BanterinBoson

Vibrational Frequency CO2 Global Warming

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studiot    1131

So far you seem to think that there are three possibilities (though not mutually exclusive as with your chlorophyll example) when light approaches something.

Transmission, reflection or absorbtion.

That is not the case.

Do you think that the radio wave is transmitted through the solid copper bar of the aerial?
We have just agreed that the wave appears on the downstream side of the bar (it is not blocked by it)

Having agreed that an aerial is frequency selective, do you understand how one works?

I suggest you forget photons here. I have already suggested that for the purposes of this thread and your on topic question classical wave theory is adequate.
 I agree that there are many additional observable effects that require alternative theories, but they are not on topic here.

Directionality is a not function of the wave alone, it is also dependent upon the source.

The issue of a propagation medium is off topic here, but I would just observe that Faraday's notion that the wave generates its own medium as is goes along is adequate here.

Finally your response to my observation that waves are larger than the obstruction leaves much to be desired.

If the waves are propagating in the z direction then they are enormous in the x and y directions since they are so far from the source they are effectively plane waves.
The 'waves' of light from the Sun are vastly bigger than the Earth itself. Hopefully you understand this much.

 

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1 hour ago, studiot said:

So far you seem to think that there are three possibilities (though not mutually exclusive as with your chlorophyll example) when light approaches something.

Transmission, reflection or absorbtion.

That is not the case.

Yes, I think there are 3 possibilities.  Why is that not the case?

Even if a wave is wide enough to flow around an object, the part that contacts the object still must flow through or bounce off of the face of the object.  See 7:08 here:

 

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Do you think that the radio wave is transmitted through the solid copper bar of the aerial?
We have just agreed that the wave appears on the downstream side of the bar (it is not blocked by it)

Having agreed that an aerial is frequency selective, do you understand how one works?

I can't answer yes or no, I have to explain:

Radio waves are produced by current that flows up and down an aerial at a specific frequency.  The radio waves propagate through space inducing current flows on anything that will resonate with the wave.  When the wave meets a receiving antenna, the wave induces current in the antenna = to the frequency of the wave.  So to answer your question, I don't think the wave is transmitted down the copper bar, but the wave is transmitted through the copper bar in the direction of the wave travel.  The current that is induced is not the same as the wave because it is current and not a EM wave.  We could say a "signal" is = to both the wave and the current, but I think the wave and the current are separate things.  Also, the induced current should steal energy from the wave.

Radio waves sufficiently low can propagate through 100s of feet of earth, therefore they must be using the earth as a medium for propagation (ie not flowing around the earth).  If they can do that, then a copper bar is no obstacle.  As we climb higher and higher in frequency up the EM scale, the less able the waves will be to pass through the copper bar until we reach a point where the waves reflect.  As we go further, we should reach frequencies that can penetrate the copper, but I don't think visible light is high enough.

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I suggest you forget photons here. I have already suggested that for the purposes of this thread and your on topic question classical wave theory is adequate.
 I agree that there are many additional observable effects that require alternative theories, but they are not on topic here.

Do you mean I should forget photons as particles?  I can do that.  I don't even think of electrons as particles, but super-directional waves where the wave-front has a high density of energy.

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Directionality is a not function of the wave alone, it is also dependent upon the source.

I agree.  The frequency of the wave is determined by the source and therefore the directionality is determined by the source.

At 12:00 here, they say it can take 150,000 years for light to find its way out of the sun.

I believe that if the light were radio waves, that would not be true.  It's the directionality of the wave that prevents it from finding its way out sooner.  Directionality is dependent upon frequency and the higher the frequency, the more like a particle a wave will act.  What do you think?

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The issue of a propagation medium is off topic here, but I would just observe that Faraday's notion that the wave generates its own medium as is goes along is adequate here.

That's fine.  If light generates its own medium as it goes, that is fine.

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Finally your response to my observation that waves are larger than the obstruction leaves much to be desired.

If the waves are propagating in the z direction then they are enormous in the x and y directions since they are so far from the source they are effectively plane waves.
The 'waves' of light from the Sun are vastly bigger than the Earth itself. Hopefully you understand this much.

I don't understand.  I don't see the light from the sun as one big wave a million times bigger than earth, but a collection of small waves emitted from tiny particles inside the sun and those waves don't spread just like a laser beam wouldn't.

I think of the sun analogous to trillions and trillions of tweeters emitting high-frequency sound that is directional and aimed at earth... not one giant bass woofer emitting sound in all directions.

I suspect that you're trying to get me to accept that high-frequency light has the same properties as low-frequency radio waves and I can't do that with my current understanding.  I need a reason to believe that gamma rays, for instance, would be omnidirectional.

xyAc-NvD.jpg

Astrophysicists say that if a quasar is not aimed directly at earth, then we have nothing to fear because the gamma rays do not spread very much, even over astronomical distances.

So I have trouble equating gamma rays with radio waves and therefore when a highly-directional (particle-ish-like) wave meets a co2 molecule, I don't see it simply flowing around it like a radio wave would to an antenna.  But even if it did, I think it would still reflect part of the wave back.  The difference could be a moot point.... whether a co2 molecule reflects an entire small wave back or if it reflects part of a large wave back, the result is probably the same.  Therefore the co2 is taking a co2-size bite out of the visible light that would otherwise be reaching earth while only re-emitting a small part of IR back to earth.  That action should be cooling.

I hope this post doesn't make you mad.  I'm trying hard not to offend you, but I can't say I understand when I don't.  

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swansont    6166
14 hours ago, BanterinBoson said:

I agree and I think it is because the photon is a wave, not a particle.

Light is both.

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What do you think about the analogy of the directionality of sound increasing as frequency increases to that of EMWs?  Are radio waves more omnidirectional than higher frequencies of light?

Whether light is omnidirectional depends on the source.

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 And the electron is so super-directional that we describe it as a particle?  I'm trying to equate "particle-ness" to directionality.

Electrons have both wave and particle behavior. It's not directionality that governs this.

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Isn't that also true of sound through a tube?

26.3.01.GIF

Wave guide cutoff is due to cross-section. The resonance you describe here is based on length. You can get that behavior with light, as well: standing waves in cavities.

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I think I can see what you're saying.  The atom "looks big" if the photon is at resonant frequency because the photon interacts significantly and it "looks small" if the photon is at a frequency higher than resonance because there is little interaction, but then I'm having trouble seeing it "looking small" if the photon is below resonance because lower frequencies will interact.

CO2 is transparent to light at several tens of microns, or less than a micron, but it has absorption bands in between. (you included this in your first post) You are clinging to this notion that frequency below resonance is not transmitted and just isn't true. There are multiple resonances. As you move off-resonance, in either direction, absorption decreases.

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For instance, holding a weight suspended by a rubber band in your hand and then slowly move your hand up and down, the weight should follow the movement of your hand.  As you move faster, you'll find the resonant frequency where the weight and your hand move in opposite directions.  As you move your hand faster than resonance, the weight will not move.

Resonant light absorption by atoms is not classical. Your model doesn't apply.

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 Don Lincoln says here (at 1:30) that electrons and top quarks have no size:

As I stated earlier. (point particles)

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I can see that, but what happens outside those values is what I'm having trouble seeing.

And you have to learn about quantum mechanics to do so.

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I'm not sure light having a constant speed regardless of the speed of the observer necessarily disproves a medium.  I can see how it would seem so, but space is actually spacetime in 4 dimensions and having zero velocity with respect to the medium necessitates maximum velocity through time and maximum velocity through space necessitates zero velocity through time, so it seems not so easy to disprove an aether with relativity due to the extra time variable and the fact that, from the point of view of light, there is no time or space.  How do we use something that sees no space or time to disprove something that exists within spacetime?

Probably a discussion for another thread, but if a physical medium exists, you have to have a velocity with respect to it, and that just doesn't work.

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If you're saying that light will pass straight through a molecule if there are no resonances, then how does light reflect off of chlorophyll?  We know that grass is green because it absorbs all frequencies of visible light except green, therefore green is reflected and that is what we see.  All other frequencies are absorbed and converted to sugar and IR radiation which is re-emitted.  So if green light reflects off of chlorophyll, then why can't light reflect off of co2?

Bulk material behaves differently. If you turned chlorophyll into a gas, its optical behavior would change. Light would reflect off of solid CO2

8 hours ago, BanterinBoson said:

So I have trouble equating gamma rays with radio waves and therefore when a highly-directional (particle-ish-like) wave meets a co2 molecule, I don't see it simply flowing around it like a radio wave would to an antenna.  But even if it did, I think it would still reflect part of the wave back.  The difference could be a moot point.... whether a co2 molecule reflects an entire small wave back or if it reflects part of a large wave back, the result is probably the same.  Therefore the co2 is taking a co2-size bite out of the visible light that would otherwise be reaching earth while only re-emitting a small part of IR back to earth.  That action should be cooling.  

Light that never reaches the earth doesn't get counted; it doesn't contribute to warming. Saying that this is cooling would be double-counting this effect.

 

 

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studiot    1131
9 hours ago, BanterinBoson said:

I don't understand.  I don't see the light from the sun as one big wave a million times bigger than earth, but a collection of small waves emitted from tiny particles inside the sun and those waves don't spread just like a laser beam wouldn't.

I think of the sun analogous to trillions and trillions of tweeters emitting high-frequency sound that is directional and aimed at earth... not one giant bass woofer emitting sound in all directions.

I suspect that you're trying to get me to accept that high-frequency light has the same properties as low-frequency radio waves and I can't do that with my current understanding.  I need a reason to believe that gamma rays, for instance, would be omnidirectional.

Your are too suspicious.
I am trying to work through the physics of something with you so that that you can see for yourself what the facts are.

It is fundamental to wave theory that a point source produces a spherical wave that spreads out in all directions.
So a point source on the surface of the Sun (Point P in my fig1) creates an expanding spherical wavefront as I have shown dashed in Fig1.
This has an average radius of 150 million kilometres by the time that front reaches Earth.
The source at P does not have a choice in this, nor does it have collimators or focusing devices.
But yes there are many such sources on the surface of the Sun and they are not coherently phased, like a laser. (Thank the Lord Huygens) or we would not be here if they were.

I said that as a result of that distance that wavefront is effectively a plane wave so the (very simple) maths of this is shown in fig2.
The deviation of a circular curve from a straight line is given by the formula (distance along the straight line squared) divided by (twice the circle radius)

With the figures shown this works out at about one tenth of a millimetre over the linear distance of the radius of the Earth.

So think how much straighter the wavefront must be over the size of a carbon dioxide molecule, whose bond lenght is 1.16 x 10-7 millimetres long.

 

sunray1.thumb.jpg.fc60f4f263655eac1f8352c367203cb7.jpg

 

This is why we can say that in another model - that of geometrical optics which treats light as a series of 'rays', that the rays from the Sun are parallel.

 

I mentioned bond length of carbon dioxide which is important because this determines the frequencies for the four fundamental modes of vibration of the molecule.

The plan is to fully understand how a straight radio aerial works and see if we can use this to understand how the stretching modes of the carbon dioxide bonds comes to be in the IR and microwave bands and not other bands of the EM spectrum.

 

But first we must look at your thoughts on how a radio aerial actually works.

9 hours ago, BanterinBoson said:

I can't answer yes or no, I have to explain:

Radio waves are produced by current that flows up and down an aerial at a specific frequency.  The radio waves propagate through space inducing current flows on anything that will resonate with the wave.  When the wave meets a receiving antenna, the wave induces current in the antenna = to the frequency of the wave.  So to answer your question, I don't think the wave is transmitted down the copper bar, but the wave is transmitted through the copper bar in the direction of the wave travel.  The current that is induced is not the same as the wave because it is current and not a EM wave.  We could say a "signal" is = to both the wave and the current, but I think the wave and the current are separate things.  Also, the induced current should steal energy from the wave.

This is not far off the truth but just need a couple of amendments. I have underlined the relevant bits.

Firstly and most importantly.

Forget resonance - the word will get you into trouble when we consider charge separation in the carbon dioxide molecule.
It has a specific and quite different meaning for chemists and bonding.

The radio waves induce current in any conductor of any length. Resonance is not required.
The issue is what happens to those currents when they have been induced.
We shall see that conductor length then becomes vitally important.

I prefer the phrase charge separation, rather than current because that is what happens in both the radio aerial and the carbon dioxide molecule.
The effects are potential driven, not current driven.

 

Finally we spoke about reflection, absorbtion and transmission.

What about refraction and diffraction of waves?

 

I think we are doing well and making real progress

Edited by studiot
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