Maxwell's electromagnetic theory of light

[copernicus1234]

"You seem to be getting hung up on induction - there is far more than induction going into Maxwell's equations and even more comes out."

 

 

Maxwell's equations are derived using Ampere and Faraday induction experiments that are not optical which is extremely important since induction is not optical. Its like two lesbians or gay men trying to make a baby.

[swansont]

 

Maxwell's equations are derived using Ampere and Faraday induction experiments that are not optical which is extremely important since induction is not optical.

 

No, really, it's not. Repeating it does not make it true.

[John Cuthber]

 

 

 

Maxwell's equations are derived using Ampere and Faraday induction experiments that are not optical which is extremely important since induction is not optical.

No.

The equations are based on the laws which were discovered using experiments that are not optical.

But the point of using experiments to derive laws is that the laws are generally applicable.

In particular, while they were discovered using very low frequencies, the laws of induction etc still apply at high (optical) frequencies.

[swansont]

No.

The equations are based on the laws which were discovered using experiments that are not optical.

But the point of using experiments to derive laws is that the laws are generally applicable.

In particular, while they were discovered using very low frequencies, the laws of induction etc still apply at high (optical) frequencies.

 

And if/when you reach conditions where the law breaks down (and in this case, must use quantum mechanics) that doesn't invalidate the equations for where they are applicable.

[John Cuthber]

It's also worth remembering that the production of EM radiation by effectively waving a coil in front of a magnet is possible and was used as a means to transmit radio signals before more efficient electronic systems were invented.

http://en.wikipedia.org/wiki/Alexanderson_alternator

 

Unless Copernicus can show a meaningful distinction between one form of em radiation and another there's no question that light is based on the same physics that Ampere and Faraday knew about.

[studiot]

copernicus, I don't know why you have chosen to ignore my posts 13 and 22 since they contain the answer to your question.

 

Maxwell extended Ampere's law, adding an extra term due to the time rate of change of an electric field.

 

It is because of this term that he realised that an electromagnetic wave could be generated.

 

In very simple terms

If something causes the electric field to vary in a dielectric, this will generate a varying magentic field, according to Maxwell's equation.

This, varying magnetic field will, in turn, generate a varying electric field, according to Faraday's law (restated by Maxwell).

This varying electric field, in turn will generate a varying magnetic field, completing the cycle.

 

and so it goes on and the wave propagates.

 

This is all due to Maxwell's displacement current in circumstances when the conduction current (Ampere current) is zero.

[copernicus1234]

ON ELECTROMAGNETIC INDUCTION" (Maxwell, part II).

 

"If, therefore, the phenomena described by Faraday in the Ninth Series of his Experimental Researches were the only known facts about electric currents, the laws of Ampere relating to the attraction of conductors carrying currents as well as those of Faraday about the mutual induction of currents, might be deduced by mechanical reasoning." (Maxwell, part II).

 

"ELECTROMAGNETIC THEORY OF LIGHT" (Maxwell, part VI).

 

"(91) At the commencement of this paper we made use of the optical hypothesis of an elastic medium throught which the vibrations of light are propagated" (Maxwell, part VI).

 

"Hence magnetic disturbances propagated through the electromagnetic field agree with light in this, that the disturbance at any point is transverse to the direction of propagation, and such waves may have all the properties of polarized light." (Maxwell, part VI).

 

Maxwell, James. Dynamical Theory of the Electromagnetic Field. Royal Society Transactions. Vol. CLV. 1864. http://rstl.royalsocietypublishing.org/content/155/459

Edited July 18, 2014 by copernicus1234

[John Cuthber]

Yes, that's the basis from which he made the extensions.

That's what Studiot said.

 

Does that mean you have now realised that there isn't a problem?

[copernicus1234]

"Maxwell's electrodynamics proceeds in the same unusual way already analysed in studying his electrostatics. Under the influence of hypotheses which remain vague and undefined in his mind, Maxwell sketches a theory which he never completes, he does not even bother to remove contradictions from it; then he starts changing this theory, he imposes on it essential modifications which he does not notify to his reader; the latter tries in vain to fix the fugitive and intangible thought of the author; just when he thinks he has got it, even the parts of the doctrine dealing with the best studied phenomena are seen to vanish. And yet this strange and disconcerting method led Maxwell to the electromagnetic theory of light!" (Duhem, 1902).

[studiot]

So Duhem didn't understand Maxwell, which is probably why he ends up as a footnote if mentioned at all.

 

Duhem had many mistaken ideas.

 

http://en.wikipedia.org/wiki/Pierre_Duhem

 

You seem to have a remarkable reluctance to acknowledge my contributions to your thread.

 

Why is this?

Edited July 21, 2014 by studiot

[swansont]

Sounds like a critique of the process, not the resulting subject matter. So what?

[John Cuthber]

I don't really understand the maths and I wasn't involved when Maxwell was working on this (obviously).

I guess that Duhem might have had a valid point (though I doubt it).

It's possible that Maxwell's route to those equations was a matter of hand-waving and guesswork.

So what?

The equations are demonstrably correct and, if you don't like the way Maxwell got them, you can derive them for yourself.

http://www.engr.uconn.edu/~lanbo/DeriveMaxwell.pdf

 

So the point remains, the equations work and I don't know or care if they were derived from Ampere's and Faraday's work (though that's who Maxwell cited so I think they almost certainly were).

And they provide the basis for the classical behaviour of light- they work just fine in a vacuum.

 

Perhaps Copernicus would like to explain why it matters if Maxwell got the right answers by maths, intuition or divine inspiration?

[Mike Smith Cosmos]

I think it was fair to say maxwell was working with electrical and magnetic field equations and when he took them through, to work out a speed of propagation or travel of these waves he came up with the figure of approx 300,000, kilometers ( 186,000 miles) per second as the speed for these electro magnetic waves , radio NOT LIGHT.

 

By the principle of equivalence , he noticed that light ( not knowing its true make up ) travelled at exactly the same speed. Already measured. So he said ah.ha ! Thus QED. Light must also be electro magnetic.

 

It's probably because everything ,(nearly everything ) is made of atoms of electrical charge and magnetic moment , so most ( not all ) of the effects coming out of , or being associated with atoms , like heat infra red waves, ultra violet waves, X-rays, gamma rays, radio waves , light waves all have similar characteristics as regards speed of propagation( travel ) . Which is why it is posited, including and starting with Maxwell, that ALL are electro- magnetic waves.

 

 

Link :- http://en.m.wikipedia.org/wiki/Emission_spectrum

 

Mike

Edited July 21, 2014 by Mike Smith Cosmos

[xiaojun]

Only with time variable electric field hospital and a time-varying magnetic field on

[copernicus1234]

I think it was fair to say maxwell was working with electrical and magnetic field equations and when he took them through, to work out a speed of propagation or travel of these waves he came up with the figure of approx 300,000, kilometers ( 186,000 miles) per second as the speed for these electro magnetic waves , radio NOT LIGHT.

By the principle of equivalence , he noticed that light ( not knowing its true make up ) travelled at exactly the same speed. Already measured. So he said ah.ha ! Thus QED. Light must also be electro magnetic.

 

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Like I have to repetively tell you that the velocity and wave effects of the radio induction effect does not justify Maxwell's theory since induction is not optical. Use some commen sense. Please no more about the electromagnetic induction, thank you. Also, the emission of light is alway acompanied with the release of electrons (ionization) yet induction is not an ionization effect. In addition, Maxwell theory also describes polarization using the vibration of an aether (elastic medium), composed of matter yet light propagates in vacuum that is void of matter.

 

 

"More artificial theories have been tried out, assuming that the real truth lies somewhere between these two limiting cases: that the ether is only partially carried by the moving bodies. But they all failed! Every attempt to explain the electromagnetic phenomena in moving CS with the help of the motion of the ether, motion through the ether, or both these motions, proved unsuccessful. Thus arose one of the most dramatic situations in the history of science. All assumptions concerning ether led nowhere! The experimental verdict was always negative. Looking back over the development of physics we see that the ether, soon after its birth, became the "enfant terrible" of the family of physical substances. First, the construction of a simple mechanical picture of the ether proved to be impossible and was discarded. This caused, to a great extent, the breakdown of the mechanical point of view. Second, we had to give up hope that through the presence of the ether-sea one CS would be distinguished and lead to the recognition of absolute, and not only relative, motion. This would have been the only way, besides carrying the waves, in which ether could mark and justify its existence. All our attempts to make ether real failed. It revealed neither its mechanical construction nor absolute motion. Nothing remained of all the properties of the ether except that for which it was invented, i.e., its ability to transmit electromagnetic waves. Our attempts to discover the properties of the ether led to difficulties and contradictions. After such bad experiences, this is the moment to forget the ether completely and to try never to mention its name." (Weaver, p. 145-6).

Edited July 24, 2014 by copernicus1234

[John Cuthber]

You say "induction is not optical".

That is a strange assertion to make.

Please prove it.

Don't just say "Use some commen sense." because common sense tells us that the theory that has been in use for ages and gives the right answers is a lot more lively to be right than some bloke on a web page.

 

Also, please address the issue of synchrotron radiation which is plainly induced and optical.

[Strange]

Also, the emission of light is alway acompanied with the release of electrons (ionization)

No it isn't.

[swansont]

Like I have to repetively tell you that the velocity and wave effects of the radio induction effect does not justify Maxwell's theory since induction is not optical. Use some commen sense. Please no more about the electromagnetic induction, thank you. Also, the emission of light is alway acompanied with the release of electrons (ionization) yet induction is not an ionization effect.

 

Repeating doesn't make it true. You've been shown an example of radiation of optical wavelengths.

 

Your objection is similar to someone rejecting gravity because nobody has measured it some distance from the ecliptic in our solar system.

 

 

In addition, Maxwell theory also describes polarization using the vibration of an aether (elastic medium), composed of matter yet light propagates in vacuum that is void of matter.

Do the equations require an ether, or merely explain how a medium would become polarized should the waves pass through one?

[copernicus1234]

Maxwell's theory is based on Ampere and Faraday induction experiments that are not optical. Poynting (1884) supports Maxwell by deriving an energy equation of light (Poynting, p. 358) but Poynting's current wire (Poynting, p. 350) is not emitting light. Hertz's (1887) attempts to structurally unify induction with light using the conduction spark experiment but Hertz's spark gap is emits electrons, when the spark is produced yet induction is not an ionization effect which contradicts Motz and Weaver statement that Hertz experiment is definitive proof. Definitive proof would be an experiment where the radio induction effect and light are emitted without the emission of electrons yet no such experiment exists since the production of light is always accompanied by the emission of electrons or other particle interactions (protons, molecules, etc...). Planck (1901) attempts to structurally unify electromagnetic waves with light, using the blackbody radiation effect, that emits the radio induction effect and light, but the blackbody radiation effect is also emitting electrons. In addition, the velocity and wave effects, of the radio induction effect, cannot be used to justify Maxwell's theory since induction is not optical.

 

"To receive or detect these oscillations, Hertz used a small loop of wire with the ends not touching. By changing the distance between the spheres, Hertz tuned the generator (or transmitter) until its frequency exactly equaled the natural frequency of the receiving loop. When he did this, he found that a spark jumped across the ends of his receiving loop whenever his transmitting oscillator was operating. With these simple devices, which were the precursors of our modern radio transmitters and radio recieveres, Hertz demonstated that the electromagnetic waves he generated were qualitatively the same as light. One of his most serious concerns was to show that his electromagnetic waves travel through a vacuum at the same speed as light, and when he did this, he was completely convinced that Maxwell's electromagnetic waves and light are identical. When he reproduced such phenomena as reflection, refraction, diffraction, and interference, his work was taken as the definitive experimental proof of Maxwell's theory." (Motz and Weaver, chapter 15).

 

 

 

++++++++++++++++++++

 

 

" First observed in synchrotrons, synchrotron light is now produced by storage rings and other specialized particle accelerators, typically accelerating electrons." (Wikipage).

 

 

"If there was no interaction of anything with anything, then it is probably unlikely that light could be produced."

 

 

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In Hertz's spark gap experiment, electrons propagating across the gap, produce the spark gap light yet induction is not an ionization effect. Yes, that could be true since electrons could be bumping into each other to produce light. The Greek used many theory of light yet modern physics uses only the wave theory but the Greek theories were similar since they involved the physical interaction of the eye or object with the eye. They inablity to change resulted in the Roman to complete destroy the Greeks. Can some tell me what section these posts are listed as since I'm having to seach to get here.

Edited July 24, 2014 by copernicus1234

[Strange]

Maxwell's theory is based on Ampere and Faraday induction experiments that are not optical.

 

I forget, how many times do you have to repeat this before it becomes relevant?

 

since the production of light is always accompanied by the emission of electrons

Still not true. Repeating doesn't make it any more true.

 

or other particle interactions (protons, molecules, etc...)

 

Well, duh. If there was no interaction of anything with anything, then it is probably unlikely that light could be produced.

Edited July 24, 2014 by Strange

[John Cuthber]

Copernicus,

Just out of idle curiosity, could you let me know where in the em spectrum from radio waves (all the way down to ELF radiation) through microwaves, into the millimetre waves, through the infra red and into the realm of visible light you imagine there is some "cut off" between the sort of things that Ampere and Hertz did and the behaviour of light?

[copernicus1234]

5. Maxwell's Equations

 

 

 

Part A

 

 

Maxwell electric curl equation is derived using Faraday's induction experiment (Hecht, p. 121). The magnetic flux (dB/dt) that is incident, normal to the plane, of the wire loop, produces the wire loop emf,

 

emf = - ʃʃ (dB/dt)· dA...........................................20

 

The wire loop emf is formed by an internal electric field E represented with,

 

 

emf = ʃ E · dl........................................................21

 

Equating equations 20 and 21,

 

ʃ E · dl = - ʃʃ (dB/dt)· dA.......................................22

 

Using Stokes' theorem,

 

ʃ E · dl = - ʃʃ (∇ x E)· dA.....................................23

 

Equating equations 22 and 23,

 

- ʃʃ(dB/dt)· dA = ʃʃ (∇ x E)· dA............................24

 

Maxwell electric curl equation is derived using equation 24

 

∇ x E = - dB/dt.................................................25

 

Only the magnetic field B, of the magnetic flux (dB/dt), that is incident perpendicular to the plane, formed by a wire loop (equ 20), forms the wire loop emf. Also, the electric field E, that forms the wire loop emf (equ 21), represents an electric field that only exists within the conduction wire. The electromagnetic fields, of this derivation, do not exist together, in free space yet Maxwell's electric curl equation (equ 25) is used to derive the electromagnetic wave equations of light that electromagnetic fields forms together, in free space, which proves the derivation of Maxwell's electric curl equation (equ 25) is a deception.

 

 

 

 

 

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Copernicus,

 

 

Just out of idle curiosity, could you let me know where in the em spectrum from radio waves (all the way down to ELF radiation) through microwaves, into the millimetre waves, through the infra red and into the realm of visible light you imagine there is some "cut off" between the sort of things that Ampere and Hertz did and the behaviour of light?

 

 

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Light and higher energy are particle and not induction effects. Also, just out of curiosity do you believe heat and sound are electromagnetic phenomena to? Is everything EM? In addition, can a position probability form a negataive value? Can you negatively not be somewhere? If your bain waves and heart failed and you were somewhere else would it not be a zero probability?

Edited July 24, 2014 by copernicus1234

[John Cuthber]

"Light and higher energy are particle and not induction effects." but I can show the photoelectric effect with energy that's not light.

In particular, I can use infra red light.

And I can do diffraction experiments with xrays so they are just as much waves as radio waves are.

 

Are you actually able to come up with any real differences?

 

"Also, just out of curiosity do you believe heat and sound are electromagnetic phenomena to?"

No.

"

Is everything EM?

No, of course not.

Please don't waste any more time with strawmen.

 

"In addition, can a position probability form a negataive value?"

Who cares?

It has nothing to do with the issues.

[swansont]

Can some tell me what section these posts are listed as since I'm having to seach to get here.

It's at the top of the page

 

Science Forums→ Other Topics→ Speculations

[copernicus1234]

"By contrast, the electromagnetic state of a region of space is described by continuous functions and, hence, cannot be determined exactly by any finite number of variables. Thus, according to Maxwell's theory, the energy of purely electromagnetic phenomena (such as light) should be represented by a continuous function of space. By contrast, the energy of a material body should be represented by a discrete sum over the atoms and electrons; hence, the energy of a material body cannot be divided into arbitrarily many, arbitrarily small components. However, according to Maxwell's theory (or, indeed, any wave theory), the energy of a light wave emitted from a point source is distributed continuously over an ever larger volume." (Einstein*, intro).

 

"In particular, black body radiation, photoluminescence, generation of cathode rays from ultraviolet light and other phenomena associated with the generation and transformation of light seem better modeled by assuming that the energy of light is distributed discontinuously in space. According to this picture, the energy of a light wave emitted from a point source is not spread continuously over ever larger volumes, but consists of a finite number of energy quanta that are spatially localized at points of space, move without dividing and are absorbed or generated only as a whole." (Einstein*, intro).

 

"These electrons also interact with the free molecules and electrons by conservative potentials when they approach very closely. We denote these electrons, which are bound at points of space, as "resonators", since they absorb and emit electromagnetic waves of a particular period." (Einstein*, 1).

 

 

 

 

" First observed in synchrotrons, synchrotron light is now produced by storage rings and other specialized particle accelerators, typically accelerating electrons." (Wikipage).

 

 

 

The synchrotrons is a enlongated Hertz's spark gap. Also, the probablity wave, of QM, is also justifying Maxwell's theory since QM is an electromagnetic theory (sometimes sometimes not)...?

Edited July 28, 2014 by copernicus1234