Everything About Science In Nepal

Clebsch–Gordan coefficients

2011-07-23T19:10:00.002+05:30

Clebsch-Gordan coefficients are mathematical symbol used to integrate products of three spherical harmonics. Clebsch-Gordan coefficients commonly arise in applications involving the addition of angular momentum in quantum mechanics. If products of more than three spherical harmonics are desired, then a generalization known as Wigner 6j-symbols or Wigner 9j-symbols is used. The

What is negetive temperture?

2011-06-30T08:59:00.003+05:30

Not all systems have the property that the entropy increases monotonically with energy. In some cases, as energy is added to the system, the number of available microstates, or configurations, actually decreases for some range of energies. For example, imagine an ideal "spin-system", a set of N atoms with spin 1/2 on a one-dimensional wire. The atoms are not free to move from their positions on

A Play to Illustrate Bose-Einstein Condensates

2011-06-29T14:47:00.003+05:30

The scene takes place on a sidewalk on 5th Avenue in New York City. A man named Dr. Bose is sitting behind a card table. On the table are some cups, balls, tape, paper and a black felt-tipped pen. [A tourist comes up to Dr. Bose's table.] Dr. Bose: "My name is Satyendra Nath Bose. Would you like to play Monte?" Tourist: "How do you play Monte?" Dr. Bose: "Well, normally a ball is placed

Bose-Einstein Condensates

2011-06-29T14:47:00.000+05:30

Named for the theorists Satyendra Nath Bose and Albert Einstein who predicted its existence, a Bose-Einstein condensate is an unusual state of matter that arises because of quantum mechanical effects on a collection of entities called bosons. Everything is either a boson or a fermion. The spin of an object determines whether it is a boson or a fermion. The reason why is

Quantum simulator prototype replicates structure of graphene

2011-06-11T17:29:00.000+05:30

A team of researchers from Columbia Engineering, the Italian National Research Council, Princeton University, University of Missouri, and University of Nijmegen (Netherlands) has developed an artificial semiconductor structure that has superimposed a pattern created by advanced fabrication methods that are precise at the nanometer scale. The pattern is similar to the honeycomb lattice that

Physics of impossibility

2011-05-14T16:03:00.000+05:30

Hay guys eager to read this book? First read this review and download it Michio Kaku doesn't know the meaning of the word "impossible". Or rather, to be slightly more accurate, he has redefined the term to enable him realistically to examine and predict the future of science and technologies, from teleportation and time travel to robots and starships. If this sounds like wild speculation, well,

Dirac And Newton and Asperger

2011-05-14T15:43:00.000+05:30

Asperger people are quite common in the general population, but it is not fully appreciated how many well-known people in the arts and sciences had the Asperger syndrome. When I came across several possibilities—namely Isaac Newton, Henry Cavendish and Albert Einstein—in the course of writing about the lives of famous physicists, I consulted Simon Baron-Cohen, the psychiatrist who heads the

Cauchy-Schwarz Inequality

2011-05-04T14:04:00.002+05:30

The Cauchy-Schwarz Inequality (or ``Schwarz Inequality'') states that for all and , we have with equality if and only if for some scalar . We can quickly show this for real vectors , , as follows: If either or is zero, the inequality holds (as equality). Assuming both are nonzero, let's scale them to unit-length by defining the normalized vectors , , which are unit-length

Cosmic Hide and Seek: the Search for the Missing Mass

2011-05-04T13:56:00.002+05:30

cientists using different methods to determine the mass of galaxies have found a discrepancy that suggests ninety percent of the universe is matter in a form that cannot be seen. Some scientists think dark matter is in the form of massive objects, such as black holes, that hang out around galaxies unseen. Other scientists believe dark matter to be subatomic particles that rarely interact

Faster than Light - is it possible?

2011-04-04T17:01:00.000+05:30

Ever since Einstein developed his Special Theory of Relativity, the speed of light has been seen as the ultimate limit of how fast we can hope to travel. This theory has been with us for over a century now, and it seems to hold wherever it is tested. So I'm not trying to overthrow special relativity, but I feel that it might not be the whole story. Below I list a number of things which suggest

Grand design book review

2011-03-29T11:59:00.000+05:30

Nobody has ever accused Stephen Hawking of thinking small. His life has been devoted to asking foundational questions about the nature of spacetime and the origin of the universe. In his famous "A Brief History of Time" (1988), he attempted to bring the mysteries of black holes and the early universe to a wide audience. Now Mr. Hawking and Leonard Mlodinow have written "The Grand Design,"

Book Review : Physics of the Impossible by Michio Kaku

2011-03-29T11:57:00.000+05:30

This is a great book for all science fiction writers. In case you're not familiar with him, Kaku is a theoretical physicist* who here takes a serious look at some of the tropes and devices commonly used in SF (time travel, phasers, teleportation etc.) But this isn't one of those works that sneers at the crazy ideas of those writer types. On the contrary, Kaku is clearly a fan and

universe in a nutshell book review

2011-03-29T11:56:00.000+05:30

Dubbed by the publishers Bantam Press as the "inspiring sequel" to his best-selling A Brief History of Time, Hawking's new book guides the reader on a "search to uncover the secrets of the universe - from supergravity to supersymmetry, from quantum theory to M-theory and from holography to duality". Reviewing the book for Physics World, astrophysicist Joseph Silk of Oxford University calls The

Does Bell's Inequality rule out local theories of quantum mechanics?

2011-03-29T11:48:00.002+05:30

In 1935 Albert Einstein and two colleagues, Boris Podolsky and Nathan Rosen (EPR) developed a thought experiment to demonstrate what they felt was a lack of completeness in quantum mechanics. This so-called "EPR Paradox" has led to much subsequent, and still ongoing, research. This article is an introduction to EPR, Bell's Inequality, and the real experiments that have attempted to address the

hi frns

2011-01-16T15:39:00.002+05:30

this blog will be updated soon..............................

Entropy and statistics

2011-01-14T11:23:00.002+05:30

Entropy ~ a measure of the disorder of a system. A state of high order = low probability A state of low order = high probability In an irreversible process, the universe moves from a state of low probability to a state of higher probability. We will illustrate the concepts by considering the free expansion of a gas from volume Vi to volume Vf. The gas always expands to fill the available space.

Postulates of Quantum Mechanics

2011-01-06T18:47:00.000+05:30

1. Associated with any particle moving in a conservative field of force is a wave function which determines everything that can be known about the system. 2. With every physical observable q there is associated an operator Q, which when operating upon the wavefunction associated with a definite value of that observable will yield that value times the wavefunction. 3. Any operator Q associated

Projection operators

2011-01-06T18:43:00.002+05:30

Armed with the bra-ket formalism we can construct any operator in Hilbert space. The projection operator Pa is defined as Pa = | a><a|, Note that and in general any projection operator P has the property P2=P. Consider operator X whose eigenstates are given by the set . If we define the projection operators Pan = | an><an|, show that operator X can be expressed as a sum of projection

Ampère's Circuital Law

2010-12-15T18:37:00.000+05:30

Next: Magnetic Field of a Up: Magnetism Previous: The Hall Effect Consider a long thin wire carrying a steady current . Suppose that the wire is orientated such that the current flows along the -axis. Consider some closed loop in the - plane which circles the wire in an anti-clockwise direction, looking down the -axis. Suppose that is a short straight-line element of this

M-theory, the theory formerly known as Strings

2010-12-03T17:39:00.000+05:30

The Standard ModelIn the standard model of particle physics, particles are considered to be points moving through space, tracing out a line called the World Line. To take into account the different interactions observed in Nature one has to provide particles with more degrees of freedom than only their position and velocity, such as mass, electric charge, color (which is the "charge" associated

Darwin May Have Been Wrong, New Study Argues

2010-08-28T16:53:00.000+05:30

A new study published in Biology Letters calls into question elements of Charles Darwin's theory of evolution. While Darwin argued that competition was the key force driving evolution, a research team from the University of Bristol argues that "living space" is in fact the primary driver. Michael Benton, a co-author of the study, said his team concluded that "competition did not play a big role

Solar Powered Toothbrush Cleans Using Electrons

2010-07-11T13:47:00.002+05:30

ext time you’re running low on toothpaste, switch to solar power. TheSoladey-3 ionic toothbrush from Japan apparently busts plaque with electrons that work with saliva to remove it from your teeth. A solar panel attached to the handle absorbs electrons from light and transmits them to your teeth through ionized water and a titanium oxide semiconductor in the upper shaft of the

Physicists explain why superconductors fail to produce super currents

2010-06-28T15:00:00.000+05:30

When high-temperature superconductors were first announced in the late 1980s, it was thought that they would lead to ultra-efficient magnetic trains and other paradigm-shifting technologies. That didn't happen. Now, a University of Florida scientist is among a team of physicists to help explain why.In a paper set to appear Sunday in the online edition of Nature Physics, Peter Hirschfeld, a UF

The 'God particle' may exist in five forms, Large Hadron Collider's rival project finds

2010-06-16T16:12:00.000+05:30

The elusive "God particle" - or Higgs boson - being sought in the Large Hadron Collider may exist in multiple forms, according to a new study. Finding the Higgs boson is the primary aim of the Large Hadron Collider (LHC) experiment in Geneva, but new results from a rival study taking place in the US suggest there may be five versions of the elusive subatomic particle, which has

Shear Force and Bending Moment Diagrams

2010-06-16T16:09:00.002+05:30

ntroduction Normally a beam is analysed to obtain the maximum stress and this is compared to the material strength to determine the design safety margin. It is also normally required to calculate the deflection on the beam under the maximum expected load. The determination of the maximum stress results from producing the shear and bending moment diagrams. To facilitate this work the