number of approaches that he was taking in his lab. The most successful one, it seems, is using glass plates containing fluorescent dye. Sunlight enters the plate via the broadside and causes the dye to emit light. This light then travels along the plate to one edge, where it can enter a photovoltaic.

The advantage is that much of the light captured by the large broadside of the plate is re-emitted as light that leaves the plate via the much smaller edges — concentrating it where it can be converted to electricity by a relatively small photovoltaic.

However, Baldo and team had to cleverly engineer the energy levels in the dye to ensure that the light destined for the phovoltaic is not reabsorbed and ultimately scattered out of the plate.

This is done using a molecules called phycobilisomes — proteins that are involved in photosynthesis.

Hopefully this will allow Baldo’s devices to be a bit more like plants — not solid chunks of semiconductor — by separating the functions of light absorbtion ad charge production.

The Cathedral of Learning

By Hamish Johnston

This year’s APS March Meeting is in Pittsburgh — a city with a history that is intertwined with the solid-state of matter, just like the conference itself.

This is Steeltown and home to the Steelers. And even though the region’s steel industry is a shadow of what it once was, the city is full of reminders of the vast fortunes that were made from digging rock from the ground and forging it into the engines of industry.

The best place to catch a glimpse of this wealth is the neighbourhood of Oakland, home the the University of Pittsburgh’s glorious Cathedral of Learning — a gothic revival skyscraper that was built in the 1920s. Sadly, I don’t think the physics department can be found there.

Just down the road from the Cathedral is the Carnegie Museum of Natural History, which rather fittingly houses a fantastic collection of minerals. Many of these are housed in glass cases in a mirrored room — and the light reflecting from all the polished surfaces is dazzling.

I can’t think of a better place to appreciate the solid state of matter.

Crystals in the Carnegie Museum

Longer casting thanks to F1

By Hamish Johnston

If you happen to be in London you might want to check out a new exhibit at the Science Museum about how Formula 1 motor racing has spun-out technologies used by furniture designers, paramedics and even fly fishing enthusiasts.

The exhibit is called Fast Forward: 20 Ways F1 is changing the world .

There’s no need to hurry because the free exhibit runs until April 5, 2010.

As for myself, I’m off to Pittsburgh tomorrow for the APS March Meeting …one week of condensed-matter physics madness, and I wouldn’t miss it for the world!