If atom is composed largely of "empty" space what happens INSIDE the atom when immersed in EM radiation? Does the EM wave propagate INSIDE the atom? For example, gas atoms in space, a radio wave goes thru the gas cloud but does it go "thru" the space inside the gas atoms? ( the word "thru" is problematic..but best word I could think of ).
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An answer elsewhere which addresses the misconception that atoms are mostly empty. – rob Dec 11 '20 at 18:41
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1Also consider that the EM radiation is also quantized, and each quantum of e.m. energy (aka photon) has a minimum location uncertainty roughly comparable to its wavelength. So if your EM energy is green light with wavelength 550 nm, it's difficult to concoct a scenario where it makes sense to specify the location of the energy of that wave more precisely than about 550 nm. Which is many times the size of a typical atom (generally 0.1-0.2 nm in diameter). – The Photon Dec 11 '20 at 20:00
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@Photon > "each quantum of e.m. energy (aka photon) has a minimum location uncertainty roughly comparable to its wavelength. " --- Shouldn't the minimal possible coordinate uncertainty be inversely proportional to uncertainty of momentum, rather than momentum? – Ján Lalinský Dec 11 '20 at 23:09
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Yes, external EM wave permeates all space its wavefront reaches, there is no way for the atom to shield its interior from it.
This is known to be true due to both theoretical reasons - Maxwell's equations and QM equations are linear, all waves are present everywhere and obey superposition; and experimental results - both electrons and nuclei can interact with external EM waves. For example, in NMR or MRI (NMR for imaging), radio-frequency EM waves interact with spins of hydrogen nuclei and some other nuclei, exchange energy with them and change their state.
Ján Lalinský
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Your question seems to imply that you are surprised that EM radiation can travel inside an atom because it is empty space, but you are OK with EM radiation traveling through space that contains gas atoms.
If that is the case (and you would be in good company), there are a number of misconceptions. The space inside atoms in no different to the space outside atoms, and EM fields permeate all of space. In fact, atoms have no edge - they kind of fade away as you get further from the nucleus so even asking about the difference is a meaningless question.
I would be wary about building a mental model of an atom as being a foam of electrons and photons and protons and exotica. Those mental models are inspired by Feynman but their subtleties require considerable sophistication.
shaunokane001
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Questions asked have to pass editor its seems? From above "Your question seems to imply that you are surprised that EM radiation can travel inside an atom" and from another comment, " "If atom is composed largely of "empty" space" This sentence is correct at high school level." Hmmm. that last one seem pretty condescending. I was trying get at the idea of "ineraction" with electrons, perhaps? I realize that "empty space" is pretty much a fiction. But such an idea is present in older ideas? And EXACTLY how can I ask such a question such that it appears to be "expert" enough INSIDE 500 Char? – DanD Dec 12 '20 at 19:54
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Rob, I am aware ( to some degree) of the "approximation" of the statement :"empty space" inside an atom. But I am not the first , nor the last to say such a thing. Is it not established how "small " the nucleolus is to total atom size? That observation alone would lead to such a statement. In short trusting English to describe the universe is quite problematic. You took the time to point out a misconception that was not the heart of my question. I deliberately put quotes around "empty" to convey the approximation such a word expresses here. – DanD Dec 12 '20 at 21:02
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Hi Dan, are you commenting on my answer or Kian's or a mixture of both? Apologies if you felt I was condescending - not my intention. You asked "Does the EM wave propagate INSIDE the atom?" The answer is YES. Calculating it would be complicated - the external EM radiation distorting the orbitals (another question?). I wouldn't think too much about the nature of empty space - IMHO it is easier to understand that way too. – shaunokane001 Dec 15 '20 at 18:51
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"If atom is composed largely of "empty" space" This sentence is correct at high school level. what I mean is that is a simplified picture. Inside atom (let's say hydrogen) is full of photons! these photons fields are exchanged between the proton and electron and this exchange of photons creates what you call electric field.
"what happens INSIDE the atom when immersed in EM radiation"? When if the EM radiation is very energetic it can collide with the photons and create new particle. if is is weak, it can pass through the atom with out interacting with anything.
**"gas atoms in space, a radio wave goes thru the gas cloud" ** definitely not. when you start to study the atoms and photon, quantum mechanics and quantum field theories start to play a significant role. A lot of things can happen. the electron can absorb the photon, the protons can absorb the photon. if you have a lot of energy you can create new particles.
Kian Maleki
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It's not only photons that may be in the volume of the atom. The atom is full of electron(s). Only considering the electron as a classical point like particle with exact localization leisured the wrong image of empty atom. – nasu Dec 11 '20 at 22:00
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What he means by saying that inside an atom is empty is that the density of the matter is very small. Thinking of particles as clouds does not increase that density. – Kian Maleki Dec 12 '20 at 16:39
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They are points but not classical points with precise location in space. No matter where the electron is inside the atom (assuming there is a meaning to this)there will be a strong interaction with photons or other electrons going "through" the atom. This does not look like empty space to me. Empty space will be if an electron would be able to go through with no interaction because the atom's electrons where "on the other side". – nasu Dec 12 '20 at 16:46
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They are mathematically a point. I didn't say that you can measure it's location. – Kian Maleki Dec 12 '20 at 16:51
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I mean "strong" as an adjective not as the name of one of the 4 types of fundamental forces. The interaction I was talking about is electromagnetic. Indeed, in terms of nuclear matter the atom is mostly empty. And I suppose this was the original meaning of the expression. I was just saying that it may give the wrong idea if it is taken without qualification. – nasu Dec 12 '20 at 16:59
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Judging by the replies it seems ITS A Difficult question to answer? So I would say that makes it a good question regardless of the "perfect phrasing " of it INSIDE 500 char? shaunokane001 suggested that I indicated surprize that EM could be INSIDE ( whatever that means) an atom. No that was not my real question. – DanD Dec 12 '20 at 20:04
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The REAL reason I asked this question is try and understand if an ATOM can be thought of as information storage device? If EM passes thru is it not storing that information(internally?) ? At least for a tiny bit of time? Does the "space" component of the atom have a longer lasting imprint of the EM event due to stored information? Can atoms store EXTERNAL information that MOVES in space time with the atom? Or another ? Can an atom "trap" a slice of space time and "move its information content"? Space time has information content, yes? It has energy, it moves charge, etc. – DanD Dec 12 '20 at 20:10