Classical Definition and 1000 Threads

(I am not sure what is the best subforum for this doubt, please move the thread if necessary) When we study the interaction of the electromagnetic waves with a charged particle (let's say an electron) we can find two totally different approaches in the literature. If we are talking about light...

Books of quantum mechanics are very ambigous in this aspect. A classical apparatus that collapse wavefunction of a quantum system must "quasieliminate" the non-diagonal elements of density matrix, or have a quasiclassical wavefunction of the form ae^{iS\hbar^{-1}} where a is a real slowly...

Homework Statement My question is part C of problem 1.9: http://facultyfiles.deanza.edu/gems/lunaeduardo/4DHW.PDF Homework Equations Pythagorean Theorem? The Attempt at a Solution I have c vector of lightwave going upwards and v going rightwards forming a right angle with the other...

My requirements are : - Text should be at an undergrad level (I will be starting my 2nd year soon). - Should contain a large number of solved examples, but not many questions (I would like the questions to be of good quality though, so that I don't have to choose which questions to...

In quantum Heisenberg model \hat{H}=-J\sum_{\vec{n},\vec{m}}\hat{\vec{S}}_{\vec{n}}\cdot \hat{\vec{S}}_{\vec{m}} ##J## can be obtained from dispersion experiment. For large spin ##S## even classical Heisenberg model is good for description of Curie temperature for example. Is that with the same...

There is an article I am reading, http://authors.library.caltech.edu/38643/1/PhysRevLett.110.174301.pdf I don't quite understand a lot of where this guy is coming from. I do not have much background in Lagrangian and Hamiltonian formulations, but it is vital that I can formulate some sort...

I was just wondering, what book would you suggest for me as a undergrad student going into 1st year at university. I will be completing an honours in math and physics, and I just want some material to self-learn over the summer and to keep myself occupied. My prior physics knowledge includes...

Are there any unanswered questions in classical mechanics? By unanswered I mean unanswered and attempted. I could easily think of a question which has never been asked. Edit: Sorry about the misspelled thread title.

Homework Statement A student kicks a frictionless puck with initial speed ## v_0 ## so that it slides straight up a plane that is inclined at an angle ## \theta ## above the horizontal. Write down Newton's second law for the puck and solve it to give it's position as a function of time How...

I am looking for the derivation to an approximation formula for the differential cross section for hard sphere scattering in the limit of high energy. The paper that mentioned this had referred to Methods of Theoretical Physics, PM Morse and H. Feshbach page 1484 but I have no access to the...

I was reading the Roger Penrose book Emperor's New Mind and he was explaining the determinism in Newtonian mechanics. He says that if we consider two solid balls colliding (assuming elastic collision) then outcome depends continuously on initial state of the balls. But if we consider triple...

Ive been learning a lot about how similar waves and particles are at the fundamental level, but today i was assaigned to discuss the difference between the CLASSICAL physics of particles vs Classical Physics of waves. Differences and similarities and well as how momentum is/isnt diferent as...

what are the differences? Every example I find usually has a derivative or integral or some kind of calculus defined concept that seems to make it easier or more understandable

So I was reading the Landau Lifgarbagez book on non-relativistic quantum mechanics and ran into this quasi-classical approximation they use at various points in the book.They have argued with an analogy that in the classical limit, the phase of the wave function will be proportional to the...

Why can't quantum behavior be explained as an extreme version of classical behavior? For instance, the idea of a small quantum particle being in superposition could be explained by that particle switching between 2 or more states at an extremely high frequency. How high a frequency? Well, on...

I'm reading Classical Mechanics (Taylor), and the 6th chapter is a basic introduction to calculus of variations. I'm super confused :confused: I've tried to go to other sources for an explanation, but they just make it even worse! So, let me see if I can get some help here...

Homework Statement I must calculate the probability that the position of a harmonic oscillator in the fundamental state has a greater value that the amplitude of a classical harmonic oscillator of the same energy.Homework Equations ##\psi _0 (x)=\left ( \frac{m \omega}{\pi h } \right ) ^{1/4}...

This came up in a thread discussing if quantum effects occur at the macro level. I always thought it was pretty much standard wisdom that Bose-Einstein condensates show quantum effects at the macro level. I mean for such states atoms loose their individuality and behave like one large quantum...

Homework Statement Attached is the picture of a dumbbell. I do not understand how the coordinate of M1 is M2 R/ (M1 + M2) It is not an assignment question but an example from a book.

Hi, I am trying to understand quantum description of electron in B field. What I am looking for is how to relate quantum and classical view? If in classical treatment electron comes in homogeneous B field, it will go in circular motion around magnetic field lines, with radius R. From...

I forget where I read it but one author said that mountains of ink have been spilled debating why quantum effects disappear at the quantum level. I don't understand why this is a problem, I think the answer is rather obvious. One poster on another thread wrote: "Technically - classical physics...

I've seen different objects described as the field in GR: the metric, the connection (and then the metric is seen as the "potential" by analogy with EM field theory), both... Could someone comment on what object should most reasonably be considered the field of the GR theory? Could for...

Just like the Euler-Lagrange differential equation $$ \frac{\partial{\mathcal{L}}}{\partial{q}} = \frac{d}{dt}\frac{\partial{\mathcal{L}}}{\partial{\dot{q}}} $$ the hamiltonian equations $$ \frac{\partial{H}} {\partial{q}} = -\dot{p} $$ $$ \frac{\partial{H}} {\partial{p}} = \dot{q} $$ and the...

Homework Statement Consider first a free particle (Potential energy zero everywhere). When the particle at a given time is prepared in a state ## \psi (x) ## it has <x> = 0 and <p> = 0. The particle is now prepared in ## \Psi (x, t=0) = \psi (x) e^{ikx} ## 1. Give <p> at time t=0. 2...

Hello folks. I am taking some courses next semester over at Wayne, one of which is a 500 level, graduate level difficulty mechanics course. It's the course typically taken at the 300 level. I was wondering if anybody knew of a great book for this course at this level. I have both Taylor and...

In Taylor's advanced text on classical mechanics, he gives an example of a non-holonomic system, I find this part very strange. He gives the example of a hard rubber ball being rolled in a triangle on a flat surface, the point is that if you take the ball out through the triangle and back to...

Guys can u suggest me some excellent books for Classical Mechanics? Thank u in advance :smile:

Two object are thrown at the same time from a surface which has an angle of θ. The first pbject is thrown parallel with the surface, with the speed v1. The second object is thrown horizontally with the speed of v2. The objects hit each other at a certain point. What is the distance between the...

Hello. In Molecular Dynamics simulations, the Newton's equation of motion is used to calculate the time evolution of system. Once, I read in an introductory text that when the thermal de Broglie wavelength $$\Lambda=\frac{h}{\sqrt{2\pi mkT}}$$ is much smaller than the interparticle distance...

http://i793.photobucket.com/albums/yy215/dweeegs/probability_zps12a67dfb.png The picture shows everything needed. This is a worksheet on the similarity of classical probability to the probability of finding a particle in a box (Schrodinger stuff etc) Basically there's a ball falling...

what is physical meaning of Lorentz gauge condition in classical electrodynamics??

Hi Question 1 i was wondering if there is any method to find the point from which the angular momentum is a conserved quantity. let me e.g. choose the case of a planet moving in an orbit around the sun. In this case, the angular momentum measured from the center of mass as the point of reference...

Energy "formulation" of classical mechanics? When discussing the different formulations of classical mechanics, those that are always mentioned are Newtonian, Lagrangian and Hamiltonian mechanics. However, it is my understanding that when dealing with conservative forces in Newtonian...

Presumably it's easy to re-formulate non-quantum (i.e., classical) physics entirely in operator -> observable form (perhaps even to the point of using bra/key and amplitude^2 notation, etc -- although since macroscopic objects are supposed to be in a single location, everything would end up...

Dear all, I'm starting to study neutron star accretion and a lot of physical phoenomena coming from different scales come along and a consistent picture is frankly hard to grasp. But for now, a real mind boggling question can't exit my mind. Are Neutron stars, as a whole Quantum, or...

Hello, so i just received a copy of introduction to classical mechanics by kleppner and kolenkow in the mail today. I was so excited unwrapping it but when i saw it i was very disspointed. it turns out the person sent me the "special indian edition". i was pretty upset and I'm thinking of...

Homework Statement This is question 3.7 from Gregory's Classical Mechanics textbook. A symmetric sphere of radius a and mass M has its center a distance b from an infinite plane containing a uniform distribution of mass ## \sigma ## per unit area. Find the gravitational force exerted on the...

Ok, so I know that law of conservation of linear momentum holds in a system in a particular direction, provided no net external force is acting in that direction. So, if we drop a ball on the Earth surface from a height much less than Earth's radius and then to analyze its momentum, we take...

Energy function ##E=-S_1S_2##. I took ##J=1##. If spin are oriented parallel energy is negative. How could energy be negative?

Can anybody please tell me how to represent a neutral antimatter body such as a planet or a star in the classical formulation of special and general relativities? Thanks.

I've seen in some probability theory books that the classical definition of probability is a probability measure, it seems fairly trivial but what is the proof for this? Wikipedia gives a very brief one using cardinality of sets. Is there any other way?

In the paper http://link.aps.org/doi/10.1103/PhysRevA.85.062329, the authors separate the position and momentum operators into classical motion and quantum fluctuations: \hat{X}_i \equiv \bar{X}_i + \hat{q}_i; \quad \hat{P}_i \equiv \bar{P}_i + \hat{\pi}_i Can someone point me to a reference...

Hello, I am looking for more information on the axiomatic treatment of physics. I have found some articles concerning the axioms of quantum mechanics, i.e. the Dirac-Von Neumann axioms. However, I am having a hard time finding anything on the classical version of these axioms. In these...

Homework Statement "The shortest path between two point on a curved surface, such as the surface of a sphere is called a geodesic. To find a geodesic, one has to first set up an integral that gives the length of a path on the surface in question. This will always be similar to the integral...

Author: Jorge José and Eugene Saletan Title: Classical Dynamics: A Contemporary Approach Amazon Link: https://www.amazon.com/dp/0521636361/?tag=pfamazon01-20

A 1kg wooden block is being pressed against a wooden wall by 12N. If the block is initially at rest will it move upward, downward or remain at rest? Picture of problem is in link below along with my working out. co-effecient of static friction of wood on wood is 0.50. I have also made...

Although I retired from active physics research almost 2 decades ago, there's a question that has annoyed/intrigued me for almost 40 years... In Classical Field Theory, matter has 2 intrinsic properties, namely mass and charge. Given Newton's 2nd Postulate, {\bf F}_{net} = m {\bf a}, I've...

I understand many classical physics concepts but I feel like my understanding of the concepts are all scattered. I can't seem to make links between concepts. For example: I understand momentum, forces and energy, but I have trouble making any links between the ideas (other than the link that...

This paper proposes an intuitive interpretation of basic aspects of Maldacena's conjecture in QFT and of the mathematical beauty of extra-dimensional theories. Its ansatz is that every particle is a reference clock. It is a peer-reviewed paper and uses an extremely original and simple formalism...

This was a lecture example and it has confused me. Can someone please help explain it? If we have the following fist order system: τ.dx/dy+y(t)=x(t) where τ=c/k where "k" is the spring stiffness and "c" the linear damper coefficient and τ is a time constant. For the unforced case x(t)=0, we...