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October 24 Information
Herbivore and carnivore
We are asked to eat balanced diet, but they eat only raw plant leaves and digest while others hunt them and eat their meat.
So the first group get all protein, minerals, fibre, calcium from leaves only and second group also don't face constipation eating only raw meat.
Right now due to urban life human beings might have become weaker, but is it possible that prehistoric humans could digest raw meat and leaves without cooking?
Well use Chad then. The point is that "what our ancestors ate ... oysters" assumes a coastal population. Unless you are going to postulate significant Pleistocene trans-continental trade routes then any population more than a few day's journey from the sea would not have a significant proportion of seafood.
Martin of Sheffield (
talk)
09:19, 24 October 2023 (UTC)reply
I believe that is what's postulated; that most humans were coastal. The incredible availability of oysters once you have figured out that you can pop them out of the sand with a stick (a method not available to any animal except the
oystercatchers), you have these 20+ meter high, kilometers-long shell middens appear in the geological record. Sea level change has submerged many of these, but those that remain are impressive. Abductive (
reasoning)18:22, 24 October 2023 (UTC)reply
Modern humans routinely eat raw leaves – see
Salad. Eating uncooked meat (including mammalian meat) is culturally more restricted, and is somewhat less favoured because of the increased possibility of disease transmission that cooking mostly eliminates, but see
raw meat.
Different species have very different anatomies and metabolisms, including those aspects of both relating to digestion. It is pointless to compare obligate
herbivores and obligate
carnivores to
omnivores such as humans in an attempt to deduce what is healthy for the latter. {The poster formerly known as 87.81.230.195}
46.65.231.103 (
talk)
09:02, 24 October 2023 (UTC)reply
Many
herbivores do not, or not only, eat plant leaves, but also whole plants or other parts of plants (stems, roots,
tubers, seeds, nuts, berries, fruits). Some of this is also routinely consumed raw by modern humans (e.g. carrots, pumpkin seeds, almonds, tomatoes, apples). --
Lambiam10:42, 24 October 2023 (UTC)reply
The most photons an electron can receive?
A week ago I askd the other way around. The most photons an electron can absorb. But I'm stuck on receiving. When an electron receives a photon, it goes up 1 shell? Big elements don't tend to have more than 7 shells, so it can only absorb up to 7 photons? Then what about the hydrogen atom?
When you shine light to an object like a solid, what happens to when photons strike the nucleus? Do majority photons miss the electrons and hit the nucleus? Thanks.
170.76.231.162 (
talk)
16:30, 24 October 2023 (UTC).reply
I don't know this subject at all, but I'm reasonably sure the electron will fly off pretty easily and leave behind an ion. Can a photon hit a loose electron? Abductive (
reasoning)18:17, 24 October 2023 (UTC)reply
That is only true if the photon energy is above the
work function of the material it is interacting with (see
photoelectric effect), or the
ionization energy if we aren't talking about solid surfaces. This is usually a fairly high amount of energy, which is good, or we would all immediately die if we turn on a lamp. Generally speaking, you need at least ultra-violet energy to start kicking off electrons, and possibly deep-UV or X-rays, especially if we are talking about core electrons as opposed to valence electrons. Again, this is why ultra-violet light is a bit dangerous; it's going to start doing things like ionizing some of the DNA in your cells, or ionizing other molecules around them into free radicals that then interact with your DNA, creating mutations that could lead to cancer. Below these energies, such as visible light (in most cases) and down, the photon will either not interact with the atom and its electrons at all, or only interact with them if the photon energy is resonant with an allowed transition of the electrons in the atom's electron cloud. As for hitting a lose electron... well, in photon/electron interactions, whether in an atomic electron cloud or a free electron, its probably better to picture these as waves interacting rather than particles interacting. An electron in an atom's cloud, for example, is a standing wave, and the electron field of the photon wave can, if resonant with an allowed transition, interact with that standing wave. The same can probably also happen with a free electron, since it is still also a wave. --
OuroborosCobra (
talk)
18:55, 24 October 2023 (UTC)reply
That's kind of true, but only if we are talking about two-photons interacting with an electron at the same time/simultaneously. You can have non-simultaneous or sequential interactions, so long as an additional photon interacts with the electron that has already been interacted with before it returns to the ground state. Since these absorptions and relaxations are not instantaneous processes, that's absolutely possible. That's one of the ways we have
Balmer series absorptions in hydrogen, for example. You can absorb a photon resonant with 1s -> 2p, and then absorb a second photon for 2p -> 4d (part of the Balmer series), but that won't happen at the same time as the first absorption; it must be subsequent, and before enough time has passed for relaxation. Of course, you can also have this with electrons being thermally excited to higher states and then interacting with a photon, but there's no reason it has to be initially thermal rather than from the electric field. --
OuroborosCobra (
talk)
19:30, 24 October 2023 (UTC)reply
Yes, and now what? You are describing multiple absorption events (and as there are in principle infinitely many excited states in an atom, it can in principle absorb arbitrarily many photons that way before ionisation), I referred to a single event involving two or more photons. And who knows what OP was asking about? --
Wrongfilter (
talk)
19:45, 24 October 2023 (UTC)reply
Exactly, who knows what they are asking about? I wouldn't assume they are asking about simultaneous absorption events anymore than their previous question was predicated on simultaneous emissions. --
OuroborosCobra (
talk)
21:15, 24 October 2023 (UTC)reply
When thinking about photons and electrons interacting, you are better off thinking of them as waves and fields interacting rather than particles. A photon isn't likely to "miss" an electron, rather, the
electric field of that photon may or may not be resonant with an
allowed transition to interact with the electron, or rather, the electric field interacting with the
standing wave that is the electron. So, for example, a photon of the proper energy can interact with an electron around a hydrogen atom and give it enough energy to get to a state more than one shell higher than than the ground state. So, that ground state 1s electron standing wave can't interact with an electric field at the frequency (energy of the photon) equal to the energy difference between a 1s standing wave and a 2s standing wave because the change in the
azimuthal quantum number must be +/- 1, and from 1s to 2s that would be a change of 0. To think of it visually, the interaction requires the electric field to be able to add a "node" to the electron standing wave, but just one additional node. So, you could have a 1s -> 2p, but nothing says that a high enough frequency in the electric field (high enough energy electron) can't be resonant with an excitation of 1s -> 3p, or 1s -> 4p, for example. However, you won't have a 1s -> 3d, since that would be a change of 2 azimuthal quantum numbers, or more than one "node" in the standing wave. There's a really great animation describing this and showing how you can only add one "node" at a time, and must add one node for that interaction to take place from Boston University,
can find it here. As the video shows, if that photon energy isn't such that the frequency of the electric field is resonant with an allowed transition, then nothing will happen and the photon won't interact with the atom. I guess that could be described as "missing," but it isn't so much that the photon "missed" the electron so much as they saw each other, and nothing happened. I really love this video, since it also shows you visually why photon absorption isn't an "instantaneous" process! It is possible for the electric field from a second photon to also interact with the same electron, you could have a 1s -> 3p, and if another photon electric field is around before the electron returns to the ground state and is resonant with an allowed transition, it could then interact and transition from 3p -> 4d, or something like that. You can see this also at
Hydrogen spectral series. So, an electron can absorb tons of photons, though those interactions need to be allowed transitions, and they can't necessarily all happen at the same time, since those absorptions are not instantaneous. As for really high energy photons, see
photoelectric effect and
ionization energy. Basically if that frequency of the electric field oscillation from the photon is really high, and we are generally talking ultra-violet or x-rays, then it might be enough to actually strip the electron off of the atom, ionizing it. Think of that animation I linked you to, but imagine that oscillation being really really fast, to the point that instead of just forming one more "lobe," it pushed the standing wave off of the atom altogether. That can happen. As for interactions with the nucleus, ultimately, protons and neutrons are themselves waves as well, so yes, they can interact with the electric field oscillating from a photon, but it is also going to be subject to proper selection rules and correct resonant frequencies. Someone else will have to answer in more detail on that, I'm not an expert on interactions of light with protons and neutrons. Lastly, lower energy/lower frequency photons can also interact in other ways, such as if they match the energy of a vibration or rotation of a molecule. See
molecular spectroscopy,
infrared spectroscopy,
microwave spectroscopy,
molecular vibration, and
molecular rotation for more information on these. --
OuroborosCobra (
talk)
19:23, 24 October 2023 (UTC)reply
I'm a bit uneasy about the statement that the standing wave is the electron. The wave function describes the state of the electron (or perhaps more accurately the atom) and is used to derive probabilities, e.g. where the electron is and probabilities to transition from one state to another, but the wave function is not the electron itself. --
Wrongfilter (
talk)
19:47, 24 October 2023 (UTC)reply
The wave isn't the electron, rather, the electron is a standing wave, when within an AO or MO.
Researchers at IBM and and the University of Liverpool have even made high resolution images of various molecular orbitals, especially HOMOs and LUMOs conjugated π systems using scanning tunneling microscopy, so there appears to be something much more physical to these standing waves than them being just the mathematical descriptions (wavefunction) useful for deriving probabilities and properties. --
OuroborosCobra (
talk)
21:47, 24 October 2023 (UTC)reply
Well, naturally the "standing waves" (as you insist on calling them) translate into something that is physically measurable, otherwise they would be useless. In this case it is time-integrated charge distributions, which are proportional to the probability density for the location of the electron(s), which in turn is the absolute square of the wave function, . (Note that I'm not making any statement on what the electron is (that would be futile), at best on what it is not).--
Wrongfilter (
talk)
09:14, 25 October 2023 (UTC)reply
I do not know what your issue is with my calling them "standing waves." At least within physical chemistry, that is pretty standard terminology and the correct term for them. Indeed, even our articles on
atomic orbital and
molecular orbitals call them standing waves. I mean, in terms of the physical description given to the mathematical model, even if you want to just consider it a "model" as opposed to something more physical or "real" (I kind of hate using the word "real" here since it could be confused with the mathematical concept of
real numbers and
imaginary numbers, which is problematic linguistically when wavefunctions are
complex), the model of these orbitals describe them as standing waves. --
OuroborosCobra (
talk)
13:39, 26 October 2023 (UTC)reply
I guess I want to see sines and cosines when talking about waves. You get these in non-stationary situations (a propagating particle), and some stationary situations like the one-dimensional potential wells. In the hydrogen atom, the eigenfunctions (solutions to the stationary Schrödinger equation) are spherical harmonics and Legendre polynomials. While these are "wave functions", they do not necessarily have to be "waves" in my mind. Maybe that's just me. I think I prefer abstract state vectors (i.e. ) anyway... --
Wrongfilter (
talk)
14:03, 26 October 2023 (UTC)reply
The wave function is a mathematically model of a physical phenomenon. As such the epistemological situation is not essentially different from that of mathematical models of physical phenomena in general. For some reason,
quantum weirdness makes people ponder whether the physical phenomenon (the wave) itself is "real" or a mirage of some deeper reality. Lacking an
operationalizable definition of "real", this ontological question is as meaningless as the question whether
reality itself is real. (It is nevertheless conceivable that one day quantum theory will be superseded by another theory in which the "weirdness" emerges from more basic assumptions.) --
Lambiam08:20, 25 October 2023 (UTC)reply
Now that's where I might object! I'd say the particular scrawling of the Schrödinger equation and the pondering of what is real, really? are equally meaningless. Meaning, I'm enthralled. —
Remsense聊08:23, 25 October 2023 (UTC)reply
I asked a physics professor yesterday who said the vast majority of light hits the valence electrons, and rarely hit the nucleus, i.e. light hitting a table. Does anyone know what %? Is it like 99%? And the remaining .9% could be the non-valence electrons, or the nucleus? It also depends on the light. UV will hit higher % of nucleus than say IR light, is there a formula to calculate this?
170.76.231.162 (
talk)
16:45, 27 October 2023 (UTC).reply
Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a
transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the
current reference desk pages.
October 24 Information
Herbivore and carnivore
We are asked to eat balanced diet, but they eat only raw plant leaves and digest while others hunt them and eat their meat.
So the first group get all protein, minerals, fibre, calcium from leaves only and second group also don't face constipation eating only raw meat.
Right now due to urban life human beings might have become weaker, but is it possible that prehistoric humans could digest raw meat and leaves without cooking?
Well use Chad then. The point is that "what our ancestors ate ... oysters" assumes a coastal population. Unless you are going to postulate significant Pleistocene trans-continental trade routes then any population more than a few day's journey from the sea would not have a significant proportion of seafood.
Martin of Sheffield (
talk)
09:19, 24 October 2023 (UTC)reply
I believe that is what's postulated; that most humans were coastal. The incredible availability of oysters once you have figured out that you can pop them out of the sand with a stick (a method not available to any animal except the
oystercatchers), you have these 20+ meter high, kilometers-long shell middens appear in the geological record. Sea level change has submerged many of these, but those that remain are impressive. Abductive (
reasoning)18:22, 24 October 2023 (UTC)reply
Modern humans routinely eat raw leaves – see
Salad. Eating uncooked meat (including mammalian meat) is culturally more restricted, and is somewhat less favoured because of the increased possibility of disease transmission that cooking mostly eliminates, but see
raw meat.
Different species have very different anatomies and metabolisms, including those aspects of both relating to digestion. It is pointless to compare obligate
herbivores and obligate
carnivores to
omnivores such as humans in an attempt to deduce what is healthy for the latter. {The poster formerly known as 87.81.230.195}
46.65.231.103 (
talk)
09:02, 24 October 2023 (UTC)reply
Many
herbivores do not, or not only, eat plant leaves, but also whole plants or other parts of plants (stems, roots,
tubers, seeds, nuts, berries, fruits). Some of this is also routinely consumed raw by modern humans (e.g. carrots, pumpkin seeds, almonds, tomatoes, apples). --
Lambiam10:42, 24 October 2023 (UTC)reply
The most photons an electron can receive?
A week ago I askd the other way around. The most photons an electron can absorb. But I'm stuck on receiving. When an electron receives a photon, it goes up 1 shell? Big elements don't tend to have more than 7 shells, so it can only absorb up to 7 photons? Then what about the hydrogen atom?
When you shine light to an object like a solid, what happens to when photons strike the nucleus? Do majority photons miss the electrons and hit the nucleus? Thanks.
170.76.231.162 (
talk)
16:30, 24 October 2023 (UTC).reply
I don't know this subject at all, but I'm reasonably sure the electron will fly off pretty easily and leave behind an ion. Can a photon hit a loose electron? Abductive (
reasoning)18:17, 24 October 2023 (UTC)reply
That is only true if the photon energy is above the
work function of the material it is interacting with (see
photoelectric effect), or the
ionization energy if we aren't talking about solid surfaces. This is usually a fairly high amount of energy, which is good, or we would all immediately die if we turn on a lamp. Generally speaking, you need at least ultra-violet energy to start kicking off electrons, and possibly deep-UV or X-rays, especially if we are talking about core electrons as opposed to valence electrons. Again, this is why ultra-violet light is a bit dangerous; it's going to start doing things like ionizing some of the DNA in your cells, or ionizing other molecules around them into free radicals that then interact with your DNA, creating mutations that could lead to cancer. Below these energies, such as visible light (in most cases) and down, the photon will either not interact with the atom and its electrons at all, or only interact with them if the photon energy is resonant with an allowed transition of the electrons in the atom's electron cloud. As for hitting a lose electron... well, in photon/electron interactions, whether in an atomic electron cloud or a free electron, its probably better to picture these as waves interacting rather than particles interacting. An electron in an atom's cloud, for example, is a standing wave, and the electron field of the photon wave can, if resonant with an allowed transition, interact with that standing wave. The same can probably also happen with a free electron, since it is still also a wave. --
OuroborosCobra (
talk)
18:55, 24 October 2023 (UTC)reply
That's kind of true, but only if we are talking about two-photons interacting with an electron at the same time/simultaneously. You can have non-simultaneous or sequential interactions, so long as an additional photon interacts with the electron that has already been interacted with before it returns to the ground state. Since these absorptions and relaxations are not instantaneous processes, that's absolutely possible. That's one of the ways we have
Balmer series absorptions in hydrogen, for example. You can absorb a photon resonant with 1s -> 2p, and then absorb a second photon for 2p -> 4d (part of the Balmer series), but that won't happen at the same time as the first absorption; it must be subsequent, and before enough time has passed for relaxation. Of course, you can also have this with electrons being thermally excited to higher states and then interacting with a photon, but there's no reason it has to be initially thermal rather than from the electric field. --
OuroborosCobra (
talk)
19:30, 24 October 2023 (UTC)reply
Yes, and now what? You are describing multiple absorption events (and as there are in principle infinitely many excited states in an atom, it can in principle absorb arbitrarily many photons that way before ionisation), I referred to a single event involving two or more photons. And who knows what OP was asking about? --
Wrongfilter (
talk)
19:45, 24 October 2023 (UTC)reply
Exactly, who knows what they are asking about? I wouldn't assume they are asking about simultaneous absorption events anymore than their previous question was predicated on simultaneous emissions. --
OuroborosCobra (
talk)
21:15, 24 October 2023 (UTC)reply
When thinking about photons and electrons interacting, you are better off thinking of them as waves and fields interacting rather than particles. A photon isn't likely to "miss" an electron, rather, the
electric field of that photon may or may not be resonant with an
allowed transition to interact with the electron, or rather, the electric field interacting with the
standing wave that is the electron. So, for example, a photon of the proper energy can interact with an electron around a hydrogen atom and give it enough energy to get to a state more than one shell higher than than the ground state. So, that ground state 1s electron standing wave can't interact with an electric field at the frequency (energy of the photon) equal to the energy difference between a 1s standing wave and a 2s standing wave because the change in the
azimuthal quantum number must be +/- 1, and from 1s to 2s that would be a change of 0. To think of it visually, the interaction requires the electric field to be able to add a "node" to the electron standing wave, but just one additional node. So, you could have a 1s -> 2p, but nothing says that a high enough frequency in the electric field (high enough energy electron) can't be resonant with an excitation of 1s -> 3p, or 1s -> 4p, for example. However, you won't have a 1s -> 3d, since that would be a change of 2 azimuthal quantum numbers, or more than one "node" in the standing wave. There's a really great animation describing this and showing how you can only add one "node" at a time, and must add one node for that interaction to take place from Boston University,
can find it here. As the video shows, if that photon energy isn't such that the frequency of the electric field is resonant with an allowed transition, then nothing will happen and the photon won't interact with the atom. I guess that could be described as "missing," but it isn't so much that the photon "missed" the electron so much as they saw each other, and nothing happened. I really love this video, since it also shows you visually why photon absorption isn't an "instantaneous" process! It is possible for the electric field from a second photon to also interact with the same electron, you could have a 1s -> 3p, and if another photon electric field is around before the electron returns to the ground state and is resonant with an allowed transition, it could then interact and transition from 3p -> 4d, or something like that. You can see this also at
Hydrogen spectral series. So, an electron can absorb tons of photons, though those interactions need to be allowed transitions, and they can't necessarily all happen at the same time, since those absorptions are not instantaneous. As for really high energy photons, see
photoelectric effect and
ionization energy. Basically if that frequency of the electric field oscillation from the photon is really high, and we are generally talking ultra-violet or x-rays, then it might be enough to actually strip the electron off of the atom, ionizing it. Think of that animation I linked you to, but imagine that oscillation being really really fast, to the point that instead of just forming one more "lobe," it pushed the standing wave off of the atom altogether. That can happen. As for interactions with the nucleus, ultimately, protons and neutrons are themselves waves as well, so yes, they can interact with the electric field oscillating from a photon, but it is also going to be subject to proper selection rules and correct resonant frequencies. Someone else will have to answer in more detail on that, I'm not an expert on interactions of light with protons and neutrons. Lastly, lower energy/lower frequency photons can also interact in other ways, such as if they match the energy of a vibration or rotation of a molecule. See
molecular spectroscopy,
infrared spectroscopy,
microwave spectroscopy,
molecular vibration, and
molecular rotation for more information on these. --
OuroborosCobra (
talk)
19:23, 24 October 2023 (UTC)reply
I'm a bit uneasy about the statement that the standing wave is the electron. The wave function describes the state of the electron (or perhaps more accurately the atom) and is used to derive probabilities, e.g. where the electron is and probabilities to transition from one state to another, but the wave function is not the electron itself. --
Wrongfilter (
talk)
19:47, 24 October 2023 (UTC)reply
The wave isn't the electron, rather, the electron is a standing wave, when within an AO or MO.
Researchers at IBM and and the University of Liverpool have even made high resolution images of various molecular orbitals, especially HOMOs and LUMOs conjugated π systems using scanning tunneling microscopy, so there appears to be something much more physical to these standing waves than them being just the mathematical descriptions (wavefunction) useful for deriving probabilities and properties. --
OuroborosCobra (
talk)
21:47, 24 October 2023 (UTC)reply
Well, naturally the "standing waves" (as you insist on calling them) translate into something that is physically measurable, otherwise they would be useless. In this case it is time-integrated charge distributions, which are proportional to the probability density for the location of the electron(s), which in turn is the absolute square of the wave function, . (Note that I'm not making any statement on what the electron is (that would be futile), at best on what it is not).--
Wrongfilter (
talk)
09:14, 25 October 2023 (UTC)reply
I do not know what your issue is with my calling them "standing waves." At least within physical chemistry, that is pretty standard terminology and the correct term for them. Indeed, even our articles on
atomic orbital and
molecular orbitals call them standing waves. I mean, in terms of the physical description given to the mathematical model, even if you want to just consider it a "model" as opposed to something more physical or "real" (I kind of hate using the word "real" here since it could be confused with the mathematical concept of
real numbers and
imaginary numbers, which is problematic linguistically when wavefunctions are
complex), the model of these orbitals describe them as standing waves. --
OuroborosCobra (
talk)
13:39, 26 October 2023 (UTC)reply
I guess I want to see sines and cosines when talking about waves. You get these in non-stationary situations (a propagating particle), and some stationary situations like the one-dimensional potential wells. In the hydrogen atom, the eigenfunctions (solutions to the stationary Schrödinger equation) are spherical harmonics and Legendre polynomials. While these are "wave functions", they do not necessarily have to be "waves" in my mind. Maybe that's just me. I think I prefer abstract state vectors (i.e. ) anyway... --
Wrongfilter (
talk)
14:03, 26 October 2023 (UTC)reply
The wave function is a mathematically model of a physical phenomenon. As such the epistemological situation is not essentially different from that of mathematical models of physical phenomena in general. For some reason,
quantum weirdness makes people ponder whether the physical phenomenon (the wave) itself is "real" or a mirage of some deeper reality. Lacking an
operationalizable definition of "real", this ontological question is as meaningless as the question whether
reality itself is real. (It is nevertheless conceivable that one day quantum theory will be superseded by another theory in which the "weirdness" emerges from more basic assumptions.) --
Lambiam08:20, 25 October 2023 (UTC)reply
Now that's where I might object! I'd say the particular scrawling of the Schrödinger equation and the pondering of what is real, really? are equally meaningless. Meaning, I'm enthralled. —
Remsense聊08:23, 25 October 2023 (UTC)reply
I asked a physics professor yesterday who said the vast majority of light hits the valence electrons, and rarely hit the nucleus, i.e. light hitting a table. Does anyone know what %? Is it like 99%? And the remaining .9% could be the non-valence electrons, or the nucleus? It also depends on the light. UV will hit higher % of nucleus than say IR light, is there a formula to calculate this?
170.76.231.162 (
talk)
16:45, 27 October 2023 (UTC).reply