Five states of matter

[polabomb]

Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume. However, different fields use the term in different and sometimes incompatible ways; there is no single agreed scientific meaning of the word "matter".
For much of the history of the natural sciences people have contemplated the exact nature of matter. The idea that matter was built of discrete building blocks, the so-called particulate theory of matter, was first put forward by the Greek philosophers Leucippus (~490 BC) and Democritus (~470–380 BC). Over time an increasingly fine structure for matter was discovered: objects are made from molecules, molecules consist of atoms, which in turn consist of interacting subatomic particles like protons and electrons.
Matter is commonly said to exist in four states (or phases): solid, liquid, gas and plasma. However, advances in experimental techniques have realized another phase, known as Bose–Einstein condensates.

Solid
A crystalline solid: atomic resolution image of strontium titanate. Brighter atoms are Sr and darker ones are Ti.
The particles (ions, atoms or molecules) are packed closely together. The forces between particles are strong enough so that the particles cannot move freely but can only vibrate. As a result, a solid has a stable, definite shape, and a definite volume. Solids can only change their shape by force, as when broken or cut.
In crystalline solids, the particles (atoms, molecules, or ions) are packed in a regularly ordered, repeating pattern. There are many different crystal structures, and the same substance can have more than one structure (or solid phase). For example, iron has a body-centred cubic structure at temperatures below 912 °C, and a face-centred cubic structure between 912 and 1394 °C. Ice has fifteen known crystal structures, or fifteen solid phases which exist at various temperatures and pressures.
Glasses and other non-crystalline, amorphous solids without long-range order are not thermal equilibrium ground states; therefore they are described below as nonclassical states of matter.
Solids can be transformed into liquids by melting, and liquids can be transformed into solids by freezing. Solids can also change directly into gases through the process of sublimation.

Liquid
A liquid is a nearly incompressible fluid which is able to conform to the shape of its container but retains a (nearly) constant volume independent of pressure. The volume is definite if the temperature and pressure are constant. When a solid is heated above its melting point, it becomes liquid, given that the pressure is higher than the triple point of the substance. Intermolecular (or interatomic or interionic) forces are still important, but the molecules have enough energy to move relative to each other and the structure is mobile. This means that the shape of a liquid is not definite but is determined by its container. The volume is usually greater than that of the corresponding solid, the most well known exception being water, H2O. The highest temperature at which a given liquid can exist is its critical temperature.

Gas
A gas is a compressible fluid. Not only will a gas conform to the shape of its container but it will also expand to fill the container.
In a gas, the molecules have enough kinetic energy so that the effect of intermolecular forces is small (or zero for an ideal gas), and the typical distance between neighboring molecules is much greater than the molecular size. A gas has no definite shape or volume, but occupies the entire container in which it is confined. A liquid may be converted to a gas by heating at constant pressure to the boiling point, or else by reducing the pressure at constant temperature.
At temperatures below its critical temperature, a gas is also called a vapour, and can be liquefied by compression alone without cooling. A vapour can exist in equilibrium with a liquid (or solid), in which case the gas pressure equals the vapour pressure of the liquid (or solid).
A supercritical fluid (SCF) is a gas whose temperature and pressure are above the critical temperature and critical pressure respectively. In this state, the distinction between liquid and gas disappears. A supercritical fluid has the physical properties of a gas, but its high density confers solvent properties in some cases which lead to useful applications. For example, supercritical carbon dioxide is used to extract caffeine in the manufacture of decaffeinated coffee

Plasma (ionized gas)
Plasmas or ionized gases can exist at temperatures starting at several thousand degrees Celsius, where they consist of free charged particles, usually in equal numbers, such as ions and electrons. Plasma, like gas, is a state of matter that does not have definite shape or volume. Unlike gases, plasmas may self-generate magnetic fields and electric currents, and respond strongly and collectively to electromagnetic forces. The particles that make up plasmas have electric charges, so plasma can conduct electricity. Two examples of plasma are the charged air produced by lightning, and a star such as our own sun.
As a gas is heated, electrons begin to leave the atoms, resulting in the presence of free electrons, which are not bound to nuclei, and ions, which are chemical species that contain unequal number of electrons and protons, and therefore possess an electrical charge. The free electric charges make the plasma electrically conductive so that it responds strongly to electromagnetic fields. At very high temperatures, such as those present in stars, it is assumed that essentially all electrons are "free," and that a very high-energy plasma is essentially bare nuclei swimming in a sea of electrons. Plasma is the most common state of non-dark matter in the universe.
A plasma can be considered as a gas of highly ionized particles, but the powerful interionic forces lead to distinctly different properties, so that it is usually considered as a different phase or state of matter.

Bose-Einstein condensate
A team of researchers led by Benoít Deveaud-Piédran from École Polytechnique Fédérale de Lausanne have announced that they have observed the strange fifth state of matter, known as the Bose-Einstein condensate, at a temperature of 19 Kelvin. While 19 Kelvin is still almost unimaginably cold, it is an extremely high temperature compared to the temperatures of less than a millionth degree Kelvin that have previously been needed to observe a Bose-Einstein condensate.
When the Indian physicist Satyendra Nath Bose wrote his article "Planck's Law and the Hypothesis of Light Quanta" in 1924, he was unable to get it published and ridiculed for what was simply considered an embarrassing statistical error. In desperation over the physics journals' continued rejections of his article, Bose sent it directly to the physicist he admired the most: none other than Albert Einstein. The German scientist immediately realized the importance of Bose's findings, translated the paper to German and got it published in "Zeitschrift fur Physik." He even added the note: "An important forward step."
Einstein's contribution did not stop there. He also realized that the strange behaviour Bose described for photons - the particles of light - would also apply to atoms. This lead to the prediction of a strange fifth state of matter, the Bose-Einstein condensate, a state of matter where the individual atoms would all be at the same energy level, and thus appear undistinguishable from each other. It's as if the lump of matter is made out of one huge super-particle.
It took 70 years from Einstein's prediction until this strange fifth state of matter could be observed. But in 1995 two American researchers at the Joint Institute for Laboratory Astrophysics, Eric Allin Cornell and Carl E. Wieman, managed to cool down a vapour of Rubidium atoms to a temperature of Less than one millionth of a degree above Absolute Zero, and the predicted state of matter indeed appeared. They were later awarded a shared Nobel Prize together with Wolfgang Ketterle for this accomplishment.
In new edition of Nature, researchers at Ecole Polytechnique Fédérale de Lausanne, collaborating with colleagues at Université de Grenoble, Cambridge, Oxford and MIT, claim they have been able to observe the condensate by cooling a special kind of quasi-particles, known as polaritons, down to the relatively easily attainable temperature of 19 Kelvin.
Polaritons are formed from photons and only live for a trillionth of a second. But the team of researchers managed to reach a critical density of the particles at 19 K where the particles formed a Bose-Einstein condensate in solid state.
The shared quantum state of the particles in a Bose-Einstein condensate resembles the coherent state of photons in a laser. And predicting the practical applications of Bose-Einstein condensates are as impossible as it would have been to predict the widespread uses of lasers when the first working laser was constructed in 1960.
For now the most important aspect of the discovery, is the unique opportunity for scientists to better understand and possibly exploit the quantum effects that occur in these very special conditions.

[polabomb]

The fermionic condensate
Scientists have created a new form of matter, which they say could lead to new ways of transmitting electricity.
The fermionic condensate is a cloud of cold potassium atoms forced into a state where they behave strangely.
The new matter is the sixth known form of matter after solids, liquids, gases, plasma and a Bose-Einstein condensate, created only in 1995.
"What we've done is create this new exotic form of matter," says Deborah Jin of the University of Colorado.

Strange brew

To make the condensate the researchers cooled potassium gas to a billionth of a degree above absolute zero - the temperature at which matter stops moving.
They confined the gas in a vacuum chamber and used magnetic fields and laser light to manipulate the potassium atoms into pairing up and forming the fermionic condensate.
Jin pointed out that her team worked with a super cooled gas, which provides little opportunity for everyday application. But the way the potassium atoms acted suggested there should be a way to turn it into a room-temperature solid.
It could be a step closer to an everyday, usable superconductor - a material that conducts electricity without losing any of its energy.
"If you had a superconductor you could transmit electricity with no losses," Jin said.
"Right now something like 10% of all electricity we produce in the United States is lost. It heats up wires. It doesn't do anybody any good."
Superconductor technology is being fed into the development of magnetically levitated trains. Free of friction these vehicles glide along at high speeds using a fraction of the energy of conventional trains.

Quark–gluon plasma
A quark–gluon plasma (QGP) or quark soup is a phase of quantum chromo dynamics (QCD) which exists at extremely high temperature and/or density. This phase consists of (almost) free quarks and gluons, which are several of the basic building blocks of matter. Experiments at CERN's Super Proton Synchrotron (SPS) first tried to create the QGP in the 1980s and 1990s: the results led CERN to announce indirect evidence for a "new state of matter" in 2000. Current experiments at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) are continuing this effort.
Although the results have yet to be independently verified as of February 2010, scientists at Brookhaven RHIC have tentatively claimed to have created a quark-gluon plasma with an approximate temperature of 4 trillion degrees Celsius.
Three new experiments running on CERN's Large Hadron Collider (LHC), ALICE, ATLAS and CMS, will continue studying properties of QGP. Starting in November 2010, CERN temporarily ceased colliding protons, and began colliding lead Ions for the ALICE experiment. They were looking to create a QGP. They were expected to stop December 6, and return to colliding protons in January. Within the first week of colliding these lead ions, the LHC appears to have created multiple quark-gluon plasmas with temperatures in the tens of trillions of degrees.
Quark–gluon plasma is a state of matter in which the elementary particles that make up the hadrons of baryonic matter are freed of their strong attraction for one another under extremely high energy densities. These particles are the quarks and gluons that compose baryonic matter. In normal matter quarks are confined; in the QGP quarks are deconfined. In classical QCD quarks are the Fermionic components of mesons and baryons while the gluons are considered the Bosonic components of such particles. The gluons are the force carriers, or bosons, of the QCD color force, while the quarks by themselves are their Fermionic matter counterparts.
Although the experimental high temperatures and densities predicted as producing a quark-gluon plasma have been realized in the laboratory, the resulting matter does not behave as a quasi-ideal state of free quarks and gluons, but, rather, as an almost perfect dense fluid. Actually, the fact that the quark-gluon plasma will not yet be "free" at temperatures realized at present accelerators was predicted in 1984 as a consequence of the remnant effects of confinement.