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B Can a wave exist independently?

  1. Jun 26, 2017 #1
    An atom of oxygen can be suspended in air, yes? Can a wave be suspended independently? Or does it need to be generated?
     
  2. jcsd
  3. Jun 26, 2017 #2

    DrChinese

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    What kind of wave are you referring to? Is this about quantum physics or classical?
     
  4. Jun 26, 2017 #3

    fresh_42

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    I moved it to General Physics, as I think there are some fundamental questions to be addressed before we talk about Schrödinger equations.

    A wave is a form of energy transmission. This can be interrupted, absorbed, created and so on. So the question is indeed, what kind of wave are you thinking of?
     
  5. Jun 26, 2017 #4

    sophiecentaur

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    Independently of what? You can have a hypothetical wave that exists purely in Maths but any Physical wave has to be in the form of some variations of a quantity and that quantity needs to be measurable and 'there'. If you can't measure or detect it then it doesn't exist.
    Gravitational Waves have only recently been shown to exist. Before some valid detection was achieved, they only 'existed' in our theories.
     
  6. Jun 26, 2017 #5

    fresh_42

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    This is mined territory! I want to remind participants (in advance) that we don't debate philosophical questions, the more as we already have plenty of threads, in which the question about the connection between "existence" and "measurement", resp. "observation" is discussed. Our search engine will be of help to all who are interested in following this path.

    The distinction is easy: measurement / observation = physics ; existence / real = philosophy.
     
  7. Jun 26, 2017 #6
    fresh_42,

    'The distinction is easy: measurement / observation = physics ; existence / real = philosophy.'

    That is very helpful. 8th grade earth science was as far as I got with science education, so this is all new territory to me.

    I will keep this distinction very much in mind before posting further questions or comments.

    Thank you.
     
  8. Jun 26, 2017 #7
    I am referring to the often posted references to waves such as in wave/particle duality. One was in a quote by a physicist:

    'If I have to express quantum physics only in one phrase, it will be: wave particle duality of nature. Rest is the detail.'
     
  9. Jun 26, 2017 #8
    Too bad "wave-particle duality" is an outdated concept since like 1925-26... You won't find it in quantum mechanics, nor in QFT.
     
  10. Jun 26, 2017 #9
    The question is confused from the beginning. What is the meaning of an atom of oxygen being suspended in air? How do you know which oxygen is part of the air itself and which is "suspended"? If you mean to have an atom completely at rest in the surrounding air, by what method do you think it was done?

    "Suspended" refers to something which will have the tendency to fall to the ground and which can be at rest if we somehow counteract the gravity. A wave is not an object to which we can apply these concepts. Will a "suspended" wave still propagate? Will the particles of the medium still move? You can attach "suspended" to "wave" but then you may have to redefine the word.

    We can link words to each other but they results does not always make sense, even though the grammar may be correct.
     
  11. Jun 26, 2017 #10
    nasu,

    As my science education ended 50 years ago, I have some catching up to do.

    Admittedly, many of my questions will be based on my personal concepts -- though I am working very hard to keep them within PF guidelines. Many, maybe most, may prove to be confused. That is why I am participating in PF. To become 'un-confused.'

    I would like to pursue the discussion with you, but am being very careful about what I write, as it is challenging to frame my thoughts within observation and measurement.

    But, perhaps you can tell me, what it is to be an atom of oxygen in air, or water, or wherever else it appears. What can physics say for certainty about its properties besides what I have read, that it has mass, charge and spin? The atom is 'somewhere' in the air I breathe. Can it be isolated from other atoms in air?

    A wave has to travel, yes? From one point to another? In its travelling, say a radio wave through the atmosphere, is it wrong to think of the wave as suspended?

    I don't know, that is why I ask.
     
  12. Jun 26, 2017 #11

    berkeman

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    You can have a stationary wave, or "Standing Wave", like the waves on a guitar string that generate traveling sound waves...

    https://en.wikipedia.org/wiki/Standing_wave
     
  13. Jun 26, 2017 #12

    anorlunda

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    Why do you ask only about the radio wave in the atmosphere? Why not in space? What do you thing the answer is for a radio wave in space?
     
  14. Jun 26, 2017 #13
    That is fascinating. I will check it out. Thank you.
     
  15. Jun 26, 2017 #14
    I did not have a reason for framing the question as I did. It was an example only. My understanding of waves and space is elementary. Perhaps you can fill me in. What are all the places where waves (quantum waves?) occur?
     
  16. Jun 26, 2017 #15
    Regarding the atom part, I am now confused about what are you asking. Atoms can be manipulated and isolated. Initially I thought you read about these atom traps where atoms are slowed down or even at rest for some time. But these experiments are done in high vacuum so if the atom can be considered suspended, it is not in air. Unless you man the "in air" as a figurative way of saying "in space".

    For the wave part, it looks more like a matter of words. I don't see how insisting on being or not "suspended" bring anything useful. The dictionary definition of "suspended", the one that would apply to a an atom, is
    " to keep from falling or sinking by some invisible support (such as buoyancy)".
    Do you think this will apply to a propagating (or standing) wave? Or even to a bullet flying through the air. Would you say that the bullet is suspended while is approaching the target?
     
  17. Jun 26, 2017 #16
    Huh! What concept has replaced it?
     
  18. Jun 26, 2017 #17

    sophiecentaur

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    What would it be suspended in? One thing about all waves is that energy is being transported. Even in a standing wave, energy can be thought of as moving leftwards and rightwards, to produce stationary peaks and nulls in the energy distribution.
    The ancient idea of particle wave duality still has some legs because it is possible to treat matter and EM waves in either of the two ways, depending on what you are actually observing. The basic lesson about EM waves is to avoid ever ever ever treating them as if the photons are like little bullets. :H The Particles that are Photons are only visualised for the purposes of discussing the interaction of EM waves with matter.
     
  19. Jun 26, 2017 #18
  20. Jun 26, 2017 #19

    sophiecentaur

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    Do not expect an easy ride on the way to getting this sorted. :smile:
    It has long been admitted that people who think they understand QM, don't. Your brain will hurt.
     
  21. Jun 26, 2017 #20
    S. - 'What would it be suspended in?'

    G. - My thought is that there are atoms of oxygen surrounding me, suspended in the air. They are also in my veins, suspended in the blood. And so on. If suspended is the wrong word, can you give me the correct one? Or, tell me, where all of those atoms of oxygen, if they are not suspended?

    S. - 'One thing about all waves is that energy is being transported.'

    G. - Excellent! That is what I need to understand.

    S. - 'Even in a standing wave, energy can be thought of as moving leftwards and rightwards, to produce stationary peaks and nulls in the energy distribution.'

    G. - Is there a specific name for the type of energy being transported by the wave?

    S. - 'The ancient idea of particle wave duality still has some legs because it is possible to treat matter and EM waves in either of the two ways, depending on what you are actually observing.'

    G. - I had to look up the definition of EM waves. Of course, ElectroMagnetic. Would you say that all waves of quantum physics are EM waves? I imagine so, as what other type of wave could there be.... except maybe sound waves.... but are those EM waves also?

    S. - The basic lesson about EM waves is to avoid ever ever ever treating them as if the photons are like little bullets. :H The Particles that are Photons are only visualised for the purposes of discussing the interaction of EM waves with matter.

    G. - Photons, it seems, are in a class by themselves. A physicist told me a few years ago that super-string theory had been replaced by 'wavicles.' Is it true that photons behave sometimes like waves and sometimes like particles? I also read that photons are particles without mass. Oi. So many new questions come to mind....
     
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