superfluids

A study of possible extended symmetries of field theoretic systems

Many physical systems, from superfluids to pi mesons, are understood to be manifestations of spontaneous symmetry breaking, whereby the symmetries of a system are not realized by its lowest energy state. A consequence of spontaneous symmetry breaking is the existence of excitations known as Goldstone bosons, which account for the broken symmetries. Here the authors investigate systems with larger than usual amounts of broken symmetry.

Pic: http://www.tcm.phy.cam.ac.uk/~bds10/dir/images/albrecht.png

There has been much recent interest, especially among cosmologists, in theories known as galileons. Galileons are an interesting and novel, though still hypothetical, class of effective scalar fields which are extremely universal and have attracted much recent attention. They arise generically in describing the short distance behavior of the new degrees of freedom introduced during the process of modifying gravity, and in describing the dynamics of extra dimensional brane worlds. Modified gravity and brane worlds are just some of the ideas that have been studied as possible solutions to the cosmological constant problem — the problem of explaining why our universe seems to be accelerating. The galileons possess several key properties: they possess non-trivial symmetries, and are well behaved quantum mechanically compared to other types of fields.

Here the authors investigate whether it is possible to extend the key symmetries of the galileons even further, by enlarging the set of transformations under which the theory remains invariant. It is found that while it is not possible to enlarge this symmetry while maintaining the symmetries of special relativity and not introducing new degrees of freedom, it is possible to create new kinds of Galileon-like theories it the system is non-relativistic.

Non-relativistic systems such as superfluids are well described by effective degrees of freedom known as Goldstone bosons. Goldstone bosons are manifestations of spontaneous symmetry breaking, where the symmetries of a system are not realized by its ground state. The new kinds of Galileon-like theories uncovered here could be useful as descriptions of systems near Multi-critical points, points in the phase diagram where multiple phases coincide.

Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Economic Development and Innovation. This work was made possible in part through the support of a grant from the John Templeton Foundation. The opinions expressed in this publication are those of the authors and do not necessarily reflect the views of the John Templeton Foundation (KH). This work was supported in part by the Kavli Institute for Cosmological Physics at the University of Chicago through grant NSF PHY-1125897, an endowment from the Kavli Foundation and its founder Fred Kavli, and by the Robert R. McCormick Postdoctoral Fellowship (AJ).

The paper can be found in the International Journal of Modern Physics D.

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Source: http://www.worldscientific.com/page/pressroom/2014-08-15-01

universal-abyss: Fascinating look into spontaneous symmetry breaking. So terribly interesting.

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An old Black and white film about superfluids and thier strange properties, such as it’s frictionless fountains, abilitie to flow upwards and pass through solid objects. A fascinating look at how the truth can definitly be stranger than fiction.

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Superfluidity

 

Superfluidity is a state of matter in which viscosity of a fluid vanishes, while thermal conductivity becomes infinite. These unusual effects are observed when liquids, typically of helium-4 or helium-3, overcome friction in surface interaction at a stage (known as the “lambda point”, which is temperature and pressure, for helium-4) at which the liquid's viscosity becomes zero.

Superfluids, such as supercooled helium-4, exhibit many unusual properties. (See Helium#Helium II state). Superfluid acts as if it were a mixture of a normal component, with all the properties associated with normal fluid, and a superfluid component. The superfluid component has zero viscosity, zero entropy, and infinite thermal conductivity. (It is thus impossible to set up a temperature gradient in a superfluid, much as it is impossible to set up a voltage difference in a superconductor.) Application of heat to a spot in superfluid helium results in a wave of heat conduction at the relatively high velocity of 20 m/s, called second sound.

One of the most spectacular results of these properties is known as the thermomechanical or “fountain effect”. If a capillary tube is placed into a bath of superfluid helium and then heated, even by shining a light on it, the superfluid helium will flow up through the tube and out the top as a result of the Clausius-Clapeyron relation. A second unusual effect is that superfluid helium can form a layer, 30 nm thick, up the sides of any container in which it is placed. See Rollin film.

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read of the day: Have We Been Interpreting Quantum Mechanics Wrong This Whole Time?
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For nearly a century, “reality” has been a murky concept. The laws of quantum physics seem to suggest that particles spend much of their time in a ghostly state, lacking even basic properties such as a definite location and instead existing everywhere and nowhere at once. Only when a particle is measured does it suddenly materialize, appearing to pick its position as if by a roll of the dice.This idea that nature is inherently probabilistic — that particles have no hard properties, only likelihoods, until they are observed — is directly implied by the standard equations of quantum mechanics. But now a set of surprising experiments with fluids has revived old skepticism about that worldview. The bizarre results are fueling interest in an almost forgotten version of quantum mechanics, one that never gave up the idea of a single, concrete reality. The experiments involve an oil droplet that bounces along the surface of a liquid. The droplet gently sloshes the liquid with every bounce. At the same time, ripples from past bounces affect its course. The droplet’s interaction with its own ripples, which form what’s known as a pilot wave, causes it to exhibit behaviors previously thought to be peculiar to elementary particles — including behaviors seen as evidence that these particles are spread through space like waves, without any specific location, until they are measured. Particles at the quantum scale seem to do things that human-scale objects do not do. They can tunnel through barriers, spontaneously arise or annihilate, and occupy discrete energy levels. This new body of research reveals that oil droplets, when guided by pilot waves, also exhibit these quantum-like features.

go read this..

(via Have We Been Interpreting Quantum Mechanics Wrong This Whole Time? | Science | WIRED)

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FRACTAL DIMENSION

Robert C. Richardson - Physicist
June 26, 1937 – February 19, 2013

NY Times
Robert Coleman Richardson was an American experimental physicist who shared (with David Lee & Douglas Osheroff) the 1996 Nobel Prize in Physics for coaxing a rare form of helium into a bizarre liquid state that had never been seen before.

In 1971, Dr. Richardson and two colleagues — David M. Lee, also a physics professor, and Douglas D. Osheroff, a graduate student — collaborated on a technically challenging experiment, exploring the properties of atoms a fraction of a degree above absolute zero.

They cooled helium-3, a lighter variant of helium, to within a few thousandths of a degree of absolute zero. Absolute zero is the lowest possible temperature, at which motion comes to almost a complete stop.

In that deep freeze, liquid helium-3 turns into what physicists call a superfluid — a liquid that flows without friction.

“I quickly tell people it has no practical applications,” Dr. Osheroff said in an interview on Wednesday. But the discovery has enabled scientists to study a variety of scientific problems, including basic quantum interactions at the atomic level. The Nobel Prize committee deemed the experiment a breakthrough in basic physics.  [READ MORE]

Photo:  NY Times

Richard P. Feynman in the style of the iconic ‘Hope’ poster by Shepard
Fairey that came to represent Obama’s 2008 US presidential campaign.

http://rdbl.co/1UkYzse

#richardfeynman #feynman #theoreticalphysics #physics #science #obama
#hope #shepardfairey #nobel #scientist #physicst #quantummechanics
#relativity #caltech #tuva #quantumelectrodynamics #qed #pathintegral
#particlephysics #superfluidity by feynmanrp http://bit.ly/1UkYxQZ

arxiv.org
[1507.00689] Self-consistent T-matrix approach to Bose-glass in one dimension

[ Authors ]
A.G. Yashenkin, O.I. Utesov, A.V. Sizanov, A.V. Syromyatnikov
[ Abstract ]
Based on self-consistent T-matrix approximation (SCTMA), the Mott insulator - Bose-glass phase transition of one-dimensional noninteracting bosons subject to binary disorder is considered. The results obtained differ essentially from the conventional case of box distribution of the disorder. The Mott insulator - Bose-glass transition is found to exist at arbitrary strength of the impurities. The single particle density of states is calculated within the frame of SCTMA, numerically, and (for infinite disorder strength) analytically. A good agreement is reported between all three methods. We speculate that certain types of the interaction may lead to the Bose-glass - superfluid transition absent in our theory.

New Post has been published on http://iloveuselessknowledge.com/2015/07/02/scientists-have-discovered-a-new-state-of-matter/

Scientists have discovered a new state of matter!

Scientists have discovered a new state of matter, called ‘Jahn-Teller Metals’.

An international group of researchers has announced the finding of a new state of matter in a material that seems to be an insulator, superconductor, metal and magnet all rolled into one, saying that it could lead to the improvement of more operative high-temperature superconductors.

When we start to talk about states of matter, it’s not just only solids, liquids, gases, and perhaps plasmas that we have to think about. We also have to study the more incomprehensible states that don’t take place in nature, but are rather produced in the lab, for example Bose–Einstein condensate, degenerate matter, supersolids and superfluids, and quark-gluon plasm.

SUPERFLUIDITY

Walk with effortless fluidity!

Recently, clinical psychologists have discovered an effortless state that creative people often fall into, popularly called “the flow”. During periods of “flow”, work projects seem to progress of their own accord, and even the deepest concentration requires no effort. As long as they are in the flow, creative people of all types feel a pleasurable sense of being…

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Willem H Keesom - Physicist
June 21, 1876 – March 24, 1956

Wikipedia
Willem Hendrik Keesom was a Dutch physicist who, in 1926, invented a method to freeze liquid helium. He also developed the first mathematical description of dipole-dipole interactions in 1921. Thus, dipole-dipole interactions are also known as Keesom interactions. He was previously a student of Heike Kamerlingh Onnes, who had discovered superconductivity (a feat for which Kamerlingh Onnes received the 1913 Nobel Prize in Physics).

He also discovered the lambda-point transition specific-heat maximum between Helium-I and Helium-2 in 1930 (Basic Superfluids p25/Tony Guenault). 

Photo:  Resources.huygens.knaw.nl