Physics

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BBC Horizon (2011) - What is Reality? (complete, uncut) Quantum time travel: Black hole not required - physics-math - 22 November 2010. You don't need to set the universe in a spin to see time travel in action – so what happened when a photon with a quantum gun went back to kill itself?

Quantum time travel: Black hole not required - physics-math - 22 November 2010

CHATTING about time travel in a room overlooking a verdant quadrangle at the Massachusetts Institute of Technology seems strangely appropriate. The building dates from 1916 and looks its age: the high ceilings, echoing corridors and musty offices with heavy wooden doors have changed little in that time. How to create temperatures below absolute zero - physics-math - 01 December 2010. ABSOLUTE zero sounds like an unbreachable limit beyond which it is impossible to explore.

How to create temperatures below absolute zero - physics-math - 01 December 2010

In fact there is a weird realm of negative temperatures that not only exists in theory, but has also proved accessible in practice. An improved way of getting there, outlined last week, could reveal new states of matter. Temperature is defined by how the addition or removal of energy affects the amount of disorder, or entropy, in a system. For systems at familiar, positive temperatures, adding energy increases disorder: heating up an ice crystal makes it melt into a more disordered liquid, for example. Keep removing energy, and you will get closer and closer to zero on the absolute or kelvin scale (-273.15 °C), where the system's energy and entropy are at a minimum. Topologist Predicts New Form of Matter : Physics. Topologist Predicts New Form of Matter  Back in 1970, a young physicist working in the Soviet Union made a counterintutive prediction.

Topologist Predicts New Form of Matter 

Vitaly Efimov, now at the University of Washington in the US, showed that quantum objects that cannot form into pairs could nevertheless form into triplets. In 2006, a group in Austria found the first example of such a so-called Efimov state in a cold gas of cesium atoms. Large Hadron Collider - How does it work? Delayed choice quantum eraser. A delayed choice quantum eraser, first performed by Yoon-Ho Kim, R.

Delayed choice quantum eraser

Yu, S.P. Kulik, Y.H. Shih and Marlan O. Scully,[1] and reported in early 1999, is an elaboration on the quantum eraser experiment that incorporates concepts considered in Wheeler's delayed choice experiment. How Quantum Suicide Works". ­­A man sits down before a gun, which is pointed at his head.

How Quantum Suicide Works"

This is no ordinary gun; i­t's rigged to a machine that measures the spin of a quantum particle. Each time the trigger is pulled, the spin of the quantum particle -- or quark -- is measured. Einstein's sceptics: Who were the relativity deniers? - physics-math - 18 November 2010. When people don't like what science tells them, they resort to conspiracy theories, mud-slinging and plausible pseudoscience – as Einstein discovered "THIS world is a strange madhouse," remarked Albert Einstein in 1920 in a letter to his close friend, the mathematician Marcel Grossmann.

Einstein's sceptics: Who were the relativity deniers? - physics-math - 18 November 2010

"Every coachman and every waiter is debating whether relativity theory is correct. Belief in this matter depends on political affiliation. " Best ever image from a neodymium rare-earth magnet. Jamie Condliffe, reporter (Image: Linden Gledhill/Cognisys) Is it a robo-hedgehog?

Best ever image from a neodymium rare-earth magnet