Classical Definition and 1000 Threads

A system can only be called semiclassical if there are parts of the system that are described classically and parts decsribed quantum-mechanically. In this paradigm, physical quantites are described in a power series of ##\hbar##, with the zero order corresponding to classical physics and higher...

How can I start Classical Mechanics, I mean by the help of which book...

Hello, I was researching the Planck Constant values and decided to build a math software to scan for potential values that relate to permittivity of free space and permeability of free space and found one of the 2010 CODATA values (specifically the Magnetic Resonance Imaging value). Can I get...

I was thinking that what is solid reason behind the failure of Classical Mechanics in Black body radiation? Why classical mechanics not explain the curve at lower or higher range of frequncies.

Hi all, I am reading an introduction on classical and quantum-mechanical statistics. The material considers a 4-particle system with discrete energy level 0E, 1E, 2E, 3E, 4E, 5E and 6E. It is said that the classical particle is indistinguishable but you can identify the different particle by...

Homework Statement A man of mass 100 kg can pull on a rope with a maximum force equal to two fifths of his own weight. [Take g = 10 ms^2] In a competition, he must pull a block of mass 1600 kg across a smooth horizontal floor, the block being initially at rest. He is able to apply his maximum...

There is also a classical model of a photon available, which to me explains a particular behavior of it. Can this model be proved to wrong ?

As a red dwarf star is donating material to a white dwarf until there is a nova. What happens to the red dwarf during the nova? Is there an increase in nucleosynthesis within the red dwarf due to its close proximity? If so, how would that change the periodicity and type of later novas? If you...

I'm a freshman in Computer Engineering at a university. I have a Classical Mechanics course that will cover these topics: Newton's law of motion Vector Algebra Equilibrium of bodies Plane Trusses First moment of area, centroid, etc. Calculation of virtual displacement and virtual work...

By classical E&M I mean the general basics. I understand that even classical EM has clear relativistic undertones, but is anything taught classically actually wrong under the context of relativistic EM? For example, does Faraday's law continue to hold etc. I know this is kind of a broad...

I think the relativity provides the Doppler shift (in a radar - double version) in a form: ##\frac{1-v}{1+v}## which is quite simple, as a square of a single Doppler: ##f' = f\sqrt{\frac{1-v}{1+v}}## But I never seen what is a classical version of this - what is a formula for a radar shift in...

In the market, it has many many physics books teaching classical mechanics. Do you read one book only or a number of books? How do you make a choice?

Hey guys, i just came across this on my classical physics course. So, I'm given that: E(z, t) = {E_{0}}sin(wt)sin(kz)\widehat{x}, and I'm supposed to find an expression for the associated magnetic field B. Usually, i just find the propagation direction, and do it's cross product with the...

I am a second year physics and I want to study CM in more depth than that of the general textbooks

Homework Statement I am stuck over a classical mechanics problem. I tried to solve it, but after having solved the first point, I got stuck on the second one. Here is the problem: >A mechanical structure is composed by 4 rigid thin bars of length $\ell = 8\ m$, mass $m = 5\ kg$ each one. Those...

Theory wise.

"A unifying principle explaining the numerical bounds of quantum correlations remains elusive, despite the efforts devoted to identifying it. Here, we show that these bounds are indeed not exclusive to quantum theory: for any abstract correlation scenario with compatible measurements, models...

Could you name your best picks of books that expand on the high school knowledge. Example is the Goldsteins Classical Mechanics which is a classic. What do you recommend for Electricity and Magnetism, Optics, Relativity and Quantum Mechanics? Also what would be the same criteria for some Math...

Is this statement true? >>... over the past several decades we’ve come to understand that the classical and quantum worlds don’t exactly operate by “different” rules. Rather, the classical world emerges from the quantum in a comprehensible way: you might say that classical physics is simply...

I am not sure what does Jackson want to talk in section 9-6? Is that just a review of something discussed previously? Chapter 9 is talking about radiation, and later about multipole expansion.

<<Moderator note: Split from thread Photon the smallest particle>> @Orodruin - Let me ask a question. This is an aspect of QFT that has always puzzled me. Suppose we have an RF cavity or a laser cavity with a standing E-M wave. I understand that we can view the field in the cavity as a...

In classical field theory, the field, φ, is usually constructed from a very large number of coupled harmonic oscillators. Let's say our φ consists of just electrons. What does φ best represent physically, a very large number of electrons or can it represent just a few electrons? Which is the...

Homework Statement Q1. What's the reason behind two identical objects interchanging their velocities upon head-on collision? Why can't just each individual particles just reverse its direction and keep traveling at its original speed? Kinetic energies and momentum would still be conserved. Q2...

I'm trying to understand how we set up the lagrangian for a charged particle in an electromagnetic field. I know that the lagrangian is given by $$L = \frac{m}{2}\mathbf{\dot{r}}\cdot \mathbf{\dot{r}} -q\phi +q\mathbf{\dot{r}}\cdot \mathbf{A} $$ I can use this to derive the Lorentz force law...

We know that unsolved problems still exist in classical physics and scientists still make reasearches , can the scientists solve those problems without using other physics branches like quantum mechanics .. ? Can they solve these problems only with a full understanding of classical mechanics ?

My professor is mentoring me through learning GR over the next year with the goal of doing research with me in the long term in the field. I need to pick up a few things along the way. The summer is going to be spent mostly picking up the necessary material for jumping into Carroll's book, and...

Homework Statement A spacecraft is protected from the Sun’s radiation by a planar baffle whose size is much greater than that of the spacecraft itself. The baffle is aligned perpendicular to the direction of the Sun. Show that the equilibrium temperature of the baffle is...

Homework Statement In this problem, you will calculate the perihelion shift of Mercury simply by dimensional analysis. (a) The interactions in gravity have ##\mathcal{L}=M^{2}_{Pl}\Big(-\frac{1}{2}h_{\mu\nu}\Box...

Homework Statement A simple classical example that demonstrates spontaneous symmetry breaking is described by the Lagrangian for a scalar with a negative mass term: ##\mathcal{L}=-\frac{1}{2}\phi\Box\phi + \frac{1}{2}m^{2}\phi^{2}-\frac{\lambda}{4!}\phi^{4}##. (a) How many constants ##c##...

Hi guys i have a problem and I'm not able to solve it. I have a cube lying on the ground that is hinged on a side in contact with the floor. Right above the hinge there is a rod hinged (at the start time the rod is horizzontal) and it is long enough to touch the cube when it fall...how much the...

They are subjective even in the classical, nonrelativistic mechanics of a pendulum, since the notions appear when you try to relate the theory to a real pendulum. In classical, nonrelativistic mechanics, the interpretation of the words ''observation'', ''experiment'' and ''measurement'' needed...

Homework Statement A class of interesting theories are invariant under the scaling of all lengths by ##x^{\mu} \rightarrow (x')^{\mu}=\lambda x^{\mu}## and ##\phi(x) \rightarrow \phi'(x) = \lambda^{-D}\phi(\lambda^{-1}x)##. Here ##D## is called the scaling dimension of the field. Consider...

If one can't ever know all the three components of (QM) angular momentum, then can it even be considered as a "vector"? Is it only cause it transforms as a vector in a coordinate transformation?

Hi I am a high school student and I am about to graduate. within few months I am planning to study physics field if I pass the University selection. I love physics after I found the beauty of Quantum Mechanics, General Relativity, Thermodynamics, etc. Although I want to dive in those field, I...

What are Hamiltonian/Lagrangian Mechanics and how are they different from Newtonian? What are the benefits to studying them and at what year do they generally teach you this at a university? What are the maths required for learning them?

Homework Statement Given the Maxwell Lagrangian ##\mathcal{L} = -\frac{1}{2} (\partial_{\mu}A_{\nu})(\partial^{\mu}A^{\nu}) + \frac{1}{2} (\partial_{\mu}A^{\mu})^{2}##, show that (a) ##\frac{\partial \mathcal{L}}{\partial (\partial_{\mu}A_{\nu})} = -...

Homework Statement Calculate the Lagrangian of this set up: Imagine having two ropes: They are both attached to the ceiling and have different lengths. One has length b and the other has length 4b. Say they are hooked to the ceiling a distance 4b apart. Now, the ropes are both hooked to a...

I am currently taking graduate course in GR following Carroll and Wald and we just started covering causal structure. In all my years studying physics this has been the first time something made me stop and go "I would love to spend a decade on this". To me it's a perfect blend of well posed...

Homework Statement Classical Mechanics: John Taylor[/B] (1.27) The hallmark of an inertial reference frame is that any object which is subject to a zero net force will travel in a straight line at a constant speed. To illustrate this, consider the following experiment: I am standing on the...

Hi, If I consider for instance N non interacting particles in a box, I can compute the energy spectrum quantum mechanically, and thus the number of (quantum) microstates corresponding to a total energy between $E_0$ and $E_0 + \delta E$. In the limit of large quantum numbers, the result is well...

The classical Klein-Gordon equation is ##(\partial^{2}+m^{2})\varphi(t,\vec{x})=0##. To solve this equation, we need to Fourier transform ##\varphi(t,\vec{x})## with respect to its space coordinates to obtain ##\varphi(t,\vec{x}) = \int...

Hi, I'm new to the forum, I'd like some recommendations of books on classical mechanics. Too vague, right? I'm a CS student, with a great disposition for mathematics and great love for physics. I've learned one-variable calculus through Stewart and I'm starting linear algebra with Strang and...

Hi! My question has to be with the equal a priori probabilities assumption in the microcanonical ensemble when we consider an interacting system, that is, particles interacting between them but no external work or heat is done over the system. Does this assumption still hold for such a system...

I have heard that identical distinguishable classical particles having different ''statistics''.It is the limit of quantum case.Then we mix many parts(cells) of identical gases, the total entropy increases.I can not derive this limit from quantum particles to classical particles(please help...

How to decide whether a particular topic is studied in classical physics or modern physics?

Is it me, or the overall problem in CED is not addressed anywhere? Statement of the problem: Let there be two massive electrically charged particles of invariant masses m1 and m2 and electric charges q1 and q2, respectively. They are free to move arbitrarily in Minkowski spacetime endowed with...

Homework Statement I was recently assigned an assignment where my instructor told us to come up with an idea for a numeric classical mechanics problem that is solved by computer methods. Some ideas the instructor gave was to simulate motion of a sun-earth-moon system or simulate the tides of a...

I believe this question will be a no-brainer for many members. I want to conceptually grasp how do atoms (and molecules) behave using QM in contrast to the classical physics model. Now there's uncertainty principle and atoms don't have a fixed position and momentum, and that's fine, I know it's...

I'm having a hard time following the arguments of how the Higgs gives mass in the Standard Model. In particular, the textbook by Srednicki gives the Higgs potential as: $$V(\phi)=\frac{\lambda}{4}(\phi^\dagger \phi-\frac{1}{2}\nu^2)^2 $$ and states that because of this, $$\langle 0 | \phi(x)...

Okay so I have a question about time dilation, kinetic energy and classical mechanics. My question is, if an object were traveling at very high relativistic speeds and experienced time dilation, would the time it experience and measure during the travels be equivalent to the travel time if it...