From: "Frank Q" 
To: 
Reply-To: "Frank Q" 


Hi All

Some food for thought ......

Speaking from a PURELY CLASSICAL STANDPOINT,

* waves can and do intersect.

* but be careful how you use the term "interact"!

If a wave interacts with something, (eg the rods and cones in our eyes) you
would expect the wave to change that something (eg induce chemical or
electrical changes). After all it is an electrical signal and not light
that is
processed by our brains.

If a wave interacted with another wave then you would expect to be able to observe
the results of this interaction, like a change in the characteristics of
the wave such as its frequency. Thus we should be able to observe this
response in two intersecting laser beams. Obviously this is not oberved
(unless your standpoint is not purely classical- which leads to QM effects
like electron-photon scattering and related phenomena).

Now for effects like interference --- Interference is the LINEAR SUPERPOSITION
of  two or more waves in a region of space. You may call this an
"interaction" if you
like. However, the waves are not changed in any way. What are changed are the
resultant electric and magnetic fields in that region of space. (yes, you
could say the
waves are altered - but the effect is temporary). If we place a piece of paper
there, we observe the bright and dark bands characteristic of an
interference pattern.
This is the way the paper responds to two or more waves impinging on it -
it "emits"
(this may not be the most appropriate term) radiation according to the
resultant electric
field which exists at the surface of the paper - ie the linear
superposition or vector
sum of the fields from all the waves impinging on it.

Hope I have confused everyone

Cheers

Frank Q



----- Original Message -----
From: "Dwight K. Elvey" 
To: 
Sent: Tuesday, January 21, 2003 9:10 AM Subject: Re: ATM intersecting light


>
> Hi
>  Intersting observation. If there were a problem, we'd have
> a hard time seeing anything. My understanding is that the
> waves only interact when the medium becomes non-linear.
> Of course, as another mentioned, there is a continuous
> interference that is right where the beams cross. Since
> these waves have different directions of travel and there
> is no non-lenear interaction, when the waves energies
> go out of the interacting area, they continue as though
> the other wasn't there. I've seen this demonstrated
> in a water wave tank at one time. If both were at the
> same frequency, there were a lot of funny standing wave
> effect where they crossed but out side the intersection,
> the waves went on there original coarse.
>  Air takes a really high energy level before non-lenearity
> is much of an issue. These are tricks used in LASER work.
> There are solid materials that have non-linear effects that
> are used for such things as frequency doublers.
> Dwight
>
>
> >From: "A. Suykerbuyk" 
> >
> >Hi,
> >
> >Everywhere in the universe light is coming from all directions,
intersecting
> >is normal.
> >
> >Regards,
> >Adrie Suijkerbuijk.
> >
> >-----Oorspronkelijk bericht-----
> >Van: Harold 
> >Aan: ATM 
> >Datum: zondag 19 januari 2003 21:30
> >Onderwerp: ATM intersecting light
> >
> >
> >>
> >>
> >>
> >>  In a typical newt. telescope, the incoming  light hits the primary
mirror
> >>and is reflected back to the secondary and is then diverted to cross
> >through
> >>the incoming beam. This probably sounds rediculus, but i find it
facinating
> >>how this intersecting doesn't somehow interfere with the optical
image.If
> >>light is invisible then how can we see it. If it's not invisible
then....
> >>humm, perhaps someone with a better understanding of light and optical
> >>properties could enlighten ( no pun intended) me.
> >>
> >>  Harold
> >>
> >>
> >
> >
> >
>
>

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