"Physicists Discover a Remarkable New Type of Sound Wave"

[koti]

Interesting, any thoughts on how to apply this into use?

https://scitechdaily.com/physicists-discover-a-remarkable-new-type-of-sound-wave

[StringJunky]

I've seen that shape along a vibrating guitar string, with a crt tv acting as a strobe source with the room  lights out. It was totally accidental and I was never able to repeat it; positioning and angle was obviously very critical. The guitar was laid flat on the floor and I was idly picking strings just listeng to its tone.

Edited December 12, 2021 by StringJunky

[joigus]

Interesting. I wonder if you would need some kind of wave guides to keep that going. The resonators that produce it seem to be very special, and I'm not sure that once the waves are on the air the vortices would be maintained. But sounds good, and sorry for the lame pun.

As to applications, I simply don't know, besides the obvious: More degrees of freedom imply that more information could be carried by the wave.

[geordief]

5 minutes ago, joigus said:

Interesting. I wonder if you would need some kind of wave guides to keep that going. The resonators that produce it seem to be very special, and I'm not sure that once the waves are on the air the vortices would be maintained. But sounds good, and sorry for the lame pun.

As to applications, I simply don't know, besides the obvious: More degrees of freedom imply that more information could be carried by the wave.

Maybe endless amusements for dolphins?

Or to cook fusilli pasta?

Edited December 12, 2021 by geordief

[joigus]

6 minutes ago, geordief said:

Maybe endless amusements for dolphins?

🤣

Humpback whales should be sounded out on this too.

And as to cooking, I don't know, but a fusilli version of Dark Side of the Moon seems interesting.

[geordief]

59 minutes ago, joigus said:

🤣

Humpback whales should be sounded out on this too.

And as to cooking, I don't know, but a fusilli version of Dark Side of the Moon seems interesting.

A sort of "Cher effect"?

Edited December 12, 2021 by geordief

[StringJunky]

57 minutes ago, joigus said:

🤣

Humpback whales should be sounded out on this too.

And as to cooking, I don't know, but a fusilli version of Dark Side of the Moon seems interesting.

That would really send you into a vortex.

[geordief]

3 minutes ago, StringJunky said:

That would really send you into a vortex.

Dark side of the Black Hole

[joigus]

7 hours ago, StringJunky said:

That would really send you into a vortex.

It already did in 1992, when I first listened to it.  

[koti]

1 hour ago, joigus said:

It already did in 1992, when I first listened to it.  

Yep, me too. 

[studiot]

Thank you for the article.

Sorry to pour a bit of cold water, but I have some doubts about the scientific veracity of both the article and its publication site.

I am wary of a site that also offers articles like "Did Hubble discover God ? Einstein amazed"  and  "DNA code points to a creator"

The article offers a description of wave motion that we teach as an introduction for 14 - 16 year olds at 'O' level.

It has actually been known for a century and a half or more that there are more types of waves than transverse and longitudinal.

Some (Rayleigh waves) are even named after the Physicist who studied them.

 

This is not to say that the Hong Kong scientists have not discovered something interesting and perhaps new.

 

But the article does not say what is vibrating in its diagrams. (Plots c and d)

Pressure is not a vector.

The demonstration device (in picture a)  looks like some sort of focusing device.
An array of sound sources.
It is well known that the sound output is more and more narrowly focused the more speakers you put into a line array.
This fact is used in stage speakers.

Pictures d and e seem to me to show interference from multiple sound sources.

However the group of pictures are entitled negative refract induced by the spin- orbital interaction in momentum space.
The false colour appears to give intensity values, but intensity of what ? It does not say.

So perhaps the scientists have engineered a clever way to manipulate sound.
 

 

 

[koti]

1 hour ago, studiot said:

Thank you for the article.

Sorry to pour a bit of cold water, but I have some doubts about the scientific veracity of both the article and its publication site.

I am wary of a site that also offers articles like "Did Hubble discover God ? Einstein amazed"  and  "DNA code points to a creator"

The article offers a description of wave motion that we teach as an introduction for 14 - 16 year olds at 'O' level.

It has actually been known for a century and a half or more that there are more types of waves than transverse and longitudinal.

Some (Rayleigh waves) are even named after the Physicist who studied them.

 

This is not to say that the Hong Kong scientists have not discovered something interesting and perhaps new.

 

But the article does not say what is vibrating in its diagrams. (Plots c and d)

Pressure is not a vector.

The demonstration device (in picture a)  looks like some sort of focusing device.
An array of sound sources.
It is well known that the sound output is more and more narrowly focused the more speakers you put into a line array.
This fact is used in stage speakers.

Pictures d and e seem to me to show interference from multiple sound sources.

However the group of pictures are entitled negative refract induced by the spin- orbital interaction in momentum space.
The false colour appears to give intensity values, but intensity of what ? It does not say.

So perhaps the scientists have engineered a clever way to manipulate sound.
 

 

 

They’re sciting the original article in Nature:

https://www.nature.com/articles/s41467-021-26375-9

[studiot]

2 hours ago, koti said:

They’re sciting the original article in Nature:

https://www.nature.com/articles/s41467-021-26375-9

And ?

[StringJunky]

3 hours ago, studiot said:

And ?

Wouldn't that suggest it's been through peer review if Nature accepted it for publication?

[studiot]

2 hours ago, StringJunky said:

Wouldn't that suggest it's been through peer review if Nature accepted it for publication?

 

How does any of this affect my technical comments ?

Did the peer reviewers not ask what was being plotted on the axes ?

The article I was presented with was almost certainly not peer reviewed.

Perhaps the Nature article was, I don't know.

Perhaps the Nature article told us what was being plotted on the graph axes.

I lost the will to plough through paper, referring to paper, perhaps referring to........

Rayleigh introduced his waves in 1885, although these are not Rayleigh waves.

[joigus]

I will add my voice to Studiot's here in formulating some criticism. I'm having more and more doubts, not so much about the correctness of the result that you can produce vortices of air that propagate following a wave equation inside a cavity or resonator, but rather about the --at the very least ambiguous-- suggestion that these vectorial waves would propagate through open air to a certain extent mimicking light waves in the vacuum. That's at least what the announcement seems to suggest. Perhaps it's a matter of how you voice your results. The exaggerated claim I think is implied in the wording,

Quote

Physicists Discover a Remarkable New Type of Sound Wave

by the editors of SciTechDaily. I think this is overstating what the authors meant, although they did call it 'sound'.

There's no fundamental principle of physics that forbids vortices to form in the air. AAMOF, they form on a regular basis. It's more difficult for me to discern from the article that these vorcices would propagate through open air satisfying a wave equation, and not breaking down due to dispersion --which seems to me to be the inevitable physical consequence from an intuitive POV.

Quote

 

The equations governing the propagation of the sound wave in the chiral micropolar medium are given by the conservation of linear momentum and angular momentum:

(My emphasis.)

Eqs. 1-8 seem indeed to imply wave equations for the so-called microrrotation field. I don't see why this merits the name of 'sound.' Neither is it sound from a formal definition, nor would it be experienced as such, IMO, by a listener. Its solutions I would call travelling eddies; meaning a travelling, rotational gust of wind, rather than sound. As Studiot says, sound is a pressure wave, which is a scalar.

These wave equations would hold inside the medium --resonators--, I think; so you would need a wave guide made of a battery of these resonators, I suppose.

The general idea that I get from it all is that they've found perhaps an interesting way to build an analogue model of light with guided waves of moving air, plus a mechanism for switching incoming sound waves into these travelling-eddy analogue of light.

I don't mean any of this to be a hard-nosed criticism, but just the kind of questions I would pose to the authors, in ordet to get a more precise idea of what this is about.