Sound waves are not electromagnetic waves at all, but they can interact with EM waves.  Sound waves are mechanical vibrations so they need a medium to propagate.  EM waves can propagate in outer space.  They don't need a medium.  This bothered early scientists and they discussed the aether.  Anyway, sound waves at the right frequency can moves charges that will interact and exchange energy with photons.  Photons are light and light is an EM wave.  When they do interact, they shift the wavelength of light due to the loss or gain of energy.  So sound can change the color of light.

No. Sound waves are not electromagnetic waves. Sound waves are mechanical waves propagated by oscillation of  physical material and needs physical medium. Where as electromagnetic waves are generated by oscillation of electrostatic and magnetic fields together and do not need physical medium. I agree that, due to oscillation of physical particles having surface charge  during travel of sound, an   oscillatory electrostatic field may get created. But the  oscillatory  flow  of these charged particles must be guided in the shape of a solenoid having ferrite material to induce magnetism thereby making a combination of elector-magnetic oscillation. During travel of sound waves such combination is not there.

http://missionscience.nasa.gov/ems/02_anatomy.html

This is a weird question 

Hi Chris,

It looks weird at first sight, YES!

Please give deeper thought.

All elasticity is electromagnetic in origin. Thus an elastic wave should be amenable to be considered as an EM wave, if not of the traditional Maxwell type, where Longitudinal fields are set to zero by hand to look for transverse solutions.

Van der waals forces in gases and liquids and Madelung forces between ionic layers in solid lattices which take part in the transmission of sound waves are in essence electrostatic forces, disturbances of which when travelling should be considered as electromagnetic.

Cheers, and thanks to all respondents.

Regards,

Rajat

Rajat, fair enough, but that's stretching the definition a bit, isn't it? If you go down that road then you can stretch quite a number of definitions, & I'm not sure if by doing so you'd add much value in explanatory or any other terms ....

Best

Chris

Chris,

Let's see if something interesting comes out of the discussion. The whole point is to have a unified description on the basis of a more fundamental theory. EM theory of Maxwell explains optics, much of atomic and molecular dynamics, whole of electromagnetic phenomena (except of course, domains where QM is essential). Now, the next great leap in understanding and explaining whole of classical physics including mechanics (and thermodynamics) by a single theory would be to explain mechanics by electrodynamics. This would be very very difficult, I admit, but we have to do it some day, since mechanical forces are not fundamental. All of mechanics involves Gravitation and Electromagnetic forces.

Therefore, we must get out of the Newtonian mould and look deeper into mechanics in terms of fundamental interactions. This is worthwhile for unification of all classical physics. Lagrangian and Hamiltonian dynamics do it in the sense of providing a formulation.

Hope you got the point.

Regards,

Rajat

@ Sandeep Joshi,

Hi Joshi,

EM waves are possible at all wave lengths. And also sound waves are possible over a very large range of wavelengths. Velocity is of course low for sound waves. The point is Longitudinal electric field oscillations which are ignored in Maxwell's theory may explain the phenomenon of sound waves in media. The low velocity may be due to photon becoming massive. QFT supports this view also, where massive spin one gauge bosons like W+, W- etc always move with speed less than c. So may be sound can be seen as  propagation of massive longitudinal photons in material media. Details are to be worked out of course.

Regards,

Rajat

Longitudinal electromagnetic waves do exist...sort of.  They do not exist for plane waves in infinite media, but they can do exist in special circumstances.  Surface plasmons are mostly longitudinally polarized.  There are longitudinal polarization states on some periodic structures.  If you study spectroscopy or atomic scale resonance phenomena, there are longitudinal electromagnetic waves that interact with the medium to produce resonances.

Thanks Raymond for your responses.

Yes, plasmon oscillations are there. But the question is whether they can be related to sound waves?

Regrds,

Rajat

Completely agree with Chris Ransford. Upon quantisation, sound waves in sold turn out to be phonons. This way as an analogue one can think of and elucidate the nature of sound waves. It is bizarre if one stretches imagination to think one in terms of the other.

Dear Arunagiri,

The whole thrill of science lies in thinking of the unthought-of and not  toeing the accepted line of thought. What is mechanical force if it is not electromagnetic? The problem with us is that we are having an unscientific attitude towards anything that seems to be going contrary to what is accepted in science.

My reasoning is this:

Since we have only four fundamental forces and we claim that everything can be explained only and only in terms of these four forces, mechanical force must be electromagnetic. Once this is accepted (and I don't think anyone will disagree with it) ,  mechanical waves will become electromagnetic waves in the long run. Some way they have to be related. That no body has so afr done it is a different matter altogether.

Many thanks for your response however,

Regards,

Rajat

Hello Friends!

I have another point to discuss -

If the sound waves can be thought of electromagnetic waves (by some means or hypothesis!!!) then I have one further question -

1) The electromagnetic waves (as of what we know them) travel even through the vacuum.

2) Therefore, in that context, even if the Sound waves "CAN" be thought of Electromagnetic in nature, then this sound should also travel in vacuum. Is that possible???

How do we justify this then???

No sound waves in vacuum.  Sound needs a physical medium.  EM waves do not.

Hello Raymond!

Thanks for your response. That is what my question or doubt was. I know that sound waves do not travel in vacuum. Therefore thinking of sound waves as EM waves cannot be justified or leads to several doubts like what I have raised here.

They are still waves and therefore share certain characteristics.  They look similar, diffract similar, mix with other waves similarly, etc.  They occur due to different physical mechanisms.  Sound is vibrations in a physical medium.  Nobody really knows what electromagnetic fields are, some sort of perturbation of space-time I suppose.

If you dig deeper, you will find that sounds and electromagnetic waves can interact.  The is most common at optical frequencies and you can search for photon-phonon interactions.

http://www.trueactivist.com/nasa-harnesses-music-from-stars-and-planets-heres-what-it-sounds-like-listen/

If this wants to be accepted, the definition of EM needs to be expanded. EM will need to be split between vacuum-capable (conventional EM) and vacuum-incapable (sound).

EM already has such distinction, e.g. visible light. If we had defined EM as "invisible wave" then light cannot be part of that definition of EM.

So if we can accept that not all EMs travel in vacuum, perhaps one day we can explain sound in terms of EM.