Is nonlinear acoustics in mainstream physics?

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Discussion Overview

The discussion revolves around the concept of nonlinear acoustics, its presence in mainstream physics literature, and the experimental evidence supporting it. Participants explore the definitions, implications, and applications of nonlinear acoustics, particularly in relation to shock waves and other phenomena, while questioning its representation in standard physics textbooks.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • Some participants note that nonlinear acoustics involves scenarios where frequency and wavelength are not linearly dependent, or where wave speed varies with amplitude.
  • Others argue that shock waves represent a special case of nonlinear acoustics, but express difficulty in finding experimental evidence or theoretical discussions in mainstream physics textbooks.
  • A participant references Hans Bethe's historical work on acoustic theory, suggesting it has not been integrated into modern physics.
  • Some contributions highlight that nonlinear acoustic phenomena are discussed in specialized texts and engineering literature, rather than general physics textbooks.
  • Participants mention that nonlinear effects can arise in materials with physical hysteresis and that these effects can complicate the understanding of acoustics.
  • There are references to specific texts and papers that discuss nonlinear acoustics, including suggestions for further reading.
  • Questions arise regarding whether nonlinear acoustics can be observed in ideal gases, with mixed responses indicating conditional agreement based on context.
  • Some participants emphasize the need to look beyond traditional physics textbooks to find relevant information on nonlinear acoustics, suggesting a broader range of sources including journal articles and military research reports.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the status of nonlinear acoustics in mainstream physics. While some acknowledge its existence and relevance, others express skepticism about the availability of experimental evidence and its representation in standard educational materials.

Contextual Notes

Participants note limitations in the discussion, including the dependence on specific definitions of nonlinear acoustics, the varying interpretations of experimental evidence, and the potential for confusion in educational contexts due to the complexity of the topic.

  • #31
russ_watters said:
C'mon. You ask about a real world event and then try to apply non real-world constraints? What are you doing here? What is your goal? What is the real question? You're getting truly spectacular instruction but you seem intent to play games with it instead of learning what they are trying to tell you. Please make your line of questioning make sense. Rapidly.
OK, but give me overnight to frame my answer carefully. I sense a sword of Damocles hanging over my answer.
 
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  • #32
Squizzie said:
Where does the ratio of ω/k (frequency/wavelength) change from a value that remains constant for 0<overpressure < 100 Pa to something different for 10,000 < overpressure?
Your question is unanswerable as asked: the onset of nonlinear acoustic propagation is a function of both the sound frequency and the distance to the source. Here's a graph from a study of the onset of nonlinearity in noise from a jet engine: https://physics.byu.edu/docs/publication/646:
1703566558160.png

Evidently, at a distance of ##305\text{ m}##, nonlinear effects begin to be seen at a surprisingly modest SPL of ##\sim100\text{ dB}=2\text{ Pa}=0.0003\text{ psi}## for frequencies from ##\sim2-20\text{ kHz}##. Can you sharpen your question by citing the specific frequency and distance you're asking about?
 
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  • #33
Squizzie said:
OK, but give me a overnight to frame my answer carefully. I sense a sword of Damocles hanging over my answer.
I agree, it will take time to manipulate scientists into saying something that agrees with your false belief. You already know the answer you want, and you are probably the most dogmatic member I know still here on PF. All you have to do now, is restrict the question to where your belief is acceptable. You will never accept that scientific terminology can have an actual meaning.

Participating in your threads is like playing musical chairs, you will win, because you are prepared to argue against the accepted science. That is Brandolini's law at play.
https://en.wikipedia.org/wiki/Brandolini's_law
 
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  • #34
Squizzie said:
I sense a sword of Damocles hanging over my answer.
Indeed. And who do you think put it there?

This thread probably is one of the best from the point of view of information provided, and one of the worst for the impact of this information. There is a great deal of information on how sound waves behave, and that's countered by, so far as I can tell, the statement that if you ignore non-linearities, what you are left with is linear.
 
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  • #35
Whereas standard acoustic textbooks may dedicate a limited space to nonlinear waves, there are whole books treating only nonlinear effects. This is an example I remember from my university years. I liked the sound of this word, "soliton".
They had conferences on these topics. So definitely not an ignored topic. This was 1978.
https://www.cambridge.org/core/jour...8-300-pp-975/5F487793DADDA3A82EAA4C1849AA3D88
 
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  • #36
russ_watters said:
C'mon. You ask about a real world event and then try to apply non real-world constraints? What are you doing here? What is your goal? What is the real question? You're getting truly spectacular instruction but you seem intent to play games with it instead of learning what they are trying to tell you. Please make your line of questioning make sense. Rapidly.
When I read the Forum Rules, I was encouraged by its Mission Statement and Guidelines, that it would be a forum in which topics could be discussed in a scholarly manner.
I am aware that members have been warned, penalised and even banned from the forum for contravening the "Non-mainstream Theories" guidelines.
I do not wish to suffer a similar fate, and so I started this thread to determine whether or not "nonlinear acoustics" falls under the category of a "Mainstream Theory".
In the process, I acknowledge that I've veered off course from my original intention by responding to comments that were somewhat unrelated to my initial query.
So, to answer your question "what is your goal?" may I refer you to the title of the thread: "Is nonlinear acoustics in mainstream physics?", and the TL;DR Summary where I state "Looking for a physics text on sound or wave theory, explaining the circumstances where frequency and wavelength are not linearly proportional."
 
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  • #37
Squizzie said:
...I started this thread to determine whether or not "nonlinear acoustics" falls under the category of a "Mainstream Theory"....

So, to answer your question "what is your goal?" may I refer you to the title of the thread: "Is nonlinear acoustics in mainstream physics?"
The answer you were given to that question, obviously and simply, is "yes". And as a bonus you were given a bunch of sources and information to help you learn about it and an explanation of why what you've tried hasn't found that answer.

So, is that it? Do you accept this answer and are we finished?
 
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  • #38
russ_watters said:
The answer you were given to that question, obviously and simply, is "yes".
So, is that it? Do you accept this answer and are we finished?
No, not at all, but since, by identifying the subject as a "Mainstream Theory", you have unilaterally declared further discussion unacceptable, I will not risk the ire of the Forum by discussing it further.

I am however deeply disappointed that a forum with such lofty ideals such as yours, has descended to accepting references from Wikipedia and commercial, non-peer-reviewed commercial publications such as Springer as "Acceptable Sources"
 
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  • #39
Squizzie said:
I am however deeply disappointed that a forum with such lofty ideals such as yours, has descended to accepting references from Wikipedia and commercial, non-peer-reviewed commercial publications such as Springer as "Acceptable Sources"
Can you cite an example of a non-commercially published, peer-reviewed publication that you find acceptable?
 
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  • #40
nasu said:
Whereas standard acoustic textbooks may dedicate a limited space to nonlinear waves, there are whole books treating only nonlinear effects.
Apart from the obscure reference in Feynman I quoted in the introduction of this thread, I have been unable to find any physics textbook with any reference at all. Maybe you can oblige with a reference?
 
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  • #41
Squizzie said:
Apart from the obscure reference in Feynman I quoted in the introduction of this thread, I have been unable to find any physics textbook with any reference at all. Maybe you can oblige with a reference?
But most all physics textbooks are published commercially to make a profit and written by academic experts but not necessarily peer reviewed. How do we know you won't simply reject and ignore any reference we propose, as you are so often prone to do?
 
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  • #42
I am adding the OP to my ignore list. I would suggest other PF members do the same.
 
  • #43
Squizzie said:
No, not at all, but since, by identifying the subject as a "Mainstream Theory", you have unilaterally declared further discussion unacceptable, I will not risk the ire of the Forum by discussing it further.
In other words, you reject the idea that there's such a thing as non-linear acoustics in mainstream science and were hoping to discuss your rejection of it. Clearly it does exist so yes, this line of discussion is a no-go on on PF. Thanks for your compliance with the rules.
Squizzie said:
I am however deeply disappointed that a forum with such lofty ideals such as yours, has descended to accepting references from Wikipedia and commercial, non-peer-reviewed commercial publications such as Springer as "Acceptable Sources"
Squizzie said:
Apart from the obscure reference in Feynman I quoted in the introduction of this thread, I have been unable to find any physics textbook with any reference at all. Maybe you can oblige with a reference?
That makes no sense. The first reference YOU WERE GIVEN was a textbook and the second was a peer-reviewed, published paper (and so I didn't check any of the others). The only viable explanation for your incredulity is that you didn't even look at any of the references you were given because you don't actually want to see them. You can't win an argument - much less learn anything - by closing your eyes and holding your hands over your ears and pretending the evidence doesn't exist. You're deeply disappointed? C'mon.

This thread is closed. Do not restart this nonsense again.
 
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