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The proposed ultrasound frequencies are 10-100 times as high as the ones usually used for imaging purposes, so the conclusion that it must be harmless does not

The proposed ultrasound frequencies are 10-100 times as high as the ones usually used for imaging purposes, so the conclusion that it must be harmless does not naturally follow.

clairity 6y ago
i haven't delved into the specifics here, but note that a higher frequency doesn't necessarily mean a higher flux of energy, so that conclusion doesn't necessarily follow either.
- _Microft 6y ago
  It does not need a "higher flux of energy" to do damage. Exciting a system at its resonance frequency can increase the amplitude of its vibrations to the point that it gets damaged. This does not take lots of energy, it does not take large amplitudes, just periodic input of power at the right frequency. Knowing that a system is fine at one frequency does not say (that) much about other frequencies.
  - clairity 6y ago
    yes, resonance can be significant, but that still doesn't necessarily mean that the energies here are significant, nor that the frequencies applied are the right frequencies, and resonant enough, for damage. the underlying point is that unless we're capable of doing the relevant experiments ourselves, we need to trust that people in the field are cognizant enough to realize these obvious issues, test them, and report their findings. it's unlikely that lay people like us are going to find and gotcha the researchers in the field. that's not to say that, in aggregate, we can't give researchers ideas about what to be researching. that, we can--and should--do, via conversations like this.
    - deleted 6y ago
      [deleted]
    - _Microft 6y ago
      > yes, resonance can be significant, but that still doesn't necessarily mean that the energies here are significant, nor that the frequencies applied are the right frequencies, and resonant enough, for damage. I did not claim that the proposed method has to be harmful. I stated that ultrasound imaging gives little to no insight in what happens at frequencies that are an order of magnitude or two higher than that. The second reply was an attempt to do away with the misconception that "higher flux of energy" was necessary for damage.
aksss 6y ago
> "...vibrations between 25 and 100 megahertz" "Ultrasound frequencies in diagnostic radiology range from 2 MHz to approximately 15 MHz" https://radiopaedia.org/articles/ultrasound-frequencies?lang=us https://radiopaedia.org/articles/ultrasound-frequencies?lang... So 10-50 times as high, but yeah.
blacksmith_tb 6y ago
But it's worth contrasting with focused ultrasound[1] which is used to either heat or shatter tissues, at higher frequencies and amplitudes. 1: https://en.wikipedia.org/wiki/High-intensity_focused_ultrasound https://en.wikipedia.org/wiki/High-intensity_focused_ultraso...
- nullserver 6y ago
  For a visualization, A lower frequency but high intensity method can be used to cook meat. https://youtu.be/LHFhnnTWMgI https://youtu.be/LHFhnnTWMgI
idrios 6y ago
Agreed. You could substitute ultrasound waves with electromagnetic waves in this same conversation. We use EM waves every day for diagnotics -- at the 740-380nm range because that's visible light. 10x-100x frequency of that is ultraviolet, which is harmful. And as for resonant frequencies, it doesn't seem unreasonable to me that certain frequencies could denature certain proteins or have other effects.

The proposed ultrasound frequencies are 10-100 times as high as the ones usually used for imaging purposes, so the conclusion that it must be harmless does not naturally follow.

clairity 6y ago

i haven't delved into the specifics here, but note that a higher frequency doesn't necessarily mean a higher flux of energy, so that conclusion doesn't necessarily follow either.

_Microft 6y ago
It does not need a "higher flux of energy" to do damage. Exciting a system at its resonance frequency can increase the amplitude of its vibrations to the point that it gets damaged. This does not take lots of energy, it does not take large amplitudes, just periodic input of power at the right frequency. Knowing that a system is fine at one frequency does not say (that) much about other frequencies.
- clairity 6y ago
  yes, resonance can be significant, but that still doesn't necessarily mean that the energies here are significant, nor that the frequencies applied are the right frequencies, and resonant enough, for damage. the underlying point is that unless we're capable of doing the relevant experiments ourselves, we need to trust that people in the field are cognizant enough to realize these obvious issues, test them, and report their findings. it's unlikely that lay people like us are going to find and gotcha the researchers in the field. that's not to say that, in aggregate, we can't give researchers ideas about what to be researching. that, we can--and should--do, via conversations like this.
  - deleted 6y ago
    [deleted]
  - _Microft 6y ago
    > yes, resonance can be significant, but that still doesn't necessarily mean that the energies here are significant, nor that the frequencies applied are the right frequencies, and resonant enough, for damage. I did not claim that the proposed method has to be harmful. I stated that ultrasound imaging gives little to no insight in what happens at frequencies that are an order of magnitude or two higher than that. The second reply was an attempt to do away with the misconception that "higher flux of energy" was necessary for damage.

aksss 6y ago

> "...vibrations between 25 and 100 megahertz" "Ultrasound frequencies in diagnostic radiology range from 2 MHz to approximately 15 MHz" https://radiopaedia.org/articles/ultrasound-frequencies?lang=us https://radiopaedia.org/articles/ultrasound-frequencies?lang... So 10-50 times as high, but yeah.

blacksmith_tb 6y ago

But it's worth contrasting with focused ultrasound[1] which is used to either heat or shatter tissues, at higher frequencies and amplitudes. 1: https://en.wikipedia.org/wiki/High-intensity_focused_ultrasound https://en.wikipedia.org/wiki/High-intensity_focused_ultraso...

nullserver 6y ago
For a visualization, A lower frequency but high intensity method can be used to cook meat. https://youtu.be/LHFhnnTWMgI https://youtu.be/LHFhnnTWMgI

idrios 6y ago

Agreed. You could substitute ultrasound waves with electromagnetic waves in this same conversation. We use EM waves every day for diagnotics -- at the 740-380nm range because that's visible light. 10x-100x frequency of that is ultraviolet, which is harmful. And as for resonant frequencies, it doesn't seem unreasonable to me that certain frequencies could denature certain proteins or have other effects.