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Physics - why questions

  1. Mar 26, 2012 #1
    Not sure if this is the right place to post this question but still:-

    I always asked "why" questions in physics but lately my proffesor told me to stop asking such questions( because sometimes i went too deep). HE says that all physics does is to give a mathematical description to natural phenomena

    This troubles me - i always thought asking why things happen is a good thing. Shouldnt i ask the "why" questions. Also lately i have many "why" questions that are difficult to answer. But they irritate me - until i get the answer i feel restless. How to deal with it?
  2. jcsd
  3. Mar 26, 2012 #2
    Sometimes "why" questions cannot be answered unless you get into philosphy.
    I always try to get my students to accept that science (not just physics) is about "what"
    happens and "how"
    Ultimately the answer to "why" is "because God wills it to be so"....depends on your God
  4. Mar 26, 2012 #3


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    I've had lecturers say similar things before. I think the point is to avoid a common confusion that occurs in the English language; that "why" indicates purpose or conscious action. Not always of course but there isn't a perfect overlap between how and why. For instance if I were to ask "why did the human race evolve" to some people that would imply a purpose behind the question, same as if I asked "why is the knife on the chopping board".

    If instead we ask how we cut out some of this confusion by changing the nature of why we are asking. "Whys" often result in logical fallacies of begging the question by presuming there is a why to answer in the first place.
  5. Mar 26, 2012 #4


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    You can keep asking - just don't be surprised if nobody knows the answer.
  6. Mar 26, 2012 #5


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    The word "why", when used in Science doesn't mean the same as in "Why did you eat the last biscuit?" In that context, you are asking for someone to give a reason which is really an excuse - "Because I was hungry", "Because I thought there were more in the cupboard".
    "Why" in physics can only elicit an answer that takes you a bit further down into the mechanism and there is no end to the process.
    A satisfactoy answer to a "why" will depend on the person who asked and must involve just enough of what they already know and feel they understand to take them a bit further along the line.
    Feynman was a grumpy sod but he was right to bite someone's head off when they demanded an 'ultimate why' answer.

    I do get cross when people on these fora demand a 'physical explanation' for some highly sophisticated or abstract topic. They are, in fact, debasing the whole thing by thinking that, 'if only' someone would use the right combination of words like Force, Time, Temperature then they would have it all sussed out. The fact is that we needed Maths long ago in order to build models of the world (dammit, there were some very bright people who got us to this stage) and the Arm Waving approach would never have got us as far as we have got.
    Expecting to understand Physics without Maths is like expecting to read a French Novel without having learned any vocabulary.
    That is the least Grumpy answer I can come up with!! :grumpy:
  7. Mar 26, 2012 #6
  8. Mar 26, 2012 #7


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    Yeah. If you are asking a "why" question, you are probably asking the wrong question. Of course, sometimes it's inevitable. I mean, knowing all the right questions is equivalent to knowing all the answers. So discouraging such questions is a bad idea. But when you ask a "why" question, be prepared for the fact that it's the wrong question, and you'll end up talking about what makes it wrong rather than get anywhere closer to the answer. Sometimes, in the process, you understand enough to ask the right question, and then you move forward, but not always.

    Edit: Watching that Feynman video. Guy asks him about magnets, and he talks about ice! Physicists! Used to drive me insane when I was a kid and I'd ask my father something. Of course, now I do the same thing quite often.
  9. Mar 26, 2012 #8
    Sometimes in a class with many students, "why" questions are a diversion or interruption from the topic being discussed. Sometimes when my high school physics teacher's answer was "I don't know", I went to the school library where there some college physics textbooks.
  10. Mar 26, 2012 #9


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    It still depends. For every person who asks a question, there are ten more who thought of it and didn't ask and ten more of these who didn't think of it, but would benefit from an answer. So these diversions are often necessary. It's really rather situational.
  11. Mar 27, 2012 #10


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    The above rash of posts is interesting (I like the idea of a diversion tactic!). Of course the 'why' question will turn up frequently because it's probably the only way-in to some discussions. I guess that "why" is really an invitation to re-jig the question into something that can actually contain some sort of answer that contains useful information.
    We could, perhaps, not discourage the use of "why" questions but make it clear that the answer will probably not be the 'reason why'.
  12. Mar 27, 2012 #11


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    I prefer students to ask "How?" (does a process function). For example, if you measure the Cosmic Microwave Background Radiation and discover some perturbations one might ask why are they present? But more important is, IMO, how was the radiation modulated? That is, by what mechanism?
  13. Mar 27, 2012 #12


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    Absolutely. Better to describe a process than some nebulous philosophy behind a phenomenon.
  14. Mar 27, 2012 #13
    In high school, we were rolling ball bearings down inclined planes, and measuring the acceleration and elapsed time. The acceleration was about 30% lower than expected, and the elapsed time too high. More measurements at different slopes further validated the results. I asked "why", and the teacher did not have an answer. This became a challenge.

    I spend the next week reading college physics textbooks about moments of inertia, and enough integral calculus to formulate and calculate the moment of a rolling ball bearing. A revised analysis of the inclined plane data including the inertia of the ball bearing showed agreement with the expected acceleration and elapsed time.

    If the teacher had known the answer, and explained it to me, it would have been a distraction for the other students, who would not have understood what a moment of inertia is, and why it affected the result. Nor would I have learned enough calculus to discover the answer myself. In the end, both the other students and I benefited from the teacher not answering my "why".
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