Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Best textbook or video or device for understanding QM

  1. Feb 18, 2015 #1
    As the title says im looking for some book to read and understand this world. I know many people say its impossible and that we can learn it by learning the math bluh bluh.. But i have passed 4 quantum courses and i know the math. I just cant get the touchable concepts ( i dont really know how to use the words right now). Help me guys!
     
    Last edited by a moderator: Feb 18, 2015
  2. jcsd
  3. Feb 18, 2015 #2

    atyy

    User Avatar
    Science Advisor

    Do you at least know the traditional interpretation, in which one makes a subjective division of the world into classical and quantum parts, and in which a measurement is when the classical measuring apparatus interacts with the quantum system such that a definite (also called "classical", "macroscopic" or "irreversible") measurement outcome is registered? The traditional interpretation needs this so-called Heisenberg cut, because there is unitary deterministic time-evolution between measurements and random non-unitary time-evolution called collapse or state reductiuon when a measurement is made, so something outside stating the initial quantum state is needed in order to say which time-evolution rule is used when.
     
  4. Feb 18, 2015 #3
    I do know that. I know these stuff otherwise i wouldnt have been able to pass those courses. I just want a visual aid. You know when i talk about momentum (classical) i can tell you about the different momentums a truck and a normal car have and you would understand me because you have seen those and felt em. For QM, we cant do that. We cant feel how small an electron is, we only know a number for that. I want a book that can show me how to feel these.
     
    Last edited by a moderator: Feb 18, 2015
  5. Feb 18, 2015 #4

    atyy

    User Avatar
    Science Advisor

    For visual aids, you can treat the electron as a wave (ie. treat the wave function as real, and treat collapse as real), and use your intuition about waves. Of course, this is just a visual aid, since in the orthodox interpretation, the wave function is just a tool.

    For a deeper understanding about what reality may be behind the wave function and the classical world, one needs something like Bohmian Mechanics or Many-Worlds.
     
  6. Feb 19, 2015 #5

    Demystifier

    User Avatar
    Science Advisor

    You definitely need a book on Bohmian mechanics. I recommend:
    https://www.amazon.com/The-Quantum-Theory-Motion-Interpretation/dp/0521485436
     
  7. Feb 19, 2015 #6
    A book that places particularly strong emphasis on a physical intuition for the concepts of QM is "Quantum Theory" by David Bohm.
    He wrote it before developing Bohmian mechanics so you will find the orthodox-interpretation point of view in it.
     
    Last edited: Feb 19, 2015
  8. Feb 19, 2015 #7

    vanhees71

    User Avatar
    Science Advisor
    2016 Award

    What the heck should this be good for, particularly for the purpose of getting an intuitive understanding of quantum theory? The Bohmian trajectories are nothing real, being unobservable!

    I think, the only way to get some understanding of "what's going on in Nature" concerning quantum theory is to look in some detail to various applications of the theory to real experiments. However, one should keep in mind that the goal of physics is not to get some "explanation" about why nature is as it is but to get a precise description of what's going on in nature by identifying as simple a set of "natural laws". This insight can only be gained by a close connection between experiment and theory, and the one and only way to express the theories leading to this type of understanding is indeed math, and the understanding becomes more and more abstract the more you leave the realm of everyday experience which is governed by the laws of classical physics (in our everyday life we are dealing with phenomena which are very well described by classical mechanics of solid bodies and fluids as well as classical electromagnetism, so that some relativity is also involved, but not in a very obvious way).

    Quantum phenomena are, on the other hand, present too. If you know that the atoms making up the matter around us are bound systems of atomic nuclei and many-electron systems, the very fact that there is stable matter at all, making the classical effective description sensible to begin with, is a generic quantum phenomenon. At least nobody has ever found any classical explanation for the seemingly obvious fact.
     
  9. Feb 19, 2015 #8

    Demystifier

    User Avatar
    Science Advisor

    Just because something is unobservable does not mean it is not intuitive. For example, I am sure you will agree that Feynman diagrams are intuitive but not observable. Perhaps you will say that Feynman diagrams are a tool which can be used to calculate something observable, but Bohmian trajectories can also be used as a tool to calculate something observable.

    Finally, you can say that Bohmian trajectories are not intuitive to you, while Feynman diagrams are intuitive to you. That's fine, different people find different things intuitive. I do not recommend Bohmian mechanics to everybody. But I think I have a lot of experience on different views of QM that different people may have, and I think I can recognize who might like which interpretation. (Test me: Have I been right that you find Feynman diagrams intuitive, even though they are not observable?) From the words of Yasmin I've got a strong impression that Bohmian mechanics would satisfy him.
     
  10. Feb 19, 2015 #9

    Demystifier

    User Avatar
    Science Advisor

    As I stressed many times, the goal of physics is determined by physicists, and not all physicists agree that one of the goals of physics is not to get some "explanation" about why nature is as it is. In particular, I am convinced that Yasmin would not agree with that. Einstein also did not agree with that. John Bell, the discoverer of the Bell inequalities, also did not agree with that. Do you want more examples?

    But there is also another "extreme" in the spectrum of the goals of physics. You probably feel proud that your goal of physics (of identifying as simple a set of "natural laws") is much more concrete than that of those who seek "explanation". But you forget that there are also applied physicists (to whom you may be jealous because they get much more money for research than you do) who will say that the goal of physics is not to identify the natural laws, but to apply them to something useful. Compared to you and me, they are concrete and we are not. The way you think about the "explanation seekers" does not differ much from how applied physicists think about you and me.
     
    Last edited: Feb 19, 2015
  11. Feb 19, 2015 #10

    Nugatory

    User Avatar

    Staff: Mentor

    Yasmin1369: you might reasonably conclude from the last two or three posts that there's more than one way to come an understanding of QM, and that works for one person doesn't necessarily work for another.

    You'd be right.
     
  12. Feb 19, 2015 #11
    Thanx guys! I will try bohmian mechanics, and btw i am a girl :)
     
  13. Feb 19, 2015 #12

    atyy

    User Avatar
    Science Advisor

    To add more examples, even the masters of-shut-up-and-calculate were very aware of the measurement problem. Landau and Lifshitz mention in passing that the need for a Heisenberg cut is strange, which if one understands the style of their wonderful books, is saying a lot. Dirac mentions the problem in his Scientific American article, and says it will probably have to be solved by a theory beyond quantum mechanics. Even though von Neumann's proof of the impossibility of hidden variables was wrong, he obviously thought about the problem, and till this day his analysis of the measurement process is a good way to show the measurement problem. Weinberg discusses the problem in his quantum mechanics text. Here are more discussions of the problem.

    Bell, Against 'measurement' http://www.tau.ac.il/~quantum/Vaidman/IQM/BellAM.pdf

    Tsirelson, This non-axiomatizable quantum theory http://cds.cern.ch/record/260158/files/P00021853.pdf

    Laloë, Do we really understand quantum mechanics http://arxiv.org/abs/quant-ph/0209123

    Wallace, The Quantum Measurement Problem: State of Play http://arxiv.org/abs/0712.0149

    For Bohmian Mechanics, some free articles are
    Passon http://arxiv.org/abs/quant-ph/0611032
    Oriols and Mompart http://arxiv.org/abs/1206.1084
     
    Last edited: Feb 19, 2015
  14. Feb 19, 2015 #13
    Screw textbooks. Either watch the lectures by Leonard Susskind. Or look for pdfs on Google, search for something like "Introduction to QM" pdf or similar words.
     
  15. Feb 19, 2015 #14

    martinbn

    User Avatar
    Science Advisor

    Oh, no! Don't watch Susskind's lectures. It seems that in these lectures (not just quantum mechanics all of them) he talks a lot without actually saying much.
     
  16. Feb 19, 2015 #15
    And this is why?
     
  17. Feb 19, 2015 #16
    BTW: Ok one book that I think is very straight forward is Paul Dirac's Book The Principles of Quantum Mechnics ! It's short and good in coordinate free notation, he even introduces a bit of quantum field theory, but it is a little outdated on that, but that doesn't do much to the whole book. And my general advise would be to read old original literature from the people who came up with the stuff. It's always much more down to earth and not compress to minimum notation and at the same time generalized to the most general case which obscures anything. You find the links to the pdfs on Wikipedia (on a specific topic) most of the time.
     
  18. Feb 19, 2015 #17

    atyy

    User Avatar
    Science Advisor

    Hey, hey - don't insult applied physicists! I first heard about Bohmian Mechanics from one :)
     
  19. Feb 19, 2015 #18

    vanhees71

    User Avatar
    Science Advisor
    2016 Award

    Feynman diagrams are very clever notations for formulas, but Bohmian trajectories are simply superfluous additions complicating the anyway complicated interpretation of quantum theory even further. Also, to apply (theoretical) physics to technology (engineering) philosophy doesn't help either :-).
     
  20. Feb 19, 2015 #19

    kith

    User Avatar
    Science Advisor

    On the other hand, you may have to do a lot of "translation" work when you get to more recent stuff. Also, some of the old papers are really obscure. I think you can easily spend as much time trying to understand Heisenberg's groundbreaking 1925 paper as on a well-written introductory textbook on QM.
     
  21. Feb 19, 2015 #20

    vanhees71

    User Avatar
    Science Advisor
    2016 Award

    Well, the drawback of reading old stuff is that you'll get a lot of the confusion of the early development of the theory. That's very interesting from a historical perspective and can help to understand the theory better. For that, however, it's good to be on firm ground concerning the physical content of the theory, and this is best achieved by reading good modern textbooks. My favorites are

    J.J. Sakurai, Modern Quantum Mechanics
    L. Ballentine, Quantum Mechanics, A modern development
    S. Weinberg, Lectures on Quantum Mechanics

    Particularly, for interpretational issues:

    A. Peres, Quantum Theory: Concepts and Methods

    Exceptions to the general rule are all papers by Dirac, Born, and Pauli, which are masterpieces in clarity. For maximal confusion, I recommend Bohr and Heisenberg :-).
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Best textbook or video or device for understanding QM
Loading...