What is Classical physics: Definition and 222 Discussions

Classical physics is a group of physics theories that predate modern, more complete, or more widely applicable theories. If a currently accepted theory is considered to be modern, and its introduction represented a major paradigm shift, then the previous theories, or new theories based on the older paradigm, will often be referred to as belonging to the realm of "classical physics".
As such, the definition of a classical theory depends on context. Classical physical concepts are often used when modern theories are unnecessarily complex for a particular situation. Most usually classical physics refers to pre-1900 physics, while modern physics refers to post-1900 physics which incorporates elements of quantum mechanics and relativity.

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  1. H

    I Time Reversal Symmetry in Classical Physics

    I try to justify time-reversal symmetry in a very simple classical problem; Free Fall. The position, ##x##, and the velocity, ##v## are obtained versus time from the equation ##-g=\ddot x##. So, if we consider the primary conditions as ##t_0,x_0,v_0## it is clear that...
  2. B

    Question about the Galilean transform in classical physics

    Shouldn't the equation be x' = x + (v')(t) instead of x' = x + (v)(t)?
  3. E

    Classical Weidner/Sells Elemenary Classical Physics

    I'm looking for full solutions to the Weidner/Sells series, published in the 1960's. I am not a student (in the usual sense) now, but had the W/S series as the text when I took freshman physics in 1965-66. I doubt that any school is using W/S now (so there's no trying to cheat on problem...
  4. K

    I Quantum fluctuation and classical physics

    Hi, Can we derive an equivalent concept of quantum fluctuation in classical physics using correspondence principle? Also, how can we account for transfer of energy back and forth at the quantum and classical border? Thanks
  5. E

    Do we have "Newtonian space-time" in classical physics?

    I've managed to thoroughly confuse myself. Before Minkowski came along and combined 3-dimensional Euclidian space and time into Minkowski spacetime, I was under the impression that we only dealt with three dimensions and that time was just a universal parameter. Thorne and Blandford write...
  6. HaoBoJiang

    It's pleased to meet everybody

    I am a physics graduate student, also a physics enthusiast.I prefer Mathematical Physics, and often do some related research.Like everyone of you, I also have a strong interest in physics, and I hope to generate more new ideas and broaden my knowledge through exchanges with you.
  7. A

    A What are the most important open questions in classical physics?

    As the tittle say. I've been out of touch with many branch of non-quantum non-relativistic physics and I would like to know what people that work in these areas would say are the most important or interesting current trents of research in classical physics.
  8. CrosisBH

    Courses Taking both Classical Physics and Quantum Physics at the Same Time.

    Hello! I'll be entering my second semester of my junior year of my Physics Degree. My uni doesn't have a bad physics program, but it's really small so I have to take my upper level classes as soon as they're offered or I won't take them for another 2 years or so. They are on a cycle so I will be...
  9. nineteen

    What is the minimum velocity needed?

    I tried to solve this problem and this is what I could come through: When the object is moving, the force acting on object is the frictional force, so, it got to be μmg. So, F = ma and as F is μmg μmg = ma μg = a So, to find out the magnitude of the initial velocity v given to the smaller...
  10. B

    How to find the equilibrium point between two masses? (Topic 6.2)

    Morning all I've recently come across a problem where I get conceptually but cannot apply mathematically if that makes sense. I understand the position of the third mass must be at the equilibrium point of ##m_1## (##9.0×10^{24}kg##), so ##\Sigma F = 0## right? And not even necessarily zero...
  11. Quantum Alchemy

    I How does Classical Physics explain Quantum Entanglement?

    As a Computer Programmer, it's hard to wrap my head around Quantum Entanglement and non locality being explained in the context of Classical Physics. In other words, if the universe at it's core is physical where does Quantum Entanglement fit within a physical picture of reality? There's been...
  12. D

    B What are the general calculus concepts used in classical physics?

    Question.
  13. N

    B Classical physics vs quantum physics

    Is classical physics independent from quantum physics? Or is classical physics an approximation derived from quantum physics? Is it dependent on interpretations? What quantum interpretations support the latter above?
  14. warhammer

    Classical Physics & Particle Motion Under Force Field

    The particle is moving under a force field with the potential energy equation described above. I find it logical that Newton's Laws can be used as in the question itself it is stated that the velocity is quite small and we could approximate its subsequent motion via the notions of Classical...
  15. R

    I How Is Particle Distribution in a Solid Angle Derived in Mechanics?

    I'm reading Mechanics by Landau and Lifshitz, chapter IV, and trying to understand how in a (closed) center of mass system, with randomly distributed and oriented particles that disintegrate, "the fraction of particles entering a solid angle element ##do_{0}## is proportional to ##do_{0}##, i.e...
  16. J

    A Geometry of Classical Physics in terms of Gauge Theory geometry?

    Reading the interesting book "Groups_and_Manifolds__Lectures_for_Physicists_with_Examples_in_Mathematica", in the introduction it is stated: (...) we have, within our contemporary physical paradigm, a rather simple and universal scheme of interpretation of the Fundamental Interactions and of...
  17. O

    I Radius vector in cylindrical coordinates

    I am starting to learn classical physics for my own. One exercise was, to calculate the vector r (see picture: 1.47 b). The vector r is r=z*z+p*p. I don’t understand this solution. My problem is: in a vector space with n dimensions there are n basis vectors. In the case of cylindrical...
  18. Q

    Other What's the value of Classical Physics?

    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...
  19. BWV

    I Do Classical Physics Still Have Unsolved Problems?

    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...
  20. Z

    Solve for x(t) and v(t) given a Force equation using Mathematica

    Homework Statement Homework Equations F= ma or F= md^2x/dt^2 The Attempt at a Solution I know that this second order differential is non linear. I attempted to solve the problem as -k/x^2 = md^2x/dt^2 but I'm getting trouble since it is a second order ODE and I haven't learned how to solve...
  21. sams

    Scleronomic or Rheonomic Mechanical System?

    I would really appreciate if someone could advise me whether the system below is a scleronomic or a rheonomic mechanical system, or a mix of both. If we consider the first pendulum, the constraint is fixed which leads to a scleronomous case while the constraint of the second pendulum is not...
  22. A

    Classical Searching for Challenging Physics Problems: E&M, Optics, Thermo & Mechanics

    Hi! As the title suggests, I am searching for some good problem books with really challenging problems for classical physics, more precisely on the topics of electricity and elecromagnetism, geometrical optics and wave optics, thermodynamics and analytical mechanics. When I say challenging I...
  23. A

    I Radiance and energy density of a black body

    How can I find the relation between the radiance and the energy density of a black body? According to Planck's law, the energy density inside a blackbody cavity for modes with frequency ##\nu \in [\nu, \nu + \mathrm{d}\nu]## is given by $$ \rho(\nu, T)\mathrm{d}\nu =...
  24. P

    Classically communicate information faster then light?

    Where in this though-experiment do I get it wrong? Even though no mass can travel faster then c, maybe information can? And I'm not talking about quantum entanglement etc. Consider a pipe, filled with balls that are very tightly arranged. If I push the outermost ball on one side of the pipe...
  25. ubergewehr273

    Resolution of vectors for problems related to mechanics

    Homework Statement Refer the given image. [Prob 2.9] Homework Equations F=ma The Attempt at a Solution I drew the normal vector perpendicular to the surface of the cone and resolved it as ##Nsin\theta=mg## ##Ncos\theta=\frac {mv_{0}^2} {r}## where ##v_{0}## and ##r## are the speed and radius...
  26. A

    B What the equal sign means in physics

    For example F=ma means that the definition of force is m*a or the quantity of left side equals to the quantity of right side or both ? or kinetic energy..we know K=1/2mu^2 but is this the definition of kinetic energy or just the formula to calculate it ?
  27. Abhishek11235

    Trajectory of a particle under the given force

    A particle of mass m in xy plane is attracted toward the origin with the force $$\begin{align}\vec{f} = - \frac{k^{2} m}{r^{6}}\vec{r}\end{align}$$ where ##\vec r## is position vector of particle measured from origin. If it starts at position ##(a,0)## with speed $$v=\frac{k}{\sqrt{2} a^{2}}$$...
  28. Rhi_heart_Phy

    What's the most effective way to study/learn physics?

    Ive always been fascinated by the subject, and i absolutely love learning new concepts, especially when theyre intriguing and brain-twisting, but i can never seem to grasp onto the depths of concepts for a long time. Suppose, if i stop working out problems for a week or so on a particular...
  29. A

    Potential ##V## and potential energy ##E_{pot}##?

    Hi, I know that in an elecric field the potential energy ##E_{pot}## is equal to the potential ##V## times the charge ##E_{pot}=q V##. Here my problem: I know that the potential energy of a spring is ##E_{pot}= \frac{1}{2}kx^2##. In my theoretical physics book i read also that the potential is...
  30. Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 31: Problems and solutions (Part 3)

    Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 31: Problems and solutions (Part 3)

    All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
    • Wrichik Basu
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  31. Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 32: Continuous groups in physics (Part 1)

    Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 32: Continuous groups in physics (Part 1)

    All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
    • Wrichik Basu
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    • classical physics
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    • Category: Classical Mechanics
  32. Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 33: Continuous groups in physics (Part 2)

    Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 33: Continuous groups in physics (Part 2)

    All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
    • Wrichik Basu
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    • classical physics
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    • Category: Classical Mechanics
  33. Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 34: Continuous groups in physics (Part 3)

    Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 34: Continuous groups in physics (Part 3)

    All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
    • Wrichik Basu
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  34. Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 35: Noether's Theorem; Special Relativity (Part 1)

    Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 35: Noether's Theorem; Special Relativity (Part 1)

    All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
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  35. Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 36: Special Relativity (Part 2)

    Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 36: Special Relativity (Part 2)

    All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
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  36. Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 37: Special Relativity (Part 3)

    Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 37: Special Relativity (Part 3)

    All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
    • Wrichik Basu
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  37. Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 38: Special Relativity (Part 4)

    Classical Physics by Prof. V. Balakrishnan (NPTEL):- Module 1, Lecture 38: Special Relativity (Part 4)

    All copyright strictly reserved to Prof. Balakrishnan and NPTEL, Govt. of India.
    • Wrichik Basu
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    • Category: Classical Mechanics
  38. J

    I Inconsistencies in classical physics

    A question I've had about the black body problem and classical physics in general has to do with the conservation of energy. One of the first things you can derive in classical mechanics is that for a conservative force the total energy of the system doesn't change. However, one of the typical...
  39. I

    Does the placement of weight affect tension in 3D?

    If you have a rectangular box connected on 3 sides with strings, and you hold all the strings together at a point, with your hand; then you put a weight in the center of the box, which is open, would the tension on the strings differ than if you put the weight at a corner. Please describe it to...
  40. H

    B Time quantization in classical physics

    Hello, It is considered that the time is continuous in classical physics, but it sounds paradoxal to me, let me explain. Let a particle inside a galilean frame of reference. This particle can only be measured either at rest, either in motion, but never simultaneously at rest and in motion...
  41. M

    Dimensional formula of distances in certain formulas

    Homework Statement Dimensional formula for 'the square of the distance between two bodies' in universal gravitation and 'distance from the axis squared' in moment of inertia. Is L^2 is the dimensional formula for both the distances in the above two cases? Homework Equations F=Gm1m2/d^2; moment...
  42. P

    Is There Such Thing as a Swing Set That's Too Tall?

    I plan on building a swing set for my daughter, and I always loved the feel of a good tall swing. I like the long range of motion, the nice glide ... but is there such thing as too tall? I was planning on going about 14' off the ground with the cross beam .. then I figured, well, let's go with...
  43. A

    Help with Python modelling of a particle in a 2D box

    Hello guys, I programmed a physics simulation where a particle with some initial conditions bounces off the walls of a 2d container. The simulation also includes gravity in the y-coordinates. The aim of the project is to produce a visual animation and further on include more particles and...
  44. A

    B Classical physics emerging from quantum physics

    Is classical physics more than just the quantum physics of a large number of particles and quanta? Thanks for your thoughts.
  45. Jianphys17

    Question about self-study of SR

    Hi, I was wondering, as in the Bachelor's degree curriculum there is no SR course, for one who is interested in theoretical physics (as me), would do it alone, perhaps with texts such as Rindler or Synge ...? Thank you in advance !
  46. Quantum Velocity

    What calculus is needed for understanding classical physics

    Hey guy, I'm a just new in physics and i want to self-teaching it. But i don't know what calculus i need for classical mechanic. Pleas help! And if you suggest me a book can you pleas help to send me a link (and the book must be in pdf pleas) Thank
  47. welssen

    Determine the angular momentum in polar coordinates

    Hi there, I've been trying to solve the following problem, which I found looks pretty basic, but actually got me really confused about the definition of angular momentum. Problem The trajectory of a point mass m is described by the following equations, in spherical coordinates: r(t) = r_0 +...
  48. G

    Entropy question in classical physics

    Hi I've been wondering about Boltzmann's equation S = k ln W Where W is the number of different distinguishable microscopic states of a system. What I don't get is that if it's the position and velocity of a particle that describes a microstate doesn't it mean that W would be infinite...
  49. Heisenberg1993

    I Is there a contradiction in Halliday and Resnick?

    In Chapter 11, section 11-4, subsection friction and rolling, it is stated that the static frictional force is along the same direction as the direction of motion because the point of contact of the wheel with the floor is moving in the opposite direction. Then, in the next subsection, the same...
  50. Zafa Pi

    I Distinguishing classical physics vs. quantum physics

    For some time I've been wondering how to eloquently distinguish classical and quantum physics. What I mean by eloquent is both simple and short. By simple I mean understandable to any college freshman, and with that caveat, as short as possible. Something like: "quantum has inherent randomness...
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