All About Neutrinos:

All About Neutrinos:

What is this thing, anyways?

Neutrinos are subatomic particles produced by the decay of radioactive elements and are elementary particles that lack an electric charge, or, as F. Reines would say, "...the most tiny quantity of reality ever imagined by a human being".

"The name neutrino was coined by Enrico Fermi as a word play on neutrone, the Italian name of the neutron."

Of all high-energy particles, only weakly interacting neutrinos can directly convey astronomical information from the edge of the universe - and from deep inside the most cataclysmic high-energy processes and as far as we know, there are three different types of neutrinos, each type relating to a charged particle....Like "Electron Neutrino is with Electron(e), Mu Neutrino with Muon(µ) and Tau Neutrino with 'tau' (τ)..

Copiously produced in high-energy collisions, travelling essentially at the speed of light, and unaffected by magnetic fields, neutrinos meet the basic requirements for astronomy. Their unique advantage arises from a fundamental property: they are affected only by the weakest of nature's forces (but for gravity) and are therefore essentially unabsorbed as they travel cosmological distances between their origin and us.

Where are they coming from?

From what we know today, a majority of the neutrinos floating around were born around 15 billions years ago, soon after the birth of the universe. Since this time, the universe has continuously expanded and cooled, and neutrinos have just kept on going. Theoretically, there are now so many neutrinos that they constitute a cosmic background radiation whose temperature is 1.9 degree Kelvin (-271.2 degree Celsius). Other neutrinos are constantly being produced from nuclear power stations, particle accelerators, nuclear bombs, general atmospheric phenomenae, and during the births, collisions, and deaths of stars, particularly the explosions of supernovae.

The neutrino was first postulated in December, 1930 by Wolfgang Pauli to explain the energy spectrum of beta decays, the decay of a neutron into a proton and an electron. Pauli theorized that an undetected particle was carrying away the observed difference between the energy and angular momentum of the initial and final particles. Because of their "ghostly" properties, the first experimental detection of neutrinos had to wait until about 25 years after they were first discussed. In 1956 Clyde Cowan, Frederick Reines, F. B. Harrison, H. W. Kruse, and A. D. McGuire published the article "Detection of the Free Neutrino: a Confirmation" in Science, a result that was rewarded with the 1995 Nobel Prize.

In 1962 Leon M. Lederman, Melvin Schwartz and Jack Steinberger showed that more than one type of neutrino exists by first detecting interactions of the muon neutrino. When a third type of lepton, the tau, was discovered in 1975 at the Stanford Linear Accelerator, it too was expected to have an associated neutrino. First evidence for this third neutrino type came from the observation of missing energy and momentum in tau decays analogous to the beta decay that had led to the discovery of the neutrino in the first place. The first detection of actual tau neutrino interactions was announced in summer of 2000 by the DONUT collaboration at Fermilab, making it the latest particle of the Standard Model to have been directly observed.

A practical method for investigating neutrino masses (that is, flavour oscillation) was first suggested by Bruno Pontecorvo in 1957 using an analogy with the neutral kaon system; over the subsequent 10 years he developed the mathematical formalism and the modern formulation of vacuum oscillations. In 1985 Stanislav Mikheyev and Alexei Smirnov (expanding on 1978 work by Lincoln Wolfenstein) noted that flavour oscillations can be modified when neutrinos propagate through matter. This so-called MSW effect is important to understand neutrinos emitted by the Sun, which pass through its dense atmosphere on their way to detectors on Earth.

it is the feeble interaction of neutrinos with matter that makes them uniquely valuable as astronomical messengers. Unlike photons or charged particles, neutrinos can emerge from deep inside their sources and travel across the universe without interference. They are not deflected by interstellar magnetic fields and are not absorbed by intervening matter. However, this same trait makes cosmic neutrinos extremely difficult to detect; immense instruments are required to find them in sufficient numbers to trace their origin.

Neutrinos can interact via the neutral current (involving the exchange of a Z boson) or charged current (involving the exchange of a W boson) weak interactions.

In a neutral current interaction, the neutrino leaves the detector after having transferred some of its energy and momentum to a target particle. All three neutrino flavors can participate regardless of the neutrino energy. However, no neutrino flavor information is left behind.

In a charged current interaction, the neutrino transforms into its partner lepton (electron, muon, or tau). However, if the neutrino does not have sufficient energy to create its heavier partner's mass, the charged current interaction is unavailable to it. Solar and reactor neutrinos have enough energy to create electrons. Most accelerator-based neutrino beams can also create muons, and a few can create taus. A detector which can distinguish among these leptons can reveal the flavor of the incident neutrino in a charged current interaction. Because the interaction involves the exchange of a charged boson, the target particle also changes character (e.g., neutron to proton).....

Thermomagnetism: Using Heat to Make Magnets-

Thermomagnetism: Using Heat to Make Magnets-

EPFL scientists have provided the first evidence ever that it is possible to generate a magnetic field by using heat instead of electricity. The phenomenon is referred to as the Magnetic Seebeck effect or ‘thermomagnetism’.

A temperature difference across an electric conductor can generate an electric field. This phenomenon, called the Seebeck effect, lies at the root of thermoelectricity (heat turned into electricity), and is used to drive space probes and power thermoelectric generators, and could be implemented for heat-harvesting in power plants, wrist-watches and microelectronics. In theory, it is also possible to generate a magnetic field by using a temperature difference across an electrical insulator (‘thermomagnetism’). This has been referred to as the Magnetic Seebeck effect, and has enormous applications for future electronics such as solid-state devices and magnetic-tunnel transistors. In a breakthrough Physical Review Letters publication that has been promoted to “Editors’ Suggestion”, EPFL scientists have for the first time predicted and experimentally verified the existence of the Magnetic Seebeck effect.

Thermoelectricity and ‘thermomagnetism’

The Seebeck effect (thermoelectricity) — named after Thomas Johann Seebeck who first observed it in 1821 — is generated when electrons in an electric conductor move as a response to a temperature gradient. On average, the electrons on the hot side of the conductor have more kinetic energy and subsequently move at higher speeds than the electrons on the cold side. This causes them to diffuse from the hot to the cold side, generating an electric field that is directly proportional to the temperature gradient along the conductor.

Using an electrical insulator rather than a conductor, researchers led by Jean-Philippe Ansermet at EPFL have shown that a Magnetic Seebeck effect also exists. Because an insulator does not allow electrons to flow, a temperature gradient does not cause electrons to diffuse. Instead, it affects another property of electrons that forms the basis of magnetism and is referred to as ‘spin.’

In an insulator, a temperature gradient alters the orientation of electrons’ spin. Under certain conditions, this generates a magnetic field that is perpendicular to the direction of the temperature gradient. Similar to thermoelectricity described above, the intensity of the thermomagnetic field is directly proportional to the temperature gradient along the insulator.

First evidence for the Magnetic Seebeck effect

Using an insulating material called YIG (yttrium iron garnet), co-author Antonio Vetrò examined the propagation of magnetization waves along it. What he found was that the direction the magnetic waves propagated along the insulator affected the degree of magnetization loss – a phenomenon called magnetic damping. When the direction of the waves matched the orientation of the temperature gradient along the YIG, then the magnetization damping was reduced; when they propagated to the opposite direction, magnetic damping increased.

The Magentic Seebeck effect combines three distinct fields of physics: thermodynamics, continuum mechanics and electromagnetism. The difficulty lies in that, until now, no-one had ever found a way to consistently unify them. Pursuing this, first author Sylvain Bréchet built upon the work of Ernst Stückelberg (1905-1984), a renowned Swiss physicist who had previously developed a thermodynamical formalism for his teaching. Out of the hundreds of equations that Bréchet produced, one of them predicted that a temperature gradient should generate a magnetic field.

Although at an early stage, this discovery opens new approaches for addressing magnetization damping. This could have a tremendous impact on future devices based on spintronics (Nobel Prize 2007), an emergent technological field that offers an alternative to traditional electronics. In spintronic devices, signal transmission relies on the spin of electrons rather than their charge and movement. For example, the spintronics field is now considering harvesting heat waste coming from microprocessors like those used in personal computers.

Source-http://www.scientificcomputing.com/news/2013/10/thermomagnetism-using-heat-make-magnets#.UmKlqjuBmCY

Schwarzschild Black Hole :

Schwarzschild Black Hole :

Few months after Einstein published his work on General Relativity (in 1915), Karl Schwarzschild (1916) found one solution to Einstein's equations : the curvature due to a massive non-rotating spherical object.

Using Einstein's equation, Schwarzschild had determined how spacetime is curved due to the presence of a nonrotating spherical mass, assuming it is spherically symmetric.

A black holewith zero charge Q= 0 and no angular momentum J= 0. The solution for such a black hole is known as the Schwarzschild solution (or Schwarzschild metric), and is an exact unique solution to the Einstein field equations of general relativity for the general static isotropic metric.

The Lepton - By: Rabbit

The Lepton - By: Rabbit

“Why The Name Lepton”

Leptons: In 1897 the first lepton was discovered by J.J. Thomson and his team of British physicists. Physicists got the name “lepton” from the Greek language, meaning “slender”. It wasn’t until 1975 that Martin Lewis Perl and his colleagues at the SLAC LBL group discovered the tau through a series of experiments. Up until 1975, it was originally thought that leptons were the lightest subatomic particles, than came the tau in 1975. Although the name “lepton” is no longer appropriate, we still use it today. Now we use it to describe all spin-1/2 particles that are not affected by the strong force.

“The Muons & Carl David Anderson”

In 1936 an American Physicist named Carl David Anderson & Seth Neddermeyer discovered the muon (it’s former name, “mu-meson”), nearly 40 years after the discovery of the electron. In 1936 Carl David Anderson was awarded the Nobel Prize in Physics for his discovery of the positron in 1932, and also for the discovery of the muon, in 1936. He unexpectedly discovered the creation of a particle that had the same mass as the electron, but it had an opposite electrical charge, while experimenting with cosmic rays. This alone validated Paul Dirac’s theoretical prediction of the existence of the positron. Shortly after, Carl David Anderson would produce conclusive evidence by blasting gamma rays into other materials, resulting in the creation of the positron-electron pairs.

After they (Carl Anderson and Seth Neddermeyer) discovered the muon, they quickly noticed this subatomic particle was 207 times more massive than the electron, but it still had the same negative electric charge and the same spin ½ as the electron. Due to it’s shear mass (207 times that of the electron), it was categorized as a meson, rather than a lepton; but this was corrected when physicists noticed it shared more commonalities with electrons, rather than mesons. Since muons do not undergo the strong interaction, muons were reclassified into a new group of particles such as the electrons, muons, and the neutrino; in which they are now known as leptons. At first glance back in 1932, they thought they seen the pion, but they were mistaken. However, the muon was the first of a long list of other subatomic particles, so that alone was a great achievement.

“The Tau & Martin Lewis Perl”

The tau lepton is a superheavy cousin of the electron, and it’s also the carrier of electrical current in household appliances. Both particles are identical in all respects, except the fact that the tau is approximately 3,500 times heavier than the electron. However, the tau only survives for less than a trillionth of a second, while the electron remains stable. In the mid 1970’s Martin Lewis Perl and his team of colleagues at the SLCA-LBL group, conducted a series of experiments that detected the presents of the tau, and before that it was believed that only two quark-lepton families existed. Their equipment consisted of SLAC, a new type of colliding rings called SPEAR, and also the LBL magnetic detector.

With this equipment, they could also detect and distinguish between leptons, hadrons, and also photons. However, they did not detect the tau directly, but rather discovered anomalous events. After more than a year’s worth of careful analysis, Martin Lewis Perl was able to convince his research team that they were in fact observing a new and different type of elementary particle, in which he named it the “tau”. This was significant because the tau turned out to be a newly discovered member of a third quark-lepton family, the top quark. It wasn’t until 1995 that Fermi scientists discovered the top quark; the same year Martin Lewis Perl was awarded the Nobel Prize in Physics for his discovery of the tau lepton.

“How Important is The Tau”

The discovery of the tau was very important because it’s the only lepton that can decay into hadrons. Like the current decay models of the tau, the hadronic decay is through the weak interaction. Being the tauonic lepton number is conserved in weak decays, a tau neutrino is created when a tau decays to a muon or an electron.

The branching ratio of the common purely leptonic tau decays at:

-17.82% for decay into a tau neutrino, electron and electron antineutrino.

-17.39% for decay into a tau neutrino, muon and nuon antineutrino.

The similarity of values of the two branching ratios is a consequence of lepton universality. The tau lepton is also predicted to be able to form exotic atoms like other charged subatomic particles. One example is the tauonium, by the analogy to muonium, consists in antiauon and an electron. Another possibility is an onium atom called true tauonium; however, it’s very difficult to detect.

“Leptons & The 6 Different Flavors”

A lepton is a member of subatomic particles that only respond to electromagnetic force, weak force, and also the gravitational force. However, they are not affected by the strong force. The leptons appear to be point-like particles without an internal structure. Although leptons are considered to be elementary particles, they do not appear to be made up of smaller units of matter. Leptons can either have one unit of electric charge or be neutral.

Each charged lepton has an associated neutral partner, or neutrino that has no electric charge, along with no significant mass. There are six different flavors of leptons; the most familiar lepton is known as the electron. As for the five other leptons, they are known as the muon and the tau particle; and there are also three different types of neutrino associated with each of them, the electron neutrino, the muon neutrino, and of course the tau neutrino. In the six different flavors of leptons, three have an electrical charge (the electrons, muons, and taus); while the other three do not have an electrical charge. The muon and tau are charged like electrons, but they carry larger amounts of mass.

As for the other three types of neutrinos, they have no electrical charge and have very little mass; not to mention, they are very difficult to find. Electrons are the lightest leptons, and only carry a mass of 1/1,840, that of a proton. The muons are much heavier, and have more than 200 times as much mass as the electrons. As for the taus, they are approximately 3,700 times more massive than the electrons. Each charged lepton including the neutrinos have antiparticles, commonly known as, antileptons.

Although the mass of an antilepton, are in fact identical to that of leptons, all the other properties are reversed and each lepton has a corresponding antimatter antilepton. When talking about antimatter, please note that all elementary particles have corresponding antiparticles known as, antimatter. Where antimatter particles have opposite charges than their usual components. For example, positrons have a +1 charge and the electrons have a -1 electric charge. The protons have antiprotons, the neutrons have antineutrons, and the electrons have “anti-electrons”.

The “anti-electrons” are common enough to have their own special name, known as positrons. Mathematically speaking, the total lepton number L is constant. The number of leptons minus the number of antileptons always remains constant. Therefore a conservation law for leptons of each different type seems to hold; the number of electrons and electron-neutrinos, for example, is conserved separately from the number of muons and muon-neutrions. However, the current limit of violation concerning the conservation law is one part per million.

Leptons have other characteristic features in addition to their charge and mass properties, and it’s their intrinsic angular momentum, or spin. Leptons are actually classified within larger groups of subatomic particles; the fermions for example, are characterized by half-integer values of their spin. However, the total number of leptons; appear to be the same in every particle reaction.

“The Effects & Influence of The Lepton in Nuclear Physics”

What’s most intriguing about the leptons is they’re involved in several different processes, like beta decay in nuclear physics. In nuclear physics, beta decay is a type of radioactive decay, where the beta particle -- the electron or positron -- is emitted from an atomic nucleus. The process of beta decay allows an atom to obtain the optimal ratio of both protons and neutrons. There are actually two different types of beta decay, a decay that is mediated by what’s known as weak force: both beta minus and beta plus. When referring to beta minus, it’s a form of beta decay that produces an electron emission; while beta plus is the emission of the positron.

Sincerely,

Rabbit

Klein Tunneling: Coupled Particles Cross Energy Wall:

Klein Tunneling: Coupled Particles Cross Energy Wall:

Model demonstrates that it is possible for two particles to cross an energy barrier together, where a single particle could not......

For the first time, a new kind of so-called Klein tunnelling-representing the quantum equivalent of crossing an energy wall- has been presented in a model of two interacting particles. This work by Stefano Longhi and Giuseppe Della Valle from the Institute of Photonics and Nanotechnology in Milan, Italy, is about to be published in The European Physical Journal B.

Klein tunnelling is a quantum phenomenon referring to the fact that a high-potential barrier can be transparent to a particle moving at a speed nearing that of light, referred to as relativistic. Most of the previous Klein tunnelling models describe the phenomenon for a single particle. However, when two particles are involved, tunnelling can be modified as a result of their mutual interaction. This means, for example, that two electrons hopping on a lattice, or two ultra-cold atoms trapped in an optical lattice can exchange energy when they occupy the same lattice site.

The authors relied on an analytical and numerical study of a landmark model of interacting particles, called the Hubbard model. It is typically used to describe particle pairs in condensed matter such as in semi-conductors and in so-called matter wave physics, used for instance to describe microscopic particles oscillating between their material and wave-like characteristics. Longhi and Della Valle predict a new type of Klein tunnelling for a couple of interacting particles confronted by an energy barrier. Even though the barrier is impenetrable for single particles, it becomes transparent when the two particles cross the energy barrier together.

They expect these predictions to be confirmed experimentally in ultra-cold atoms trapped in optical lattices. If this is the case, similar quantum simulation could be a tool for emulating multiple-particle systems that cannot be modelled using classical computations.

Non-locality & Quantum Theory

Non-locality & Quantum Theory

---------------------------------------

Locality means that an object is influenced directly only by its immediate surroundings and not by remotely located objects.

The fact that quantum mechanics is at odds with this principle is not new. Back in the 1930s, Einstein, Podolsky, Rosen, and Schrödinger, first spotted this striking aspect of quantum theory as they pointed out the possibility of quantum entanglement.

This led them to think that something was not quite right with quantum mechanics and that the theory had to be completed in a way that would restore locality.

But this hope was to fall apartyears later, when Bell proved that quantum mechanics is an inherently nonlocal theory that is simply incompatible with any physical theory in which the principle of locality holds.

Bell argued that in any local theory there are limits to how distant events are correlated. Mathematically, the correlation statistics must obey certain inequalities, now called Bell inequalities. Bell showed that two observers measuring states that are entangled would observe strong correlations between the results of their measurements: such correlations can be so strong that they violate Bell’s inequalities.

This phenomenon, called quantum nonlocality, has been repeatedly observed experimentally. For instance, in quantum optics experiments, it is now standard to create pairs of photons entangled in polarization. Then, each photon of the pair is sent (e.g., via an optical fiber) to a distant observer holding a polarization analyzer. The observed correlations between the results of both polarization measurements can lead to Bell-inequality violations, providing evidence that the physical world can be nonlocal.

Entanglement and nonlocality were first considered as two facets of the same physical effect, but they are now recognized as two different concepts, as research carried out in our group has demonstrated.

However, the relation between them is yet to be fully understood.

"Einstein's Special Relativity" for dummies

"Einstein's Special Relativity"

By: Andrew Zimmerman Jones and Daniel Robbins from String Theory for Dummies

Theory For Dummies

In 1905, Albert Einstein published the theory of special relativity, which explains how to interpret motion between different inertial frames of reference — that is, places that are moving at constant speeds relative to each other.

Einstein explained that when two objects are moving at a constant speed as the relative motion between the two objects, instead of appealing to the ether as an absolute frame of reference that defined what was going on. If you and some astronaut, Amber, are moving in different spaceships and want to compare your observations, all that matters is how fast you and Amber are moving with respect to each other.

Special relativity includes only the special case (hence the name) where the motion is uniform. The motion it explains is only if you’re traveling in a straight line at a constant speed. As soon as you accelerate or curve — or do anything that changes the nature of the motion in any way — special relativity ceases to apply. That’s where Einstein’s general theory of relativity comes in, because it can explain the general case of any sort of motion.

Einstein’s theory was based on two key principles:

The principle of relativity: The laws of physics don’t change, even for objects moving in inertial (constant speed) frames of reference.

The principle of the speed of light: The speed of light is the same for all observers, regardless of their motion relative to the light source. (Physicists write this speed using the symbol c.)

The genius of Einstein’s discoveries is that he looked at the experiments and assumed the findings were true. This was the exact opposite of what other physicists seemed to be doing. Instead of assuming the theory was correct and that the experiments failed, he assumed that the experiments were correct and the theory had failed.

In the latter part of the 19th century, physicists were searching for the mysterious thing called ether — the medium they believed existed for light waves to wave through. The belief in ether had caused a mess of things, in Einstein’s view, by introducing a medium that caused certain laws of physics to work differently depending on how the observer moved relative to the ether. Einstein just removed the ether entirely and assumed that the laws of physics, including the speed of light, worked the same regardless of how you were moving — exactly as experiments and mathematics showed them to be!

Unifying space and time

Einstein’s theory of special relativity created a fundamental link between space and time. The universe can be viewed as having three space dimensions — up/down, left/right, forward/backward — and one time dimension. This 4-dimensional space is referred to as the space-time continuum.

If you move fast enough through space, the observations that you make about space and time differ somewhat from the observations of other people, who are moving at different speeds.

You can picture this for yourself by understanding the thought experiment depicted in this figure. Imagine that you’re on a spaceship and holding a laser so it shoots a beam of light directly up, striking a mirror you’ve placed on the ceiling. The light beam then comes back down and strikes a detector.

(Top) You see a beam of light go up, bounce off the mirror, and come straight down. (Bottom) Amber

(Top) You see a beam of light go up, bounce off the mirror, and come straight down. (Bottom) Amber sees the beam travel along a diagonal path.

However, the spaceship is traveling at a constant speed of half the speed of light (0.5c, as physicists would write it). According to Einstein, this makes no difference to you — you can’t even tell that you’re moving. However, if astronaut Amber were spying on you, as in the bottom of the figure, it would be a different story.

Amber would see your beam of light travel upward along a diagonal path, strike the mirror, and then travel downward along a diagonal path before striking the detector. In other words, you and Amber would see different paths for the light and, more importantly, those paths aren’t even the same length. This means that the time the beam takes to go from the laser to the mirror to the detector must also be different for you and Amber so that you both agree on the speed of light.

This phenomenon is known as time dilation, where the time on a ship moving very quickly appears to pass slower than on Earth.

As strange as it seems, this example (and many others) demonstrates that in Einstein’s theory of relativity, space and time are intimately linked together. If you apply Lorentz transformation equations, they work out so that the speed of light is perfectly consistent for both observers.

This strange behavior of space and time is only evident when you’re traveling close to the speed of light, so no one had ever observed it before. Experiments carried out since Einstein’s discovery have confirmed that it’s true — time and space are perceived differently, in precisely the way Einstein described, for objects moving near the speed of light.

Unifying mass and energy

The most famous work of Einstein’s life also dates from 1905 (a busy year for him), when he applied the ideas of his relativity paper to come up with the equation E=mc2 that represents the relationship between mass (m) and energy (E).

In a nutshell, Einstein found that as an object approached the speed of light, c, the mass of the object increased. The object goes faster, but it also gets heavier. If it were actually able to move at c, the object’s mass and energy would both be infinite. A heavier object is harder to speed up, so it’s impossible to ever actually get the particle up to a speed of c.

Until Einstein, the concepts of mass and energy were viewed as completely separate. He proved that the principles of conservation of mass and conservation of energy are part of the same larger, unified principle, conservation of mass-energy. Matter can be turned into energy and energy can be turned into matter because a fundamental connection exists between the two types of substance.

Read More At: http://www.dummies.com/how-to/content/einsteins-special-relativity.html