Classical Definition and 1000 Threads

I know little about these issues, so my questions may be dumb. 1. Do exact solutions exist for non-Abelian gauge theory without matter fields? 2. Do exact solutions exist for Abelian/Non-Abelian theory with matter fields (scalar or spinor)? 2. Are solutions well-behaved? I'm asking because no...

Hi I would like to know how you get from the classical 4-vector polarization to the two component quantum polarization? thank you Mark

Hi, Movement of an electron in constant magnetic field, according to semiclassical QM, give rise to Landau levels - a quantization of energy. Everything would be fine but i find it difficult to reconcile these findings with classical point of view in which Lorentz force is acting on moving...

Homework Statement In each of the following, an order of magnitude estimate is required. Estimate i) the gravitational energy of a 100kg satellite in low Earth orbit, the velocity of the satellite, and the period of the orbit. ii) the kinetic energy of a car traveling at 70mph and the...

I am currently in University Physics 1(calc-based intro to classical mechanics), and I talked with my adviser about taking Mechanics I(junior/senior level mechanics) course next semester. My adviser said it would probably be hard for me, but said he would let me "try it out." The reason I want...

I'm a secondary school student as yet, wondering and want to know whether scientists still do researches on Classical Physics, or they have just known everything that they wanted to know about the Newtonian Physics In other words, are there still problems in Classical Physics the solutions of...

Homework Statement Having a unidemsional array of N oscillators with same frequency w and with an anharmonic factor ax^4 where 0 < a << 1 Calculate, up to the first order of a, the partition function. Homework Equations For one oscillator...

I have a question regarding quantization. In most cases one never starts with a quantum theory, but always writes down a classical expression, goes through quantization, implementation of constraints (Dirac, BRST, ...), construction of Hilbert space, inner product, measure of an path integral...

I'm trying Zee's quantum field theory text as self-study (I'm years out of college) and about 100 pages into it. I can usually get something on the second or third reading. Oddly, one thing that keeps resisting me is quite early. In I.2, he says to apply an appendix on the method of steepest...

Has anyone ever seen the treatment of a closed classical string loop. Like if you had a loop of string on the space shuttle and subject it to accoustic driving or initial impulses. I post this here in beyond the standard model because no one in the classical physics section seems to have heard...

Has anyone seen a treatment of how to use the wave equation to describe a closed loop of string. I am talking ordinary strings here not the fancy string theory kind.

From what I have understood, electrodynamics can be completely explained using classical mechanics, i.e. by plugging in the electromagnetic force and then predicting the dynamics using classicla mechanics. With classical mechanics being the more fundamental of these two classical theories, I...

Homework Statement Now, consider the relativistic velocity addition formula: speed= (v+u)/(1+vu/c2. If v = u = 0.01c = 1 % of c, what is the relativistic sum of the two speeds? Express your answer as a percentage of the speed of light to five significant figures. Homework Equations the...

Is it possible that concepts of relativity are just a mathematical tool, but reality is simply classical if you understand one more piece of the puzzle? I'll try to explain. For example if somehow everything is made up of light processes (going at the speed of light), but if you accelerate...

Let's say someone wanted to describe the motion of a 3D object in 3D space, for example maybe a ball in real space. Instead treating the ball as a 3D entity as a whole, how about just taking any point on the ball 1d point and just describe it's motion. In my example I'm assuming the point I...

(This was first posted to a newsgroup but there were no replies; so I am trying to post it here). I understand quantum teleportation works on qubits, but i can also work on regular bits. Suppose Alice has a message bit S. S is repeatable, because it is a regular bit. Now Alice wants to...

Statement: The ancient Greek philosopher Plato theorized that the http://en.wikipedia.org/wiki/Classical_element#Classical_elements_in_Greece". I'm not a philosophy or science student, so please keep your reply plain and straightforward. Thanks. I can understand the literal meaning of the...

I was wondering whether any members of this PF sub-forum would help me towards some physical interpretation of Maxwell’s time-dependent equations, which must ultimately underpin any classical description of EM wave propagation. I know that some might simply suggest reading a good textbook, but I...

I'm thinking about where the classical limit would begin in terms of a particle's rest mass. If we start at the smallest mass scales consisting of subatomic particles, we would have to use quantum mechanics (due to the significant wave nature of particles with small momenta). If we consider...

I'm leafing through "Engineering Mechanics - Statics" by Hibbeler, and it seems almost entirely a review of my Physics I class that was on Classical Mechanics. How is a class dedicated to Statics or Dynamics (both of which I will have to take) different from my classical mechanics class? It...

Is "classical" differential geometry still useful? As a physics major I have seen in general relativity the power of modern differential geometry such as coordinate-free treatment of manifolds and Riemannian geometry. However, I've also encountered math textbooks devoted to "classical"...

So, we start with special relativity in c = 1 units. The equations for energy and momentum can be written as: E = E_{0} \gamma \vec{P} = E_{0} \gamma \vec{v} where E_{0} is the rest energy, \gamma = \frac{1}{\sqrt{1-v^2}} and \vec{v} is the (dimensionless) velocity. We...

Just a few questions that are really confusing me... 1. Where is the cut off boundary between the existence of Quantum mechanics and Classical mechanics, is there a specific point where classical takes over from quantum and if so where is that point? 2. Is the micro quantum world...

Homework Statement http://img337.imageshack.us/img337/3014/classicalmechs.jpg I'm fine until showing that those 4 things are constants. Homework Equations dxj/dt=dh/dpj and dpj/dt=-dh/dxj The Attempt at a Solution I can't show they are constant, for example, can someone show...

Homework Statement Why does the classical theory of light waves not explain the existence of a threshold frequency? The Attempt at a Solution I'm not sure but I think that this is because each "photon" has a specific energy. If this energy is below the E = hf where f is the...

Can someone explain to me how two parallel electron beams can be attracted to each other according to special relativity. Classical physics says each beam will generate a magnetic field so the beams will be attracted to each other. Relativity says the magnetic field only exists for observers...

The purpose of this post is to present the established tenets of classical physics and to create a point where this thread can be split if there is still disagreement as to the validity of these tenets. If the participants in this thread agree to the split, all further discussion of the...

I have a question about the e-m explanation of radiation pressure. As I understand it, when an e-m wave with low frequency strikes a material with a much higher resonance frequency, the displacement of the electron relative to the atom will be in phase with the electric field (well opposite...

Homework Statement A particle of mass m is subject to a force F(v)=-bv^2 The initial position is zero, and initial speed is v_o Find x(t) The Attempt at a Solution for convenience's sake, define Q=-\frac{b}{m} therefore, {\ddot{x}}=Q{\dot{x}}^2 Let u=\dot{x} \dot{u}=Qu^2 then I just made...

Ouch, had just written a big post when my university internet connection timed out on posting, so I'll keep this one short but powerful: I came to the understanding E and B fields are modified when changing reference frames. But what about the following situation: Charge q (named 1) is...

Homework Statement A heavy weight is suspended by a cable and pulled to one side by a force F. How much force is required to hold the weight in equilibrium at a given distance x to one side. From classical mechanics, TcosX= W and TsinX=F. Find F/W as a power series of X(angle). Often in a...

Hello all quantum nerds! :D I have a question regarding the "classical" limit of quantum fields, and in particular gauge fields. When we for instance do a surface integration in QFT, we let phi -> 0 as V->oo why? this is said in textbooks to correspond to the "classical limit", and...

I don't profess of a knowledge of QED, and am in fact incredibly ignorant of its formulation and nuances, however I do understand that its never been refuted and is the crown jewel of physical models. So I will take it as fact for this post. What confuses me, is that in quantum mechanics...

If I send a pulse down a string with mass (m1), consider what happens at a point where the mass of the string becomes (m2): i) If m1 > m2, the wave is reflected with the same phase as the incident wave. ii) If m1 < m2, the wave is reflected 180 degrees out of phase with the incident wave...

Hi I have a classical projectile problem: Car moving west at 50mph. If I am south ten miles and wish to his the object with a canon traveling at 500mph i) What bearing should I shoot at? ii) What pitch? Thanks Jo Homework Equations for projectile x=(Vo cos...

Can anyone tell me how a constructivist philosopher would view concepts in classical thermodynamics, say like the state variables pressure, temperature, internal energy, and entopy? I read in Wikipedia that "Constructivists maintain that scientific knowledge is constructed by scientists and...

Homework Statement Sally the physics student conducts the following experiment: There is a popular playground ride which is just a horizontal wooden disk free to rotate around a vertical axis. Sally hops onto the disk (spinning counter clock wise with angular velocity \omega ) with a bunch...

Homework Statement Sally the physics student conducts the following experiment: There is a popular playground ride which is just a horizontal wooden disk free to rotate around a vertical axis. Sally hops onto the disk (spinning counter clock wise with angular velocity \omega ) with a bunch of...

Hello. I come across a problem: how to calculate the partition function of a classical spring whose energy is 1/2kx^2, and use thermodynamics to show that the force on the spring is linearly proportional to its elongation x? I got stuck at the first step. What is the energy of the spring, is...

Hello, I wonder if you got any suggestions for classical mechanics video lectures? I don't mean freshman physics, but rather the course which includes the topics such as central body motion, lagrangian, hamiltonian, etc. (I guess it is considered as an upper level course on most schools)

Hi, I was looking for a book that would explain classical field theory in a Hamiltonian setting. What I mean by this is that there be no *actions* around, no *Lagrangians* and *Legendre transforms* to define the Hamiltonian and so on. What I'm looking fo is an exposition of (classical) field...

Dear forum, I recently took an analytic mechanics course at UCLA in which the average grade on the first midterm was something like a 27 out of 80. The teacher was a brilliant man but unfortunately could not convey the material to the students. I don't think anyone felt as though they had...

Anyone know a good place to read about the Lagrangian or Hamiltonian approach to the equations of motion of classical point particles in Minkowski spacetime? It doesn't have to go very deep into it, but it should at least include a discussion of symmetries and conserved quantities.

Homework Statement A system with only one degree of freedom is described by the following Hamiltonian: H = \frac{p^2}{2A} + Bqpe^{-\alpha t} + \frac{AB}{2}q^2 e^{-\alpha t}(\alpha + Be^{-\alpha t}) + \frac{kq^2}{2} with A, B, alpha and k constants. a) Find a Lagrangian...

I know that the classical picture of QED is Coulomb interaction, magnetic interaction etc. But what does the classical phi^4 theory look like? In particular, do particles attract or repel each other in this theory? P.S. I'm surprised that my field theory books never discuss this. (At least in...

I just started CM (I had 2 classes until now) and the professor said that if you know the position and velocity of say all the particles, then you know how the system will evolve. This, I already read and knew. I've probably a common question so feel free to redirect me to any similar...

Hello people, its been a while since i used physics forums. My assignment is basically a comparison between classical physics and the Quantum physics and to explain why we don't use classical physics. While surfing on the web, i came across a text implying that the definitions of light, energy...

Calculate the speed and radial acceleration for an electron in the hydrogen atom. Do the same for the Li++ ion. v = e (4pie0mr)^(-1/2) ar = (v^2)/r r ~ 10^-10 m v = 2.24 x 10^6 The book makes note that we can allow a nonrelativistic treatment since the velocity ~ .007c. And for the lithium...

Many "theoretical mechanicians" seem to awesome that motion is a {C^\infty } function(at least that is how I learned it). However, it seems like the postulates of Newtonian/Lagrangian/Hamiltonian/Vakonomic mechanics seem to "work" in the general case where only the motion is a {C^2}(ie the...

This may be a very basic question, but I've had now some background on the quantum theory, and I think I am missing something. Roughly speaking, I feel like the main difference is that quantizing involves going from field amplitudes to counting operators, implying that a quantum process involves...