Classical Definition and 1000 Threads

1st page of Chapter 7, p.276, very last line, p=p'. I get that in Newtonian mechanics, the forces, times and masses are the same in two different inertial reference frames, but shouldn't the momenta measured be different?

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1/ Amongst what seems like the plethora of classical Unified Field Theories; that seemed to exist in the first half of the 20th century; see for example https://link.springer.com/article/10.12942/lrr-2014-5 [caution 50MB download] were they all abandoned just because of failure to account for...

The Schrödinger equation can be derived from the path integral quantization of the Lagrangian of classical, non-relativistic particles. Can the Klein-Gordon (and maybe the Dirac) equation be derived from the path integral quantization of a given classical (supposedly relativistic) Lagrangian of...

I'm a bit confused about the idea of "Change of Signature in Classical Relativity". As I see it, a metric is just a scalar function that I make up. For example, in the x,y plane I can define the functions x^2+y^2 and x^2-y^2 simultaneously. What, then, is the significance of "changing" the...

hi, I'm currently taking a classical field theory class (electromagnetism in the language of tensors and actions and etc) and we have just encountered the gauge symmetry, that is for the 4 vector potential we can add a gradient of some smooth function and get the same physics (if we take Aμ →...

I am trying to understand ergodic theory, i.e. how simple systems reach equilibrium. I consider a classical particle in a 2D (or 3D) box. Funnily, I have never seen this example in books (probably due to lack of knowledge). Instead, in QM, the particle in a box is a prototypical example. My...

Epoch of thick textbooks in classical mechanics was ended at the edge of 19-20 century. There appear a lot of new branches of physics and classical mech. is no longer considered by physicists as a cutting-edge branch but only as an educational subject. Nevertheless, I believe that we should not...

I have been revisiting my notes from my 2nd and 3rd year physics degree - especially the ones covering Fourier Optics, and other classical wave optics - and it is quite rewarding to revisit the historical / exploratory aspect of the series of discoveries, that built the foundations of this...

Greg Bernhardt submitted a new blog post A Classical View of the Qubit Continue reading the Original Blog Post.

The pressure of a scalar field is: Φ˙2−V(Φ) so to have zero or negligeable pressure it needs to have equipartition of its energy in potential and kinetic form ==> the potential must be positive. In particular a mass term m2Φ2 ... could be all right: the field should tend to roll down this...

I have been reading about the quantum effects that limit the Maxwell-Boltzmann Distribution under certain conditions which leads to the Bose-Einstein or Fermi-Dirac Distribution. I have difficulty grasping the reasons why these quantum-effects occur only at certain conditions and why exactly...

I don't know where to put this but it is a question which is bothering me. From the perspective of a physicist who wants to generate new theories, what's the value in spending significant time learning classical theories? People slave always at books like Jacksons Electrodynamics but it's not...

Are there any? This Wikipedia article https://en.m.wikipedia.org/wiki/List_of_unsolved_problems_in_physics Only lists one under classical mechanics: Singular trajectories in the Newtonian N-body problem: Does the set of initial conditions for which particles that undergo near-collisions gain...

Homework Statement Acceleration experienced by an astronaut in a rotating space station. Homework Equations What force would he experience is his own rotating frame of reference. The Attempt at a Solution Newton's second Law for a rotating frame is: mr'' = F net+ Fcor + Fcf Fnet (In the...

In Griffiths,Quantum Mechanics 2nd edition,Chapter 2,he gives a problem to calculate the revival time of a wave. Revival time is defined as the time taken by a wave to go from one side(x=0) to other side(x=a). Now let's calculate the revival time with 2 methods. Method 1: Now to go from 1...

I am studying Classical Mechanics in this semester, I want to know if there are any suggestions on some problem sets that will help me to master the skills needed.

Homework Statement CLASSICAL MECHANICS [/B]Homework Equations E=U+K[/B]The Attempt at a Solution Guys, can you please help me with part b) ? I am not sure how to find the velocity. Thanks

My question is can we have negative energy in classical mechanics? Also I would need help for finding the velocity in part b)

In quantum mechanics, there exist some systems where the potential energy of some particle is a Dirac delta function of position: ##V(x) = A\delta (x-x_0 )##, where ##A## is a constant with proper dimensions. Is there any classical mechanics application of this? It would seem that if I...

Hello i have the difficulty in solving this two problems..thank you for your help math help boards :-)

Does anybody know if there is work being done on quantum locality vs nonlocality. Specifically, approaching the Planck scales there is no nonlocality. That is all points in space and time are local. This would also provide an explanation for Einstein Minkowsky's space time. Any material /...

Does a single photon travel in two different waves at once? If photons are particles like the Photoelectric Effect, Compton Scattering, and Blackbody radiation all suggest, how do polarizing filters block light completely? Is a particle from a radio antenna actually that large in size?

Homework Statement I am having a issue relating part of this question to the Galilean transformation. Question Relative to the laboratory, a rod of rest length ##l_0## moves in its own line with velocity u. A particle moves in the same line with equal and opposite velocity . How long dose it...

Im planning on taking a course on classical differential geometry next term. This is the outline: The differential geometry of curves and surfaces in three-dimensional Euclidean space. Mean curvature and Gaussian curvature. Geodesics. Gauss's Theorema Egregium. The textbook is "differential...

There is no absolute electric potential. Is it due to classical ignorance (because we don't know the static fields, capacitive coupling, etc. of the surrounding environment) or is it due to quantum ignorance (the potential can fluctuate to any value due to HUP)? My question is valid because...

[Moderator's note: Post spun off from another thread.] That is correct but it doesn't mean Eo=0. The rest energy is unlimited in classical mechanics. Therefore it is impossible to find a relation between total energy and momentum.

Considering classically a light ray in a medium with lightspeed ##c_1## and entering a medium with lightspeed ##c_2## moving with speed ##v## along let say ##y## in the plane of the interface, is it correct to obtain a very complicated formula, having even 3rd power of trigonometric functions of...

Any good lecture notes for classical mechanic?

Hello! I am a high school student and I would need some guidance regarding a thermodynamics book. I am reading and solving through these three: 1.Resnick,Halliday and Walker 2.University Physics- Young and Freedman 3.An introduction to mechanics-Kleppner and Kolenkow(purely for mechanics) Based...

Rehashing this topic because I believe a clear misconception is stated in many threads. Classical mechanics is an incorrect ( by the definition of correct ) theory which is only an approximation that uses incorrect assumptions ie. Constant time but yet makes accurate predictions in its regime...

I’m a high school student reading through Young and Freedmans University Physics. The book has gotten my very interested in classical mechanics, and I wish to read more about it outside the textbooks. However, I don’t know where I can read more about it. Sure, there are books that I can read...

I have a problem finding ##\left|Ψ(x,t)\right|^2## from the following equation: $$Ψ(x,t) = \frac 1 {\pi \sqrt{2a}} \int_{-∞}^{+∞} \frac {\sin(ka)} k e^{i(kx - \frac {ħk^2} {2m} t)} dk$$ and tried to plot like the pic below (Source Introduction to quantum mechanics by David. J. Griffiths, 2nd...

In the last paragraph of these notes, https://ocw.mit.edu/courses/physics/8-04-quantum-physics-i-spring-2016/lecture-notes/MIT8_04S16_LecNotes3.pdf, it says how a state with large number of photons is not classical. Why is that? I thought quantum mechanics' laws were most applicable when we...

In classical physics electrostatic potential energy is: ##U=k_e\frac{q_1q_2}{r}## So amount of potential energy is not limited as ##r\rightarrow 0## But obviously potential energy (= binding energy) is limited by masses of charge carrying particles. Say when electron and positron annihilates...

Homework Statement Freight car and hopper* An empty freight car of mass M starts from rest under an applied force F. At the same time, sand begins to run into the car at steady rate b from a hopper at rest along the track. Find the speed when a mass of sand m has been transferred.Homework...

What assumptions underlie the classical uncertainty principle? The principle doesn't seem to apply when I want to know the precise pitch of a tone from a bowed violin string, since I can measure the duration (as precisely as I want) of the beats produced when I interfere it with a sine wave of...

I am confused about the difference between the two In Griffith's 2.3 The Harmonic Oscillator, he superimposes the quantum distribution and classical distribution and says What I understand for quantum case is that ##|\Psi_{100} (x)|^2## gives the probability we will measure the particle...

In the video: The professor mentions how the wavelength will be the same for a moving observer vs a moving observer for a classical wave like a sound wave. However, how does that explain doppler shift? Don't we observe the effect because a moving observer measures a different wavelength than a...

I am preparing for an exam which requires me to solve problems in electrodynamics and electrostatics problems along with classical mechanics and geometrical optics problems. The concern is that I do not have electrodynamics in my course in school so I have to study it completely on my own. I...

I'm working through Gregory's Classical Mechanics and came across his derivation of energy conservation for a system of N particles that is unconstrained. We get to assume all the external forces are conservative, so we can write them as the gradient of a potential energy. There's a step he...

Hello, all. These are not the circumstances under which I would have preferred to have made my first post, but unfortunately, as the question suggests, this semester (second semester of freshman year), I earned a C in my calculus-based Intro to Classical Mechanics course. Not really for lack of...

I'm wondering if one can arrive at E=mc^2 using only the physics of the late 19th century, in the following way: As light waves pass over an electrically charged particle, they push it in the direction of the wave motion, transferring both (kinetic) energy and momentum to the particle. Let's...

Can Stimulated Emission in lasers be explained semi classically? If so, how?

Some time ago I was playing with the oscillator when I noticed a few funny things. Consider first the 1D oscillator with Hamiltonian $$ \displaystyle H(q,p) = \frac{p^2}{2m} + \frac{m\omega^2}{2}q^2$$ whose solutions are $$ q(t) = q_0cos(\omega t) + \frac{p_0}{m\omega}sin(\omega t), p(t) = m...

Does the Cluster Decomposition Principle explain the spacelike non classical correlations in EPR experiments without action at a distance ? With CDP defined : S α1α2β1β2 = S α1β1Sα2β2 Does this definition equate to the locality assumption : P(A,B|a,b,λ) = P (A|a,λ)P(B|b,λ) If so then does...

Homework Statement so I was going over my notes on classical mechanics and just started to review rotation matrices which is the first topic the book starts with. On page 3, I've uploaded the page here The rotation matrix associated with 1.2a and 1.2b is \begin{pmatrix} \cos\theta &...

Hello, I'm a high-school student and I was assigned to do this kind of a paper as a senior (one of the requirements of graduating is a short monograph on a subject of interest.) My topic includes an analysis of Mercury's orbit using Newton and Kepler's equations and comparing the predicted...

Hi there. I was wondering if there are classical theories for the weak and strong interactions. I am relatively new to physics so I do not know the answer. Also, is there any classical theory for the electroweak interaction? Thanks in advance.

I started studying the book "A Student's Guide to Maxwell's Equations" by Daniel Fleisch some time back. It is an excellent book, giving a very good idea about the main laws of electromagnetism. I will soon finish the book. Now I need some book(s) which has problems on all the laws in classical...