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Quantum Mechanics
Quantum Mechanics is the branch of physics that deals with the study of the structure and behavior of atoms and molecules. It is primarily based on Max Planck's Quantum theory, which incorporates Heisenberg's uncertainly principle and the de Broglie wavelength to establish the wave-particle duality on which Schrodinger's equation is based.
916 Questions
Does a laser make use of the wave nature of light or the particle nature of light or both?
Lasers don't really "make use" of either the wave or particle nature of light. Or they make use of both. But because a laser emits what is called coherent light, it could be argued that the wave nature of light is best at describing the light the laser emits.
Lasers make use of Boltzmann energy distribution statistics, which doesn't have anything to do with the particle or wave description of light. Lasers work by creating a population inversion in a chemical compound which creates stimulated emission when excited.
Light has both wave-like and particle-like properties at the same time. It is said to exhibit particle-wave duality. Light is what it is -- the fact that we describe it using both a particle and a wave description is only a reflection of our inability to fully describe light in using one single intuitive model (because we have no intuitive experience with things that have both wave and particle properties simultaneously).
What is de broglie wavelength of one photon?
No, they don't have de-broglie wavelength since this concept is valid for substances having some mass. This concept is mainly used to calculate the wavelength of electrons.
The photons are just energy packets and they are not matter and don't have weight.
Therefore, they don't have de-broglie wavelength
What is a Bose-Einstein condensate?
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From Wikipedia: "A Bose-Einstein condensate is a phase of matter formed by bosons cooled to temperatures very near to absolute zero. The first such condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of Colorado at Boulder NIST- JILA lab, using a gas of rubidium atoms cooled to 170 nanokelvin (nK). Under such conditions, a large fraction of the atoms collapse into the lowest quantum state, at which point quantum effects become apparent on a macroscopic scale."
See the related link "Wikipedia: Bose-Einstein condensate" for more info.
What are the best books for understanding quantum mechanics?
Answer (1)
The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory Written by Brian Greene
Quantum Mechanics, written by Albert Messiah
The Quantum Universe, by Tony Hey and Patrick Walters
http://books.google.com/books?id=mwssSDXzkNcC
Answer (2)
The Elegant Universe, though a good book, covers too many topics. If you are particularly interested in quantum mechanics then I would recommend, it may require previous knowledge about the topic as it covers much on String Theory, T.O.E., and Grand Unified Theories.
Answer (3)
The New Quantum Universs .By Tony Hey - Patrick Walters-Popular Physics book (No math)
In Search of Schrodinger's Cat
By John Gribbin
-Textbook (Junior Level Undergraduate text, minimum of Calculus II necessary)
Introduction to Quantum Mechanics
By David Griffiths
I would definitely recommend "In Search of Schrodinger's Cat" I have read it about 6 times and its a great book.
What is a quantam state with zero spin?
A quantum state with zero spin is a state where the angular momentum of the system is zero. This means that the system has no intrinsic angular momentum or spin. In other words, it has a spin quantum number of 0.
Is de broglie wave an electromagnetic wave?
No, the de Broglie wave is not an electromagnetic wave. It is a wave associated with particles, such as electrons and other subatomic particles, and is used to describe their wavelike behavior. electromagnetic waves, such as light, are different phenomena that involve oscillating electric and magnetic fields.
Does antimatter have the same laws of physics with itself as matter?
Yes.
If we could communicate with intelligent life in a distant galaxy composed completely of anti-matter, we would have no way of determining that fact. No matter what experiment we asked them to perform, their results would be identical to the results we see in our galaxy composed of matter.
What are important properties of quantum mechanics?
There are many important quantum mechanic properties of particles. Some of them include spin, isospin, momentum, mass, rest mass, electrical charge, colour charge, quark structure (only hadrons) wave function (wave - particle duality), strangeness, interactions (electromagnetism, strong nuclear force, weak nuclear interaction, gravity) etc. There are many more.
Who are founders of quantum theory?
The founders of quantum theory are Max Planck, Albert Einstein, Niels Bohr, Werner Heisenberg, Erwin Schrödinger, and Max Born. These physicists made significant contributions to the development of quantum theory in the early 20th century.
What is the fundamental assumption behind quantum mechanics Who first proposed it?
The fundamental assumption behind quantum mechanics is that particles and systems can exist in multiple states or positions simultaneously, until they are observed or measured. This is known as superposition. The theory was first proposed by Max Planck in 1900, and later developed by Albert Einstein, Niels Bohr, and others.
What is the field of physics overlapping time and space?
The field of physics that studies the interactions between time and space is called spacetime physics or, more specifically, relativistic physics. This field encompasses Albert Einstein's theories of special relativity and general relativity, which describe the behavior of objects in relation to time, space, and gravity. It explores phenomena such as time dilation, length contraction, and the curvature of spacetime.
Why normalization in quantum mechanics?
Take a wavefunction; call it psi.
Take another wavefunction; call it psi two.
These wavefunctions mus clearly both satisfy some sort of wave equation (say the Schrodinger Wave Equation 1926).
It turns out (if you do some maths) that if you addthese wavefunctions, psi+psiTwo is also a solution of the wave equation.
HOWEVER: SINCE THE SQUARE OF THE WAVE EQUATION IS THE PROBABILITY, THE TOTAL PROBABLILITY OF FINDING THIS PARTICLE ANYWHERE IN THE UNIVERSE IS NOW 1+1 = 2!!!!! How can the probability be two? It clearly can't. And so the new wave function has to be halved (normalisation) to give: 1/2 (psi+psiTwo) which satisfies this condition that the total probablility of finding the particle must be equal to one.
This condition is called the "Normalisation Condition" and is written mathematically thus:
Integral( psi^2 ) d(x^3) = 1.
Are quarks traveling at the speed of light?
Quarks have not been observed to exist separately - they are "confined" within larger particles such as protons and neutrons, that are made up of several quarks (3 each, in the case of protons and neutrons).
Has the Higgs boson been found yet?
We are not sure if the theorized Higgs boson is real or not. If it is, it would be provide some support to ideas about what mass (and, therefore, gravity, which is associated mass) really is. We're still looking for experimental support that the Higgs boson is real, and now that the Large Hadron Collider is up and running, all (interested) eyes are on CERN and awaiting results.
What are the Similarities between classical and quantum mechanics?
They both have protons and electrons.
And both the theories agree to the supposition that electrons revolve around the nucleus of the atom. They both state that higher energy electrons are located further from the nucleus.apex approved!!
Quantum theory is the mathematical representation of the universe assuming that everything is divided into well defined amounts (quanta, plural of quantum if we ignore the context) that behave both like particles and waves.
One of its basic concepts is that nothing is in one defined position but exists as a distribution of probabilities dispersed in space. The particle itself may react at any point, but it has different probabilities of "appearing" at different positions.
Another characteristic of Quantum Theory is that in it, whatever you cannot measure can be in an infinite different amount of states. The actual state you see when you you finally observe the system depends, not only on what you observe, but also on how you observe it.
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Quantum theory is the language of all particle theories. It is formulated in a well-defined mathematical language that makes predictions for the relative probabilities of the various possible outcomes, but not for which outcome will occur in any given case.
The word quantum means a definite but small amount.
The basic quantum constant h, known as Planck's constant,and its value is 6.626 x 10-34 Js
The quantum theory of physics was developed in order to explain the relationship between matter and energy at an atomic level as well as subatomic. The theory was created by the ideas of Max Planck, Albert Einstein, Niels Bohr, Werner, and many others. It includes basic ideas of quantum physics. One of the most prominent ideas is that matter acts as waves AND as a particle (wave-particle duality). Another crucial idea to the theory is the uncertainty principle. This principle states that certain pairs of values about matter cannot be simultaneously known. For example, if the position of a particle is measured, its momentum value will become less accurate.
At its simplest - it states that the universe is grainy, that energy (like matter) comes in discrete packets rather than being continuous (as it seems to be).
What conducts radio waves through space?
Radio waves are not conducted. They propagate. They do not need a medium through which to propagate. They just move.
What does an alpha decay look like?
It can be difficult to visualize something so small that it cannot be seen directly with any light-based instrument. But we can make a stab at it, so let's do that.
An atomic nucleus is tiny beyond anything we've ever seen. It's really, really small. But picture a fuzzy sphere hanging in space. (The electrons will not be part of the picture because they are far, far away on the scale in which an atomic nucleus would be visible.) There's a little vibrating fuzzy sphere, and something is happening to it. Is it changing shape in subtle ways?
A very short distance from the nucleus, we'll see a tiny fuzzy sphere appear almost out of nowhere. That's the alpha particle, and its much smaller than the nucleus. It is composed of a pair of protons and a pair of neutrons bound together. It's a helium-4 nucleus, but you may have figured that out. The reason it seems to "magically appear" near the nucleus is because the alpha particle is believed to escape the nucleus via the mechanism of quantum mechanical tunneling. In one moment, the nucleus is whole, though it is unstable, and the next instant it has lost some of its mass and the alpha particle appears. That little alpha particle has tunneled out of the nucleus and was not seen actually exiting the mass of that nucleus. We might add that the nucleus has just undergone a nuclear transformation, and we call it nuclear transmutation. Where one chemical element existed before, another one that is two atomic numbers down on the periodic table will be left.
That alpha particle, the one that slipped unseen from the nucleus, will appear, but it won't be still. It will materialize and be off in a flash. It comes away with a tremendous amount of kinetic energy. It's really moving! It will rocket out away from the nucleus and blow through the electron cloud like it wasn't even there. It's a helium-4 nucleus as we mentioned, and its a nucleus without electrons, but it is moving far too quickly to have a high probability of "capturing" any electrons from the atom from which it arose. It isn't taking any "baggage" with it. There will be some "shape changes" in the nucleus of the atom that the alpha particle left, but it ends up a bit smaller and as indistinct in our view as it was in the beginning.
Following the alpha particle farther out, we'll see that little guy slamming into air or whatever else is in its way. These "collisions" will be scattering events, and atoms will be ionized in the process. If any solid material is present, the alpha particle will pretty much be hammered into a stop. Alpha particles don't have a lot of penetrating power. A piece of paper will block them. The alpha particle will then snatch a couple of electrons from just about anywhere around it, and the "transformation" of that alpha particle into a helium-4 atom will be complete.
Is it true that electrons are arranged in different energy levels in an atom?
It simply means that electrons can only have certain energies. These "levels" are often in terms of n, such as n1, n2, n3, and so on. Let's say that n1=1000 eV (a unit for energy) and n2=2000 eV. It would be impossible for an electron in an atom to have any energy between those two values. This follows true for any energy level; this can be shown better like this: there can be no electron energy found between nx and nx+1 when the electron is in an atom.
If it is found it is expected to explain the various masses of the known particles, if it is not found it might be too massive for the LHC to make. If it is proven not to exist we may have to wait for the Supersymmetry theory to explain particle masses.
A Buddhist would be best to answer, but here goes...
A common theme in religion and science is the inability to project time back infinitely into the past.
Christianity holds that "In the beginning, God created the heavens and the earth...", before which nothing but God existed.
Modern physics can project back to a singularity (the "big bang"), prior to which we can't give any description, because we can't describe the conditions that led to the singularity.
I'm guessing that Buddhism also has hit this problem - what *can* one say about the time before time began? The answer seems to be that it's a fruitless question.
Time has always been, and didn't "begin" anywhen.
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I suspect there isn't one simple answer for all Buddhists however here's my thought. As time is relative (from a physics as well as spiritual perspective), beginningless time refers to the entire relative experience. The life of the current universe may be 50 billion years, then the process will begin again - there are countless rebirths of the universe. Time is relative to the physical condition, when the mind is no longer connected to the physical condition the orbit of the earth around the sun (relative time) is unlikely to have any absolute significance.
How did Erwin Schrodinger achieve quantum mechanics?
Erwin Schrodinger developed a wave equation, known as the Schrodinger equation, that describes how the quantum state of a physical system changes over time. This equation is a fundamental tool in quantum mechanics, providing a mathematical framework for predicting the behavior of particles at the quantum level. Schrodinger's work was crucial in the development of quantum mechanics as a coherent and successful theory.
What is the units of wave function?
m^(-1/2)
Because probability dP to find a particle in a small interval of width dx, is
dP=(|Psi|^2)dx
and probability is unitless. dx has unit of m (meter), therefore |Psi|^2 must have unit m^(-1).
And Psi (wave function) has unit of m^(-1/2).
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Above answer is mistake; hereprobabilityis " probability of position" and holds length dimension, therefore the wave function is unit less
What does the Heisenberg Uncertainty principle mean?
In any measurement, the product of the uncertainty in position of an object and the uncertainty in its momentum, can never be less than Planck's Constant (actually h divided by 4 pi, but this gives an order of magnitude of this law). It is important to note that this uncertainty is NOT because we lack good enough instrumentation or we are not clever enough to reduce the uncertainty, it is an inherent uncertainty in the ACTUAL position and momentum of the object.
