Lenses

Good informative post - I wanted to say that as some times it seem I pick on you. I can only add mica cleaves very thin and has been used as small windows, expecially for hot furnaces.

Also "Iceland Spar" can be a clear crystal with double vision thru it as the orthogonal polarization have quite differnt refractions. (I do not know what it is chemically and too lazy to look it up.)

 

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It has to do with the wavelength I guess.
I checked it and apparently it also heats fats and sugars..
So I retract my earlier post about paraffin molecules being too large to get excited.

 

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It is not the "size" of the molecule that is important - it is the resonace frequency of the molecular bonds (vibrational mode I think) that is important.

 

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Macroscopically, some dielectrics (like sugars and fats) have a very poor power factor rating at microwave frequencies, but I don't recall the microscopic explaination.

 

Refraction is because electromagnetic energy slows down as it passes through the medium, but it has to pass through coherently for the medium to be transparent. I don't know how well anyone has worked out why a given medium is transparent, does not scatter light or other electromagnetic radiation, but still slows that radiation down.

 

i love these:

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that is well understood. The light's E field accelerates bound electrons and they re-radiate in the classical POV. All in one wave front plain are re-radiating in phase but not in the phase of the incoming wave. Effectively you have something like the sum of two sin waves of the same frequency but different phases. This sum is equal to another sin wave of same frequency with a delayed phase compared to the original. The quantum POV is also understood. Ithink it is basically that the energy is brielfy stored before being released again. In fact in the last few years some tricks have been done to make the storage long and than the speed of light IN THE MATERIAL can be slower than a bicycle! the scientist who demonstrated that known all about how light slows going thru materials.

Even how the cornea of the eye is transparient is now well understood - thanks to some friends of mine at APL/JHU. One way to think about it is: if the energy can not be absorbed it must scatter or "forward scatter," which it alway does in non-absorbing regular lattice structure (AND IN SOME OTHERS like glass, but understand them is tougher.).

 

A visible photon is from about 7000 angstroms to 4000 angstroms. An atom runs from about .62 to 5.2 angstroms. That means that a typical photon had a cross section about a billion times as large as an atom. Here's a funny thing: Chop a photon into smaller bits and you get several larger photons.

Looking at it that way, in truly transparent materials the photon must be passing through the material the way that smoke passes through a screen. A photon has a mass equivalent far smaller than an electron does and it's a billion times more voluminous than an atom so it must be far more than a billion times less dense, thus it should not interact much with single atoms.

 

LA WOW they look cool

Actually the chick in the midoory ad has cute contacts (if they are contacts rather than CGI), always been a sucker for red heads with bright green eyes

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The oldest known lens was found in the ruins of ancient Nineveh. It was made of polished rock crystal and probably used to burn things, as the earliest reports of lenses are for burning parchment, erasing the writing on wax tablets, and cauterizing wounds (the later according to Pliny).

As late as ancient Rome, being over forty meant you had to give up reading. Senaca is reported to have read "all the books of Rome" by looking thru a glass jug filled with water. Reading stones (polished hemispheres of glass laid on reading material to provide magnification) came into use about 1000 ad. It wasn't until sometime around 1280 that the first lenses were mounted on a frame to create actual glasses. A monk in Piza apparently knew the guy who make them,

Sadly, he made no mention of the guy's name, and it is lost to history. The next major improvement in glasses came in 1780 and was made by Ben Franklin,

http://www.teagleoptometry.com/history.htm

 

I am trying to decide if there are two pieces of Nonsense here or only one.

That your logic is completely false nonsense is very clear if you consider a small "shirt-pocket" radio. Its antenna is very small compared to the wavelength of the radiation it is absorbing - often about the same size ratio as the photon to atom size ratio. But I am not yet sure your first statement is pure nonsense because to decide, I need you to tell what you mean by "Chop a photon into smaller bits." Here are some of the ways the energy in a photon can be discretely changed (I do not mention things like Compton scatter or red shift as they can continuously change the energy and that would not be referred to as "chop"):

It is possible to use many photons in a highly non-linear dielectric crystal (if cut so that the dispersion of two different frequencies matches the index along the direction of propagation thru the crystal) to create less than half as many with twice the frequency. Much easier is to cut the frequency in half, but I am not sure you can gain more photons in practice. Then there is the Raman or Stokes effect where in certain materials, usually liqiuds, (I have done this using CS2) you can with reasonable ease slightly drop the frequency by creating a phonon in the liquid, and with much lower probability, actually boost the photon energy by removing one phonon form the liquid. (This is called the anti-Stokes radiation, I was able to just barely make it and record it in a spectrograph film.)

I have no doubt your second comment is pure nonsense. For example, in any dispersed matter (no atoms near each other) photons will be selectively absorbed at the same characteristic frequency the atom would radiate. (Same is true if the "matter" is molecules, instead of atoms.) The most famous case of this is Helium. The name comes from that fact it was first detected in the absorption spectra of the sun.

The solar continumium radiation has dark lines in it, some corresponding to Helium, which had never been observed in any gas discharge made on Earth when observed in ths solar absorption spectra. In general these dark absorption lines made by ONE atom of the colder outer parts of the expanded solar corona absorbing ONE photon at a time. They are called the Franhoffer lines, but I may not have his name spelled correctly. This part of your post is PURE NONSENSE.*

I will wait till you tell what you meant by "Chop a photon," but can tell you now that the length of a photon is not in any way related to its frequency (energy). It is related to the transition probability of the radiation of emittng atom for the radiative decay of the upper state to the lower. (This is required by quantum uncertainity on the product of time and energy and Fourier math.)**

BTW I have measured the length of photons (of the Sodium D lines) from a common sodium lamp. - They were about 30cm long. Years ago, one of the mercury's isotopes (198? - seems to ring a bell in my memory, but being too lazy to look it up, I do not know if Hg even has that isotope) lines was used as the standard of length as it is very long - almost a "forbidden" transition.* (The precision was such that the isotope effect on the frequency forced the use of a nearly pure isotope - probably cost NBS 10,000 times it weight in gold)
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* ONE atom absorbing ONE photon often is not rare event. It is directly depends up on the transition probabilities for the radiation. For example, if you pass a narrow LASER beam thru a flask filled with modest or low pressure gas, which can radiate the LASER frequency well, it will absorb it well also. (ONE atom absorbing ONE photon at a time). This excites the atom to the upper state of the transition and it quickly re-radiates, but in all directions with equal probability. Thus, the entire flask will glow with the same color light as the LASER. - Photon are being absorbed an rerdiated many times by all the atoms in the flask.

**If photon is long, then when it was made is very uncertain. (large delta T) Thus its energy uncertainity must be very small. (Many essentially identical wavelength cycles in Fourier analysis for the frequency - extremely well defined energy)

PS It only seems like I pick on you, but I can not let nonsense go uncorrected and unfortunately you often cause me work. Thus, when you do post something good, as you did in post 21 of this thread, I go out of my way to tell you "good post"

 

Billy, it's very basic theory about the photon and it is accepted as absolute by the scientific community. The "frequency" of a photon is directly proportional to its energy, as in Planck's formula: E=hf. E is energy, f is frequency, H is Planck's constant (6.626*10^-34 Joules/seconds). Solve for f: f=E/h. W=wavelength, solve for w: w=c/f w=c/(E/h) w=hc/E

In any case, the size of a photon is completely dependent on the energy of that photon and it is inversely proportional to that energy. If you know the wavelength the first formula tells you how much energy is in that photon.

My first statement may be more clear if I say this: If you can chop a photon up into fragments, you end up with photons with less energy but larger physical size. The nature of the hypothetical mechanism for doing this does not matter. Call it "dividing the energy contained in a photon into smaller packets of energy." Trouble is, by the laws stated above, you get larger photons but they have less energy each. This principle is accepted as absolute by the scientific community, as are the size of the atom and the wavelengths of visible light. An Angstrom is a tenth of a nanometer. I learned all this in high school.

A visible photon runs from about 4000 Angstroms to 7000 Angstroms in physical diameter, wavelength, whatever. Since it is considered to be a packetized quanta of energy, I presume a spherical shape in free space. An atom runs from about .62 to a bit over 5 angstroms in diameter. Assuming a spherical shape for both, a visible photon is over a thousand times as wide, over a million times the area, and over a billion times the volume of an atom, especially if you stick with smaller atoms. So it is a mystery how an atom can even absorb a photon.

No matter what your spectral evidence is, the statements about the size of a photon versus the size of an atom are incontrovertibly true. These are very basic and very well known. Every single place that you go to look up the size of an atom or the size of a photon, it will say the same thing: about one to five angstroms for the atom and about 4000 to 7000 angstrom units for the wavelength of the visible photon. That 30 centimeters that you mention is almost exactly 1000 megahertz, just off the high end of the television band.

I don't know of any physics that says that all of a photon has to be absorbed if any of it is absorbed. If you even have a photon at one megahertz, each one's energy is going to be 6.626*10^-28 joules and its wavelength will be 3000 meters. Now we are talking about an object that is much more extremely diffuse as it is far less energetic than a visible photon and it is some ungodly number of orders of magnitude larger in volume. A pocket radio responds to this by simple induction, delta V of the magnetic field. Maybe the antenna sucks that entire photon in or something but I don't know either way.

 

Thank you MadAnt!!!!
Your info was what I was looking for.

Billy T and MetaKron...wha???

 

Orleander, why is a material transparent? I'm looking for clues at the scene of it all.

 

ooooo, that's a good question. And so many things are clear, like water, boiled sugar, sap, rocks, air, my eyes....is hair ever clear?

 

To MetKron:

Your first paragraph of post 32 is OK. Not in dispute. The remained is your typical nonsense.

I think the fundamental reasons you are so wrong is that you seem to be identfying the size of a photon with a single wave length. I told you I have measured the length of the sodium D photons and found them to be about 30 cm long. I will not look their wave length up, but that is a very large number of wave lengths in each photon. If you knew any Fourier analysis theory, which you obviously do not, you would realize that many wavelenghts are required for the frequency (or the energy) to be well defined. Some spectral lines are very sharp (pure frequencies, narrow line widths, precise wavelengths - all the same fact.) A single cycle of a sine wave, one wavelength, your very erroneous concept of the photon size, has a quite broad frequency spectrum. You do not know even the most elementary things like this.


Photons are just one of many examples of the fact that a resonate structure can be very small compared to the wavelenght of the energy it is absorbing or emitting. - For a very unrelated example of this same fact: Many resonate ocean energy wave machines are much smaller than the water wave length they extract energy from.

Read my post 31 a few times again until you have enough understanding of it to at least ask a sensible question about it. Especially the text associated with the the second (**) footnote and that footnote to undersand what it is that determines the length of a photon. It is the transition probability of the upper to lower states radiation, not the energy of the radiation, for the quantum mechanical reasons explained there, (but to fully understand you do need to know some Fourier analysis theory also.)

At least stop posting nonsense derived form your faulty logic as it is conflict with the facts. Photons are not little round balls but long energy packets with millions of wave lenths in them typically. I do not reacal the leangth of the Hg isotope line that years ago was the definition of the meter, but believe it was several meters long. (Had to be to have its frequency, energy and wavelenth so precisely defined, but you do not understand this as you do not know anything about Fourier analysis.)

 

Billy, this is old and classic physics that I am talking about, and I am correct both about the size and the definition of a photon. You may or may not believe the Wikipedia entry which says exactly what I said, but you might have a physics book or two gathering dust.

A sine wave has exactly one frequency to it. Fourier analysis is based on the theory that any periodic wave can be built from the sum of some number of pure sine waves.

Will someone please tell this man that I am right about the basic facts here? They are first year physics. It doesn't get much more basic than that.

 

I would welcome comment about who is correct, but until it comes I just note that you are not even internally consistent.

A sin wave extends to infinity in both directions. Only when it is of this infinite extent does it have one pure frequency. A infinite extent wave cannot be your little ball of well defined energy and frequency. YOU CONTRADICT YOUR SELF! (Claim of one wavelength diameter photon and yet a pure frequency / well defined energy)

Any finite length electrometric wave (SUBJECT OF MAXWELL'S EQUATIONS like light or radio waves) is not a pure frequency. If there are many wavelengths present then the spectrum of frequencies is quite narrow. For example, in the case of radiation from atoms there are millions of cycles in the typical photon. That is why when a spectrograph is used to record on film the frequency (or wave length as they are directly linked) the exposures produced are very narrow - so nearly one pure frequency or wavelength that they are called "spectral lines." You can look up these lines for most element and they have typically at least six significant places in the designation of their wavelengths. - I.e. their photons have more than a million cycles or wavelengths in each. As I have told you twice now, I have measured** the length of the yellow light (called the sodium D lines - there are two of them close together in wavelength) from a common sodium lamp and they were in that case about 30 cm long. (Others can be many meters long and have "zillions of wavelenth cycles" in EACH of their photons.)

It is only a measure of your stubbornness and inability to learn that keeps you assuming that the photon is a tiny ball with diameter of one wavelength and yet, in self contradiction, that it has a pure frequency.

Yes I welcome some comments by others.

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*Quoting from your post 32: "A visible photon runs from about 4000 Angstroms to 7000 Angstroms in physical diameter, wavelength, whatever. Since it is considered to be a packetized quanta of energy, I presume a spherical shape in free space."

**To measure their length you use an interferometer with two paths (Two half silvered and two full silvered mirrors at the corners of a trapezoid but start with the special case of rectangle so both paths are equally long). You observe the interference pattern on the screen and begin to increase the length of one of the paths. As you do so the interference pattern starts to fade out. This is because each photon goes via both paths and when recombined on the screen the first cycles arriving via one path have no cycles yet from the other path to cancel out with so the previously dark line of the interference pattern begin to fill with some light. In the case of the Sodium Lamp I used, when one path was ~30 cm longer than the other the pattern was completely abolished – uniform in intensity everywhere. This because with 30 cm longer path to travel there was zero over lap and thus no destructive interference anywhere on the screen. Thus not only is your nonsense contradicted by Fourier theory applied to the existence of spectral lines (nearly pure wavelengths), but also by experimental fact.

Again: Yes I welcome some comments by others. I will not be so crude, but perhaps someone else will tell your where your head is placed to so completely keep you from seeing the light now that I have three times explained these facts to you.

 

You actually keep going on this?

Just go drink your damned sugar cane ethanol if there is any left in the bottle.

 

Really, what in the HELL are you thinking?

Fuck you, Billy. Fuck you, fuck you, fuck you. Go to Hell, eat shit, and die.