Photon properties.

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Daniel Pitts - 20 Feb 2006 04:18 GMT

I have some questions about "light" waves.

I know that a Photon has an energy related to its frequency, and that
somewhat makes sense to me. What I wonder though.. A light wave has
"length" (the distance between "peaks"), but does it have an
"amplitide"?
If so, Is it also related to the frequency; is it quantized, like spin,
or is it constant?
Also, is it measurable? Are there any easy to perform experiments to
determine it?

Thanks,
Daniel.

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PD - 20 Feb 2006 15:48 GMT

> I have some questions about "light" waves.
>
[quoted text clipped - 6 lines]
> Also, is it measurable? Are there any easy to perform experiments to
> determine it?

OK, first of all, be careful mixing photon and wave descriptions. A
photon is not "really" a wave, and a light wave is not "really" a
photon. Light is what it is, and it has properties that are both like a
wave and like a particle, without being really one or the other.

A light *wave* does have an amplitude. It is the amplitude of the
electric and magnetic fields that oscillate at any given location that
the wave passes through. Yes, it is measurable. Is the magnitude of the
electric field quantized? This is a question with an obvious answer.

PD

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Daniel Pitts - 20 Feb 2006 16:14 GMT

> > I have some questions about "light" waves.
> >
[quoted text clipped - 18 lines]
>
> PD

Thank you, that helps some...
What is the scale of the amplitude? nanometers? 10^-3 nanometers?
Planck scale?
It makes sense to me that the osillation is an oscillation of the
electric and magnetic fields, but that to me implies that an
electric/magnetic field is not quantized, or if it is quantized, that a
light wave is not a "smooth" function.
If the answer is obvious, why would I have had to asked the question?

Hmm, one more question. What happens if a photon has enough energy that
the wavelength is shorter than the Planck length? Does the universe get
aliasing effects? (where a frequence appears lower than it really is.
This is an effect observed in Audio, and sometimes in Video, when a
frequency is above the scale of the sampling rate)

Thanks for the help,
Daniel.

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PD - 20 Feb 2006 23:02 GMT

> > > I have some questions about "light" waves.
> > >
[quoted text clipped - 22 lines]
> What is the scale of the amplitude? nanometers? 10^-3 nanometers?
> Planck scale?

The amplitude is an amount of electric *field* and magnetic *field*,
that is, in V/m or tesla, respectively. Please do not get the
impression that anything moves back and forth in *space* as the field
oscillates.

If you want to get a feel for what's going on here, stand in a doorway
and place one hand on the wall inside a room and one hand on the wall
outside the room, so your palms are facing each other. Now do this:
Push with your right hand, then push with your left hand, then push
with your right hand, then with your left hand, and so on, so that the
*force* you apply on the wall at that spot oscillates back and forth
(roughly sinusoidally), even though the wall doesn't go anywhere. That
oscillation of a *force* is something akin to the oscillation that the
electric or magnetic field has at any given spot.

> It makes sense to me that the osillation is an oscillation of the
> electric and magnetic fields, but that to me implies that an
> electric/magnetic field is not quantized, or if it is quantized, that a
> light wave is not a "smooth" function.

Right, and this is where what it means to quantize a field gets tricky.
It's not what you think.

> If the answer is obvious, why would I have had to asked the question?
>
> Hmm, one more question. What happens if a photon has enough energy that
> the wavelength is shorter than the Planck length?

Such a photon has never been observed, and we're pretty sure that the
laws of physics would be substantially different enough at that end of
the scale that it's improper to extrapolate cavalierly.

> Does the universe get
> aliasing effects? (where a frequence appears lower than it really is.

I don't think that's a reliable prediction at this point, no.

> This is an effect observed in Audio, and sometimes in Video, when a
> frequency is above the scale of the sampling rate)
>
> Thanks for the help,
> Daniel.

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brian a m stuckless - 21 Feb 2006 09:43 GMT

$$ *Space* case cavalieriTY.

> > > > I have some questions about "light" waves. -=-
> > > A photon is not "really" a wave, and a light wave is not "really"
[quoted text clipped - 5 lines]
> > > electric and magnetic fields that oscillate at any given location
> > > that the wave passes through. -=- > > > PD

-=-

> Please do not get the impression that anything moves back and forth
> in *space* as the field oscillates.

-=-

> Push with your right hand, then push with your left hand, then push
> with your right hand, then with your left hand, and so on, so that
[quoted text clipped - 3 lines]
> oscillation that the electric or magnetic field has at any given
> spot.

-=-

> > What happens if a photon has enough energy that the wavelength
> > is shorter than the Planck length?

-=-

> the laws of physics would be substantially different enough at
> that end of the scale that it's improper to extrapolate cavalierly.

-=-

> > Thanks for the help, > > Daniel.

Re: Photon properties.
Re: *Space* case cavalieriTY.
Re: ..it's improper to [oscillate] cavalierly. END of POST.

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Do Do - 21 Feb 2006 00:37 GMT

"OK, first of all, be careful mixing photon and wave descriptions. A
photon is not "really" a wave, and a light wave is not "really" a
photon. Light is what it is, and it has properties that are both like a

wave and like a particle, without being really one or the other."

Vergon

Saying" Light is what it is" explains nothing.
What our man is concerned with here is the wave/particle duality.

If you would like to see a model that explains it all in understandable
terms, see the monograph "On the Quantum as a Physical Entity".

Go to http://www.wbabin.com, Then go to
"List of Authors" and click on Vertner Vergon.
This is the General Science Journal. Excellent.

Reply to this Message

PD - 21 Feb 2006 14:25 GMT

> "OK, first of all, be careful mixing photon and wave descriptions. A
> photon is not "really" a wave, and a light wave is not "really" a
[quoted text clipped - 5 lines]
>
> Saying" Light is what it is" explains nothing.

That's true. We define light by what it does, because we have an
inadequate terminology to capture what it is. Unfortunately,
understanding what it does takes a substantial amount of work to get a
good feel for it, precisely because we don't have a familiar
pigeon-hole to drop light into to help us frame a concept of it.

> What our man is concerned with here is the wave/particle duality.

And that's precisely what I briefly described above.

> If you would like to see a model that explains it all in understandable
> terms, see the monograph "On the Quantum as a Physical Entity".
>
> Go to http://www.wbabin.com, Then go to
> "List of Authors" and click on Vertner Vergon.
> This is the General Science Journal. Excellent.

Not that it matters to you, but I withhold endorsement of this paper.

PD

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Natural Science Forum / Physics / Particle Physics / February 2006

Photon properties.