1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Is Classical Physics Wrong

  1. Dec 9, 2014 #1
    Basically the title. Take relativity it has the Lorenz factor 1/sqrt(1-(v/c^2)) and if v is not zero it's something that isn't accounted for in classical mechanics. Does that make classical mechanics wrong?
     
  2. jcsd
  3. Dec 9, 2014 #2

    Stephen Tashi

    User Avatar
    Science Advisor

    It only makes it "wrong" if you consider an approximation that applies to some situations ( v small relative to c) to be "wrong". If you consider approximations "wrong" then most physics is wrong. Mathematical solutions to real life problems are usually approximations.
     
  4. Dec 9, 2014 #3

    jedishrfu

    Staff: Mentor

    No, its not wrong, I would say its imcomplete. As we extend our understanding of the very small, the very large, and the very fast we discover that there are things CM can't explain.

    This causes us to extend our theories to explain the discovered anomalies and predict new things. The guiding principle is that the new theories must in the limit of everyday experience predict the same outcomes as Classical Mechanics.

    Relativity is a good example when we consider everyday velocities the v^2/c^2 term becomes zero and the equations reduce to classical ones.
     
  5. Dec 9, 2014 #4
    SR is just incomplete, or rather it's a simplification, but in a some different way.

    In the classical physics the (v/c)^2 is usualy omited only, and this is a simplicity also, and that's all story.
     
  6. Dec 9, 2014 #5
    Classical kinetic energy is the lowest series expansion of gamma,.
    Classical mechanics is correct up to and including the second order in v.
     
  7. Dec 9, 2014 #6

    Nugatory

    User Avatar

    Staff: Mentor

  8. Dec 9, 2014 #7
    But, and unfortunately for such improvised claims, the gamma is a simple classical thing, because easily derivable, for example using the light clock, which is a completely classical entity.
     
  9. Dec 9, 2014 #8

    jedishrfu

    Staff: Mentor

  10. Dec 9, 2014 #9

    Nugatory

    User Avatar

    Staff: Mentor

    Sometimes the word "classical" is used to mean Newtonian/Galilean, so that relativity and QM are both non-classical. Other people prefer to treat SR as a classical theory because it is a logical extension of classical electrodynamics, and reserve "non-classical" for QM. You appear to be using the word in the latter sense while my2cts is using it in the former sense.

    The historical accident that QM and relativity were both shaking up the comfortable Galilean/Newtonian world at the same time may have contributed to the conflicting uses of the word.

    Please don't start an argument over this..... :)
     
  11. Dec 9, 2014 #10
    All physical laws are approximations of reality. Most of physics is finding the appropriate approximations that simplify the problem enough to be solvable, but not too much that the answer is meaningless. So is all physics wrong? Classical mechanics are a great approximation in many situations.
     
  12. Dec 9, 2014 #11

    phinds

    User Avatar
    Gold Member
    2016 Award

    All of the bridges and skyscrapers ever built and all of the moon landing made so far are just two sets of examples of VAST number of things that show just how right classical physics is. As has been stated in the thread several times, it DOES fail under conditions that are outside normal human experience but that just makes it incomplete, not wrong.
     
  13. Dec 9, 2014 #12
    Physics is right. The absolute proof is the destruction of two cities by weapons created purely from physical theory.
     
  14. Dec 9, 2014 #13
    A horrible proof, yet a proof.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Is Classical Physics Wrong
  1. Classical physics (Replies: 12)

Loading...