Perfect transparency?

Are there materials around that have almost perfect transparency?
Something that is transparent in not only light wavelengths, but let's
say in IR, microwave, radio, UV, X-ray, and Gamma? Okay, I know that's
got to be impossible, but what comes closest?

Transparency and translucency - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Transpa...d_translucency

Yousuf Khan

Dear Yousuf Khan:

On Wednesday, October 23, 2013 4:59:14 AM UTC-7, Yousuf Khan wrote:
....
Are there materials around that have almost
perfect transparency? Something that is
transparent in not only light wavelengths,

.... most molecules are active here.

but let's say in IR,

.... diatomic molecules are inactive here.

microwave,

.... all molecules can be made to spin here, so monatomic noble gases.

radio,

Easy.

UV, X-ray, and Gamma?

Helium will interact the least

Okay, I know that's got to be impossible, but
what comes closest?

Hydrogen plasma, not too thick. With no oxygen contaminants, missing 5 electrons, which allows it to interact with x-rays and more energetic.

David A. Smith

On 23.10.13 13:59, Yousuf Khan wrote:
Are there materials around that have almost perfect transparency?
Something that is transparent in not only light wavelengths, but let's
say in IR, microwave, radio, UV, X-ray, and Gamma? Okay, I know that's
got to be impossible, but what comes closest?

Transparency and translucency - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Transpa...d_translucency

Yousuf Khan
Try a cubic metre of vacuum, perfectly transparent...

On 23/10/2013 1:00 PM, Sjouke Burry wrote:
On 23.10.13 13:59, Yousuf Khan wrote:
Are there materials around that have almost perfect transparency?
Something that is transparent in not only light wavelengths, but let's
say in IR, microwave, radio, UV, X-ray, and Gamma? Okay, I know that's
got to be impossible, but what comes closest?

Transparency and translucency - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Transpa...d_translucency

Yousuf Khan
Try a cubic metre of vacuum, perfectly transparent...

I know you're being sarcastic, but actually you're getting close to what
I'm trying to get at here. The reason I asked this question is to figure
out if there are gases in space that cannot be detected from light
shining through them. Any kind of light, from radio through to Gamma.
The reason I ask is if there is a sufficiently transparent gas like
this, which when taken over the galactic scales would create a
sufficient refractive index to act as a lens to objects behind it. I
don't necessarily mean a gravitational lens, but possibly a hybrid
gravitational and refractive lens?

Yousuf Khan

On Wed, 23 Oct 2013 15:10:06 -0400, Yousuf Khan wrote:

if there are gases in space that cannot be detected from light
shining through them.


In interstellar space there is not much choice for gases. There
is only one: hydrogen.

Hydrogen gas itself will *emit* radiation, even if it may be
"dilute" enough to transmit most radiation.

On 23/10/2013 5:09 PM, FC wrote:
On Wed, 23 Oct 2013 15:10:06 -0400, Yousuf Khan wrote:

if there are gases in space that cannot be detected from light
shining through them.


In interstellar space there is not much choice for gases. There
is only one: hydrogen.

Hydrogen gas itself will *emit* radiation, even if it may be
"dilute" enough to transmit most radiation.

Yet, there are different forms of hydrogen to choose from in space. Such
as atomic hydrogen, ionic hydrogen, and molecular hydrogen. Not to
mention the isotopes of hydrogen too, deuterium & tritium. Do any of
these form a substance that don't get affected by most common
wavelengths of light?

Molecular hydrogen wouldn't be affected by the same wavelengths as
atomic or ionic hydrogen, right? Would deuterium have different resonant
frequencies than hydrogen? Etc.

Yousuf Khan

On Wed, 23 Oct 2013 17:15:50 -0400, Yousuf Khan wrote:

Do any of
these form a substance that don't get affected by most common
wavelengths of light?


It depends on the particular conditions.

See, for a start:

http://casswww.ucsd.edu/archive/publ...orial/ISM.html

Also, wait for a response from a practicing astromomer.

Dear Yousuf Khan:

On Wednesday, October 23, 2013 12:10:06 PM UTC-7, Yousuf Khan wrote:
On 23/10/2013 1:00 PM, Sjouke Burry wrote:

On 23.10.13 13:59, Yousuf Khan wrote:

Are there materials around that have almost perfect
transparency? Something that is transparent in not
only light wavelengths, but let's say in IR,
microwave, radio, UV, X-ray, and Gamma? Okay, I
know that's got to be impossible, but what comes
closest?
....
Try a cubic metre of vacuum, perfectly transparent...

I know you're being sarcastic, but actually you're
getting close to what I'm trying to get at here.
The reason I asked this question is to figure
out if there are gases in space that cannot be
detected from light shining through them.

Yes. We found through absorption of X-rays by oxygen contamination of this hydrogen plasma at about 25 million degrees, and most of the normal mass is still *not* in stars or planets.


Any kind of light, from radio through to Gamma.

Hydrogen plasma fits the bill, as I stated.

The reason I ask is if there is a sufficiently
transparent gas like this, which when taken
over the galactic scales would create a
sufficient refractive index to act as a lens to
objects behind it.

No. Since the medium is "uniform", it will do NO lensing.

I don't necessarily mean a gravitational lens,
but possibly a hybrid gravitational and
refractive lens?

Refraction depends on interaction with the light. The substance *must* interact with the light to produce refraction. So you engineered out the required properties. Additionally, it *must* refract differently at different energies...

David A. Smith

On 23.10.13 21:10, Yousuf Khan wrote:
On 23/10/2013 1:00 PM, Sjouke Burry wrote:
On 23.10.13 13:59, Yousuf Khan wrote:
Are there materials around that have almost perfect transparency?
Something that is transparent in not only light wavelengths, but let's
say in IR, microwave, radio, UV, X-ray, and Gamma? Okay, I know that's
got to be impossible, but what comes closest?

Transparency and translucency - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Transpa...d_translucency

Yousuf Khan
Try a cubic metre of vacuum, perfectly transparent...

I know you're being sarcastic, but actually you're getting close to what
I'm trying to get at here. The reason I asked this question is to figure
out if there are gases in space that cannot be detected from light
shining through them. Any kind of light, from radio through to Gamma.
The reason I ask is if there is a sufficiently transparent gas like
this, which when taken over the galactic scales would create a
sufficient refractive index to act as a lens to objects behind it. I
don't necessarily mean a gravitational lens, but possibly a hybrid
gravitational and refractive lens?

Yousuf Khan
Well, in that case, 90+ percent of intergalactic gas is hydrogen,
neutral as well as ionized.
Add some helium, and the rest of all possible molecules are found
only in trace amounts, and as such have virtually no chance to
have some influence on lensing, only lots of absorption lines..
And for hydrogen and helium the effects on light are well known
I would think.

On 23/10/2013 11:39 PM, Sjouke Burry wrote:
Well, in that case, 90+ percent of intergalactic gas is hydrogen,
neutral as well as ionized.
Add some helium, and the rest of all possible molecules are found
only in trace amounts, and as such have virtually no chance to
have some influence on lensing, only lots of absorption lines..
And for hydrogen and helium the effects on light are well known
I would think.

These elements are pretty easy to spot inside a galaxy where the
concentrations are higher. But what about in the intergalactic region?
Is the density low enough to not detect the gas or plasma itself, but
high enough to produce a small refractive lensing effect? I think some
intergalactic gas near the Milky Way has recently been discovered
streaming into the MW replenishing the gas within the galaxy, that was
right under our proverbial noses.

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

Yousuf Khan