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. T

    Increasing intensity causes a contradiction in classical physics?

    According to my prof, increasing intensity of the light source in a photocell for the photoelectric effect does not increase the kinetic energy of photoelectrons emitted. Instead, the number of electrons emitted (and current) increases. Changing the colour of the light causes an increase in...
  2. P

    Relativistic corrections to classical physics formulae

    How are classical formulas in physics (such as p = mv, or kinetic energy, or maxwell distribution of speeds) treated with the appropriate relativistic correction/modification? Is it done by using the Lorentz transformation equations? Could anyone give me a few examples of relativistic...
  3. P

    Energy of photons vs classical physics energy

    Relativity says photons have energy E=pc. Classical physics says E=1/2 pv. There seems to be a factor of 2 missing in one case or the other or does the energy formula change as the speed of light is reached? There must be a simple explanation but I have not found it yet. I did not know where...
  4. K

    Indeterminism in Classical Physics

    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...
  5. A

    What equations should I know about Classical Physics?

    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...
  6. J

    Reinterpretation of classical physics in operator/amplitude/e.v.?

    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...
  7. T

    Any compilation of all classical physics concepts?

    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...
  8. J

    Classical physics vs quantum physics

    Why do we say that classical physics is a lot different from quantum physics? The laws that determine the macroscopic world should be derivable from quantum laws. So in a way the Newtonian or classical laws are basically quantum laws( maybe a bit approximated) So why differentiate between...
  9. D

    Quantum physics vs classical physics

    what i want to know is why classical physics does not work on quantum level particles? what are the consequences of using classical physics on quantum level particles?
  10. D

    Why classical physics work in quantum mechanics

    im finally writing my conclusion for my Extended Essay. The extended essay (EE) is a mandatory core component of the IB Diploma Programme. It is a research paper of up to 4,000 words giving students an opportunity to conduct independent research or investigation on a topic that interests...
  11. D

    Classical physics: Motion question

    I just want to know if I'm thinking about these the correct way. Something is put on a track of length d where it slides down and at a certain point, the time is taken given t. Acceleration is constant. How long do you need to make the track for the time to be 2t. Initial velocity is...
  12. ShayanJ

    Classical physics and Group theory

    You know that the current theories in particle physics are expressed in the language of group theory and the symmetries of the theory describe its properties I don't know how is that but my question is,can we do that to classical physics too? I mean,can we use maxwell's equations and derive a...
  13. A

    Derivation in classical physics

    Hi, I am getting started on analytical mechanics but need some help understanding some of the things that is said in my book. Therefore I have attached a section of the derivation and for that I have some questions: 1) First of all the author says that in cartesian coordinates, i.e. (x,y,z)...
  14. A

    Having a test in classical physics after 2 two months

    So ye the test begins in 2 months, and i will need to memorize all the phyisc book, its like 300 pages of good ol' physics, conitaining everything everything from electromagnetic induction, alternating current, lasers, wave osscilaitons, sound, em waves etc etc. i would like to ask about your...
  15. Y

    Quantum Physics from Classical Physics with an epistemic restriction

    talking about ψ-epistemic, ψ-ontic and ψ-complete models.How would the world appear to us if its ontology was that of classical mechanics but every agent faced a restriction on how much they could come to know about the classical state? http://arxiv.org/pdf/1111.5057v1.pdf...The success of this...
  16. M

    Noncommutative geometry in leaf spaces of classical physics

    I was trying to think of natural physical reasons to want to study noncommutative geometry, and it seems to me that it should be relevant even in a classical scenario. Let me know what you think of this as I am no expert. I'm not being terribly precise, either, so let me know if I should...
  17. F

    Retarded Central Force Problem in Classical Physics

    There are many good treatments of the classical central force problem in many undergraduate and graduate textbooks. But I was unable to find a similar treatment of the retarded central force problem. I am looking for the classical treatment of the potentials of type: \delta(t'-t +...
  18. P

    Can Someone give me a good despriction of Classical Physics?

    Also, what are some good resources for learning ABOUT physics?
  19. T

    Studying Recommended upper division classical physics books for self-learning

    Hey guys, I'm an electrical engineering student with a strong interest in physics. I would like to work through classical mechanics, E&M, and thermodynamics books. I'm not sure if there's another subject that is usually covered in classical physics (perhaps waves/optics?) but if so, I'd like...
  20. R

    Cool classical physics proof I came up with today

    Check out this pdf on this website. No signing up or anything, It took me the better half of today to do this. Anyways, this might be well known for people above my basic physics knowledge, but I came up with this all by myself knowing a few simple equations...
  21. A

    Mysteries in Classical Physics

    Are there any mysteries yet unexplained in Classical Physics, Thermodynamics or Statistical Mechanics? Or do all the mysteries in physics come out of Modern Physics?
  22. M

    Canonical Conjugates and Fourier Transforms in Classical Physics

    In quantum mechanics one can convert the wave function of one variable into the wave function of its conjugate pair (e.g., momentum and coordinate) using a Fourier transform. Now consider the classical case. Suppose there is a particle in a potential well with insufficient energy to escape...
  23. J

    Why is turbulence the most important unsolved problem of classical physics?

    I've heard it said that 'we don't really understand turbulence', and that it is one of the biggest outstanding problems in classical physics right now. (Or at least Feynman thought so back in his day) But what is there to understand about turbulence and why don't we understand it? I thought...
  24. M

    Good Book(s) for Self-learning Classical Physics

    Hello PF group. Long time reader, first time poster. Can someone please make some recommendations for a good classical physics textbook, particularity suited to self-learning classical physics? I'd also like the recommendation to not be calculus based. My preferences are for something...
  25. S

    Classical Physics compared to Quantum Physics?

    After studying both areas of classical and quantum physics in some depth, I've reached the conclusion classical physics is more elegant and ingenious than quantum physics. Newton's law of gravitation is elegant because its sheer simplicity allows us to map the trajectory of satellites...
  26. Phrak

    Initial Conditions in Classical Physics

    According to the usual way of applying determinism in physics:- If we know all the intitial conditions of a closed system at time t0, we can fully specify the the system at a time t1>t0. This seems natural and obvious within classical physics, but is it really true? I have never heard of a...
  27. X

    Fundamental Equations of Classical Physics

    So I want to get all the Equations that describe classical Physics together because I think it would make a kick *** poster. Tell me if I am missing anything or if you don't think one should be on here. [PLAIN]http://img694.imageshack.us/img694/9646/classicalequations.gif
  28. D

    Classical physics (phase diagram

    A ball of mass m rests at times t less than 0, at height h above the ground. at time t=0 the ball is released and fell on the ground after hitting the ground, the ball rests there. a) x represents distance from the ground, drive and expression for the phase diagram when the ball moving toward...
  29. alemsalem

    Professor Balakrishnan's Quantum & Classical Physics Lectures: Worth a Watch!

    These are professor Balakrishnan's quantum physics lectures, he also has classical physics lectures, they're worth watching,, he's good.. Enjoy ^_'' Edit: These are not very introductory, for that you can see Susskind's Lectures, or something else you might find..
  30. A

    Uncertainty Principle in Classical Physics

    I have often seen it stated that the Uncertainty Principle (UP) is a unique feature of Quantum Physics, but surely it applies classically too? For example, if someone throws a ball across a room, and I take a photo with a shutter speed of 1 second, the resultant photo will tell me a lot about...
  31. E

    Cross Post from Classical Physics: Calculus in Impulse Momentum Theorem

    Hi, This is my first post. Sorry for the mistakes it certainly contains. I have two questions. First, is there a tutorial for using embedded LaTex? I found some general tutorials on LaTex, but I couldn't get some of the commands listed in that tutorial to work in the embedded LaTex code...
  32. X

    Hi, Momentum (Classical Physics) Help

    Homework Statement Using the graph below, what is the magnitude of the impulse provided to a 48 g tennis ball that is swerved due south? Also, What is the velocity of the ball when the racquet and ball separate? Homework Equations p=mv (I think). Fnet x delta Time = P (maybe)?The Attempt...
  33. maverick_starstrider

    Are Maxwell's Equations The Most Pivotal Postulate of Classical Physics?

    Every textbook I read seems to follow the same logic/derivation of physics: -Gauss' Law is observed experimentally, shows us there's this thing E -Biot-Savart's Law is observed experimentally, shows us there's this thing B -Ampere's Law (after fixed by Maxwell) observed experimentally, along...
  34. U

    Good book for Classical Physics II?

    Hey, I am starting this course very shortly, and I always found that the books the professor recommended, I couldn't quite understand. So these are my syllables: Electrostatics: electric charge and field, Coulomb law, Gauss law; potential; energy; conductors; Poisson and Laplace equations and...
  35. R

    Find Books for Classical Physics Beginners

    Hi everyone , can you find some books for classical physics for begginers pls ? thnx
  36. P

    HELP Boltzmann law in terms of classical physics?

    The Stefan-Boltzmann law is as follows: The energy radiated by a black body radiater per second per unit area is directly proportional to the fourth power of the absolute temperature. Equation: I = σT^4 Is it possible to explain this law by means of classical physics only? If so...
  37. A

    Classical physics vs relativity: parallel electron beams

    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...
  38. A

    The validity of classical physics (split from: DWFTTW)

    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...
  39. S

    Modern Physics vs Classical Physics

    Just curious, what's the difference? I was told be someone that modern physics has ways of accurately defining what a force is, while classical physics does not define forces, only acceleration in terms of force and mass. Again, just curious.. What are the major differences? Is one wrong...
  40. W

    Why symmetry is not important in classical physics?

    but ultra important in quantum physics? i can see it is important in quantum physics but i can not see why it is less important in classical physics.
  41. J

    Classical Physics and the Bohr Model of Hydrogen Atom

    Homework Statement Classical physics applied to the bohr model of the hydrogen atom would predict that light could be emitted continuously, rather than in discrete chunks of energy. Transitions between what kinds of energy levels would come close to the classical viewpoint? A. Only levels...
  42. P

    Galilean Relativity & Inconsistency with Classical Physics

    Hi, I am a novice here and i am trying to solve the following problem: 1.Show that Galilean relativity transformation produces inconsistent classical physics result when used with equation of expansion of light sphere. (2 different frames) 2. x2 = x1 - vt1 y1 = y2 z1 = z2 t1 = t2...
  43. V

    Escape Velocity Calculation using Energy Conservation

    I do not have a solution to a question I'm working on, so I just wanted to make sure the procedure was correct. Homework Statement I have a force acting on a particle in one dimension. It is given an initial speed v-0 and the problem wants to know what the maximum speed v-0 will be...
  44. R

    Transition from QFT to Classical Physics using Path Integrals?

    I have a question in Srednicki's book regarding path integrals, but first I'll set it up so that no familiarity of the book is required to answer the question. The vacuum to vacuum transition amplitude for the photon field in the presence of a source is given by: <0|0>_J=\int \mathcal D A...
  45. michael879

    Classic Physics: Exploring Symmetry of E&M & Gravity

    "classical" physics is completely defined by three basic theories. It starts with the basic theory, F=dp/dt, p = mv, etc. (sorry, I'm blanking on what its called). The forces, E&M and gravity, are then defined by Maxwells equations and the GEM equations. You could include special relativity...
  46. K

    Symmetry of Quantum vs Classical Physics Systems

    I read a introductory book on symmetry of physics system. The author says symmetry of quantum mechanical system is VERY different from that of classical system. I just wonder what's the main difference?
  47. N

    Question: How can I calculate the steepest slope of a hill using its equation?

    Equation of the height of the hill z = 2xy - 3x^2 -4y^2 -18x + 28y +12 z: Height of the hill x: Distance East y: distance South Question: In which compass direction is the slope at x = y = 1 steepest? My question: What does this suppose to mean? The vector that is tangent to that...
  48. K

    Being ready for Classical Physics

    Hello, My math is good enough for Classical physics however, I believe my physics is not. I did not take high school physics which I regret but now I must catch up and take this class at my community college that is supposed to get me caught up. I am more than happy to take it because physics...
  49. N

    Quantum physics vs classical physics

    the chapter of quantum physics vs classical physics will be one of the topic that i will be tested in final exam,but I'm a little confused by them..so i need a good references to refer to..could you please recommend me some good website as i can refer to..i have found this...
  50. M

    The Borderworld between Quantum and Classical Physics

    The "Borderworld" between Quantum and Classical Physics A perpetual problem in physics has been that there is a discrepancy between where quantum mechanics holds, such as in microscopic phenomena, and where it falls apart at the macroscopic level. For example, photons and electron, under...
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