Physics

A temperature below absolute zero: Atoms at negative absolute temperature are the hottest systems in the world

On the absolute temperature scale, which is used by physicists and is also called the Kelvin scale, it is not possible to go below zero – at least not in the sense of getting colder than zero kelvin. According to the physical meaning of temperature, the temperature of a gas is determined by the chaotic movement of its particles – the colder the gas, the slower the particles. At zero kelvin (minus 273 degrees Celsius) the particles stop moving and all disorder disappears. Thus, nothing can be colder than absolute zero on the Kelvin scale.

Magnetic shell provides unprecedented control of magnetic fields

(Phys.org)—A general property of magnetic fields is that they decay with the distance from their magnetic source. But in a new study, physicists have shown that surrounding a magnetic source with a magnetic shell can enhance the magnetic field as it moves away from the source, allowing magnetic energy to be transferred to a distant location through empty space. By reversing this technique, the scientists showed that the transferred magnetic energy can be captured by a second magnetic shell located some distance away from the first shell.

Asteroid May Become Moon for Earth's Moon

So far our galactic adventures have included landing men on the moon, taking pretty pictures of Saturn, and roaming the surface of Mars. So what's next on NASA's to-do list? Perhaps snagging an asteroid to keep in our own backyard.

Researchers from the Keck Institute for Space Studies proposed a plan [pdf] in April to bring an asteroid into the moon's orbit so astronauts can study it up close. How big an asteroid are we talking? Researchers said the sweet spot would be right around 500 to

Researchers force a gas to a temperature below absolute zero

(Phys.org)—A team of physicists in Germany have succeeded in forcing a gas to become colder than absolute zero. Using lasers and a magnetic field to manipulate an ultra-cold gas, the researchers, as they describe in their paper published in the journal Science, managed to coax the temperature of the gas to a few billionths of a Kelvin below absolute zero.

Atoms at negative absolute temperature: The hottest systems in the world

(Phys.org)—In cold regions on earth, negative temperatures on the Fahrenheit or Celsius scale can often occur in winter; in physics, however, they were so far impossible. On the absolute temperature scale that is used by physicists and also called Kelvin scale, one cannot go below zero – at least not in the sense of getting colder than zero Kelvin. According to the physical meaning of temperature, the temperature of a gas is determined by the chaotic movement of its particles – the colder the gas, the slower the particles.

Reversal of magnetic moment by an electrical voltage in a single material could lead to new low-power electronic devices

Researchers at the Advanced Science Institute at Wako, Japan, have discovered a material whose magnetic orientation can be fully switched by electric voltages. Such switchable materials have applications for magnetic data storage or novel electronic devices that use the electron's magnetic properties. As Yusuke Tokunaga from the research team explains, "Reversal of magnetization by a voltage enables ultra-low power consumption electronic devices because applying a voltage and not an electrical current means that such devices are free from Joule heating loss."

Large Hadron Collider hiatus sets stage for more discovery

The world's largest and most powerful atom smasher goes into a 2-year hibernation in March, aiming to reach maximum energy levels that may lead to more stunning discoveries after hunting down the so-called "God particle."

Testing Einstein's E=mc2 in outer space

(Phys.org)—University of Arizona physicist Andrei Lebed has stirred the physics community with an intriguing idea yet to be tested experimentally: The world's most iconic equation, Albert Einstein's E=mc2, may be correct or not depending on where you are in space.

Can we accurately model fluid flow in shale?

(Phys.org)—Given that over 20 trillion cubic meters of natural gas, a third of the United States' total reserves, are thought to be trapped in shale, and given the rush to exploit shale oil and gas resources by Australia, Canada, China, and other countries around the world—even oil-rich Saudi Arabia—it's a wonder that producers still rely on models of how fluids flow underground that were devised in the heyday of oil and gas development.

Power spintronics: Producing AC voltages by manipulating magnetic fields

Scientists are putting a new spin on their approach to generating electrical current by harnessing a recently identified electromotive force known as spinmotive force, which is related to the field of spintronics that addresses such challenges as improving data storage in computers. Now, a novel application of spintronics is the highly efficient and direct conversion of magnetic energy to electric voltage by using magnetic nanostructures and manipulating the dynamics of magnetization.

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