I'm reading a physics book for dummies. It explains light waves by comparing it to a stone being thrown into a pond. It looks like the waves move out but that isn't the case, the water moves up and down as the energy waves passes outward.
Sound waves are a different case entirely.

So, do photons of electromagnetic radiation bounce up and down like the water used to illustrate waves? I expect the comparison breaks down, it's too simple but I don't know.

... It explains light waves by comparing it to a stone being thrown into a pond. It looks like the waves move out but that isn't the case, the water moves up and down as the energy waves passes outward. ...

So, do photons of electromagnetic radiation bounce up and down like the water used to illustrate waves?...

Simple answer, nope. It is all an illusion! ;-)


The description "photon" describes a single quanta of electromagnetic energy. You can't get 'half-photons' for example.

A photon is detected as a 'wave packet' (you can't see a photon in flight without destroying it as is done by detecting it). A crude visualization is perhaps that of a snake wriggling along in an S-shaped pattern along a sand surface. Any one part of the snake's body oscillates from side to side. The sequence of oscillating parts give the illusion of an S-shape continuously flowing backwards as the snake makes progress forwards. The trail in the sand shows the oscillation followed.


A light beam is made up of a vast stream of individual photons, usually all oscillating their own ways individually.

And then you get the very clever and highly unusual spectacle of laser light whereby a large number of photons are emitted almost simultaneously so that their oscillations are all in sync...

I'll let someone else pick up that story.


And a question for others:

Do our radio-frequency transmissions from wire aerials in effect generate a "laser-beam-like" but continuous coherent radiation?

How does that then break down into quanta as the radiation disperses?

All a crazy Feynman game of superposition of quanta?



The ripples on the surface of water are more analogous to the pressure profile for the compression waves that we hear as sound.


Hope not too confusing!

Keep searchin',
Martin

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See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Thanks ML1:

This part I like and that is what I had thought too:

The ripples on the surface of water are more analogous to the pressure profile for the compression waves that we hear as sound.




This part where you say 'oscillating' sounds awfully like bouncing up and down though (like a sine wave).:

A light beam is made up of a vast stream of individual photons, usually all oscillating their own ways individually.


That part about not being there if we look at it, I will Never understand.

This part where you say 'oscillating' sounds awfully like bouncing up and down though (like a sine wave).:

A light beam is made up of a vast stream of individual photons, usually all oscillating their own ways individually.

For the snake analogy, it is the snake that is the photon.

Does the snake 'bounce up and down'?

As a whole it doesn't. Over an average, the snake moves in a straight line.

Similarly so for what we call a photon.

Only if you could somehow look at a smaller scale than the photon, you might 'see' the electromagnetic oscillations 'inside' that as a group we call "a photon"...

That part about not being there if we look at it, I will Never understand.

All a part of our fundamental observation that energy can neither be created nor destroyed: You must always convert energy into another form.

Hence, when you manipulate a packet of energy such as a photon, you convert it into for example an electrical impulse on your camera photo-detector. (And so destroy the original photon. However, the energy from the photon lives on... As electrons in the detector.)


Keep searchin',
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

Thanks ML1,

I really love this conversation. The last part though?
By looking at it I destroy it. What does that have to do with
energy can't be created or destroyed?

--edit--
Are you saying that when I look at the photon it turns into an electron as it hits my eye?

--edit2
As I look at the stars I am destroying those photons that reach my eye. They do not pass thru me.

As I understand it when the photon stikes something such as an eye it becomes electricity or heat.

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A photon can be considered as an energy transfer medium - it transfers energy from one location to another. These "locations" can be electrons - the source is in an elevated energy state, and in producing the photon it returns to a lower energy state. On reaching the target the energy is transferred to the target. No electron is created or destroyed in the process.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

rob smith,

That is very interesting. Mind bending. So many ways to think of things.
Thanks

... No electron is created or destroyed in the process.

Rob, thanks for clarifying that one :-)


A fascinating aspect of photons is that they appear to be timeless... We can detect photons still from those first visible from the very early years of our universe... And they uniquely propagate/travel at the speed of light...


Keep searchin'
Martin

---

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)

But the arriving photon must cause an electron to be stripped off of one of your atoms? Or?

A photon can be considered as an energy transfer medium - it transfers energy from one location to another. These "locations" can be electrons - the source is in an elevated energy state, and in producing the photon it returns to a lower energy state. On reaching the target the energy is transferred to the target. No electron is created or destroyed in the process.

Not unless the arriving photon causes an electron to reach a high enough energy state.
The extra energy may be stored within the atom, or be released as another photon(s) of different energy (and this release may be more than that of the arriving photon if the atom's energy was already at an elevated level compared to its final level).


(This is the easy stuff, and there are all sorts of more complex things around than photon/electron interactions.....)

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?