Re: An experiment for longitudinal waves

[Franklin Hu]

My own recent experiment on longitudinal waves is this video

https://youtu.be/Ob9b8Iuavms

This is based on the assumption that a transvserse E field is being generated from tip to tip of a dipole antenna as is shown in some illustrations. This compares with a longitudinal transmission which would output a longitudinal wave in the same shape as the transmitting rod. My results were inconclusive due to the type of transmitter I was using which would only drive one side off the dipole.

What do you think of this experiment to determine if EM is longitudinal?

I also did another recent experiment showing how longitudinal waves encode polarization:

https://youtu.be/-FdkpSmDmk4

This eliminates the #1 reason why we think the wave is transverse, but it isn't necessary to support polarization.

I have heard of this experiment, although, I think I read that nobody has ever been able to replicate this, so this is why this is largely ignored. If I tried to replicate it, I would anticipate it not working as well and is fairly complex and generally beyond what I would attempt. This is also presuming that the longitudinal wave is still an electric field. However, my own personal (and unpopular) opinion is that the EM wave is actually just a longitudinal pressure wave and has no measurable electric or magnetic fields. Only when these pressure waves impinge upon electrical wires, do we see currents arise and it has nothing to do with induction or external electric fields. That is what I would ultimately like to prove. I think if you hit a metal pipe at one end, you would also see this generate electric current and this is how the EM pressure waves are generating the observed signal, literally by hitting the atoms of the metal.

I would say that my own theory says that spherical transmission just means that the wave will be completely unpolarized since the symmetric shape of the transmitter has no orientation that can be polarized like a rod.

Aside from the experiment in the paper, did you have a specific different experiment that I could run with a similar to what I used in my longitudinal wave experiment? (transmitter, antenna, oscilliscope)

-Franklin

On Saturday, September 6, 2025 at 08:23:42 AM EDT, Dennis Allen <alle...@sbcglobal.net> wrote:

Franklin,

Dr. Ian Cowan & I have both been working on correcting J.P. Wesley's formula for the energy density of electric & magnetic fields involving both transverse and longitudinal radiation (see first attached email to Christian Monstein who, however, was unable to help us as he no longer has access to his university's laboratory) and we have come to the point where we need a simple, elementary experiment to resolve our (small) differences.  

And it now occurs to me that you do interesting experiments involving electromagnetism, and so that you might be interested in doing our little experiment to possibility detect longitudinal radiation that, of course, is not supposed to exist according to big academia physics (but see the second attached!).  

And if, as I expect, longitudinal electrodynamic radiation is detected in performing this, then we would hope that you could also create a short video concerning it and then place it on YouTube as hard evidence of the existence of this (disputed) type of radiation.

Please feel free to send me any questions or comments you might have concerning this matter.

God Bless,

Dennis

[Dennis Allen]

Franklin,

Many thanks for the substantial reply.  We'll, I must admit that I also don't agree with your pressure wave thinking.  But I admire your two videos in that it seems to me that you have a good attitude of testing your thinking in ingenious ways and so are not just another a slave to big academia.  

And now, let me explain more clearly the experiment I'd like you to do.  In your first video, you apparently performed an experiment much like the one I'm about to describe here.  You had a center-fed straight line transmitting antenna of about a meter in total length and a similar receiving antenna that was parallel to the transmitting antenna and also the end points of the two antennas formed a horizontal rectangle on the floor whose two straight line wires (neglecting their center feedings) were of length of about one meter while both the other two rectangle sides were of the same length as each other but both were of variable length which could be adjusted on the floor shown in that video.  So all that would be required to completely define my experiment would be three brass (or aluminum!) rods of the same length (i.e. about one meter) as the two straight line antennas, and these three rods would be parallel to each other and at a distance from each other of a quarter wavelength apart so that they formed a square (with bisector) on the floor on (say) a piece of cardboard.  This piece of cardboard should be so that this parallel array of three brass rods can be manually rotated about the center point of the square (with bisector) and this point should also be the center of the above mentioned rectangle (made up by the vertexes of the endpoints of the two straight line antennas).  And these rods need not be large in diameter.

Now the physics here seems to be this: when the array's rods are parallel to the two antennas, they should quench reception of transverse radiation, and when they are perpendicular to the two antennas, they should quench reception of longitudinal radiation since the brass rods are sufficient conductors of the right (half wavelength) length to convert the appropriate type of radiation into interior current & hence largely quench it.

And that's about it.  All that's needed then is an ammeter across the receiving antenna's leads to measure the received current in the two situations and a sinusoidal signal generator generating a signal at about two meters wave length (i.e. twice the two straight line antenna's common length) across the leads of the transmitting antenna.  And if, as expected (by me), the first current measurement involving the quenching of the transverse radiation is not significantly smaller than the second measurement involving the quenching of the longitudinal radiation, then you might want to further rotate the three rod array using the same two centers of rotation but using smaller angles than 90 degrees and so get some good additional data.

Please let me know if you have any further questions or comments.

God Bless,

Dennis