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The Pugilistic Albert - Round 1

  1. Apr 12, 2004 #1
    Sorry about the title of this, but with 50+ views of my previous message and only one reply, I surmised that I need to be a bit more "punchy" in my delivery.

    In his book, Relativity, Dr. Einstein tells us that the fact that an organ pipe on a train carriage sounds the same no matter what its orientation (relative to the carriage) is "a powerful argument in favor of the principle of relativity."

    But I do not think that this is right. Would not the medium of sound (the air in the carriage) be moving in the carriage's inertial frame, and thus at rest with respect to the carriage? And would this not negate any effect of the motion of the carriage on the sound produced by the pipe?

    Any help here would be greatly appreciated. Perhaps I am missing something here - some subtle effect of motion on the sound waves generated by the organ pipe.

    I am not trying to comment on the principle of relativity here. I am just saying that I don't think that this experiment can prove or disprove the principle of relativity.

    Any help?
  2. jcsd
  3. Apr 12, 2004 #2


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    I am not familiar with this statement by Einstein. I am suspicious of the context. I agree with your assessment, if this is indeed the case.

    OK, I just read that chapter (I just so happen to have a copy with me). I'm assuming that you're talking about Chapter V: "The Principle of Relativity (In the Restricted Sense)." I agree that the organ pipe is not a very good demonstration, but it is not intended to be taken very so literally, or as a working example.

    Fistly, note that this chapter is aimed at disuading the reader from an absolute frame of reference. That is, any inertial frame of reference is just as simple/no more complex than any other.

    Secondly, note that the example of the pipe on the train was just to get the reader to think about the next few sentences of the concluding remarks. That is, since the earth moves around the sun so fast, and since it must change direction in order to "close" its orbit, then, wrt any given inertial frame, at some point in time during the course of a year and for an extended duration, we, the earth observatory, are in a moving frame of reference whose motion is quite pronounced. The fact that the physical laws behave in the same manner all year round, he proclaims, is evidence in strong support of "the principle of relativity in the restricted sense."

    Finally, note that "the principle of relativity in the restricted sense" is NOT synonymous with "special relativity."
    Last edited: Apr 12, 2004
  4. Apr 12, 2004 #3


    Thank you so much for your direct reply.

    I appreciate the remarks of your unnamed commentator. Again, I am not trying to puncture SR on the grounds of this limited question.

    Really, all I am doing is reading the Doctor's work, thinking about it, and asking questions.

    If I understand you correctly, then you are saying that, no, this example does not actually serve Dr. Einstein's intent. Which is what I suspected, but I wanted to know for sure.

    What does this portend for special relativity? Nothing, obviously. No part of the theory stands or falls on the grounds of this one example. But as I read this section of the book, I had cause to question this example. Either the example was not valid, or I was wrong. I was willing to countenance either possibility. I simply had a question.

    So, thank you for your help. I may now pass on to other questions.
  5. Apr 12, 2004 #4


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    Well, that is certainly nothing to be ashamed of, on the contrary. Good job, and keep it up.

    Well, I would say that it is a matter of taste. If you want to approach the material the way that I (and apparently you, as well) prefer to do, then I would do better off to skip the pipe example.

    Exactly. That was one of the main points of my previous response.

    I would say neither. It just didn't fit your learning style. That's why physicsforums is here for you, 24/7, working diligently to fulfill your physics learning needs. Well, some of us, anyway.
  6. Apr 13, 2004 #5
    Well, again, thank you for your assistance. I will now move on in my public study of the book.
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