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Should quantum mechanics be learned first before relativity?

  1. Jul 28, 2012 #1
    That is, is it possible to understand one before understanding the other and vice versa?
     
  2. jcsd
  3. Jul 28, 2012 #2
    Yes, you can learn them without each other. However, special relativity becomes necessary for relativistic quantum field theory. GR certainly doesn't need to be leaned for quantum mechanics (or QFT for that matter).
     
  4. Jul 28, 2012 #3

    Nugatory

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    They are independent enough to be taken in on in either order, but the more natural progression is to do special relativity first. Two reasons, one practical and one a matter of taste:
    1) QM requires much more math than SR, as well as a decent understanding of classical wave mechanics (that's a one-semester topic in it's own right). So you can start in on SR while you're still picking up the math skills for QM.
    2) For anyone who is not planning to be a practicing physicist, SR will be more valuable. It's a lot easier to make the case that SR should be part of every well-rounded person's education than QM.
     
  5. Jul 28, 2012 #4

    Ibix

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    Both before and after, and you'll never be able to determine what order you actually studied them.
     
  6. Jul 28, 2012 #5
    wow i didn't know quantum mechanics when i solved irodov problems in relativity.no need i bet.just optics,electromagnetism(which i do not know) is far than needed just optics is required to understand the postulates.
     
  7. Jul 28, 2012 #6
    Non relativistic QM and relativity are disjoint.
    Elementary relativity is easier than elementary QM though.
     
  8. Jul 28, 2012 #7
    Huh, I would rather say the reverse. Cases where SR is important outside the life of a physicist are pretty limited (I only know of GPS). QM, however, is crucial in for example chemistry or understanding things like transistors etc.

    In what direction are you thinking?
     
  9. Jul 28, 2012 #8

    Nugatory

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    I put SR into the list of things that make us better thinkers, even if we don't use them directly: things such as learning a foreign language, being familiar with the literature and history of your culture, playing a musical instrument, basic economics, theory of evolution, history of philosophy, .... You don't need any of these, but almost no matter what you're going to do in life, you'll do it better and get more out of it with these experiences.

    The great value of studying SR, for anyone who is not going to be using physics in their day job for the rest of their life (and that's nearly everybody), is the experience of rigorously and logically analyzing and then moving beyond our intuitions about how the world works... and it's accessible to anyone with even high-school algebra!

    I agree that QM has more practical applications; it is essential to understanding why atomic bonds, semiconductors, chemistry all work the way the way they do. However, if we look at what most practitioners in these fields are doing... They don't need to and aren't bothering to really seriously understand QM, they only need to accept the results and apply them.

    I also think that there is much to be said for studying QM in the context of philosophy, working through the problems of interpretations and observation and decoherence and Bell's theorem... Even if you're going to be a lawyer, you'll be a better lawyer for having done that study. But you don't have to invest the skull sweat involved in understanding the hydrogen atom, let alone some more complex system, to do that.
     
  10. Jul 28, 2012 #9
    I don't think basic quantum mechanics is inaccessible to anyone that had 1 year of calculus. It is seriously possible to teach at least basic wave mechanics with basic calculus and you can get to interesting conclusions with just a background of general physics and calculus.

    Also depends on what you mean by "seriously understand QM". Many engineers and chemists seriously understand QM, just in a different way from how physicists do. Chemists apply QM all the time in interpreting molecular spectra, designing functional materials and simulating chemical processes, for instance.
     
  11. Jul 29, 2012 #10
    There is a confusion between special relativity and general relativity. Special relativity makes nuclear bombs go boom and nuclear power plants generate electricity, so it's pretty important. It's also pretty easy, and you can learn basic special relativity in a week or two.
     
  12. Jul 29, 2012 #11
    There is, but you should realize that most physics courses in quantum mechanics are intentionally set up to remove as much philosophy as possible. The physics courses tend to be calculation based, so and there is one place where you have to do "something weird" and you might miss it if you blink.
     
  13. Aug 2, 2012 #12

    Nugatory

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    This is indeed true, and the effect is that a QM course is even less valuable to any non-specialist - if you aren't going to be doing these calculation later in life, what are you getting out of the time spent learning how to do them?

    By contrast, just about anyone who can hack the (not nearly as demanding) math of SR will benefit from making the the effort to learn SR. It improves general thinking skills in the same way that learning another language or studying literature does.
     
  14. Aug 2, 2012 #13
    But there's non-physics fields where you seriously have to do the calculations of QM. I agree some of the formalism is useless for applications but wave mechanics at the Griffith level is definitely applicable to real world uses like chemistry and engineering. Otherwise chem/MatSci/EE programs wouldn't require quantum mechanics.
     
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