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Why would I travel as a wave?

  1. Jan 5, 2010 #1
    I'm an undergraduate physics student and whilst Quantum Physics is a fascinating area, it has me constantly asking questions - probably a good thing right?

    Now one of the fundamental principles to Quantum theory is the wave-particle duality of particles and light. I understand the history behind the concept (I think), but I still struggle to understand why a particle would ''want'' to travel as a wave. In my head I'm watching a particle zooming through the air in a sinusoidal motion. (I know there are lots of problems with this, i.e. uncertainty principle etc) but essentially this is right? Now in classical mechanics, a billiard ball (The generic object in EVERY book) moves in straight lines, it's a logical shortest-path motion. Quantum effects can be ignored due to the significantly large mass of the ball. Straight lines make sense for getting to places as quickly as possible. Waves don't. The only way I can see a wave making sense is if the medium I'm travelling through (as a photon or quantum particle) is forcing me to take a wave-like motion.

    Throw your stuff at me! I know this is a very crude question, with very crude analogies, but I hope you can see my line of thought. Or wave of thought, whatever...
  2. jcsd
  3. Jan 5, 2010 #2


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    The theory doesn't say that it's doing anything "sinusoidal" as it's moving from an emission event to a dectection event. Actually it doesn't tell you anything at all about what the particle does between emission and dection. It just tells you how to calculate the probability of detection. (The infamous "interpretations" of QM are all offering suggestions about what happens in transit, but QM itself doesn't).

    There's an active thread about the double slit experiment that you should find interesting. https://www.physicsforums.com/showthread.php?t=367343.

    You would also like Feynman's "QED: The strange theory of light and matter", or the videos of the lectures that he turned into that book. http://vega.org.uk/video/subseries/8
  4. Jan 5, 2010 #3


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    Welcome to PhysicsForums, randybryan!

    The thing to remember is that none of this has to make sense. We are lucky if we know the "how", but I don't think there is an answer to the "why". The purpose of science is to describe and/or predict. But fundamental questions will always defy answers.
  5. Jan 5, 2010 #4
    So defeatist! Randybrian - you're visualisation has obvious flaws. But don't give up trying to understand wave particle duality. Seperating the how from the why is a
    strawman argument in this case. And it ignores the what question. We may as well give up thinking. It reminds me of Lord Kelvins statement a century ago, about...
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