A New look at the intensity of light.

In summary, the conversation discusses the speed of light through glass and the time it takes for a single photon to be absorbed and re-emitted by electrons, as well as the process of photon conduction. It then moves on to discuss the process of light reflection by a green surface and how different frequencies of white light are absorbed and re-emitted by the atoms of the surface. The conversation also addresses the question of whether electrons emit photons randomly or in a single line, and concludes that they emit them in a single line. The observer in the room then conducts an experiment to measure the intensity of light and comes to the conclusion that the intensity varies inversely with the square of the distance from the source. The conversation ends with a discussion on the
  • #1
McQueen
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Suppose that you are an observer in a room equipped with only one window measuring 1 m sq. The window is glazed with a glass pane 1 cm. Thick. The only source of illumination is a green surface outside the window. Hence the only light entering the room is the green light from this surface. Taking the following:-
1) Speed of light through glass = 2.5 x [tex]10^{5}[/tex]km/sec
2) diameter of atom = [tex]10^{-10}[/tex]m
3) thickness of glass = 3 mm.
Then we find that the light passes through the glass in approx. 1.2 x [tex]10^{-11}[/tex] secs. and that the time taken for a single photon to be absorbed and re-emitted by an electron as it passes through the glass in the process known as photon conduction is an incredible 4 x [tex]10^{-19}[/tex]secs.
Having demonstrated the incredible speed with which a photon of light is absorbed and re-emitted by the electrons of the atoms belonging to the substance it is passing through , the glass pane in the window has served its purpose and can be removed. We turn next to the green surface outside the window whose reflected light illumines the interior of the room and examine the process by which this takes place. Making, for the moment , the assumption that the origin of the reflected light is an intense source of white light , we come to the following conclusions:- Some frequencies of the white light are absorbed by the atoms of the green surface , but are not re-emitted , their energies being absorbed instead by recoiling against the nucleus , this raises the energy of the atom resulting in the emission of heat , other frequencies of the white light find no corresponding energies in the electrons present in the atoms of the green surface and pass through the substance without any interactions taking place , lastly the energies and wave lengths corresponding to green light (i.e., those of 550Nm and an energy of 2.2 eV) are absorbed and re-emitted by the electrons of the atoms of the green surface at the rate of 5.4 x [tex]10^{14}[/tex]Hz/sec}. We now deal with the question of the manner in which the electrons emit these photons , do they emit these photons at random in the manner of a spinning Catherine wheel or do they emit the photons in a single line? The manner in which photons are absorbed and emitted as they pass through a substance like glass would seem to indicate that the latter is true , however we will not draw any conclusions from this at present but depend on further observations to inform our views. To do this we must re-enter the room and join the observer. Let us assume that the observer is equipped with a particularly sensitive densiometer with which he can measure the intensity of the light coming through the window. At first he stands at a distance of 1m. from the window and notes down the intensity. He then shifts back from the window to a distance of 2m and again measures the intensity of the light , he finds that the intensity of the light is now 1/4 that of the intensity he had recorded at a distance of 1m from the window. He keeps repeating the readings at varying distances until he comes to the conclusion that the intensity of the light varies inversely with the square of the distance from the window and also that the area over which the light spreads varies directly with the square of the distance from the window. ( In actual fact of course the window is large and diffraction would make such a measurement difficult , remember this is an experiment.) He repeats his readings under identical circumstances over the course of several days and always gets the same results. What conclusions does he draw from his observations ? Firstly he notes that the intensity of the light varies inversely with the square of the distance from the window and secondly he notes that the area over which the light spreads varies directly with the square of the distance from the window. He concludes that originally the light was more intense because more photons were being absorbed per atom (i.e a number of photons were giving up their energy in succession) and also that due to the interaction of the light with the air or with some medium in the air , the number of photons being absorbed by each individual atom has been reduced and that this reduction has taken place uniformly , in other words the photons which originally were arranged in a single line had spread out into a number of lines while at the same time maintaining a uniform intensity (i.e., each of the new lines has an equal number of photons.) Thus it would seem that the intensity of light is not due to the energy of the photon alone but to its energy x frequency and that the number of photons due to this frequency varies inversely with the square of the distance from the source.. Thus at the source the intensity would be 2.2 x 5.4 x [tex] 10^{14}[/tex] = 1.18 x [tex]10^ {14}[/tex]eV per sec. or roughly 1 x [tex]10^{-5}[/tex] watts per atom per sec. And so on. Notice that if the duration is reduced the intensity is also reduced , thus the amount of energy reaching an electron in the destination point in [tex] 10^{4}[/tex] secs would be 2.2eV . Further it must be assumed that as each electron absorbs a photon it immediately re-emits it at the same frequency.
Also light emitted by a photon bound to an atom will always obey the inverse square law because it is a point source while light from lasers also obey the inverse square law but since they are being emitted by a comparatively massive source of free electrons , travel longer in a coherent beam. At a distance of 1,609m , a helium-neon laser (which is a well collimated source ) will spread out over an area of 1.3m.
 
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  • #2
McQueen said:
light from lasers also obey the inverse square law, since they are being emitted by a comparatively massive source of free electrons

Ouch, this is most definitely not the case.

1) The inverse square law is only approriate for a perfectly isotropic source (i.e. not a laser).

2) Light from lasers are not emitted by free electrons, but by bound electrons (it is the nature of bound electrons, i.e. energy levels and so forth that allows things like population inversions and hence lasing to occur). The one exception is an electron laser, but these are hardly typical lasers.

Claude.
 
  • #3
im not sure this is true, no laser sends exact parallel light there is always a little bit of scattering which at a distance R from the laser forms a part of a sphere with radius R so i think lasers do obey the inverse square law only instead of it being of the form a/r^2 its something like a/xr^2 with x being smaller with lasers which emit more parallel radiation.
 
  • #4
" Thus it would seem that the intensity of light is not due to the energy of the photon alone but to its energy x frequency and that the number of photons due to this frequency varies inversely with the square of the distance from the source.. Thus at the source the intensity would be 1.18*10^14 eV per sec. or roughly 10^-5 watts per atom per sec. "

intensity = energy* frequency -> which frequency? the frequency of a photon, or the frequency of photons colliding with the detector at a distance r from the source?

Inverse square law only applies to a point source right? if light were emitted from an ideal plane doesn't the intensity decrease as 1/r rather than 1/r^2? or at least, until you are far enough away from the source that it appears to be a point source? If the plane had infinate boundries, intensity would decrease as 1/r.

shouldn't it be watts per atom, and not watts per atom per sec? since a watt = joule/sec
 
  • #5
What are the differences in calculating light intensity between your way and cannonical physics?
 
  • #6
Sorry Claude . The post should have read as follows :- Also light emitted by a electron bound to an atom will always obey the inverse square law because it is a point source while light from lasers also obeys the inverse square law but since they are the result of a comparatively massive collection of photons moving in unison , travel longer in a coherent beam. At a distance of 1,609m , a helium-neon laser (which is a well collimated source ) will spread out over an area of 1.3m.
Thank you Anzsas , this is the point I was trying to make .
 
  • #7
Johnny : I will take my time over this , since I do not wish to make another gaff , as I did with the lasers.
 
  • #8
Jonny Trigonometry wrote :

What are the differences in calculating light intensity between your way and cannonical physics?

Obviously one cannot explain the intensity of light in a new way without going into the whole question of what light actually is . The only available alternative is to examine one particular aspect of the subject. Take the photoelectric effect , according to the photoelectric effect , the emission of electrons from a metal surface when it is irradiated with a monochromatic light depends solely on the wave-length or the frequency of the monochromatic light and not on the intensity of the light, in other words the photoelectric effect does not depend on the amount of light but on the energy of the monochromatic light in question. (i.e., the type of light that the metal is being irradiated with) Now this according to the theory I have put forward , is a simple question of the use of AND and OR. The Laws of Photoelectric effect enunciated by Einstein , in 1908 and remember this was a century ago , states that the photoelectric effect depends on the wave-length OR the frequency of the light in question , while the theory I have put forward states that the photo-electric effect depends on the wave-length AND the frequency of the light. Thus the photoelectric effect as it is at present understood , attributes the property of frequency to a single photon , while in the classical sense the term frequency refers to a succession of events and therefore cannot apply to a single particle , especially when used in this sense (i.e., to state that it is the frequency of a single photon which is responsible for the photoelectric effect. ) This means that , according to my theory , the kinetic energy of electrons ejected from a metal surface should decrease with increasing distance from the source of illumination. This statement should be easily verifiable.
The reason that I make this statement is that at the time (i.e in 1908 ) when the photoelectric was first put into mathematical form , physicists could have had no idea at the speed with which an electron emits and absorbs photons , which as I had pointed out at the beginning of this thread can be as high as 4 x [tex] 10^{-19} [/tex] secs per photon emission and absorption , when light is traveling through glass. In fact at the time photons had not even been discovered , it would take another twenty years or so before the term photon was coined. In view of this we have to examine the possibility , even given the calculations of the work function (i.e., the energy needed for an electron to leave the metal surface ) that the photoelectric effect is intimately connected with frequency when used in the conventional sense (i.e., as a succession of absorptions and emissions ) resulting in the raising of the energy of the electron. The problem does not end here because it then raises the question of how light is propagated , because we find that the intensity of light varies uniformly over a given area, which would seem to indicate that photons are emitted by the electron along straight lines. If the electron absorbed and emitted photons in the manner of a spinning Catherine wheel , this uniform lowering in intensity in a regulated manner varying with distance would be difficult to explain. So when light falls on a substance (which reflects that particular colour of light ) the electrons of the substance absorb and emit photons at the rate of approx . [tex]10^{14}[/tex] Hz in straight lines , obviously ( as we can observe ) different electrons would emit these photons in different directions.
 
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  • #9
"The Laws of Photoelectric effect enunciated by Einstein , in 1908 and remember this was a century ago , states that the photoelectric effect depends on the wave-length OR the frequency of the light in question , while the theory I have put forward states that the photo-electric effect depends on the wave-length AND the frequency of the light."

the photoelectric effect uses the idea that the energy of a photon = it's frequency (or color) times plank's constant. It uses this idea because this idea is the only way of fully explaining the photoelectric effect. to say frequency OR wavelength is to refer to the same thing, because C=(wavelength)(frequency), so E=hf OR E=hC/(wavelength). That is all. It has nothing to do with the number of photons emmitted per second. The number of photons emmitted per second (from a monochromatic source) times the energy of the photons (since they all have the same energy because the source is monochromatic) divided by the cross-sectional area that they pass through (dependant on the distance from the source) is the intensity of the light. And the photoelectric effect demonstrates that the intensity is independant of the amount of energy absorbed by bounded electrons in the metal surface.

"This means that , according to my theory , the kinetic energy of electrons ejected from a metal surface should decrease with increasing distance from the source of illumination. This statement should be easily verifiable."

In fact, the photoelectric effect verifies the exact opposite of your claim. You may be thinking that the frequency of the light steadily decreases as it propogates through space, but this is not the case, what really happens is the intensity decreases as the photons spread out since they aren't all traveling parallel, even in a lasar (although in a lasar they are very closely parallel). It is true that the NUMBER of electrons stripped from the metal surface per unit time increases when the distance from the source (assuming it is emitting photons with energy greater than the work function of that particular metal) decreases, but the kinetic energy of each ejected electron will not increase.
 
  • #10
I think the confusion is with the use of the word frequency. There are two independant frequencies that we are considering here, the frequency of the photons (the color of the light) and the frequency of photons moving through a cross-sectional area. The first refers to the occilations per second of the electromagnetic disturbance (photon). The second refers to the number of photons (each with a specific frequency) moving through a cross-sectional area per second.

A photon doesn't output energy over time, only a photon source does. Photons have energy, but no power, a light source has power since it outputs energy (photons) over time. I shouldn't say a photon has no power at all times. It does output power when it collides with a particle, but it outputs all it's energy in roughly the time you suggested (4 x 10^-19 sec). Or at least, this is how (I think) they are thought to interact with particles.
 
  • #11
Jonny Trigonometry

Much of what you write is true and as such is part of the established wisdom on the subject. For instance when you state that “I think the confusion is with the use of the word frequency. There are two independant frequencies that we are considering here, the frequency of the photons (the color of the light) and the frequency of photons moving through a cross-sectional area..” you are right in stating that much of the confusion arises from the fact that frequency is often treated as being synonymous with energy forgetting to add that it is also an inherent part of the properties of that particular electromagnetic radiation. You cannot talk of the number of photons moving through a cross sectional area per second without also taking into consideration that the frequency you refer to is an inherent property of that particular electromagnetic radiation and that it therefore follows that if there are a number of photons of a particular frequency moving through a cross sectional area , they would have to be in sequence , (i.e ., a number of photons of the same energy following the same path.). This leads to the second point of confusion which is that there did not exist in 1908 and that there still does not exist today in 2005 , apparatus which can determine whether an electron has absorbed a single photon or a number of photons in succession. To take one example , in the photoelectric effect , suppose the metal plate is 50 cms away from the light source then in the time taken for the light (using green light with a wave length of 555nM) to reach the metal plate in approx. 3.3 x 10^10 secs. an electron would have emitted 1.5 x 10^4 photons. Taking this into consideration is it possible to speak of single energies of photons giving rise to the photoelectric effect ? Although as I had earlier stated there exists no apparatus at present which can be used to determine whether an electron has absorbed a single photon or a number of photons in succession , observations and logical deduction can be used to establish whether in fact electrons emit single photons or whether they emit multiple photons in rapid succession in numbers corresponding to the frequency and wave length of the particular electromagnetic radiation under consideration. If we are to accept the first viewpoint put forward in your post , that frequency is a property of a single photon , then we must assume that photon emission with reference to visible light , consists of electrons emitting single photons at random , thus when a source is emitting green light we would have to assume (using your theory ) that an individual electron emits a single photon with a wave-length of 555nM and an energy of 2.2eV in a time of 5.4 x 10^14 secs and then becomes quiescent until it is again excited at some later time, in other words using your view of light , it must be assumed that photons are emitted at random and not in sequence . Yet our observations , particularly in the matter of light as it travels through glass , show that this is probably not true and that electrons are capable of emitting and absorbing photons at a phenomenal rate over long periods of time , which raises the conjecture that photons are emitted in sequence.
 
  • #12
Anzas said:
im not sure this is true, no laser sends exact parallel light there is always a little bit of scattering which at a distance R from the laser forms a part of a sphere with radius R so i think lasers do obey the inverse square law only instead of it being of the form a/r^2 its something like a/xr^2 with x being smaller with lasers which emit more parallel radiation.

Okay, what Inverse square law are we talking about here, the inverse square law I am referring to is;

[tex] I=\frac{P}{4\pi r^2} [/tex]

Where I is the Irradiance (W/m^2), P (W) is the emitted power and r (m) is the distance from the source.

McQueen said:
particularly in the matter of light as it travels through glass , show that this is probably not true and that electrons are capable of emitting and absorbing photons at a phenomenal rate over long periods of time , which raises the conjecture that photons are emitted in sequence.

There is a lack of understanding here about the propagation of light through a dielectric medium. In a dielectric, such as glass, with no free charges and currents, Maxwell's equations can be decoupled and formed into a wave equation. Thus light propagates in a dielectric medium much the same way it propagates through a vacuum (on a macroscopic level anyway).

The propagation of light through transparent media can also be discussed on this thread.

https://www.physicsforums.com/showthread.php?t=76246

After reading your initial post, and subsequent posts, I'm still not quite sure what the point to your post was. What conclusions are you drawing, and why is this 'A new look at the intensity of light'. Do you mean intensity as in W/m^2 (more correctly called Irradiance), or W/sr?

Claude.
 
  • #13
yes this is the inverse square law we are talking about

p is divided by 4*pi*r^2 because that's the surface of a sphere with radius r and the power is divded between the surface area.

no laser sends exact parallel radiation so at a distance r from the laser the radiation scatters as well and the power is divided between the surface area which is actually a part of a sphere with radius r. so lasers do obey the inverse square law.
 
  • #14
Okay, I have a CO2 laser in my lab, which runs at 50W (which is smallish) at full pelt.

The inverse square law predicts that the Irradiance will be about 4 W/M^2 at a distance 1 m from the laser. What I actually get is about a 5mm diameter spot (a large estimate), so the irradiance is actually about 637 kW/M^2 a factor of about 160,000 off. In this instance, the inverse square law does not work. You cannot apply the inverse square law to lasers.

What I suspect you are claiming is the Irradiance goes down with increasing area, which is a statement of the bleeding obvious since Irradiance is in units W/m^2, so for a fixed power, this is exactly what you would expect.

Hardly a new look at Irradiance.

P.S. What do you mean the laser radiation scatters? Do you mean the laser radiation diffracts diffract?

Claude.
 
  • #15
Claude Bile
Okay, what Inverse square law are we talking about here, the inverse square law I am referring to is; I=\frac{P}{4\pi r^2}
I have just read Anzas latest post which is self explanatory.Basicall I agree with what he has to say. My own theory is that the divergence of a laser is less because it results from a massive collection of photons all moving in unison rather than as the result of individual emissions by electrons , as a result of this the majority of photons in a laser beam are shielded from interactions as the beam propagates. Of course it is only a theory.
There is a lack of understanding here about the propagation of light through a dielectric medium. In a dielectric, such as glass, with no free charges and currents, Maxwell's equations can be decoupled and formed into a wave equation. Thus light propagates in a dielectric medium much the same way it propagates through a vacuum (on a macroscopic level anyway).
As regards your statements with regard to the propagation of light through glass , once again you are right and polarization has a lot to do with the manner which light propagates through glass , however “photon “ conduction also plays an important role. At higher temperatures, photon conductivity (radiation) becomes the predominant mechanism of energy transfer. This is a rapid sequence of absorptions and emissions of photons that travel at the speed of light. This mode of conduction is especially important in glass, transparent ceramics, and porous ceramics.
After reading your initial post, and subsequent posts, I'm still not quite sure what the point to your post was. What conclusions are you drawing, and why is this 'A new look at the intensity of light'. Do you mean intensity as in W/m^2 (more correctly called Irradiance), or W/sr?
Unfortunately , according to the rules of this forum I am not allowed to advertise or elaborate on my own theories and so am unable to post a link. That doesn’t matter .
However I can tell you is that my theory depends upon a new model of the photon which is a symbiosis of a particle and a wave i.e., it possesses the properties of a particle and a wave simultaneously , further this model of the photon allows for the storage and delivery of electrical energy while itself remaining electrically neutral , lastly this model of the photon also explains long wave length electromagnetic radiation such as radio waves and wave lengths of 5 x 10^6 m and more which present theories seemingly are unable to do in a satisfactory manner.
 
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  • #16
McQueen said:
have just read Anzas latest post which is self explanatory.Basicall I agree with what he has to say. My own theory is that the divergence of a laser is less because it results from a massive collection of photons all moving in unison rather than as the result of individual emissions by electrons , as a result of this the majority of photons in a laser beam are shielded from interactions as the beam propagates. Of course it is only a theory.

First of all, what is the divergence of the laser beam less than? What interactions are the photons being shielded from? What does your theory predict that Gaussian optics does not? How can this theory be tested? You are being awfully vague with your terminology.

McQueen said:
As regards your statements with regard to the propagation of light through glass , once again you are right and polarization has a lot to do with the manner which light propagates through glass , however “photon “ conduction also plays an important role. At higher temperatures, photon conductivity (radiation) becomes the predominant mechanism of energy transfer. This is a rapid sequence of absorptions and emissions of photons that travel at the speed of light. This mode of conduction is especially important in glass, transparent ceramics, and porous ceramics.

Is this 'photon conductivity' your own term you have coined? I have never seen this term used, and I have been involved with the field of photonics for quite a few years now (most people just use the word transmission). The explanantion you have given is the simplified version, oversimplified in my opinion as it contains many inconsistancies, for example why do the photons always emit in the same direction, when stimulated emission, by its nature is isotropic? (Also energy does not propagate at the speed of light in media).

McQueen said:
However I can tell you is that my theory depends upon a new model of the photon which is a symbiosis of a particle and a wave i.e., it possesses the properties of a particle and a wave simultaneously , further this model of the photon allows for the storage and delivery of electrical energy while itself remaining electrically neutral , lastly this model of the photon also explains long wave length electromagnetic radiation such as radio waves and wave lengths of 5 x 10^6 m and more which present theories seemingly are unable to do in a satisfactory manner.

Don't current theories model the photon as having both particle and wave properties? Don't they also predict electrical neutrality? I was not even aware that long wavelength radiation is unexplainable using current theory. What is unsatisfactory about current theories and what does your theory do to rectify it? Also, you would meet strong opposition if you tried to suggest that photons store and deliver electrical energy (I would give that role to electrons and other charged particles).

Again, I fail to see the relevance of all this to intensity.

Claude.

P.S. I just noticed an error on my previous post, obviously, the final 'diffract' should be omitted.
 
  • #17
here i made a small pic in paint to show what i mean

the left figure is an antenna (from above) it sends radiation in all directions (even though in the image it looks 2d its actually a sphere) so its power is divided by the sphere surface which is
4*pi*R^2

the right figure is a laser (also from above) it sends radiation in only one direction but the radiation is not completely parallel (no laser sends exact parallel radiation) so at a distance R from the laser the power is divdided by a so called "part of a sphere" (im not sure what the exact term is in english) so the power is divided by 4*pi*R^2/x
x depends how parallel the radiation from the laser is.
 

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  • #18
Claude Bile

First of all, what is the divergence of the laser beam less than? What interactions are the photons being shielded from? What does your theory predict that Gaussian optics does not? How can this theory be tested? You are being awfully vague with your terminology.

OK if a laser beam did not diverge , we would be using laser pulses for all deep space missions , which is not being done for the obvious reasons. Secondly my theory states firstly that photons are solenoidal points , this means that they are the fundamental unit of electromagnetic energy , and are therefore the source of electromagnetic radiation and not the symptom.

Finally , one of the fundamental hypotheses behind my theory is that electricity is transmitted in a wire by photons and not by electrons. Look at the facts , a current is established at close to the speed of c , whereas the drift velocity of electrons is about 10^-5 m/s . How do you account for this , it represents a discrepancy of about 10^15 , this is not a small discrepancy. Remember that electrons are separated by about 10^5 their diameter , for one electron to bump into another would be the equivalent of trying to hit one billiard ball with another at a distance of about 6 Kms. Again using extant theories , how is it possible for an ion about 10^-10 m in size to produce by vibrations , an electromagnetic wave of 5 x 10^6 m wave length ? Let’s face it , there a lot of facts to do with electromagnetic radiation which do not gel together. At present electromagnetic radiation in the range of visible light is supposed to have different origins than electromagnetic radiation of longer wave lengths , although both these phenomena exhibit identical properties . They preserve their energies , move with the speed of light , have no mass etc., Is this good science , attributing two different causative factors to two identical phenomena. The same applies to the magnetic field around a current flowing in a wire and the magnetic field around a permanent magnet. The first is thought to be due to the vibration of ions in the lattice structure of the wire while the other is thought to be due to the lining up of electron spin. Again the rationale behind the explanation for the double slit experiment is literally out of this world , for it states that particles possessing both dimensions and mass , such as neutrons are able to disassociate and be in two places at once , (i.e., pass through both slits at the same time!). What about the polarization of light ? All these explanations do not make sense , my theory , provides a simpler and more rational explanation for all these phenomena. My theory explains electricity , explains electromagnetism , explains magnetism , explains super conductivity and even gravity without deviating from a central hypotheses. Finally , there are several simple experiments which would prove my theory , it is also possible to prove the theory mathematically.
Don't current theories model the photon as having both particle and wave properties?
According to present theories light is either a wave or a particle , it can never possesses both properties simultaneously.
 
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  • #19
Claude Bile
Don't they also predict electrical neutrality? I was not even aware that long wavelength radiation is unexplainable using current theory. What is unsatisfactory about current theories and what does your theory do to rectify it?
Here is a very brief synopsis of my theory , without which , nothing I say will make sense. It is a widely accepted fact that electrons emit and absorb photons. Since electrons are charged particles I thought it not unlikely that what in fact the electrons were exchanging were pulses of electrical energy , when an electron had an excess of charge it emitted an electrical pulse and absorbed a pulse when it was deficient. Next I reasoned that because of the extremely small size of the electron , ( the classical radius of the electron is something like 10^-15m ) that these pulses would be released in short bursts . Thus the picture that emerges is of short bursts of electrical energy separated by a di-electric. The possibility then arose that the bursts of energy first released by the electron were more electrically charged than subsequent bursts of energy , therefore the system takes on polarity. Obviously a structure such as I have outlined would form around itself a solenoidal field and would therefore be electrically neutral. It would have no mass , because of its condensor like structure it would be able to store energy almost indefinitely and it would also deliver up all of that energy on contact. Thus such a structure would seem to answer to all the properties that a photon is said to possesses and at the same time sounds more reasonable in terms of dimensions etc., for the electron to deal with. My theory also sets a limit on the size of the largest wave length photon that an electron can emit. This size I have worked out is about 8 x 10^-7m. This is only slightly larger than the longest visible wave-length. Thus all wave lengths greater in length than 8 x 10^7m are composite waves and are made up of joined together or linked together photons.
 
  • #20
Anzas said:
here i made a small pic in paint to show what i mean

the left figure is an antenna (from above) it sends radiation in all directions (even though in the image it looks 2d its actually a sphere) so its power is divided by the sphere surface which is
4*pi*R^2

the right figure is a laser (also from above) it sends radiation in only one direction but the radiation is not completely parallel (no laser sends exact parallel radiation) so at a distance R from the laser the power is divdided by a so called "part of a sphere" (im not sure what the exact term is in english) so the power is divided by 4*pi*R^2/x
x depends how parallel the radiation from the laser is.

The "Part of a sphere" is termed a solid angle in english, whose units are steradians (which are dimensionless). All you are doing is manipulating the inverse square law so the power is only being spread out over a portion of the sphere and not the whole sphere right?

I'm not saying you're wrong, I an arguing that once this equation is modified, you are no longer using the inverse square law.

McQueen said:
OK if a laser beam did not diverge , we would be using laser pulses for all deep space missions , which is not being done for the obvious reasons.

I asked what you were comparing the divergence of the laser to. In your earlier post you wrote;

McQueen said:
My own theory is that the divergence of a laser is less...

Less than what? That was my original question.

McQueen said:
Finally , one of the fundamental hypotheses behind my theory is that electricity is transmitted in a wire by photons and not by electrons

What? even DC? Why then do metals make good conductors and dielectrics bad conductors?

McQueen said:
Look at the facts , a current is established at close to the speed of c , whereas the drift velocity of electrons is about 10^-5 m/s

Drift velocity and the group velocity of a disturbance in the electric field of a wire are two different quantities. Current theory does not claim that the electrons move at c, it is the disturbance (or, more correctly, the pertubation) that moves at c.

McQueen said:
how is it possible for an ion about 10^-10 m in size to produce by vibrations , an electromagnetic wave of 5 x 10^6 m wave length ?

Easy, you just jiggle it up and down at around 50 Hz. The free electrons in a conductor are not bound to any nucleus, thus they do not require transitions of any kind to emit certain frequencies, they are free to emit all frequencies.

McQueen said:
At present electromagnetic radiation in the range of visible light is supposed to have different origins than electromagnetic radiation of longer wave lengths , although both these phenomena exhibit identical properties.

What do you mean they have different origins? Also, I would argue that electromagentic waves have properties that vary with wavelength. Try convincing someone that Gamma rays and visible light have identical properties.

McQueen said:
the rationale behind the explanation for the double slit experiment is literally out of this world , for it states that particles possessing both dimensions and mass , such as neutrons are able to disassociate and be in two places at once , (i.e., pass through both slits at the same time!).

This touches on Quantum Mechanics, one of the most outstandingly successful theories in modern physics. You need to have damn good reasons to question it's validity (i.e. much more than "it doesn't make sense").

McQueen said:
My theory explains electricity , explains electromagnetism , explains magnetism , explains super conductivity and even gravity without deviating from a central hypotheses. Finally , there are several simple experiments which would prove my theory , it is also possible to prove the theory mathematically.

So prove your theory then, (mathematical proofs don't count, they need to be backed up by observation). You'd probably get a nobel prize.

McQueen said:
According to present theories light is either a wave or a particle , it can never possesses both properties simultaneously.

Light posesses wavelength (a wave property) and momentum (classically, a particle property), simultaneously.

McQueen said:
when an electron had an excess of charge

What? An electron with an excess of charge? Never mind the evidence that the charge on the electrons has been measured to 9 significant figures last time I looked.

McQueen said:
The possibility then arose that the bursts of energy first released by the electron were more electrically charged than subsequent bursts of energy

Energy cannot posess charge, charge is a particle property.

McQueen said:
Thus such a structure would seem to answer to all the properties that a photon is said to possesses and at the same time sounds more reasonable in terms of dimensions etc., for the electron to deal with

What do you mean "for the electron to deal with". What about blackbody radiation?

McQueen said:
My theory also sets a limit on the size of the largest wave length photon that an electron can emit. This size I have worked out is about 8 x 10^-7m. This is only slightly larger than the longest visible wave-length. Thus all wave lengths greater in length than 8 x 10^7m are composite waves and are made up of joined together or linked together photons.

So the longest wavelength photon is 800nm? What about all those lasers that emit wavelengths much longer than 800nm. I'm sorry to say that your theory falls apart right here.

Claude.
 
  • #21
The "Part of a sphere" is termed a solid angle in english, whose units are steradians (which are dimensionless). All you are doing is manipulating the inverse square law so the power is only being spread out over a portion of the sphere and not the whole sphere right?

I'm not saying you're wrong, I an arguing that once this equation is modified, you are no longer using the inverse square law.

yes in lasers the power is spread over a porotion of the sphere.
its not me manipulating the inverse square law its nature :smile:
the inverse square law simply states that the power is reduced by a factor of the square of the distance it doesn't even have to be realted to electromagnetic radiation
[tex]F= \frac{Gm1m2}{R^2}[/tex]
also uses the inverse square law because the force is reduced by a factor of the square of the distance.
 
  • #22
Claude Bile

I will have to say this , a very interesting and stimulating post. Although there are several factors which need to be elaborated on.

What? even DC? Why then do metals make good conductors and dielectrics bad conductors?
Yes , even DC. In general those conductors having an excess of mobile valence electrons make the better conductors. However this is not the only criterion , the properties of a good conductor are dependant on the crystalline lattice structure which the conductor possesses. Almost all good conductors possesses either a BCC (Body centered cubic) structure or a FCC (Face centered cubic ) structure. Now in the BCC structure the valence electrons involved in the conduction process are more tightly bound to their atoms , examples of this type of structure are iron and manganese , these metals also make good permanent magnets and are called ferromagnetic materials. In the FCC type of structure the valence electrons are free to move from atom to atom , examples of this type of structure include silver and copper , these metals are excellent conductors of electricity but are paramagnetic (i.e., they possesses magnetic properties only for so long as a current is flowing.) Lastly you have the di-electrics or insulators which possesses various other types of lattice structures , but in which the electrons are tightly bound to the atoms. The lattice structure plays a vital part in conductivity properties , for instance diamond and graphite have identical atomic properties but have completely different properties due to their crystalline structure , while diamond is a very good insulator , graphite is a good conductor.
Drift velocity and the group velocity of a disturbance in the electric field of a wire are two different quantities. Current theory does not claim that the electrons move at c, it is the disturbance (or, more correctly, the pertubation) that moves at c.
What is this disturbance or perturbation , QM generally accepts that all interactions between electrons are via photons , thus when two electrons interact it is via photons , where does the perturbation come from if no photons are present ?
Easy, you just jiggle it up and down at around 50 Hz. The free electrons in a conductor are not bound to any nucleus, thus they do not require transitions of any kind to emit certain frequencies, they are free to emit all frequencies.
So if you jiggle an ion up and down over a distance of say 10^-12m at a frequency of 50Hz it produces an electromagnetic radiation which is 5x 10^6 m. in length ? Look at the difference between these two numbers. Secondly free electrons in a conductor , according to present theory can in no way emit within the conductor , they are forbidden from doing so by the Pauli Exclusion Principle.
What do you mean they have different origins? Also, I would argue that electromagentic waves have properties that vary with wavelength. Try convincing someone that Gamma rays and visible light have identical properties.
This is something like saying that the reason a ball is thrown further , is because it was thrown by a professional as opposed to an amateur. Although logically true it does not represent the facts . It is not until the concept of force is introduced that things begin to make sense. It then doesn’t matter who threw the ball but the force with which it was propelled. Gamma rays of 100nM and radio waves of 5 x 10^6 m. possesses identical properties , they travel at the speed of light , have no mass , preserve their energies (identities) intact until absorbed etc., The fact that they possesses different energies is irrelevant in the sense that it is a merely a function of their frequency.
Light posesses wavelength (a wave property) and momentum (classically, a particle property), simultaneously.
According to QM , light can never posses both properties simultaneously as proposed by Bohr’s complementarity theory.
What? An electron with an excess of charge? Never mind the evidence that the charge on the electrons has been measured to 9 significant figures last time I looked.
An electron’s energy varies with its velocity and since it is in constant motion around the nucleus in different orbits , its energy or charge also varies. It gets rid of this extra energy by emitting photons or gains more energy by absorbing photons.
 
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  • #23
Anzas

I understand where you are coming from, the inverse square law for EM radiation has additional significance, particularly for those working with antennas (I actually tutor this topic at university). But I can see how physicists from different fields could mean different laws.

McQueen

You claim that electrical energy is transmitted by photons, I ask the question, what frequency are these photons for direct current. Also note that by attributing the transferrance of energy to photons, you invalidate current explanations as to why metals make good conductors and dielectrics poor conductors. Your theory would thus have to explain this using your own hypothesis.

McQueen said:
What is this disturbance or perturbation , QM generally accepts that all interactions between electrons are via photons , thus when two electrons interact it is via photons , where does the perturbation come from if no photons are present ?

QM says momentum is transferred via virtual photons (as opposed to real photons). Real photons need not be present.

MCQueen said:
So if you jiggle an ion up and down over a distance of say 10^-12m at a frequency of 50Hz it produces an electromagnetic radiation which is 5x 10^6 m. in length ? Look at the difference between these two numbers.

Wavelength depends of frequency and velocity, it has nothing to do with amplitude. Comparing amplitude to wavelength is like comparing apples to oranges.

McQueen said:
This is something like saying that the reason a ball is thrown further , is because it was thrown by a professional as opposed to an amateur. Although logically true it does not represent the facts . It is not until the concept of force is introduced that things begin to make sense. It then doesn’t matter who threw the ball but the force with which it was propelled. Gamma rays of 100nM and radio waves of 5 x 10^6 m. possesses identical properties , they travel at the speed of light , have no mass , preserve their energies (identities) intact until absorbed etc., The fact that they possesses different energies is irrelevant in the sense that it is a merely a function of their frequency.

They share some properties sure, but Gamma radiation can kill you in minutes, while radio waves can't, I would argue that there is a difference in properties there.

McQueen said:
According to QM , light can never posses both properties simultaneously as proposed by Bohr’s complementarity theory.

No it doesn't. Bohrs theory of complimentarity says that in the case of QM approaching classical limits, QM becomes classical mechanics.

McQueen said:
An electron’s energy varies with its velocity and since it is in constant motion around the nucleus in different orbits , its energy or charge also varies. It gets rid of this extra energy by emitting photons or gains more energy by absorbing photons.

This statement makes me question your experience in the field of physics. Energy and charge are TWO TOTALLY SEPERATE THINGS. Saying they are the same thing makes you sound like you don't know what you are talking about.

Claude.
 
  • #24
Claude Bile
An electron’s energy varies with its velocity and since it is in constant motion around the nucleus in different orbits , its energy or charge also varies. It gets rid of this extra energy by emitting photons or gains more energy by absorbing photons.

This statement makes me question your experience in the field of physics. Energy and charge are TWO TOTALLY SEPERATE THINGS. Saying they are the same thing makes you sound like you don't know what you are talking about.


Alright , no need to shout ! I just needed some time to think about what you had said and to frame a suitable reply. I think I can see what you are getting at. Suppose we take two surfaces and charge them unevenly , so that there are more electrons on surface A than there are on surface B. If we keep putting more electrons on A then eventually the attraction between the two unevenly charged surfaces would become too great and electrons would jump from A to B thereby neutralizing the difference in charge. In this sense charge is fundamental , because it is not until an exchange of electrons takes place that the situation is normalized. Now take the analogous situation of a capacitor connected into an AC circuit , here what we see is that , although no electrons cross the capacitor plates a current is established in the circuit. So , this leads to two points. The first is that your idea that it is virtual photons which nudge the electrons and change their momentum thereby establishing a current is wrong because no charge carriers (i.e ., electrons ) are seen to cross the gap between the capacitor plates. Secondly we know that Maxwell explained this phenomena by postulating the existence of a displacement current . However , when considering this we must take into account the fact that photons had not then been discovered , it would take another almost two hundred years before photons were taken into account. If their existence had been known at the time then surely the possibility would at least have come under consideration that it is photons which carry electrical energy.
 
  • #25
McQueen said:
Alright , no need to shout !

Sorry, it's just that saying that energy and charge are the same thing will send most physicists into fits. I think you got off lightly! (I will also say that the charge on the electron is a fundamental constant, and saying that it also varies would likely cause more fits.)

McQueen said:
Suppose we take two surfaces and charge them unevenly , so that there are more electrons on surface A than there are on surface B. If we keep putting more electrons on A then eventually the attraction between the two unevenly charged surfaces would become too great and electrons would jump from A to B thereby neutralizing the difference in charge.

Agreed.

McQueen said:
Now take the analogous situation of a capacitor connected into an AC circuit , here what we see is that , although no electrons cross the capacitor plates a current is established in the circuit.

Agreed.

McQueen said:
So , this leads to two points. The first is that your idea that it is virtual photons which nudge the electrons and change their momentum thereby establishing a current is wrong because no charge carriers (i.e ., electrons ) are seen to cross the gap between the capacitor plates.

Firstly, it's not my theory, this theory is well accepted, in fact I believe Stephen Hawking refers to virtual photons in his book "A Brief History of Time". Secondly, since the forces between the charges on the two plates a transferred via EM fields, virtual photons would, in this case bridge the gap between the plates of the capacitor. Thirdly, it is not a requisite that charge moves between the plates of the capacitor in order for a current to be established. Recall that current is the net flow of electrons, electrons on one plate can readily introduce current flow in the other plate.

McQueen said:
Secondly we know that Maxwell explained this phenomena by postulating the existence of a displacement current . However , when considering this we must take into account the fact that photons had not then been discovered , it would take another almost two hundred years before photons were taken into account. If their existence had been known at the time then surely the possibility would at least have come under consideration that it is photons which carry electrical energy.

The major problem I have with the idea of photons carrying electrical energy is this, if electrical energy was transferred by photons why doesn't glass make a good conductor?.

Also, as it turns out Maxwell's equations have been modified, this theory is known as Quantum Field Theory or QFT. Theorists have elegantly taken things like photons and incorporated them into a coherent EM theory. Note that this does not invalidate the classical Maxwell's equations, it extends the validity of Maxwell's equations into quantum scale phenomena.

Claude.
 
  • #26
Claude Bile

Your comments are appreciated. However taking the points you had made :-
Sorry, it's just that saying that energy and charge are the same thing will send most physicists into fits. I think you got off lightly! (I will also say that the charge on the electron is a fundamental constant, and saying that it also varies would likely cause more fits.)
Let me stress , that when I attempt to answer this statement , that I am not insisting that my point of view is correct and that your point of view is wrong. I am merely attempting to state in a logical manner certain facts associated with the charge of an electron and to try and draw conclusions from these statements. Firstly it is widely held , both in the classical and QM schools of thought , that the electron is held in place in its orbit by Coulomb forces. Normally the electron occupies its ground state . (i.e., the orbit closest to the nucleus in which state it never emits. ) We must assume that it is orbiting at this particular distance from the nucleus because of Coulomb forces. Suddenly , the electron in the ground state absorbs a photon and shifts to another orbit , which ( according to QM ) it can occupy for an appreciable period of time. When the distance from the nucleus varies then obviously the charge and therefore also the Coulomb forces involved , also vary. A different Coulomb force or charge would be necessary to maintain the electron at this new distance from the electron. The inevitable conclusion that has to be drawn from this is that the charge of the electron varies with the emission and absorption of photons.
Firstly, it's not my theory, this theory is well accepted, in fact I believe Stephen Hawking refers to virtual photons in his book "A Brief History of Time". Secondly, since the forces between the charges on the two plates a transferred via EM fields, virtual photons would, in this case bridge the gap between the plates of the capacitor.
Granted , I am not trying to deny the existence of virtual photons , however .look at it from this point of view . We know that electrons in a conductor carrying a current drift extremely slowly at the rate of fractions of a millimeter a second. Given this how is electricity actually transferred . Surely the kinetic energy of the electron cannot be the concerned factor ? Since that is the case the end transfer of energy has to be via photons , if photons are the end factor in the transfer of electrical energy why can’t they also be the motivating factor ?
The major problem I have with the idea of photons carrying electrical energy is this, if electrical energy was transferred by photons why doesn't glass make a good conductor?.
Light propagates through glass , not because of the properties of the individual atoms concerned , pure silicon is opaque to light , but rather due to the crystalline structure of the glass. We have to accept that a combination of these two factors , (i.e., that the electrons are strongly bound to the atoms in question and the crystalline structure involved ), that only photons possessing a certain threshold of energy can propagate through glass. In metals , the low energy photons associated with electrical energy can propagate because the electrons are relatively loosely bound to the atoms of the crystalline structure. This is just a hypotheses.
Also, as it turns out Maxwell's equations have been modified, this theory is known as Quantum Field Theory or QFT. Theorists have elegantly taken things like photons and incorporated them into a coherent EM theory. Note that this does not invalidate the classical Maxwell's equations, it extends the validity of Maxwell's equations into quantum scale phenomena.
This is precisely the point that I am trying to make. A theory that was formulated 155 years ago , when the electron had not even been named and the photon had not been thought of , dealing with precisely these subjects might possibly have some oversights. Many of which have not been cleared up. For instance even in the case of electromagnetic radiation , ( I refer to longer wave-lengths ) it is sometimes attributed to the up an down oscillation of ions which come into contact with electrons and sometimes to the acceleration of the electrons themselves. Electromagnetic radiation ( of radio wave lengths ) is thought to be composed of “virtual “ photons , yet the induced energy due to these waves can be measured in hundreds of amps.
 
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  • #27
McQueen said:
When the distance from the nucleus varies then obviously the charge and therefore also the Coulomb forces involved , also vary.
Why? This is the crucial hypothesis in your argument, yet you produce no valid reason for making this assumption. The Electrostatic potential does not change, it is the energy that varies between (non-degenerate) orbitals. Moreover, if the charge were to vary, this could be easily verified experimentally. To date, no such evidence has been found.
McQueen said:
We know that electrons in a conductor carrying a current drift extremely slowly at the rate of fractions of a millimeter a second. Given this how is electricity actually transferred . Surely the kinetic energy of the electron cannot be the concerned factor ? Since that is the case the end transfer of energy has to be via photons , if photons are the end factor in the transfer of electrical energy why can’t they also be the motivating factor ?
I think this thread is relevant, Gokul's post is particularly neat.
https://www.physicsforums.com/showthread.php?t=77706
McQueen said:
Light propagates through glass , not because of the properties of the individual atoms concerned , pure silicon is opaque to light , but rather due to the crystalline structure of the glass. We have to accept that a combination of these two factors , (i.e., that the electrons are strongly bound to the atoms in question and the crystalline structure involved ), that only photons possessing a certain threshold of energy can propagate through glass. In metals , the low energy photons associated with electrical energy can propagate because the electrons are relatively loosely bound to the atoms of the crystalline structure. This is just a hypotheses..
First, the propagation of light through a substance is very dependant on the properties of the individual atoms and molecules, as it is the atoms and molecules that determine what wavelengths are transmitted and what wavelengths are absorbed in a medium. Crystalline structure determines non-linear effects and other subtleties like birefringence. Any photon can propagate through glass, provided it does not lie on an abosrption line.

Low energy photons such as microwave photons can propagate through metal quite readily, and metals are the material of choice for creating waveguides for these wavelengths.
McQueen said:
This is precisely the point that I am trying to make. A theory that was formulated 155 years ago , when the electron had not even been named and the photon had not been thought of , dealing with precisely these subjects might possibly have some oversights. Many of which have not been cleared up. For instance even in the case of electromagnetic radiation , ( I refer to longer wave-lengths ) it is sometimes attributed to the up an down oscillation of ions which come into contact with electrons and sometimes to the acceleration of the electrons themselves. Electromagnetic radiation ( of radio wave lengths ) is thought to be composed of “virtual “ photons , yet the induced energy due to these waves can be measured in hundreds of amps.
It would be ignorant to claim that any theory is perfect, but the current theory of electromagnetism is the most complete theory in the history of physics. Sure there may be oversights, but I certainly am not aware of any inconsistancies that are plagueing researchers at the moment. EM radiation is not thought to be composed of virtual photons, these photons are very real.

Claude.
 

1. What is the purpose of studying the intensity of light?

The study of the intensity of light allows scientists to understand the behavior and properties of light, which has many important applications in various fields such as astronomy, physics, and optics. It also helps in developing new technologies that utilize light, such as lasers and optical communication systems.

2. How is the intensity of light measured?

The intensity of light can be measured using a device called a photometer, which measures the amount of light that falls on a surface. The unit used for measuring intensity is called the candela (cd), and it is defined as the amount of light emitted by a standard candle in a specific direction.

3. Can the intensity of light change?

Yes, the intensity of light can change depending on various factors such as the distance from the light source, the medium through which light travels, and the properties of the light source itself. For example, as light travels through space, its intensity decreases due to the inverse square law.

4. How does the human eye perceive the intensity of light?

The human eye perceives the intensity of light through the retina, which contains specialized cells called rods and cones. These cells convert light into electrical signals, which are then sent to the brain for interpretation. The intensity of light can affect the sensitivity of these cells and determine the brightness of what we see.

5. How does the intensity of light affect the colors we see?

The intensity of light can affect the colors we see by influencing the amount of light that is reflected or absorbed by an object. For example, if a red object is exposed to intense light, it may appear brighter and closer to orange in color. Additionally, the intensity of light can also affect the contrast and saturation of colors in our vision.

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