Re: What causes light to accelerate after refraction?



On Apr 23, 1:33 pm, "g...@xxxxxxxxxxx" <g...@xxxxxxxxxxx> wrote:
On Apr 23, 10:15 am, Randy Poe <poespam-t...@xxxxxxxxx> wrote:





On Apr 22, 2:50 pm, "g...@xxxxxxxxxxx" <g...@xxxxxxxxxxx> wrote:

On Apr 20, 2:39 pm, Randy Poe <poespam-t...@xxxxxxxxx> wrote:

On Apr 20, 12:46 pm, "g...@xxxxxxxxxxx" <g...@xxxxxxxxxxx> wrote:

On Apr 20, 11:30 am, Randy Poe <poespam-t...@xxxxxxxxx> wrote:

On Apr 20, 10:21 am, "g...@xxxxxxxxxxx" <g...@xxxxxxxxxxx> wrote:

On Apr 20, 9:24 am, Randy Poe <poespam-t...@xxxxxxxxx> wrote:

On Apr 20, 7:58 am, "g...@xxxxxxxxxxx" <g...@xxxxxxxxxxx> wrote:

1. What causes light to accelerate after refraction?

It's a bulk effect. The average forward velocity of the energy changes
in refraction. But the individual photons always move at c.

Acceleration requires energy loss, I presume light loses intensity
when it accelerates back to "c" after exiting a refracting medium
(like a thick gel(beam) that squeezes out thinner as it exists)?

No individual photon loses energy. All real materials are also
absorptive, so some photons are absorbed and the overall
wave front loses energy.

2. Light must come out truncated?.....because the photons exiting are
faster then the ones in the refraction?

No.

Full of massive misconceptions, as usual.

- Randy

Ok that is what "they" say and this discovery that began only recently
in 1999 is due to the time delay between molecules absorbing and
releasing a photon.

I'm very skeptical since they didn't even mention if the chance of
this slower velocity is proportional to the permittiviy and
permeability of the medium?

Yes, of course it is determined by those things. Those things
determine what fields are set up inside the medium in reaction
to the incoming EM energy, and it is the sum of all of those
fields which is the slower "moving" field.

And if the velocity becomes slower the farther it travels in the
medium (since the more molecules absorbing & releasing = the more time
delay) or if it's a constant slower velocity??

A constant except perhaps for the first couple of wavelengths
distance from the interface.

Why? What interface as they exit or as they enter the medium?

Are you asking "where is the interface when you exit a
medium"? It's the boundary where one medium ends and the
other begins.

A few wavelengths deep into the material, any bulk
approximation would be reasonably good since you are
surrounded in all directions by the medium. But near
the interface you are seeing a combination of fields
generated in two different media and there is an
intermediate zone.

Obvious basic two questions that demand attention before any
deduction, yet they don't even mention an answer??

What questions are those? Who are "they" and where is
this place where "they" do or don't mention an answer?

The web links I posted specifiy that lightspeed is reduced due to atom/
molecule time delay between "accumulated" (One incidident won't do
much) absorption and re-emission of photons and the links never
mention permeability and permittivity.

There's no reason why a brief press release has to include
all of electromagnetic theory. It wouldn't fit, and it wouldn't
be of interest to their intended audience.

If you want the technical description of what is happening,
read their scientific papers, not their press releases.

Now since you say that it is related to permeability and permittiivity
and for their above statement to ALSO be valid then that would mean:

The factors that determine permeability and permittivity are related
to the molecules time to abosb and re-emit em waves

No, but it is related to the absorptions and reemissions
of em waves by molecules. In fact, you can calculate
those quantities as a function of frequency, by adopting
a suitable model of those molecules.

But that's for more ordinary materials. A Bose-Einstein
condensate is a very special state, and I don't think the
interaction of photons and electrons can be calculated in
such a simplistic way.

Now, I'm out of my depth here, but here are a few thoughts.
In ordinary matter, you can have the concept of a free path
for photons between atoms. You can calculate the average
rate at which a photon will encounter an atom, and how
it will interact.

I think a Bose-Einstein condensate is more like one giant
electron cloud without the concept of "free path". So I'm not
sure how the interaction of photons with that cloud is really
described.

.....if so that
would defeat the explanation of permeabilty and permittivity values of
vacuum space where there are no molecules and thus logically
permeabilty and permittivity values in "vacuum empty" space should be
zero (or infinite).

No, they shouldn't be zero or infinite. The values they have
are basically artifacts of the system of units. You are adding
some unwarranted assumption when you say "logically they
should be zero", like that they are proportional to molecular
density or something.

Their values are consequences of the density and nature of
the molecules, but there's no such simple-minded relation.

Here's a more technical description of the "slow light":http://www.spie.org/web/oer/may/may99/cover2.html

- Randy- Hide quoted text -

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Ok but that link above doesn't explain any relation with of the
condensate medium with permittivity and permeability.....in fluids,
permeability = flow rate ...don't know if that is similar to group
velocity...

Where do you get "in fluids, permeability = flow rate"? That
bears no resemblance to any EM theory I've ever seen.

- Randy- Hide quoted text -

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That's why I said fluid and not EM, yet they have similar
characteristics.

There is both a permititvity(defined as porosity in the dictionary)
and permeability for fluids as they travel through sediments.

(permittivity for fluids) Porosity is the total empty space versus the
amount of blockage(stones/matter) = Area = meters^2.

Permeability for fluids they define as the total flow rate.

I believe they also use viscosity in the equations (in comparison for
light perhaps it's frequency...wavelength)....the bigger the porosity
I believe the less effect the viscosity.


When an electron is pushed, a proton is pulled.
That difference in a fluid of fundamental particles and a
fluid of complex particles doesn't make for a good analogy.

Again... you are trying to build a brick, with collection
of little houses. Get your feet out of the air and your
head off the ground and learn the fundamentals.

Time-independent Maxwell equations
Time-dependent Maxwell's equations
Relativity and electromagnetism
http://farside.ph.utexas.edu/teaching/em/lectures/lectures.html
http://web.mit.edu/8.02t/www/802TEAL3D/visualizations/light/index.htm

Sue...






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