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Tobias Reichenbach

Cyclic competition. (This is an artist’s rendition; the actual output of the computer simulation is the image below.)

In many ecosystems, several competing species coexist because none is best at everything. Tobias Reichenbach of the Ludwig Maximilian University in Munich and his colleagues ran computer simulations of three virtual bacteria species fighting a sort of rock-paper-scissors game.

One species produces a toxin. A second is immune to the toxin and outcompetes the first. A third species is sensitive to the toxin but can overtake the second species because it’s unburdened by the metabolic cost of producing an antidote. Each virtual population, shown here in a different color, propagates in waves as it pushes aside its weaker competitor while being chased by the stronger one, the researchers explain in an upcoming Physical Review Letters. Scientists have observed similar patterns among certain marine organisms.

Tobias Reichenbach

(From Science News, Nov. 3, 2007.)

The experiment ran for seven days, and magnesium-40, like Adam, didn’t show up until the fifth day. It was a long-sought isotope thought to be the heaviest magnesium that can exist, having 16 more neutrons than the most common form of magnesium. Three nuclei of magnesium-40 were recorded, and it was very good. But then, something even more interesting happened (think Eve). The researchers also saw 23 nuclei of aluminum-42. Experts generally thought it couldn’t exist.

Now, astrophysicists may have to rethink their models of how supernovae create heavier elements. On the other hand, they may also be able to explain anomalous X-ray flashes coming from neutron stars. When matter falls onto a neutron star and starts sinking into its crust, pressures 10 trillion times as high as those at the sun’s center force electrons and protons to merge, forming neutrons. Aluminum-42 and magnesium-40 may be among the elements that form temporarily during that process.

Read my article from this week’s Science News

Washed away

Last year, physicists reported seeing tantalizing experimental traces of the axion, a hypothetical subatomic particle that’s been mentioned as a possible constituent of cosmic dark matter. But the axion was showing up where theory said it shouldn’t be. It now looks as if it wasn’t there after all.

The particle sprang from an attempt to explain certain differences between the strong and weak nuclear forces. Cosmologists seized on the axion because its properties made it a plausible component of dark matter, the unseen material that far outweighs ordinary matter in the universe.

Read the rest of my article, freely available on the Science News Web site.

As I recounted in my end-of-year special last year, MIT physicist Frank Wilczek called the particle after a brand of detergent, because it was supposed to wash away all of the problems of the so-called standard model of particle physics. The brand is not longer sold in the U.S., but it apparently still is in France.

In the latest experiment, researchers attempted to demonstrate the axion’s existence by looking for an effect known as photon regeneration, or, in Zenlike fashion, as “light shining through a wall.” As I write in this week’s Science News:

Researchers shoot a laser beam through a magnetic field toward a metal plate. The metal wall blocks photons, but any axions created in the field would pass through. On the other side of the wall lies a second magnetic field that would convert some of the axions back into photons, making it appear that some photons had passed through.

They detected no axions at all. However, physicists say other types of experiment might have a better chance at discovering the particle. The most intriguing one would look for “light shining through the sun.” As the sun passes in front of a source of gamma rays located far away in the universe, some of the source’s photons could turn into axions. Those would easily zip through the sun, and then perhaps convert back into gamma ray photons, wihch astrophysicists could then pick up.

Wilczek told me that he has kept a box of the U.S.-brand detergent in his basement. Perhaps, if one day the axion is discovered, he could make loads of money by selling it on eBay.

Carbon flatland

“Graphene has always been before our eyes, but no one ever tried to look,” says Andre Geim, a physicist at the University of Manchester in England. A single-atom-thick, chicken wire web of carbon atoms, graphene forms the layers that stack up to make the graphite found in pencil lead and carbon soot.

However mundane the stuff may be, physicists have long predicted that if it were possible to isolate single graphene sheets, they would be sturdier than diamond and would have almost preternatural abilities to manipulate electrons. That could make graphene a better material than silicon for making computer chips. Until recently, though, no one had been able to isolate graphene sheets, let alone do anything useful with them.

In 2004, Geim and his collaborators startled the physics community by announcing that they had peeled graphene layers off graphite using common adhesive tape. The discovery raised a buzz in physics circles reminiscent of the excitement that greeted carbon nanotubes a decade ago.

(more…)

While calling NASA’s “manned” space flight programs (such as [the International] Space Station) worthless with regards to science, Steven Weinberg calls NASA’s “unmanned” space flight programs (such as Martian robots Spirit and Opportunity robots and Hubble Telescope) very important to the advancement of science.

Steven Weinberg stated at the Tuesday, September 18, 2007 Science Writers’ Workshop called “Dark Energy: A Decade of Discovery and Mystery” at the Space Telescope Science Institute [home of the Hubble Space Telescope] in Baltimore, Maryland, U.S.A., “The International Space Station is an orbital turkey. No important science has come out of it. I could almost say no science has come out of it. And I would go beyond that and say that the whole manned spaceflight program, which is so enormously expensive, has produced nothing of scientific value.”

(From Nobel Laureate Weinberg calls space station an “orbital turkey”)