photons

[god-of-course]

Can someone explain to me what exactly a photon propogates/mediates through, regarding the theory of aether as entirely false and is this somethign to do with the particle characteristics of a photon etc? cheers

[AndersHermansson]

I think it's valid to say that light propagates through the electromagnetic field.

[John Connellan]

I dont like to think of light as "being" a particle (since it has no rest mass) but as having particle-like properties. I think of a photon as a disturbance of an electromagnetic field so u have to have that to have a photon. That seems to be its 'medium' if u like.

[lethe]

do you believe that an electron can move through a vacuum? or an astronaut in interstellar space? do you need some æther when you walk down the street?

because the photon doesn t need one either. photons, electrons, protons, and any combination of them (like people) moves through empty space with no problem. the photon simply doesn t need an æther

the only reason that anyone ever talks about an æther is because of two reasons: 1. it was before relativity was invented, 2. they just don t understand relativity. without relativity, you need an æther for photons, but with relativity, the photon is free to move through a vacuum just as much as you yourself are.

[god-of-course]

why so aggitated about it? i know that an aether contradicts relativity and so i have no time for the theory...some people here however do and i dont want there answers. and what electromagnetic field? how can this exist independant of mass ie in space etc?

[god-of-course]

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[lethe]

Originally posted by god-of-course
why so aggitated about it? i know that an aether contradicts relativity and so i have no time for the theory...some people here however do and i dont want there answers. and what electromagnetic field? how can this exist independant of mass ie in space etc?

who is agitated? not me.

so what is your question? electromagnetic field just describes the evolution of a photon. the photon moves through a vacuum.

[god-of-course]

a photon as a disturbance of an electromagnetic field so u have to have that to have a photon

electromagnetic field just describes the evolution of a photon

I guess what I am getting at is can you put these two together please.

I cannot understand the nature of a photon, if its a wave then a wave of/in what? if electromagnetic fields then what is generating these? if it is independant of these fields why how does it consist of electric and magnetic waves? blah blah blah. :( i have just never studied electro-magnetism.

[lethe]

Originally posted by god-of-course
I guess what I am getting at is can you put these two together please.

I cannot understand the nature of a photon, if its a wave then a wave of/in what? if electromagnetic fields then what is generating these? if it is independant of these fields why how does it consist of electric and magnetic waves? blah blah blah. :( i have just never studied electro-magnetism.

well, it seemed that your original question was about photons, and this is a particle question, and can be discussed quite outside the context of electromagnetism. this is why i did not mention electromagnetism in my first post.

maybe i will discuss this in terms of electromagnetism now.

the electromagnetic fields are just numbers that tell you how strong a force you will feel if you put a charged particle somewhere. it turns out that these fields are dynamical, meaning that they can change in time, and when they do, the generate more fields. if, for some reason, the electric field is changing in time, this automatically generates a magnetic field. if a magetic field is changing in time, it automatically generates some electric field.

so when the electric field is changing in time, at a variable rate, then it generates a changing magnetic field which generates a magnetic field which generates an electric field which generates a magnetic field etc....

this self generating field moves down the highway at the speed of light, and is what we call electromagnetic radiation. since electric fields are always present in the vicinity of a charged particle, we can create electromagnetic radiation simply by oscillating the charged particle in time, which will make the electric field oscillate in time, which will make the magnetic field oscillate in time, etc etc etc.

so in this context, an electromagnetic wave does not need an æther any more than you need an æther to make two neighboring charges repel. they feel each others fields, even if the two particles are in a total vacuum.

[god-of-course]

ahh ok, so will an electric charge, when moving, make the magnetic field at a 90 degree angle to itself? and vice versa?

[lethe]

Originally posted by god-of-course
ahh ok, so will an electric charge, when moving, make the magnetic field at a 90 degree angle to itself? and vice versa?

it will make a magnetic field at 90 degrees to the direction it is moving, yes.

[James R]

It is important to realise that a photon is neither a particle nor a wave. Rather, it is a quantum object which has some of the properties of both particles and waves.

People often ask "if a photon is a wave, what's doing the waving, especially in a vacuum?". The wave description of a photon (as opposed to a classical electromagnetic field), describes the photon as a wave packet made of probability waves. In fact, that's how quantum theory describes <b>all</b> particles. So, if you ask what's waving, the best answer is probability amplitudes.

[lethe]

Originally posted by James R
It is important to realise that a photon is neither a particle nor a wave. Rather, it is a quantum object which has some of the properties of both particles and waves.


this is just a matter of semantics, but i wouldn t say that a photon is not a particle. what you probably mean is that a photon isn t a classical particle. nor is it a classical wave. i guess when i use the word "particle", i always mean elementary particle, which are always quantum.

and in fact, everything in nature is a quantum object, on some level. so rather than say a photon is not a particle, i would prefer to just clarify that a photon is a quantum mechanical object, not a classical object.

[James R]

Agreed, lethe.