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Author | Topic: Atoms | ||||||||||||||||||||||||
AdminIRH Inactive Member |
Please go to the thread I mentioned in my previous post if you have any comments.
And please try to be civil.
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AdminHambre Inactive Member |
sidelined, quote:No, you don't. This is called "feeding the troll" and we're trying to get this sad bastard out of the forum. You're a respected poster and there are plenty of others to engage here. Adminssimo Hambre < !--UB -->
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FlamingHomosexual  Inactive Member |
Please go to the thread I mentioned in my previous post if you have any comments. I TRIED to, but a certain AdminHambre BANNED ME ON SIGHT before I was able to....... It seems perfectly clear that most admins aren't INTERESTED in a fair discussion.
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FlamingHomosexual  Inactive Member |
This is called "feeding the troll" and we're trying to get this sad bastard out of the forum. Wow, personal attack........looks like AdminHambre's gonna have to be banned now too.......right, admins IRC and JazzLover?
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sidelined Member (Idle past 6156 days) Posts: 3435 From: Edmonton Alberta Canada Joined: |
AdminHambre
My apologies and if Jason wishes to debate he may respond via my email
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Tony650 Member (Idle past 4280 days) Posts: 450 From: Australia Joined: |
Greetings Happy!
happy_atheist writes: Atoms all have a characteristic spectra consisting of one or more colours. When they absorb energy, the electrons in them get excited from one orbital to another, and the energy gap between orbitals is very well defined. Am I right in understanding that electrons don't so much "shift" orbits as leap orbits, literally jumping, instantaneously, from one orbit to another?
happy_atheist writes: You were right that the width of an atom is much less than the wavelength of visible light though (measured best in angstroms rather than microns). Yes, this is what I find confusing. I didn't think an atom could emit a photon with a wavelength in the visible part of the spectrum. If this is correct, then how can a single atom even be directly seen, much less show colour? I understand that each atom possesses the properties that result in what we call "colour," but I'm not sure I understand how an individual atom can actually display colour. I'd have thought it would require a collection of atoms comparable in size to a visible wavelength of light, like (from the aforementioned example) a large clump of sand similar in size to at least one cannonball. Perhaps I'm looking at this the wrong way. Is it possible that I'm getting confused by particle/wave duality?
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Tony650 Member (Idle past 4280 days) Posts: 450 From: Australia Joined: |
Hi Coragyps,
Coragyps writes: Correct, if you'll let me replace "detectable" with "able to be imaged." Ah, so individual atoms are too small to be able to be imaged by any wavelength visible to humans. Ok, thanks for the correction.
Coragyps writes: The gas in a neon light, for instance, emits photons at one per atom that we can see, so the atoms are "detectable" at our eyes' wavelengths. So, each atom (in a neon light) emits a photon with a wavelength far bigger than the atom itself? I'm having a hard time picturing this. Is this analogous to the grain of sand "emitting" a cannonball? Or are we concerned not so much with the size of the photon itself, but that of its wavelength? And are they the same thing or different? Wave/particle duality still ties me up in knots, I'm afraid. Is the size of a photon equal to the size of its wavelength?
Coragyps writes: There are "pictures" of atoms lined up in crystals and the like - these are made using atomic force microscopy or AFM. This is probably what I was thinking of. Thanks for the link, Coragyps.
Coragyps writes: No, it's not that simple. Your cannonball analogy still applies, for one thing. What I'm having trouble getting my head around is how an atom can reflect/emit a wavelength of light significantly larger than itself. I realize, of course, that my understanding being based on such a simplified view of particle physics as the cannonball analogy probably isn't helping. Perhaps likening the scenario to a grain of sand being bombarded by cannonballs is too limiting, as the cannonballs are too "particle-like" an analogy for light, which is both particle-like and wave-like.
Coragyps writes: I read a little more detail on this 30 years ago, but that detail is gone, along with its source, from my brain. Heh, no problem. My questions regarding the properties of "colour" in individual atoms are all based on half-remembered material that I read years ago, so I know the feeling.
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Tony650 Member (Idle past 4280 days) Posts: 450 From: Australia Joined: |
Hi Melchior,
Melchior writes: This works ONLY on an atomic or molecular level, and if you have more of them, it just adds up the intensity. So if we could actually photograph individual atoms, they would display colour?
Melchior writes: You are correct that reflection, and other similar phenomena like the usage of x-rays to examine crystalline structures, often (but not always) depend on more than one atom, but those are not what determines colour. Yes, I understand that the properties of colour are inherent in each atom. What I'm not clear on is whether or not those properties actually manifest themselves as colour, in the case of a single atom which is smaller than the wavelength of the colour itself. I realize that the property of colour is there, in the atom. Are you saying, then, that this property, even in a single atom, is exerted in the way that we're familiar with (i.e. as visible colour)? Sorry for being so repetitive. I'm just trying to make sure I understand correctly. You seem to be saying that if we could magnify far enough to look at a single atom, we would actually see its colour. Is this correct?
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sidelined Member (Idle past 6156 days) Posts: 3435 From: Edmonton Alberta Canada Joined: |
Tony650
Yes, I understand that the properties of colour are inherent in each atom. What I'm not clear on is whether or not those properties actually manifest themselves as colour, in the case of a single atom which is smaller than the wavelength of the colour itself. Since visible light is dependent upon wavelength and is emitted by the atoms through the photon exchange particles it must be the photons themselves that are colored or rather the photons impinging upon electrons in the color cones of our eyes.The nucleus of the atom does not use photons for an exchange particle and therefore cannot have color nor indeed be seen.The electron itself is not visible except indirectly through the gaining and losing of photon energy. "Calling Atheism a religion is like calling bald a hair color." --Don Hirschberg
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Melchior Inactive Member |
Single atoms would display colour in the same way that they do when there are millions other around them. Most theoretical models of how light is sent out does actually model just a single atom, because that's all that is needed for the principles to hold.
We see colour because stuff in our eyes recieves photons. If a photon that has the wavelenght of, say, green enters the eye, it's detected as green light. If it's just a single one, it's basically filtered away as random noice, but it's still detected. A single photon does not show up as a large bright green blob in your brain, because then you'd be blinded constantly. You are not conciously aware of the single photons you see, if that's what you are wondering. You'd need to magnify them quite a bit first. The wavelenght has nothing to do with the size of the atom. A normal radio-antenna can pick up wavelenghts far longer than it's own lenght. The two lenghts are not at all related.
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Tony650 Member (Idle past 4280 days) Posts: 450 From: Australia Joined: |
Hi sidelined,
sidelined writes: Since visible light is dependent upon wavelength and is emitted by the atoms through the photon exchange particles it must be the photons themselves that are colored or rather the photons impinging upon electrons in the color cones of our eyes. I'm not sure I understand. I thought that "colour" was simply how our eyes interpret a certain range of frequencies within the visible portion of the spectrum; is this what you mean by the photons themselves being coloured? Are you simply referring to the wavelength of the light in question? Something else...I just realized that I'm using the words "frequency" and "wavelength" interchangeably. Are they, in fact, the same thing, in this context? I've never given it a great deal of thought but I've always assumed that "wavelength" refers to...well...the length of a given wave, while "frequency," I would guess, refers to the number of waves. I can see how they may be used in similar contexts, but perhaps there's a subtle difference that's contributing to my confusion.
sidelined writes: The nucleus of the atom does not use photons for an exchange particle and therefore cannot have color nor indeed be seen.The electron itself is not visible except indirectly through the gaining and losing of photon energy. Hmm...so an individual atom won't display colour? Melchior seems to be saying that it will (I think). Or did I misunderstand you? Perhaps you meant that the nucleus, specifically, will not show colour, but the overall atom (nucleus and electron/s) will? What I'm really having trouble with is how a single atom can show colour when the necessary wavelengths are so much larger. I keep falling back (no doubt due to my layman's understanding of particle physics) on the analogy of the cannonballs and the grain of sand. Is this a mistake on my part? Perhaps it's giving me an inaccurate impression. Just to clear it up in my mind, how does a photon compare in size, roughly, to an atom. Is the grain of sand/cannonball analogy (representing atom/photon, respectively) anything close to reality? Or perhaps the particle sizes are comparable and it is specifically the wavelength of the light that is larger than the atom? If this is the case then I may simply be having difficulty with the nature of particle/wave duality. Admittedly, I've never had a particularly firm grasp of it. Thanks for the help, sidelined.
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Tony650 Member (Idle past 4280 days) Posts: 450 From: Australia Joined: |
Hi Melchior,
Melchior writes: Single atoms would display colour in the same way that they do when there are millions other around them. Most theoretical models of how light is sent out does actually model just a single atom, because that's all that is needed for the principles to hold. Hmm...ok, at this point, I think I must be reading somebody wrong. You seem to be saying, here, that an individual atom will display colour, and sidelined seems to be saying, in post 54, that it won't. I hope I'm not misrepresenting either of your positions. I'm not trying to put words in anyone's mouth; I am genuinely reading these posts that way. You may both be telling me the same thing, but I'm afraid I see a conflict here. My apologies.
Melchior writes: A single photon does not show up as a large bright green blob in your brain, because then you'd be blinded constantly. You are not conciously aware of the single photons you see, if that's what you are wondering. Oh no, I understand that individual photons, atoms, etc are far too small to discern with the naked eye. I was assuming, for the sake of argument, that we have a way of magnifying far enough to allow us to look directly at the atoms and see if they display colour. Sorry for my lack of clarity.
Melchior writes: You'd need to magnify them quite a bit first. Yes, this is what I assumed for the purpose of my question. That is, hypothetically, if we were able to magnify far enough to see an individual atom, would it display colour? Also, I should clarify specifically what we're magnifying. I'm not talking about magnifying to the point where you can see the individual atoms within a group, I am assuming that we have one single atom isolated somehow (don't ask me how...magnetic field within a vacuum? ) and we are zooming in on that. So, I suppose, in a nutshell... Premise: We have an atom, isolated from all others, in a total vacuum. We have technology capable of magnifying down to the atomic level. We zoom right in and focus on the atom. Question: Do we see its colour?
Melchior writes: The wavelenght has nothing to do with the size of the atom. A normal radio-antenna can pick up wavelenghts far longer than it's own lenght. The two lenghts are not at all related. I think I must be getting confused over the particle/wave nature of light. As I said to sidelined, I am proceeding from an amateur's understanding of particle physics. The grain of sand/cannonball analogy may be giving me more grief than assistance. I keep picturing a grain of sand being struck by a cannonball and returning a cannonball. Not only is this a simplified view, but it also fails to take the wave-like nature of light into account. That may be part of my problem; perhaps I'm thinking too much in terms of its particle-like properties. Thanks again, Melchior. I appreciate your help with this.
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Melchior Inactive Member |
A single atom isolated somehow will, if you exite it via sunlight or electricity or heat radiation or whatever, send out photons of it's own, yes. It is not in any way dependant on surrounding photons to do so.
What I ment with magnify is that if we have a machine that picks up a single photon, and sends out 10 photons of the exact same type, our brain can see that as a coloured dot. When we say atoms have a colour, we mean that the electrons of that atom sends out light with a certain frequency that is interpreted in the brain as colour. The other parts of the atom, like neutrons, does not send out light and are as such invisible. We still consider the light coming from the electrons as coming from the atom as a whole. Wavelenght and frequency are directly related by a simple formula, in the case of light it's Frequency = Speed of light divided by Wavelenght. So each frequency have one specific wavelenght, since the speed of light is constant. The wavelenght of an EM-wave is not related to how large the wave is, or how much space it takes up. It is only related to the shifting of the electrical (E) and magnetical (M) fields. A ray is completely straight. The frequency also depends only on the EM properties of the ray, and describes how many 'peaks' (in field strenght) that passes a certain point per second. None of these has anything at all to do with size or largeness; all light-waves are exactly the same size. It's just the behaviour of the energy it carries that changes.
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sidelined Member (Idle past 6156 days) Posts: 3435 From: Edmonton Alberta Canada Joined: |
Tony650
I thought that "colour" was simply how our eyes interpret a certain range of frequencies within the visible portion of the spectrum; is this what you mean by the photons themselves being coloured? Are you simply referring to the wavelength of the light in question? Light in the 400 - 700 nanometer range is the visible light we percieve as colors.At the 400 nm end light is violet and at the 700nm range it is red.Our brain interprets the colors based on their unique wavelength or combination thereof. There is a site that deals with the application of light and vision in normal people and colorblind people that might help explain things in greater depth and clarity. http://home.pacifier.com/~ppenn/page7sc.html
Something else...I just realized that I'm using the words "frequency" and "wavelength" interchangeably. Are they, in fact, the same thing, in this context? No they are different but connected.The smaller the wavelength the greater the frequency.Wavelength times frequency equals the speed of light.At the highest frequency/smallest wavelength {most energetic} are the gamma rays at 10*-6 nm while at the lowest frequency/largest wavelength {least energetic} are the radio waves.
Hmm...so an individual atom won't display colour? The nucleus is not involved in the propogation of electromagnetism only the eletron as they gain and then release energy as photons when transitioning from one energy level to another
What I'm really having trouble with is how a single atom can show colour when the necessary wavelengths are so much larger. I keep falling back (no doubt due to my layman's understanding of particle physics) on the analogy of the cannonballs and the grain of sand. Is this a mistake on my part? Perhaps it's giving me an inaccurate impression. Well that because the photons come in discrete packets known as quanta and are measurable individually and at the same time they are elctromagnetic waves propogating through space.The individual photons quanta aspect will confuse you but the wave aspect is what will allow the colour to be mediated as its interacts with the color cones in our eyes.the electrons in the color cones absorb the photons and again release them as the information is transmitted through the nervous system to the brain.Poton to electron to photon on and on in a cascade effect throughout our biological pathways.It does take an accumulation of photons to stimulate the cones though I do not at the moment recall how many. Welcome to the mysteries of our humanity.Deep wonders indeed.Puzzles within puzzles. Hope you enjoy them because it gets better with the depth you go in studying these phenomena.
Just to clear it up in my mind, how does a photon compare in size, roughly, to an atom. Is the grain of sand/cannonball analogy (representing atom/photon, respectively) anything close to reality? Feynman descrbed it this way.If you were to take an atom and enlarge it to the size of a room in your house the elctrons would occupy the walls while the nucleus would be just a barely visble speck in the center.The electron would be about 10,000 times smaller and invisible at this scale.As for photons though I am not sure if there is a definite size since the energy is dependent on the frequency multiplied by Planck constant.This is getting into an area that is difficult for me due to the mathematics involved. I will try to see if I can get my head around the concepts involved and bring back a satisfactory answer. "Calling Atheism a religion is like calling bald a hair color." --Don Hirschberg
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Tony650 Member (Idle past 4280 days) Posts: 450 From: Australia Joined: |
Hi Melchior,
Melchior writes: A single atom isolated somehow will, if you exite it via sunlight or electricity or heat radiation or whatever, send out photons of it's own, yes. It is not in any way dependant on surrounding photons to do so. Just to clarify (although, I do think you understood my meaning), I was speaking of isolation only from other atoms, not from photons, as I assumed that, in order to see it, you would need a light source.
Melchior writes: What I ment with magnify is that if we have a machine that picks up a single photon, and sends out 10 photons of the exact same type, our brain can see that as a coloured dot. Mmm...ok, I think I'm getting you. So, in essence, all of the properties of the colour are present in the individually emitted photon? Alright, this is what I suspected. I'm still not sure that I'm sufficiently communicating my question, though. I'm not so much concerned with whether or not our eyes are capable of detecting the photon, as whether or not its colour is physically manifested in exactly the same way, even though it is too small for us to see. For instance, if we had a microscope that could take the image and "blow it up" to a size that we could see, would the image show the atom's colour? That is, if we were able to simply magnify an atom as we can, say, a microscopic organism. As I re-read my question, I'm starting to think that I'm overlooking something. I may be running into problems by trying to simply magnify things to a viewable size, without considering what physically happens during optical magnification. I was trying to avoid the necessity of multiplying the photons, by just detecting one and then "blowing the picture up." However, it now occurs to me that multiplying the photons is precisely what "blowing the picture up" does. Any way you cut it, I would have to replicate the photon before I could create any kind of visual representation of it large enough for my eyes to see, wouldn't I? I mean, even if I had a live view of it, magnified millions of times on a monitor, I still wouldn't actually be seeing the photon; I'd be seeing millions of photons, codified by the data received from the single photon, and organized in such a way as to visually represent it on the screen. Incidentally, you said, in your example, that our brain would see a coloured dot if we had a machine that could detect one photon and relay ten of the same type to our eyes. I have to ask; is this just a figure you pulled out of the air for the purpose of describing the machine's function, or did you actually mean to say that our eyes are capable of discerning a point of light comprised of a mere ten photons? I must say, if you meant the latter, I am very surprised; I would never have thought that our eyes were that sensitive. In fact, I would have guessed that it'd take thousands of photons to create light significantly large (and intense) enough for us to see. I'm quite amazed by the idea that we are able to see a group of just ten, if indeed this is what you meant.
Melchior writes: Wavelenght and frequency are directly related by a simple formula, in the case of light it's Frequency = Speed of light divided by Wavelenght. So each frequency have one specific wavelenght, since the speed of light is constant. Ah, I see. Ok, that makes sense.
Melchior writes: The wavelenght of an EM-wave is not related to how large the wave is, or how much space it takes up. It is only related to the shifting of the electrical (E) and magnetical (M) fields. A ray is completely straight. Hmm...alright, so the term "wavelength" isn't actually the measure of the physical length of a wave? Once again, my layman's understanding rears its ugly head, it seems. I wasn't aware that it had anything to do with the shifting of fields, as such. I thought that a "wave" was simply a displacement that travels through a medium. Or are you saying that fields, too, can act as mediums for waves? I'm probably even less familiar with waves than I am with particles. For some reason, I generally find it easier to visualize the transfer of particles than I do of waves. Perhaps it's just because I'm not clear on their specific properties. I keep seeing old diagrams, in my head. They would show wavy lines describing "crests" and "troughs," as I recall. And I thought that frequency and wavelength were illustrated by showing the range of wave configurations; from a few long drawn-out waves, to many compressed waves squeezed tightly together. This, however, may simply be a way of illustrating the concept, and not indicative of their actual physical configuration.
Melchior writes: The frequency also depends only on the EM properties of the ray, and describes how many 'peaks' (in field strenght) that passes a certain point per second. Yes, that sounds right (not that I think anything you've said is wrong, it's just that this at least sounds familiar to me).
Melchior writes: None of these has anything at all to do with size or largeness; all light-waves are exactly the same size. Oh, ok. I didn't know that. Again, I have difficulty with particle/wave duality, so I'm not sure how light's particle-like properties relate to its wave-like properties. Is the size of a light-wave equivalent to that of a photon (which I assume are all the same size, but I may be wrong )? And how does this compare, in size, to an atom (approximately)? Is the grain of sand/cannonball analogy accurate, in terms of the relative sizes of atoms/photons, respectively? By the way, thanks for the tuition, Melchior. This is an interesting topic, and I appreciate your help in understanding.
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