Phasing

Why iron-based superconductors work

Science: The first superconductors were discovered in 1911. Half a century passed before physicists came up with a theory that could explain why some compounds had zero resistance at a few degrees above absolute zero. In 1986, researchers discovered complex compounds nicknamed “cuprates” containing copper and oxygen that become superconductors at much higher “critical temperatures”—now as high as 138 kelvin, but couldn’t explain how or why they worked.

In the last couple of years, researchers have discovered a new type, four families of iron-based superconductors with distinct crystal structures, that superconduct at temperatures as high at 27 Kelvin. Using tools honed on the cuprates they have made measurements that took decades to achieve in the older materials.

More importantly, although physicists cannot say exactly how the iron-based superconductors work, they have developed a scheme that many say captures the essence of what’s going on. “We don’t have a full solution yet,” says MIT theorist Patrick Lee, “but the situation is better than in the cuprates.”

In fact, the emerging portrait of the iron-based superconductors jibes with some theories of the cuprates and seems to undermine more-exotic alternatives. So if physicists are on the right track with the iron-based superconductors, then the cuprates may not be so inscrutable after all.

Antarctic ice is melting

NPR: In Antarctica, you’ll find 90 percent of the world’s glacial ice, but new research from the US Geological Survey shows that every ice front in the southern part of the Antarctic Peninsula is retreating.

Jane Ferrigno US Geological Survey is the lead author of that new report. She tells NPR that scientists have known for a while that some of the peninsula’s ice shelves are breaking up.

Public outreach program catches interstellar dust grains

Nature News: Scientists say they have caught the first pieces of interstellar dust—the fundamental building blocks of the Sun, Earth and the rest of the Solar System. The discovery required an army of volunteers, including a Canadian man who spent 15 hours a day studying images online and eventually discovered the first dust sample.

Vlatko Vedral on information

guardian.co.uk: Physicist Vlatko Vedral explains to Aleks Krotoski why he believes the fundamental stuff of the universe is information.

Is fusion power really viable?

BBC News: 2010 is a big year for nuclear fusion but experts fear that a lack of fuel could push the dream of cheap, safe, clean and limitless energy far into the future.

The UK’s weapon lab’s scalpel

Nature News: With the launch of a powerful laser facility, called Orion, the UK’s atomic weapons establishment (AWE), which is generally closed to academic research, is opening up.

Researchers will use Orion to explore two key parameters for materials used in nuclear weapons: their opacity and their equation of state.

The first describes how radiation travels through a material—in this case, the two stages that make up a weapon, particularly as how the opacity changes with age

The other parameter—the equation of state—describes how a material behaves at enormous pressures and temperatures. By generating data on these and other crucial parameters, Orion will give nuclear-weapons scientists the information they need to ensure that their models are correct.

If the US National Ignition Facility is a thermonuclear hammer, then Orion is a scalpel says Peter Roberts, head of the AWE’s plasma-physics theory department to Nature’s Geoff Brumfiel.

Can you still be an audiophile in the digital world?

Sciencebase: Back in the 1970s LP’s were the common medium of choice for Hi-fi enthusiasts. When the compact disc emerged on to the market with its claims of superior quality and scratch resistance, the hi-fi enthusiasts split into two camps: those who clung to vinyl and those who went digital.

But, was concentrating on audio quality all for nothing? Within another generation the notion of digital audio had changed with compressed formats such as MP3’s becoming popular.

Jerald Hughes of University of Texas Pan American in Edinburg writing in the International Journal Services and Standards has a nice table showing the technical specification of the human ear and comparing it to the various analogue formats. It turns out that if you want the best quality, LP’s are not the way to go, an older format reel-to-reel better matches to the audio range of the human ear.

Related Link
Int. J. Services and Standards, 5 (4), 333-353

Dirty Cheating Texan! A Fine-Tuned Critique of William Lane Craig (Part 1)

Thursday - get ready!

New Revolutions in Particle Physics - Part 9

Part 9 of this tour-de-force lecture series by Leonard Susskind is now available online. I’ve updated the original blog entry to include this video.

Zz.