Perfect transparency?

Dear Yousuf Khan:

On Wednesday, October 23, 2013 9:59:59 PM UTC-7, Yousuf Khan wrote:
....
These elements are pretty easy to spot inside
a galaxy where the concentrations are higher.

No, they aren't. If they are in a ground state, as molecules, yes. But ionized to atoms, no they take very energetic photons to knock off even one electron.


But what about in the intergalactic region?

Just as hard, but we have distant x-ray sources and less dust. Just have to wait for us to "move" those sources around...

Is the density low enough to not detect the
gas or plasma itself, but high enough to
produce a small refractive lensing effect?

They are dense enough to be a gravitational lens, and *CANNOT* refract, since they cannot interfere with the passing photons *at all*. And if they did, they would spread the spectrum... which we do not see.

I think some intergalactic gas near the Milky
Way has recently been discovered streaming into
the MW replenishing the gas within the galaxy,

.... or simply in orbit...

that was right under our proverbial noses.

Damned straight.

Obviously, I'm trying to figure out if there
are alternative explanations for the so-called
Dark Matter lensing around galaxies.

Su
- ionized gas
- cold neutrinos
- rogue planets, brown dwarves
- black holes
- calibration errors based on a lack of application of recently revealed galactic physics:
* the center of a spiral galaxy is swept clean of dust
* the stars of the center of a spiral galaxy appear hotter, because their photospheres have been stripped due to tidal action... so smaller mass looks hotter.
* dust away from the center tends to make intensities lower, and redden the spectrum, so it looks like less mass than is really present.

"Refraction" isn't going to help.

David A. Smith

On 24/10/2013 11:38 AM, dlzc wrote:
Dear Yousuf Khan:

On Wednesday, October 23, 2013 9:59:59 PM UTC-7, Yousuf Khan wrote:
...
These elements are pretty easy to spot inside a galaxy where the
concentrations are higher.

No, they aren't. If they are in a ground state, as molecules, yes.
But ionized to atoms, no they take very energetic photons to knock
off even one electron.


But what about in the intergalactic region?

Just as hard, but we have distant x-ray sources and less dust. Just
have to wait for us to "move" those sources around...

It probably depends on how long it takes electrons to spontaneously
discharge back down to a ground state, then we'd see these sources light
up a bit more. I heard somewhere that it takes 30 million years for an
electron to spontaneously discharge back to the ground state, from an
X-ray energy level. Don't know if it's true or not. I assume Gamma rays
would take even longer.

Is the density low enough to not detect the gas or plasma itself,
but high enough to produce a small refractive lensing effect?

They are dense enough to be a gravitational lens, and *CANNOT*
refract, since they cannot interfere with the passing photons *at
all*. And if they did, they would spread the spectrum... which we do
not see.

Well, then how does glass act as a lens? The photons of light aren't
energetic enough to excite the electrons of glass, that's why its
transparent, yet the glass can bend the light just the same. It's
because the light slows down when entering the glass medium from the air
medium. So what about a similar effect, except much smaller refractive
index (even smaller than air), so the light barely seems slowed at all?
Speed of light in air is 0.999723 c.

Here we would only be talking about the difference between two different
vacuums. Let's say the difference between the vacuum of an intergalactic
void and a galactic cluster! A galactic cluster would be more dense than
an intergalactic void. Then there would be an even denser medium right
in the halos near individual galaxies vs. a galactic cluster
environment. We're getting more and more progressively denser as we go
down the individual scales.

I think some intergalactic gas near the Milky Way has recently been
discovered streaming into the MW replenishing the gas within the
galaxy,

... or simply in orbit...

I think just about everything is in orbit around everything else when
we're talking about intergalactic space.

Obviously, I'm trying to figure out if there are alternative
explanations for the so-called Dark Matter lensing around
galaxies.

Su - ionized gas - cold neutrinos - rogue planets, brown dwarves -
black holes - calibration errors based on a lack of application of
recently revealed galactic physics: * the center of a spiral galaxy
is swept clean of dust * the stars of the center of a spiral galaxy
appear hotter, because their photospheres have been stripped due to
tidal action... so smaller mass looks hotter. * dust away from the
center tends to make intensities lower, and redden the spectrum, so
it looks like less mass than is really present.

"Refraction" isn't going to help.

But what if there isn't enough Dark *Baryonic* Matter to explain the
lensing effect, entirely gravitationally? Then finding a refractive
cause might explain it.

Yousuf Khan

Dear Yousuf Khan:

On Friday, October 25, 2013 5:38:33 AM UTC-7, Yousuf Khan wrote:
On 24/10/2013 11:38 AM, dlzc wrote:
....
But what about in the intergalactic region?

Just as hard, but we have distant x-ray
sources and less dust. Just have to wait for
us to "move" those sources around...

It probably depends on how long it takes
electrons to spontaneously discharge back
down to a ground state, then we'd see these
sources light up a bit more.

More than 4 billion years, perhaps as much as 13.4 billion years, and t has not happened yet. In the CMBR state, it stopped emitting either because it reached ground state, or it was ionized and pressure dropped so low that releasing another photon was impossible. Rememeber, like in a good conductor, there are just as many positive charges at equal distances all around.... no reason an electron has to "bond".

I heard somewhere that it takes 30 million
years for an electron to spontaneously
discharge back to the ground state, from an
X-ray energy level. Don't know if it's true
or not.

Hydrogen is all we need to worry about. There are a lot of "forbidden transistions", so who really knows.

I assume Gamma rays would take even longer.

The highest energy level in an orbital electron in hydrogen is far UV, 13.6 eV (infinity to 1s orbital). Gamma will simply move the proton away from the electron and be scattered, but most likely will miss everything.

....
Is the density low enough to not detect
the gas or plasma itself, but high enough
to produce a small refractive lensing effect?

They are dense enough to be a gravitational
lens, and *CANNOT* refract, since they cannot
interfere with the passing photons *at all*.
And if they did, they would spread the
spectrum... which we do not see.

Well, then how does glass act as a lens? The
photons of light aren't energetic enough to
excite the electrons of glass, that's why its
transparent, yet the glass can bend the light
just the same.

You have forgotten this class. Light is not transmitted through media, "electron bucket brigades" carry incident light's momentum through the media. That is the only reason "light slows down" in a medium. Gamma and x-rays pass through lenses at c. The molecular bonds (and crystal bonds) are much lower energy... near optical wavelength energies.


It's because the light slows down when entering
the glass medium from the air medium.

As first pass, you can say this. But this is an approximation for high school students. And they are finally taught that the index of refraction form violet light is different from red light.

So what about a similar effect, except much
smaller refractive index (even smaller than air),
so the light barely seems slowed at all?

Speed of light in air is 0.999723 c.

.... does not spend much time dancing with electrons in ground-state molecules. And radio and x-rays and more energetic radiation pass through air at c:
http://en.wikipedia.org/wiki/Radio_w..._and_frequency

....
I think some intergalactic gas near the Milky
Way has recently been discovered streaming into
the MW replenishing the gas within the galaxy,

... or simply in orbit...

I think just about everything is in orbit around
everything else when we're talking about
intergalactic space.

We have had "comets" on hyperbolic orbits that we have seen. So there may be a small amount of stuff that is as yet unbound. But we know Dark Matter forms a halo, based on rotation curves and microlensing. And the two effects point at about the same amount of matter... adding "refraction" is counterproductive.

Obviously, I'm trying to figure out if there
are alternative explanations for the so-called
Dark Matter lensing around galaxies.

Su
- ionized gas
- cold neutrinos
- rogue planets, brown dwarves
- black holes
- calibration errors based on a lack of
application of recently revealed galactic
physics:
* the center of a spiral galaxy is swept
clean of dust
* the stars of the center of a spiral galaxy
appear hotter, because their photospheres
have been stripped due to tidal action...
so smaller mass looks hotter.
* dust away from the center tends to make
intensities lower, and redden the spectrum,
so it looks like less mass than is really
present.

"Refraction" isn't going to help.

But what if there isn't enough Dark *Baryonic*
Matter to explain the lensing effect, entirely
gravitationally? Then finding a refractive
cause might explain it.

No refraction mechanism we know of, can explain even in part, what we see. Refraction spreads the light out, refracting a narrow portion of the spectrum, and doing so differently.

"Dark" in this context means "unknown", not necessarily "exotic" or "unknowable". We have your "what if" condition right now, we cannot see enough baryonic matter right now. So we are required to measure the unknown, and try really stupid things (like "here be dragons") which we then try and disprove (you may recall the recent concentration on trying to locate WIMPs).

This is science at work. Refraction does not work here.

David A. Smith

On 25/10/2013 10:50 AM, dlzc wrote:
On Friday, October 25, 2013 5:38:33 AM UTC-7, Yousuf Khan wrote:
It probably depends on how long it takes electrons to spontaneously
discharge back down to a ground state, then we'd see these sources
light up a bit more.

More than 4 billion years, perhaps as much as 13.4 billion years, and
t has not happened yet. In the CMBR state, it stopped emitting
either because it reached ground state, or it was ionized and
pressure dropped so low that releasing another photon was impossible.
Rememeber, like in a good conductor, there are just as many positive
charges at equal distances all around... no reason an electron has to
"bond".

Where do those numbers of years you talk about come from?

I guess an electron will only release its energy if gets captured by the
orbital of another ion. Or could it bump into another electron along the
way, and lose some of its energy too? Both would have to be accidental,
random occurrences in space.

I heard somewhere that it takes 30 million years for an electron to
spontaneously discharge back to the ground state, from an X-ray
energy level. Don't know if it's true or not.

Hydrogen is all we need to worry about. There are a lot of
"forbidden transistions", so who really knows.

What sort of "forbidden transitions"?

I assume Gamma rays would take even longer.

The highest energy level in an orbital electron in hydrogen is far
UV, 13.6 eV (infinity to 1s orbital). Gamma will simply move the
proton away from the electron and be scattered, but most likely will
miss everything.

Well, Gamma is mainly associated with nuclear reactions, so that means
these photons come from movements within the nuclei of atoms, rather
than from the electrons of atoms. So yes, gamma is far too high for
electrons to generate. But what about X-rays? Those come from the
electrons too, aren't they? They're much higher than UV.

Is the density low enough to not detect the gas or plasma
itself, but high enough to produce a small refractive lensing
effect?

They are dense enough to be a gravitational lens, and *CANNOT*
refract, since they cannot interfere with the passing photons *at
all*. And if they did, they would spread the spectrum... which we
do not see.

When we look at a distant galaxy through a nearby lensing source, is it
possible that we just don't see all of the spectrum anyways? Our
telescopes are often just watching these things in specific restricted
wavelengths, like near IR, or far IR, or radio, etc. Maybe our modern
digital instruments aren't sufficiently broad spectrum enough to
distinguish these "rainbow effects"?

Well, then how does glass act as a lens? The photons of light
aren't energetic enough to excite the electrons of glass, that's
why its transparent, yet the glass can bend the light just the
same.

You have forgotten this class. Light is not transmitted through
media, "electron bucket brigades" carry incident light's momentum
through the media. That is the only reason "light slows down" in a
medium. Gamma and x-rays pass through lenses at c. The molecular
bonds (and crystal bonds) are much lower energy... near optical
wavelength energies.

If it's electron brigades carrying the light, then how do they carry the
light when the light isn't sufficiently energetic enough to knock it off
its ground state? After-all, we're talking about transparent materials
here, so that means by definition that the light is passing through
without affecting the material's electrons.

Also if photons are "bouncing off" electrons, then wouldn't they bounce
around in odd, random directions? Whereas in transparent materials, they
are basically all going in a well-defined direction.

http://www.youtube.com/watch?v=Omr0J...11dRxxYp9eo1nf

But what if there isn't enough Dark *Baryonic* Matter to explain
the lensing effect, entirely gravitationally? Then finding a
refractive cause might explain it.

No refraction mechanism we know of, can explain even in part, what we
see. Refraction spreads the light out, refracting a narrow portion
of the spectrum, and doing so differently.

As I said, if refractive index is extremely tiny, the spreading of the
spectrum out would be almost unnoticeable.

Yousuf Khan

Dear Yousuf Khan:

On Monday, October 28, 2013 3:40:32 AM UTC-7, Yousuf Khan wrote:
On 25/10/2013 10:50 AM, dlzc wrote:
....
In the CMBR state, it stopped emitting either
because it reached ground state, or it was
ionized and pressure dropped so low that
releasing another photon was impossible.

Rememeber, like in a good conductor, there are
just as many positive charges at equal
distances all around... no reason an electron
has to "bond".

Where do those numbers of years you talk about
come from?

Estimations of the age of interstellar medium (mostly ionized), and the visible age of the Universe.

I guess an electron will only release its
energy if gets captured by the orbital of
another ion.

No reason this must happen unless pressure is present. For billions of years, oxygen between the galaxies is missing 5 electrons. If it does not have to happen, then it won't.

Or could it bump into another electron
along the way, and lose some of its energy
too? Both would have to be accidental,
random occurrences in space.

And since electrons are point particles, it *never* happens. They do all heir "bumping" with their fields, and they can divert one another from relatively large distances.

I heard somewhere that it takes 30 million
years for an electron to spontaneously
discharge back to the ground state, from an
X-ray energy level. Don't know if it's true
or not.

Hydrogen is all we need to worry about. There
are a lot of "forbidden transistions", so who
really knows.

What sort of "forbidden transitions"?

http://en.wikipedia.org/wiki/Forbidden_mechanism

I assume Gamma rays would take even longer.

The highest energy level in an orbital
electron in hydrogen is far UV, 13.6 eV
(infinity to 1s orbital). Gamma will simply
move the proton away from the electron and
be scattered, but most likely will miss
everything.

Well, Gamma is mainly associated with nuclear
reactions, so that means these photons come
from movements within the nuclei of atoms,
rather than from the electrons of atoms. So
yes, gamma is far too high for electrons to
generate.

First, do not worry about the *source* of the light. Stick to "whatever might lens it along the way.

Second, they make TeV gamma photons by intersecting a high energy electron beam with a visible light laser. They don't get many, but they do get a few.

But what about X-rays? Those come from the
electrons too, aren't they?

Electrons in orbitals of heavy elements. Not much of that between the galaxies, mostly hydrogen there.

They're much higher than UV.

Sure, but you cannot refract X-rays... even energetic UV cannot be.

....
They are dense enough to be a gravitational
lens, and *CANNOT* refract, since they cannot
interfere with the passing photons *at
all*. And if they did, they would spread the
spectrum... which we do not see.

When we look at a distant galaxy through a
nearby lensing source, is it possible that we
just don't see all of the spectrum anyways?

Now you are putting us in a "special place". We see Dark Matter microlensing from local, fully optical sources. And no, until out of the infrared range, we get full spectrum images. Some even include UV through infrared.

Our telescopes are often just watching these
things in specific restricted wavelengths, like
near IR, or far IR, or radio, etc. Maybe our
modern digital instruments aren't sufficiently
broad spectrum enough to distinguish these
"rainbow effects"?

We don't see it locally, we don't see it at all.

....
Well, then how does glass act as a lens?
The photons of light aren't energetic
enough to excite the electrons of glass,
that's why its transparent, yet the glass
can bend the light just the same.

You have forgotten this class. Light is not
transmitted through media, "electron bucket
brigades" carry incident light's momentum
through the media. That is the only reason
"light slows down" in a medium. Gamma and
x-rays pass through lenses at c. The
molecular bonds (and crystal bonds) are much
lower energy... near optical wavelength
energies.

If it's electron brigades carrying the light,
then how do they carry the light when the light
isn't sufficiently energetic enough to knock it
off its ground state?

How do conduction electrons work? How is sound transmitted in matter? How is heat propagated through matter?

I am not teaching a class here. I am not qualified.

After-all, we're talking about transparent
materials here, so that means by definition
that the light is passing through without
affecting the material's electrons.

No. Clearly you have a bias here that prevents you from doing any independent study.

Refraction is not seen. Refraction does not work. Drop it.

Ask yourself why all matter passes gamma thru X-rays and radio at c, but photons near bonding energies of the various structures "move" at less than c.. How can something that cannot be altered *in any way*, by electric or magnetic fields, between emission and absorption, suddenly move more slowly?

David A. Smith

In article ,
Yousuf Khan writes:
Obviously, I'm trying to figure out if there are alternative
explanations for the so-called Dark Matter lensing around galaxies.

It wasn't obvious to me. Anyway, gravitational lensing is wavelength
independent. Any other kind of lensing I can imagine would have
significant wavelength dependence.

As an aside, there has been an enormous amount of nonsense written in
this thread. Don't trust any posts without checking.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

On 28/10/2013 10:21 AM, dlzc wrote:
On Monday, October 28, 2013 3:40:32 AM UTC-7, Yousuf Khan wrote:
After-all, we're talking about transparent
materials here, so that means by definition
that the light is passing through without
affecting the material's electrons.

No. Clearly you have a bias here that prevents you from doing any independent study.

Nope, clearly you have a bias. Refraction is not caused by "electron
bucket brigades" as you call it. That's your misunderstanding of refraction!

It's caused by the superposition of all electromagnetic disturbances in
a medium as it affects the light that is travelling through it. Here's
the real explanation:

"At the microscale, an electromagnetic wave's phase speed is slowed in a
material because the electric field creates a disturbance in the charges
of each atom (primarily the electrons) proportional to the electric
susceptibility of the medium. (Similarly, the magnetic field creates a
disturbance proportional to the magnetic susceptibility.) As the
electromagnetic fields oscillate in the wave, the charges in the
material will be "shaken" back and forth at the same frequency.[13] The
charges thus radiate their own electromagnetic wave that is at the same
frequency, but usually with a phase delay, as the charges may move out
of phase with the force driving them (see sinusoidally driven harmonic
oscillator). The light wave traveling in the medium is the macroscopic
superposition (sum) of all such contributions in the material: the
original wave plus the waves radiated by all the moving charges. This
wave is typically a wave with the same frequency but shorter wavelength
than the original, leading to a slowing of the wave's phase speed. Most
of the radiation from oscillating material charges will modify the
incoming wave, changing its velocity. However, some net energy will be
radiated in other directions or even at other frequencies (see scattering)."

Refractive index - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Refract...ic_explanation

So basically, it doesn't matter whether the light is radio, X-ray, Gamma
Ray, visible light, etc., they will *all* be refracted equally by the
medium, as long as the frequencies don't correspond with an internal
energy state of that particular medium. If they do correspond to an
internal energy state, then it won't be transparent to those
frequencies, but absorbed instead.

With all of the ionized gas floating around in space, there are tons of
free electrons orbiting around galaxies to create a little bit of
refraction within the light passing through it.

Refraction is not seen. Refraction does not work. Drop it.

Consider it undropped! Because you were wrong!

Ask yourself why all matter passes gamma thru X-rays and radio at c, but photons near bonding energies of the various structures "move" at less than c. How can something that cannot be altered *in any way*, by electric or magnetic fields, between emission and absorption, suddenly move more slowly?

Completely irrelevant, absorption and emission lines are clearly not
transparent to those wavelengths of light! We're only talking about
transparency here.

Yousuf Khan

Dear Yousuf Khan:

On Monday, November 4, 2013 1:39:16 AM UTC-7, Yousuf Khan wrote:
On 28/10/2013 10:21 AM, dlzc wrote:

On Monday, October 28, 2013 3:40:32 AM UTC-7, Yousuf Khan wrote:

After-all, we're talking about transparent
materials here, so that means by definition
that the light is passing through without
affecting the material's electrons.

No. Clearly you have a bias here that prevents
you from doing any independent study.

Nope, clearly you have a bias. Refraction is not
caused by "electron bucket brigades" as you call
it. That's your misunderstanding of refraction!

It's caused by the superposition of all
electromagnetic disturbances in a medium as it
affects the light that is travelling through it.

No. Light cannot be so affected. The electromagnetic disturbance *is* electrons propagating the momentum of absorbed photons.

But excellent work, you did research, and now you know about "group velocity", and how such a mechanism will spread the spectrum, and show an effect we do not see with Dark Matter.

Refraction is not seen. Refraction does not
work. Drop it.

Consider it undropped! Because you were wrong!

Please reconsider what you yourself have reported here. No E or M field can effect propagating photons in any way.

Ask yourself why all matter passes gamma
thru X-rays and radio at c, but photons near
bonding energies of the various structures
"move" at less than c. How can something that
cannot be altered *in any way*, by electric or
magnetic fields, between emission and
absorption, suddenly move more slowly?

Completely irrelevant, absorption and emission
lines are clearly not transparent to those
wavelengths of light! We're only talking about
transparency here.

No we are talking about "refraction" which as you have found out, absorbs those photons close to binding energies, and "spreads the spectrum".

I am only trying to get you to realize that "refraction", as in "optical lensing effects", are obviated by observation. We do not see any such sorts of optical aberration with Dark Matter. And we can see x-rays through radio waves... so "optical only" or "inclusive of infrared" effects do not help explain gravitational microlensing.

David A. Smith

In article ,
Yousuf Khan writes:
So basically, it doesn't matter whether the light is radio, X-ray, Gamma
Ray, visible light, etc., they will *all* be refracted equally by the
medium,

I don't know where you got that. Both real and imaginary parts of
the index of refraction are frequency-dependent, and in general the
real and imaginary dependences differ.

Look up "achromatic doublet" if you want a practical example from
optics. The key point for practical use is that the real part of
the index depends on frequency.

As I wrote earlier, gravitational lensing is frequency-independent.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA