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One of the surprising things about Web sites is that, in certain cases, a very small machine can handle a huge number of visitors. For example, imagine that you have a simple Web site containing a number of static pages (in this case, "static" means that everybody sees the same version of any page when they view it). If you took a normal 500MHz Celeron machine running Windows NT or Linux, loaded the Apache Web server on it, and connected this machine to the Internet with a T3 line (45 million bits per second), you could handle hundreds of thousands of visitors per day. Many ISPs will rent you a dedicated-machine configuration like this for $1,000 or less per month.
How do large Web sites handle millions of visitors a day?"
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Kinetic isotope effect - Wikipedia, the free encyclopedia
The kinetic isotope effect ( KIE ) is the ratio of reaction rates of two different isotopically labeled molecules in a chemical reaction . It is also called "isotope fractionation," although this term is somewhat broader in meaning. A KIE involving hydrogen and deuterium is represented as: with k H and k D are reaction rate constants .quantum mechanics
Statistical mechanics or statistical thermodynamics [ note 1 ] is a branch of physics that applies probability theory , which contains mathematical tools for dealing with large populations, to the study of the thermodynamic behavior of systems composed of a large number of particles . Statistical mechanics provides a framework for relating the microscopic properties of individual atoms and molecules to the macroscopic bulk properties of materials that can be observed in everyday life, therefore explaining thermodynamics as a result of classical and quantum-mechanical description of statistics and mechanics at the microscopic level. Statistical mechanics provides a molecular-level interpretation of macroscopic thermodynamic quantities such as work , heat , free energy , and entropy . It enables the thermodynamic properties of bulk materials to be related to the spectroscopic data of individual molecules.
Statistical mechanics - Wikipedia, the free encyclopedia
Quantum mechanics - Wikipedia, the free encyclopedia
Quantum mechanics (QM - also known as quantum physics , or quantum theory ) is a branch of physics dealing with physical phenomena where the action is on the order of the Planck constant . Quantum mechanics departs from classical mechanics primarily at the atomic and subatomic scales, the so-called " quantum realm ". QM provides a mathematical description of much of the dual particle-like and wave-like ("wavicle") behavior and interactions of energy and matter . In advanced topics of quantum mechanics, some of these behaviors are macroscopic and only emerge at extreme (i.e. very low or very high) energies or temperatures . The name "quantum mechanics" derives from the observation that some physical quantities can change only in discrete amounts (Latin quanta ), and not in a "continuous" ( cf. analog ) way.In physics , more specifically relativistic quantum mechanics , the Dirac equation [ 1 ] is a wave equation , formulated by British physicist Paul Dirac in 1928. It provided a description of elementary spin-½ particles, such as electrons , consistent with both the principles of quantum mechanics and the theory of special relativity , and made relativistic corrections to quantum mechanics. It accounted for the fine structure of the hydrogen spectrum in a rigorous way. The equation also implied the existence of a new form of matter, antimatter , hitherto unsuspected and unobserved, later discovered experimentally.
Dirac equation - Wikipedia, the free encyclopedia
Attaining strong than quantum non-locality would require us to break the uncertainty principle -- but then there is no telling what may be unleashed! Credit: Illustration by Frans Bartels, concept by Haw Jing Yan. Researchers have uncovered a fundamental link between the two defining properties of quantum physics. Stephanie Wehner of Singapore's Centre for Quantum Technologies and the National University of Singapore and Jonathan Oppenheim of the United Kingdom's University of Cambridge published their work today in the latest edition of the journal Science . The result is being heralded as a dramatic breakthrough in our basic understanding of quantum mechanics and provides new clues to researchers seeking to understand the foundations of quantum theory . The result addresses the question of why quantum behaviour is as weird as it is—but no weirder.
Heisenberg Uncertainty Principle sets limits on Einstein's 'spooky action at a distance,' new research finds
Some Frequently Asked Questions About Virtual Particles
I hear physicists saying that the "quantum of the gravitational force" is something called a graviton. Doesn't general relativity say that gravity isn't a force at all? One of the first steps in the development of quantum mechanics was Max Planck's idea that a harmonic oscillator (classically, anything that wiggles like a mass bobbing on the end of an ideal spring) cannot have just any energy.
heisenberg uncertainty principle, propulsive and attractive interaction of charged particles by Nov 28