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Author Topic: Is this the way to do it?  (Read 3500 times)

Offline Dominus

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Is this the way to do it?
« on: 18/03/2011 11:44:22 »
Last week, I was shopping around, or as they say navigating the web, when I stumbled in to the pictures you see below. I could hardly believe my eyes, I was shocked to see the electromagnetic spectrum represented from beginning to end with the same amplitude. Hundreds of drawings, man-made sketches, diagrams, figures and what not; they all had a thing in common: all types of radiations running along with the same amplitude inside of a long cylinder. Be it gamma rays, visible spectrum, microwave radiation, radio waves, or whatever: they all have the same amplitude. I was stunned. The first thing I thought was: I must be one of the very few who still draws the electromagnetic spectrum with a cone-like figure. Incredible.


I don’t know what you out there think about it, please speak your mind. As for me, I thought about it for a day or so and I came out with some sort of an answer, here it is.
The study of the waveform of musical notes is usually represented by the fundamental frequency f0 and all the overtones 2f0, 3f0 etc., which have different amplitude, and they are mostly studied singly one at the time. Likewise, the study of stationary waves in pipes and of stationary waves in strings suggests a preference for the waveform (same amplitude) in its longitudinal aspect. A similar thing we see with water waves spread along the surface where although no particle of water is displaced the waveform is studied for a 2π, 3π distance and the fact that it is a dying wave is hardly mentioned. With sound waves, for example, the displacement or direction of travel is shown to take place with the same waveform, this is the way sound waves carry energy. With electromagnetic waves is even worst. We all have learned and are familiar with the wave so-called progressive moving to the left or to the right while retaining the same sinusoidal form, or if you prefer same waveform, or same wave profile, or same amplitude. Light waves, for example, are said to be carried by electromagnetic waves from the radiating body to the absorber. And lastly, the study of alternate current (A.C.) circuits is perhaps what has influenced the mind more than the rest in the sense that the visual study through oscilloscopes have shown time and again the wave retaining the same profile in all its applications at very low frequency (50 or 60 cycles per second).
Coming now to a conclusion, is it possible that all these bits and pieces have brain-washed the mind and the constant waveform of the plane wave has outshone the expanding wave as well as the spherical wave?


 

Offline Geezer

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Is this the way to do it?
« Reply #1 on: 18/03/2011 21:42:09 »
Yup. When it comes to photons, the energy is all about frequency rather than amplitude. It's a strange business.
 

Offline Dominus

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« Reply #2 on: 19/03/2011 14:02:20 »
Hello Geezer, long time no see. Agreed if it were always the same, but there are instances in which the frequency doesn't come into it and the energy seems to come from other sources.
 

Offline JP

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« Reply #3 on: 19/03/2011 22:23:39 »
Plane waves are generally taught early on on a physics or engineering education because they're simple waves that still show a lot of fundamental wave-like properties.  It's true that a single plane wave doesn't represent a lot of physical situation, but you have to start simple and build up from there.  When you get to more advanced wave theory, you learn Fourier synthesis, which explains how you can add up plane waves to get more general wave structures.  For example, spherical waves can be explained by adding up plane waves going in all directions.
 

Offline Geezer

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« Reply #4 on: 19/03/2011 23:24:05 »
I was just about to point that out, but JP beat me to it  ;D
 

Offline Bored chemist

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« Reply #5 on: 20/03/2011 09:40:48 »
"I was shocked to see the electromagnetic spectrum represented from beginning to end with the same amplitude. "
What's wrong with that?
The amplitude of a wave is arbitrary, so they might as well depict them all as the same.
 

Offline Phractality

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« Reply #6 on: 20/03/2011 18:41:05 »
The energy of a photon is inversely proportional to it wavelength. E = hc/λ. How that relates to amplitude depends on you model of the universe. In my model, e/m waves are treated like acoustic waves in the medium of the ether, and amplitude is a measure of how far the medium is distorted from side to side as the wave passes. Unfortunately, I don't know how to relate amplitude to energy in my own model; perhaps an acoustic engineer could do it. My wild guess is that amplitude of a photon is constant, as shown in the images you found.

When a photon enters a gravity well, such as near a star or black hole, it trades potential energy for radiant energy, and becomes blueshifted from the perspective of someone outside the gravity well. An observer falling into the same gravity well with a laser beam would not observe a blueshift of the laser beam.

Matter falling into a gravity well, if I'm not mistaken, gets length contracted in its direction of relative velocity; its width does not change. That is why is suspect that a photon is similarly distorted, and its amplitude doesn't change.

I don't think your drawings are labeled to indicate what the vertical scale represents. It's hard to say they're wrong if the vertical scale is not labeled.
 

Offline Dominus

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« Reply #7 on: 20/03/2011 20:19:35 »
Hello JP,
I go along with it, but I was concerned more with the amplitude. In my days (early fifties) the electromagnetic spectrum was represented with a cone-like figure. It’s kind of funny to see an X-rays wave encased in the same cylinder size of a light wave and both displaying the same size amplitude.
 

Offline Dominus

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« Reply #8 on: 20/03/2011 20:20:25 »
Yes Geezer,
Thank you.
 

Offline Dominus

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« Reply #9 on: 20/03/2011 20:22:10 »
Hello Bored chemist,
I am sorry, but I must disagree. I understand the electromagnetic spectrum to be a gradation scale along which the wave expands from Planck’s length to the fully expanded length of 300 million metres. If it is true that the amplitude cannot exceed the wavelength, then I don’t see how you can apply your arbitrariness to display with the same amplitude an ultraviolet wave whose wavelength is in the order of say 200 nanometres and a medium radio frequency used by ships at sea to send SOS signals when in distress the wavelength of which is 600 metres. How can you do that? However, you would be right if we apply the concept to radiation bands along which the wavelength is always the same.
 

Offline Dominus

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« Reply #10 on: 20/03/2011 20:23:29 »
Hello Phractality,
The vertical scale is also the wavelength scale, and that’s the point I am trying to make. You all might “label” me old fashioned, but I stick to the cone-like figure; it tells me everything I want to know and there is no risk to find myself on the high seas.
 

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