So did you not get enough information to work it out? you could find out the volume /each and them express that as a sphere, find the radius and the double it.
What do you need that for anyway? I'm not going to work it out unless it is important!
Will CO2 absorb photon in all directions?
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What do you need that for anyway? I'm not going to work it out unless it is important!
Not as close as in the case of dry ice. I can say that much for certain!
I am pretty sure you cannot measure the distance in microns. Perhaps nanometers?
It is important.
It remains to be seen.
You can use as you like: micro, nano, pico, femto,atto, zepto, yocto.
Or using powers of ten (10 ^ a)
No because the air is not at 0 degress Kelvin, but the molecule of it have large random motions. The mean speed fowhich is at least the same order as the average speed which is to the east. Also there are many molecules moving with several times the mean speed, in the high energy "tail" of the thermal distribution. There are millions of molecules that have the correct Doppler shifted speed to match the energy of the photon. But maost of the air is N2 or O2 and these symetric molecules do not have ability to absobe even IR much less visilble sunlght - why the air is transparent, but they can b ionized by UV solar photons. - why the radio wave reflecting "ionosphere" does exist.
There will be slightly more ionization on the limb with the blue shifted photons as photons which just dont have enough energy to ionize non-moving air molecules will be able to ionize when they "see" these "too weak" photos as slightly higher energy blue shifted ones.
Not sure I undersand your question as the photons are 1 AU from the sun and going away from it so it has no "perspection" on or about these near Earth photons. Part of your problem I think is that you assume velocities near light speed add like they do at low speeds. Two photons each headed at the other both see the approching photon coming only at the speed of light not twice the speed of light. No matter how fast you move light´s velocity is always the same for you but its color does depend upon your speed.
again not sure what you are asking but as most of the air can only interact with the ionizing UV and there is slightly more of it on the limb side that sees them as blue shifted that is the limb receiving the greater momentum transfer.
No. the solar UV torque on the limb would be very tiny I am sure compared to that made by the moon. Hell that moon torque even lifts up the sea and acts on the air too! Posibly birds flying more east than west (or conversely) make a far greater torque than the differential absorption of UV on the two limbs. Your whole ideas is very tiny and lost in the noise of much greater torques acting on the air mass.Would this in itself maybe enough to generate the wind effect we need?
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I'm going to work it out and when you get the answer we will compare the results OK.
Emil - a gas has at least 1000 times greater volume than a liquid or solid.
Emil - Are you using the figure 101325 Pa as your pressure?
2.69*10^25 molecules per m^3 Standard Temp and Pressure (STP)
3.33746E-09 meters apart at STP
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Yes you are right. The hypothetical situation would be so unlikely. It would have to extreme to get the situation I was questioning.
You more or less did answer it in the first section of your reply when you said "There will be slightly more ionization on the limb with the blue shifted photons as photons which just don’t have enough energy to ionize non-moving air molecules will be able to ionize when they "see" these "too weak" photos as slightly higher energy blue shifted ones."
So if you see your reply quote above you too use words like "see" and "too weak" when describing attributes from the gas perspective, just like I was looking at things from the Sun' perspective. I won't use words like that again for it confuses the situation.
All I can say is that I was trying to focus on Venus but we have come back to Earth, but that's OK for we are only discussing science principles rather than specifics.
http://wikivm.boulder.swri.edu/mediawiki/index.php/Venus_Winds_Wiki
The atmosphere of Venus rotates up to 60 times faster than its solid body. The mechanism that drives this atmospheric 'superrotation' is not understood. OK to me that means there is a very large movement of the atmospheric mass, speeding faster than the planet's surface, but also moving in the same direction as the planet turns.
So what drives molecules to do that? Solar radiant pressure is a possibility, but at first glance the net pressure should be the same on both sides, so not net pressure forward or counter to rotation.
Heat radiating from the planet would have no effective means to cause a net forward motion either.
The only major source of energy for Venus is the Sun.
So out of desperation we are left with discovering in some other field of science a mechanism that will turn the radiant energy of the Sun into a uni-directional force that ultimately adds energy and momentum.
The one thing certain was the winds on one side of the planet blow toward the Sun and opposite on the opposite side. Yet the radiant energy has both energy and momentum (two types), and from multiple sources on the internet, you find you can't just reduce a photon's energy so that its momentum no longer exists.
Both the conservation of the energy and momentum (two types) need to be shown.
The easiest way for this motion to occur was if the molecule and the photon had a common direction to the momentum vector.
[There seems to be other proven science that may lend support to this, but I haven't found it spelt out like this before. So if this happens and it could be proved it would be a minor scientific discovery provided it hasn't been described before. To check this out I'm looking on the net for clues.]
Any ideas most welcome. Are there any particular areas of physics where a similar effect is observed?
I still feel it maybe as basic as a photon can be absorbed by a gas molecule and this increases both the kinetic energy and momentum of the molecule.
Can't a gas be directly heated? For this to occur the laws of conservation must be met. To satisfy the conservation laws molecules with opposing velocity and momentum can't take up the photon. Direct heating can this happen?
It is so difficult to get a link to a single website that answers this question.
Why not? Do you have any evidence that gas molecules can even have opposing velocity or momentum?Robbitybob1 said:
What do you mean by "direct heating"?
Say with a gas is it only heated by contact with the container. Say can UV light heat a gas directly, somehow the energy and momentum of the photon enter the molecule without it having to hit a solid first? And the resultant molecule having higher kinetic energy?
Every collision between molecules in a gas are elastic collisions where the momentum and the energy are conserved. They don't often suffer frictional effects or chipping, they bounce for a better word.
By opposing velocity and momentum that implies they collide The paths they take meet and hence the interact and change direction. Surely this is common knowledge, but what is not commonly discussed is how a gas heats up in the first place. How does a fire produce hot gas?
I know there is combustion but how does the chemical reaction produce a hot gas? What is the connection between the release of energy and the kinetic energy change of the molecules.
I find it bizarre that I'm asking these questions, since fire was one of man's first developments.
Could this sentence be changed "All objects constantly emit radiation according to
their temperature and wavelength. " to "All [gas molecules] constantly emit radiation according to
their temperature and wavelength. "
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This lecture from UCLA answers some part of my question:
http://www.atmos.ucla.edu/~liougst/Lecture/Lecture_2.pdf
The UV light is absorbed by O2 and O3 molecules. Does that mean they are heated by that?
http://www.atmos.ucla.edu/~liougst/Lecture/Lecture_2.pdf
The UV light is absorbed by O2 and O3 molecules. Does that mean they are heated by that?
Robbitybob1 said:
Ok. But how does that affect the absorption of photons by any of the gas molecules?
Or the number of interactions between gas molecules that transfer energy throughout the gas? Heat is random motion, after all, so the transfer of heat in a gas shouldn't depend on specific motion of molecules (and it doesn't, it depends on the distribution of kinetic energy).
Can you explain how a photon can interact with a free moving gas molecule?
I know of:
1. ionization i.e. it knocks off an electron
2. it could also participate in the photoelectric effect and put an electron into a higher energy level
3. Dissociation of molecules to single atoms O2 => 2 O atoms or O3 => O2 + O
Well you say what happens in a sentence and I'll put the key words of your sentence into Google and see if anyone else has said the same thing.
But can it simply speed up a molecule i.e. give it kinetic energy and momentum? Like participate in a blackbody interaction?
A good clear YouTube video of O2 and O3 absorbing radiation
http://www.youtube.com/watch?v=WE3y1Gj2dec
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Well, here's the thing. You might think a photon acts like a particle when it interacts with gas particles.
But a photon is a spherically expanding wave (not really a particle) which is absorbed randomly by one of the gas particles; this process depends on the energy of the photon and of the particle (actually also a kind of spherical wave, but "localised" because of its mass and Coulomb potential--atoms and molecules don't expand in all directions like photons do).
When the photon is absorbed (randomly) the absorbing particle-that-isn't-really-a-particle gains kinetic energy (it can vibrate or rotate or translate, remember), as if it's been "hit" by another particle.
But a photon is a spherically expanding wave (not really a particle) which is absorbed randomly by one of the gas particles; this process depends on the energy of the photon and of the particle (actually also a kind of spherical wave, but "localised" because of its mass and Coulomb potential--atoms and molecules don't expand in all directions like photons do).
When the photon is absorbed (randomly) the absorbing particle-that-isn't-really-a-particle gains kinetic energy (it can vibrate or rotate or translate, remember), as if it's been "hit" by another particle.
Robittybob1,
A cubic meter of gas is 1000 times greater than one cubic meter of liquid or solid?
Why you just don't find it on the internet? (I have not found it.)
Although many, even Ph.D. physicists, believe that, the bold is not correct, except possibly during the brief period when the photon is being "born". I.e. during that tiny time interval when it really does not make much sense to say things like: "The electron is falling from the upper state of the radiative transition and is now half way into the lower state" etc. During this brief transition interval it really does not make much sense to say anything, including "The photon is an expanding spherical wave." but I will not argue with you if you do.
I.e. once the photon is completely away from the source atom, that is now in a lower energy state, the photon is not an "expanding spherical wave". It has a definite direction of propagation and surprisingly a mesurable length along that direction of propagation. My post below some comments I now give is how I have shown that by measuring some "Sodium D" (yellow color) photons that were approximate 30cm long.
They could have been longer, but they came from a moderate presure lamp, so were "collisionally broaden" (atom´s energy levels were dynamically changing during the transition by approach of another atom) so photon´s energy was not as precisely defined as if it had come from well isolated atoms i.e. a low presure lamp or even better large near vacuum sodium cloud in space.(Those clouds have been made and observed by release of hot Na vapor from earth orbiting satellites.).
Also what determines the lenght of the photon is the "transition probablity" (sort of the inverse of the life time of the upper state against radiative decay) This is directly related to the uncertainity principle product (delta T)(delta E). I.e. well isolated atoms (no collisonal broadening) with low transiton probably (long upper state life time) can have photon lengths of more than 5 meters. For example the very high altitude green line (from oxygen atom) that often is most prominate color of the "Northern lights" is actually a first order "forbidden" transition (does not obey the normal selection rules for radiative transitions) I.e. has a very large (delta T) and consequently a very precise energy (very small delta E).Those photons are at least 20 meter long!
PS: Because that transition between those oxygen levels is "forbidden" it took a long time (years I think from when physicist began to ask) for the source of the green Northen Lights line to be identified!
The way that photon can have very precisely defined energy is that there are a huge number of cycles in its EM field. - Simple Fourier analysis shows that if E is percise, the wavelength is almost unique - not a spread of many wavelengths in a narrow range as when the energy is not so well defined. (Energy is directly proportional to frequence - to be precise the wavelength, or its "spectral line," must be very narrow.)
Above is slightly compressed version of post here: http://www.sciforums.com/showpost.php?p=2539172&postcount=52… Photon are long energy packets. Some are more than a meter long. Here is how you can demonstrate that (as I have done). You set up any two path interferometer such as this diagram from Wiki and slightly modify it as described below:
The redish “sample” shown in the “SB path” and “detector 2” are removed as we are not using the interferometer to investigate any matter – only to measure the length of the photons; however the beam labels, SB & RB, are convenient for my discussion. Also the “detector 1” is replaced by a simple screen you can look at and see a classical interference pattern of many alternating parallel bright and dark lines.
Then we progressively increase the path length of the SB beam but make no change in the length of the RB path. I.e. we slightly rotate counter clockwise the first beam splitter so that the SB beam swings off the full reflection mirror it was hitting and pull that mirror back into the SB beam again. (We will need to slightly rotate it also so that after it reflects the SB beam the beam continues on to the second beam splitter as before.) Now the length of SB path is greater than that of RB path. If the extra length is only a few centimeters, you will not notice any difference in the interference pattern so we rotate the first beam splitter a little more, etc. As the path difference is increased you will notice that the interference pattern is becoming less clear. The black lines are no longer without light and the bright lines are less bright. With more increase in the path difference the interference pattern has completely faded away – the screen is uniformly illuminated. When this first occurs, the photon length is equal to that path difference.
Now let me explain why: First you must know something that is very strange. Each photon travels to the screen BY BOTH PATHS! (Just as in young’s double slit experiment, each goes thur the two separated slits.) This is so hard to believe that I give links to four first rate universities telling and demonstrating this fact at end of this post. So each photon is interfering only with itself, not with the other photons. (The interference pattern remains if the “screen” is a photographic film exposed for many hours when the light intensity is so reduced that most of the time there is not even one photon present. – experimental fact.)
What is happening, to speak in terms humans can understand, is when the path difference is half of the photon length, the first half of the photon energy going by path RB arrives at the screen before any of its energy going by path SB does, so interference is only possible for the second half of the “RB path energy” when the first half of the “SB path energy” is also present at the screen. I.e. the interference pattern is “half washed out.” When the path difference is equal (or greater) to the photon length, all of the energy going by the longer path SB arrives at the screen too late to interfere with any of its energy going by path RB. So the screen is uniformly illuminated (No hint of any interference pattern remains).
That is how I measured the photons from my source to be ~30 cm long. ... For discussion of fact each photon in some sense goes by all available paths and then interferes with its self, when the paths are brought back together at a screen (or in any detector) see:
http://www.fas.harvard.edu/~scidemo...tonInterference/SinglePhotonInterference.html
http://ophelia.princeton.edu/~page/single_photon.html
http://departments.colgate.edu/physics/research/Photon/root/P120/lab_photon.pdf
http://www.physics.brown.edu/physics/demopages/Demo/modern/demo/7a5520.htm
Also read this. (part of an exchange with James R) who did not really understand the above.
“…. The fundamental thing you MUST understand is that each photon goes by both paths and when "recombined" at the screen INTERFERES ONLY WITH ITS SELF.* Thus, when the distance the "part" going the longer of the two paths is greater than the length of the photons, the "part" of the photon energy that is traveling that longer path arrives too late to interfere with the part of the photon energy that went the shorter path. - I.e. the interference pattern completely "washes out" (Uniformly illuminated screen) as the path difference length become as large as the length of the photons. When the path length difference is half the length of the photo, 15 cm in my case, then only the "front half" of the energy going the longer path arrives at the screen in time to interfere with the "back half" (last part) of the energy going the shorter path. Thus there is no longer any completely dark lines (or any twice intensity bright lines) on the screen. I.e. as the path difference increases the interference pattern gets progressively smoothed out into uniform screen illumination.
Note I am fully aware that photons are quantum beasts can not actually be divided by a half-silvered beam splitter etc. but in ways impossible for humans to understand each photon does know about all the possible paths. So to describe this strange to humans part of physics one does speak of the photon going thru both slits of the Young's two slit interferometer or traveling both paths after passing thru a wave-front-division two beam interferometer. What "really" happens and how it happens, only the photon knows. ….”
Quote from: http://www.sciforums.com/showpost.php?p=2568018&postcount=154
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So you had a lab or access to equipment to run some experiments! Now I understand why you have come from B&E and trying to help me on the science and math forum.
That You Tube on Ozone production if watched will tell you the answer we were looking for. There was momentarily a high energy ozone that was unstable. It either broke up or collided with another atom and transferred its excess energy.
So the energy package was transferred by contact with another atom.
Had you ever heard of this before?
Reactions of this type could be unbalanced on either side of the planet Venus so on one side the energy remains in the form of broken bond energy (it takes energy to break bonds) and on the other kinetic energy (when the ozone remains stable after transferring excess kinetic energy). The energy side driving the wind (for the momentum of the photon is not lost).
That You Tube on Ozone production if watched will tell you the answer we were looking for. There was momentarily a high energy ozone that was unstable. It either broke up or collided with another atom and transferred its excess energy.
So the energy package was transferred by contact with another atom.
Had you ever heard of this before?
Reactions of this type could be unbalanced on either side of the planet Venus so on one side the energy remains in the form of broken bond energy (it takes energy to break bonds) and on the other kinetic energy (when the ozone remains stable after transferring excess kinetic energy). The energy side driving the wind (for the momentum of the photon is not lost).
NOTE: Before I comment on the above quote(s), let me admit that in a recent reply in another thread, I stated that as a light sphere expands from its point of origin, it does appear to do so essentially as a 3D wave front and there does not appear to be any widening distance between individual photons, as the total area of the light sphere increases. (I really thought someone would jump on that one and even considered several times countering my own post.) While this may be as things appear, it is not entirely consistent with our experience of light and photons.
To this I add my comment from Post #44 of this thread,
OnlyMe said:
This last part does raise some issue with how we interpret the results we obtain in a number of experiments involving the wave vs particle nature of EM radiation and even electrons. We are, as I said to some extent fish in a fish bowl. Our understanding of what is happening is unavoidably influenced by the quantifiable way in which light, or photons, interact with atoms, or matter.
There is a question that continually comes up for me where experiments as described above are involved. They are almost always conducted using a light source composed of many photons and yet the conclusions are often, as above projected as descriptions of the nature and character of individual photons.
When the same or similar experiments are conducted with single photons or single electrons, the result invariably appears as a particle event, which if repeated using again single photons or electrons, over time seems to result in a pattern consistent with the interference pattern associated with the classical experiment and a concentrated "beam" of light.
How are we to know with any certainty that even when we are using a "beam" of light the interference pattern is not just a statistical representation of particle behavior, as opposed to a true wave interference?... And if our understanding of EM radiations as photons is an artifact of the quantifiable manner in which an EM "wave" interacts with atoms or matter, how are we with certainty, to know that the photon actually exists? You see on one hand what we "see" are photons and on the other we cannot with certainty know that the photons we see, are not just artifacts of the process of observation and measurement.
I know this is sliding a long way into the philosophical, but it is just such seemingly paradoxical situations that, suck me down the rabbit hole.
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