Superluminal Sound

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A friend of mine has always been a proponent of the idea that longitudinal phase conjugate waves form the basis of the universal aether. I must admit that we’ve rarely if ever agreed. He recently shared the following about a 10yr old paper we would have discussed. Sound beyond the speed of light - Sorry that’s behind a paywall, https://doi.org/10.1063/1.2423240 I haven’t see it. Let’s make do with the Phys.org article about that paper instead.

'Mach c'? Scientists observe sound traveling faster than the speed of light
January 17, 2007, https://phys.org/news/2007-01-mach-scientists-faster.html.



Superluminal sound! Well, not really. Soon after the attention grabbing title, we’re told that the sound pulses traveling faster than light is the signal’s group velocity.

In their experiment, the researchers achieved superluminal sound velocity by rephasing the spectral components of the sound pulses, which later recombine to form an identical-looking part of the pulse much further along within the pulse. So it’s not the actual sound waves that exceed c, but the waves’ “group velocity,” or the “length of the sample divided by the time taken for the peak of a pulse to traverse the sample.”

So there’s really no paradox or violation of relativity, a group velocity is not the same as a signal velocity. The group waveform received through the loop filter is a narrow replica of the transmitted wave, we are assured that the information transferred does not exceed light speed. While all this is well and good and has been observed for electromagnetic signals, the big surprise here is that the effect is demonstrated with sound.  

The article doesn’t go much further into the details. The scalar guy thinks they’re hiding something, and I’m tempted to agree.

The mainstream has always attributed signal propagation to electromagnetic waves, and so light speed must be the limit. Here at this site we’ve discussed how electrical circuits can behave like antenna elements, the charge differential between the wires becomes the source for a net charge flow in both directions – two way signal flow, not just one (scalar phase-conjugate?). It seems to me that the two sides of the audio loop filter are linked in exactly the same way, although the acoustic energy must be far less than that available with a high voltage differential.

Just a few thoughts. Your comments are welcome.
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Interesting. Whenever I think of Sound waves... I seem to only see them as 2-D like a sonograph or wave pattern. How do these waves combine?
https://en.wikipedia.org/wiki/Sonograph

I remember seeing some articles about ultrasonic sonar imploding bubbles as light waves.  Of course the waves were not traveling at light speed but the sound is causing the light to result. Miles had a comment in one of his papers if I recall that ran against the conventional wisdom of the cause and effect of this phenomenon.

https://thetechjournal.com/science/sonoluminescence-light-is-created-by-sound-wave.xhtml
http://www.nanoscience.gatech.edu/paper/2017/17_NE_05.pdf
Why isn't radar used underwater instead of sonar if radio waves are faster than sound waves?
Asked by: Andrew Campbell
http://www.physlink.com/Education/AskExperts/ae456.cfm


https://en.wikipedia.org/wiki/Sonoluminescence

Found this... how to reduce impedance to nothing? Yikes c is still fast... (983,571,056.43 feet per second (ft/sec))

Mach c wrote:For the first time, scientists have experimentally demonstrated that sound pulses can travel at velocities faster than the speed of light, c. William Robertson’s team from Middle Tennessee State University also showed that the group velocity of sound waves can become infinite, and even negative.

Past experiments have demonstrated that the group velocities of other materials’ components—such as optical, microwave, and electrical pulses—can exceed the speed of light. But while the individual spectral components of these pulses have velocities very close to c, the components of sound waves are almost six orders of magnitude slower than light (compare 340 m/s to 300,000,000 m/s).

Read more at: https://phys.org/news/2007-01-mach-scientists-faster.html#jCp

Also, ITC recommended Robert J. Urick's book, Principles of Underwater Sound (1975), for further reference to impedance matching and underwater acoustic principles. Urick explains that the acoustic pressure of any sound wave will be inhibited by the impedance of the medium in which it propagates. Stresses, thus, set up in the elastic medium diminish the kinetic energy of the particles in motion that create sound (Urick 12). This phenomenon can be expressed and quantified, furthermore, by the following equation, which relates intensity (I) to the instantaneous acoustic pressure of a sound wave (p) (Urick 12):

I = p2 / þc

where þ is the density of the medium in which the sound propagates and c is the speed of sound in that medium. The intensity, or power, of a sound wave is, thus, inversely related to the factor þc, called the specific acoustic resistance of the medium (Urick 12). The greater this resistance, the less intensity a particular sound will have. Since the speed of sound is nearly five times faster in water than in air (1150 ft/s in air vs. 4750 ft/s in water—reaching 5050 ft/s in some areas of salt water) and since the density of water is much greater than air, furthermore, seawater has a specific acoustic resistance of 1.5 * 105 g/cm2·s, whereas air only has a resistance of 42 g/cm2·s: this is a difference of substantial magnitude—the specific acoustic resistance being 360,000% greater in water than in air! All this boils down to is that it is much harder to make a sound underwater than in air: sound waves of equal sound pressures will have much less intensity in water because of the greater acoustic resistance, or "impedance," of the medium. (Note: impedance should not be confused with attenuation or transmission loss; though more input energy is required to initiate the propagation of sound in water, signals can travel to surprisingly long distances in some cases.)

Like ITC, Urick also relays that ceramics are used in the construction of hydrophones to better match the high impedances involved with underwater sound: "In air, other kinds of transducers are commonly used. Among these are moving-coil, moving-armature, and electrostatic types. In water, piezoelectric and magnetostrictive materials are particularly suitable because of their better impedance match to water. Ceramic materials have become increasingly popular in underwater sound because they can be readily molded into desirable shapes. Present-day sonars use ceramic transducer elements almost exclusively because of their inexpensiveness and availability" (Urick 32). Urick explains, furthermore, what is meant by piezoelectric: "[In water, the ability to transduce sound to electrical energy] rests on the peculiar properties of certain materials called piezoelectricity (and its variant, electrostriction).... Some crystalline substances, like quartz, ammonium dihydrogen phosphate (ADP), and Rochelle salt, acquire a charge between certain crystal surfaces when placed under pressure; conversely, they acquire a stress when a voltage is placed across them. These crystalline substances are said to be piezoelectric. Electrostrictive materials exhibit the same effect, but are polycrystalline ceramics that have to be properly polarized by being subjected to a high electrostatic field; examples are barium titanate and lead zirconate titanate" (Urick 31-32). It is interesting to note, furthermore, that ITC does indeed use lead zirconate titanate as the electrostrictive ceramic in their hydrophones, as specified for their basic model ITC-4066 on their website: "Constructed of Channelite-5400 lead zirconate titanate (Navy Type 1 ceramic)" (ITC).

https://ccrma.stanford.edu/~blackrse/h2o.html

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Cr6 wrote. Interesting. Whenever I think of Sound waves... I seem to only see them as 2-D like a sonograph or wave pattern. How do these waves combine?
https://en.wikipedia.org/wiki/Sonograph

Thanks Cr6, as usual, I’ll try to describe charge field aspects from my limited understanding. Learning by explaining - I’m a fool most of the time - I’ll make some effort at it. Please feel free to slap me silly.
 
With respect to combined waves, most sounds can be represented as a mix of waves, or multiple frequencies at various amplitudes. In my humble opinion, that also happens to be the most important fact of electromagnetic field wave theory. Breaking sounds into discreet frequencies allows all kinds of mathematical operations. Time varying sounds – i.e. the frequency increase of a ‘chirp pulse’ – add to the complexity. I don’t recall ever having thought about the word sonograph before your post. Let’s start with plain old sound.

From Wiki https://en.wikipedia.org/wiki/Sound . In physics, sound is a vibration that typically propagates as an audible wave of pressure, through a transmission medium such as a gas, liquid or solid.

Given the charge field, I must assume that sound propagation is due entirely to photons. “Audible pressure wave” needs plenty of explaining. Photon bombardment does cause pressure, but what’s the nature of sound pressure? How do photons cause matter to vibrate?

Higher than average numbers of high energy photons are released by mechanical events, usually accompanying abrupt transfers of energy, as with two hands clapping. The sounds created depend on the intensity, duration, material, medium, structure, ..., and component frequencies of the matter involved. The “speed of propagation” is delayed from light speed, dampened and attenuated by the many atoms that channel the photons emitted by the energy event.

Sounds may be entirely due to charge channeling. The rate at which an average atom present recycles photons may be the major determinant of the resulting sound. A deep breath of Helium makes my manly voice sound like Minnie Mouse’s. Note that sound in a vacuum is excluded by definition. We know that photons traveling in a vacuum will encounter the least amount of matter interference, it may be correct to say that space conducts sound perfectly, at light speed and without any distortion, although we might have a hard time recognizing the resulting ‘sound’.

Music must be a special case. Given the standard atmosphere, air pressure, and temperature, instruments are a wonderful source of sound, the atoms of which spin-up the photons channeling through them. The photons are emitted at rates far faster than the atom’s own mechanical vibrations within the instrument’s structure. The vibrations become the sounds. Little tiny hairs within your inner ears resonate with every vibration.

I may not have convinced you or anyone else, but I don't see any problem thinking of light speed photons as mechanical energy carriers emitted by the source of sounds, vibrating atoms. The sound is delayed and propagated by additional atoms channeling and resonating those vibrations.    

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Sonoluminescence and cold fusion greatly interested me before I began learning about the charge field. I’d need to think a good deal more before interpreting fusion in terms of the charge field.

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The Underwater Sound links are overwhelming. I especially enjoyed the attenuation information.
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I too see my thoughts of phenomenon in terms of pre-Mathis and post-Mathis...and have to rethink a lot of things I thought I kind of had a "grasp" on. Sound is definitely one of them.

LTAM wrote:Sounds may be entirely due to charge channeling. The rate at which an average atom present recycles photons may be the major determinant of the resulting sound. A deep breath of Helium makes my manly voice sound like Minnie Mouse’s. Note that sound in a vacuum is excluded by definition. We know that photons traveling in a vacuum will encounter the least amount of matter interference, it may be correct to say that space conducts sound perfectly, at light speed and without any distortion, although we might have a hard time recognizing the resulting ‘sound’.

Music must be a special case. Given the standard atmosphere, air pressure, and temperature, instruments are a wonderful source of sound, the atoms of which spin-up the photons channeling through them. The photons are emitted at rates far faster than the atom’s own mechanical vibrations within the instrument’s structure. The vibrations become the sounds. Little tiny hairs within your inner ears resonate with every vibration.

I may not have convinced you or anyone else, but I don't see any problem thinking of light speed photons as mechanical energy carriers emitted by the source of sounds, vibrating atoms. The sound is delayed and propagated by additional atoms channeling and resonating those vibrations.    

Image of a Violin spectrogram... can you see the charge field?    

A spectrogram of a violin waveform, with linear frequency on the vertical axis and time on the horizontal axis.

The bright lines show how the spectral components change over time.

The intensity coloring is logarithmic (black is −120 dBFS).

https://upload.wikimedia.org/wikipedia/commons/d/d1/Violin_for_spectrogram.ogg