Physics news

Henry J · Post by **Henry J** » Sun Mar 12, 2006 1:32 pm

Physics lesson for the day:

One atom to another: "I think I lost an electron."
second atom: "Are you sure?"
First atom: "I'm positive."

Henry

Henry J · Post by **Henry J** » Mon Mar 13, 2006 10:04 am

Sandia’s Z machine exceeds two billion degrees Kelvin

Sandia’s Z machine has produced plasmas that exceed temperatures of 2 billion degrees Kelvin — hotter than the interiors of stars.

(That's even warmer than Florida!)

Henry J · Post by **Henry J** » Mon Mar 20, 2006 10:34 am

Did "Dark Matter" Create the First Stars?

Dark matter may have played a major role in creating stars at the very beginnings of the universe. If that is the case, however, the dark matter must consist of particles called "sterile neutrinos". Peter Biermann of the Max Planck Institute for Radio Astronomy in Bonn, and Alexander Kusenko, of the University of California, Los Angeles, have shown that when sterile neutrinos decay, it speeds up the creation of molecular hydrogen.

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The Cosmic Dance of Distant Galaxies

Studying several tens of distant galaxies, an international team of astronomers found that galaxies had the same amount of dark matter relative to stars 6 billion years ago as they have now.

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Website · Post by **brian** » Wed Mar 22, 2006 9:07 am

Geomagnetic flip may not be random after all
21 March 2006

One of the most fascinating natural phenomena on Earth is the flipping of its magnetic field, which has occurred hundreds of times in the last 160 million years. When the magnetic field flips, the North Pole becomes the South Pole and vice versa. The last time this happened was some 780,000 years ago, so we could be heading for another reversal soon. Now, physicists in Italy have found that the frequency of these polarity reversals is not random as previously thought but occurs in clusters, revealing some kind of "memory" of previous events (physics/0603086).

Although a full geomagnetic polarity reversal can take thousands of years to complete, the implications could be enormous. As well as affecting the migration trajectories of birds and other animals, the disruption to the Earth's magnetic field could expose the Earth to hazardous cosmic rays -- a scenario that some researchers have linked to mass extinction events like the one that wiped out the dinosaurs around 65 million years ago. Geoscientists believe that our planet's internal magnetic dynamo is responsible for pole reversals, but the actual mechanism is not well understood.

Previous analyses assumed that the number of times the poles have reversed over last 160 million years follows a Poisson distribution, implying that the events are random. The Poisson distribution tells you the probability of a number of events occurring in a fixed time if the events are independent and the average rate is known. A good example of the Poisson distribution in physics is the likelihood of unstable radioactive nuclei decaying in a certain period.

Now, a team of physicists led by Vincenzo Carbone of the University of Calabria have discovered that the sequence of polarity reversals can be well described by a Lévy distribution instead. In contrast to Poisson statistics, the Lévy distribution describes stochastic processes that are characterised by the presence of "memory" effects -- or long-range correlations between the events in time. Lévy distributions are widely used to study many critical phenomena, such as earthquakes, and also when analysing financial data. The researchers obtained their results by careful statistical analysis of different sets of paleomagnetic data containing estimates of when the Earth's poles reversed.

"The result means that polarity reversals are not random events that are independent of each other," explains team member Fabio Lepreti. "Instead, there is some degree of memory in the magnetic dynamo processes giving rise to the reversals," he says. "We hope that our work will serve as a useful reference point for models that aim to describe the phenomenon of pole reversal." The Italy team now plans to build new dynamic models to describe the field reversal sequences in a simple way, so that the physical mechanisms that trigger pole reversals can be more easily explained.

Henry J · Post by **Henry J** » Wed Mar 22, 2006 9:10 am

The Earth has a magnetic personality?

lswot · Post by **lswot** » Wed Mar 22, 2006 11:45 am

Henry J wrote:The Earth has a magnetic personality?

Yeah....from one poisson to another.......

Xjmt · Post by **Xjmt** » Wed Mar 22, 2006 11:56 am

lswot · Post by **lswot** » Thu Mar 23, 2006 10:51 am

Xjmt wrote:

LHawke · Post by **LHawke** » Fri Mar 24, 2006 8:15 pm

Wow, lswot, I didn't know you spoke French!

L'Hawke

lswot · Post by **lswot** » Sat Mar 25, 2006 1:42 pm

LHawke wrote:Wow, lswot, I didn't know you spoke French!

L'Hawke

Buttof course!

Henry J · Post by **Henry J** » Mon Apr 03, 2006 11:26 am

Scientists discover the Universe's strongest magnetic field

Scientists from The University of Exeter and the International University, Bremen have discovered what is thought to be the strongest magnetic field in the Universe. In a paper in the journal Science, Dr Daniel Price and Professor Stephan Rosswog show that violent collisions between neutron stars in the outer reaches of space create this field, which is 1000 million million times larger than our earth's own magnetic field.

(Who knew the universe had a magnetic personality?

)

Henry

Henry J · Post by **Henry J** » Tue Apr 04, 2006 11:22 am

MINOS experiment sheds light on mystery of neutrino disappearance

An international collaboration of scientists at the Department of Energy's Fermi National Accelerator Laboratory announced today (March 30, 2006) the first results of a new neutrino experiment. Sending a high-intensity beam of muon neutrinos from the lab's site in Batavia, Illinois, to a particle detector in Soudan, Minnesota, scientists observed the disappearance of a significant fraction of these neutrinos. The observation is consistent with an effect known as neutrino oscillation, in which neutrinos change from one kind to another.

(Some of our neutrinos are missing?!?!?

)

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Single-molecule diode may change Moore's "law" of microchip memory

Using the power of modern computing combined with innovative theoretical tools, an international team of researchers has determined how a one-way electrical valve, or diode, made of only a single molecule does its job.

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Henry

lswot · Post by **lswot** » Tue Apr 04, 2006 11:45 am

An international collaboration of scientists at the Department of Energy's Fermi National Accelerator Laboratory announced today (March 30, 2006) the first results of a new neutrino experiment. Sending a high-intensity beam of muon neutrinos from the lab's site in Batavia, Illinois, to a particle detector in Soudan, Minnesota, scientists observed the disappearance of a significant fraction of these neutrinos. The observation is consistent with an effect known as neutrino oscillation, in which neutrinos change from one kind to another.

I don't know about you but I ain't usen that transporter!

Xjmt · Post by **Xjmt** » Tue Apr 04, 2006 3:12 pm

Based on that Fermi lab exercise Spock should have lost the points to his ears years ago. And Kirk would've lost his.........phaser?

Gee, I don't think I'd recognize Kirk without his phaser.

Henry J · Post by **Henry J** » Tue Apr 11, 2006 10:05 am

A telescope is born on the floor of the Mediterranean

The first detection line of the Antares neutrino telescope, lying under 2,500 meters of water, was connected by Ifremer's remotely operated robot Victor 6000 to the onshore station at La Seyne-sur-Mer (Var) on Thursday 2 March at 12:11. Several hours later, Antares took its first look at the heavens and detected its first muons(1).

Henry