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I do not understand this. May someone help me with an ELI16? An electron is a cloud that is contained with a perfectly round sphere. Does cloud mean a thing th

I do not understand this. May someone help me with an ELI16? An electron is a cloud that is contained with a perfectly round sphere. Does cloud mean a thing that contains a particle that travels very fast in a perfect sphere? What does cloud entail in this instance? If we have determined that an electronic cannot be made up of other particles then there should only be one particle in the cloud? Or is the particle a gas / cloud? I thought that the general consensus was that the precise location of an electron was impossible (?) to fully predict? If you can't predict where an electron is with a high degree of certainty How can you measure it ? This might be outdated, or just my brain pulling tricks on me again.

dave333 4y ago
I think the measurements don't say anything about the size or how the electron is distributed in the probability distribution other than that it's spherically symmetric to a very small tolerance. It's interesting that there is another model of the electron orbit in atoms that is a spinning fluid shell of charge with an exact radius. See https://brilliantlightpower.com/theory-overview/ https://brilliantlightpower.com/theory-overview/
- ThinkBeat 4y ago
  > I think the measurements don't say anything about the size or how the electron is distributed in the probability distribution I fully admit i dont understand most of what I hear about particle physics anymore A lot seems non intuitive with the (dumb) model I have in my head. (That doesn't say much about tis accuracy) If you are to make such extremely detailed measurements of anything you need to be able to observe it over time? (Though how much time varies a lot) Presumably, a constantly moving electron whose location cannot established is a difficult thing measure?
  - dave333 4y ago
    Well it depends how it is moving. Think of a spinning axle that is featureless - does it appear to move? How about a featureless disc bike wheel that is spinning? And the Mills model of the electron "orbitsphere" is a spherical fluid shell of charge that is spinning along all great circle routes. The charge distribution is not changing but the charge is spinning.
perardi 4y ago
Yeah, I am not used to seeing the term “cloud” for a single electron. Is that a common term in physics for a single electron? I am very much used to seeing that phrase as the probability space for electrons in orbitals in an atom. https://en.wikipedia.org/wiki/Atomic_orbital https://en.wikipedia.org/wiki/Atomic_orbital In this article I take it to mean “any point particle has a non-zero physical radius, but because quantum mechanics shows everything has a measure of uncertainty, the possibility of the charge within that non-zero space is an amorphous cloud”. But still a weird lexical overlap with the high school physics electron cloud meaning of things.
- drdeca 4y ago
  Consider the case where the atom in question is hydrogen, with just one electron orbiting it. I would still think the word "cloud" would be used?
LegitShady 4y ago
The electron has no known internal structure. As far as we know its a fundamental particle and isn't made up of other things, the way protons or neutrons are made up of quarks held together by gluons. An electron's location is subject to all sorts of rules. The Heisenberg uncertainty principle says that the more we know about a particles momentum (mass*velocity), the less we know about its position, and vice versa. This is not a matter of the observer effect (measurement upsetting one of these values), as some people state, but something fundamental due to the wavefunction nature of matter. The location of a subatomic particle is determined by its wavefunction (Squared) - where the wavefunction is big you have a high probability of finding a particle, and where it is small you have a small probability to find a particle. the wavefunction is a probability density function - the probability of finding a given particle at a given place in a given time. The next important idea is that subatomic particles can be considered both particles and waves, and thus have a wavelength. High momentum particles (high energy) have a short wavelength, low momentum (low energy) particles have long wavelengths. Waves are disturbances spread out in space, and we can identify the distance between two peaks (the wavelength), but then we wouldn't know anything about its position - it could be in lots of places. To localize a wave you add together lots of waves (into a localized wavepacket) until the resulting wave gives you areas where you are likely to find a particle where those added waves overlap in crests, and areas where you are unlikely to find the particle where those added waves overlap in troughs. This is a tradeoff, though - you are still subject to the heisenberg uncertainty principle so the more you know about the location, the less you know about the momentum. Thus the electrons, which move very quickly, and are interchangeable with one another being identical to each other, appear to exist as a cloud of probabilistic locations. They aren't themselves a cloud, rather their position is always uncertain until directly measured to a high degree of certainty. Now you may say "but we know electrons live in orbitals around atoms - how can we know that if we can't know their precise positions". This is because electrons obey the pauli exclusion principle, which states that two or more particles with half integer spin (fermions of which the electron is one, which have antisymmetric wave functions) cannot have the same set of four quantum numbers - n (the shell number or general region for value of energy of the electron), l (orbital angular momentum/the shape of the orbital), m sub l (the magnetic orientation of the orbital), and m sub s (quantum spin, which for fermions can be +/- 1/2). (the minus is what makes fermions antisymmetric) This principle is why electrons are more likely to be found in some places around an atom described as shells, and thus why electrons exist in discrete locations around an atom and why atoms and chemistry exist. The reason for the pauli exclusion principle is also wave related - I'll link a video below: https://www.youtube.com/watch?v=Zlp2GQ3OLeE https://www.youtube.com/watch?v=Zlp2GQ3OLeE This was a pretty surface level explanation - we didn't even get into the dirac equation (which is where the existence of antimatter was first derived) or spinor theory! but I think its good enough to have some understanding of why the fundamental wave nature of subatomic particles leads to uncertainty in their location, which means they appear to live in a cloud around atoms.
ineptech 4y ago
The old "is" strikes again. An electron is definitely not a cloud, nor a particle nor a wave, we don't know what the hell it is and stopped trying to describe it in those terms many years ago. Instead, we limit ourselves to trying to come up with models that accurately predict how they behave, and call the models useful when they predict the right answers to experiments. "All models are wrong but some are useful", as the saying goes. Like all subatomic particles, electrons don't seem to have a discrete location; when we try to measure their location, we get different results each time, as you said. However, these apparently-random results follow a predictable pattern, so we describe it using an equation predicting where it is most likely to be found (the Schrodinger wave equation). For electrons in some stable states, that area is roughly spherical, meaning that there is some point where it is most likely to be found, a fuzzy area near that point where it is fairly likely to be found, and a distance from that point past which it is very unlikely to be found. We can therefore model the electron as being a tiny discrete thing that whizzes around in a roughly spherical area, which is the "cloud" in this article. All that "can be modeled as" stuff is unwieldy, so people say the electron "is" a spherical cloud when they mean that modeling it as a spherical cloud is useful for understanding the matter at hand. What this article is describing is an attempt to measure whether that spherical region is perfectly spherical. If it weren't - meaning, if the electron was slightly more likely to be found on one side of the sphere than the other, then it would have an electrical dipole moment, which is what they were trying to find.
- ineptech 4y ago
  Fake edit: this is why it's helpful when discussing quantum mechanics to banish "is" from your vocabulary. For example, the debate over whether an electron "is" a particle or "is" a wave is much more tractable when you switch to debating whether it behaves like a particle or a wave in some situation. In college, I found this very similar to how it is useful when learning relativity to avoid the word "simultaneously".
  - gitfan86 4y ago
    Yes, if you view Time, Space, Intelligence and Consciousness as emergent, things make a lot more sense. This upsets people because it implies that the most fundamental parts of their existence are not "real", but to your point it is very helpful to approach them as if they are not "real" regardless of what is actually fundamental to reality.
vihren 4y ago
You are not to blame for not understanding this, it's just that the analogy for the electric dipole moment coming from a non-spherical 'shape' of the electron is extremely bad. Moreover it's missing the most important reason why we search for EDMs, because the existence of one in an elementary particle would indicate the violation of the time-reversal symmetry (T), which assuming CPT conservation [1] leads to CP violation (Charge conjugation and parity symmetries). CP violation [2] is needed to explain the matter-antimatter asymmetry of the Universe. A more proper way, in my opinion, to reason about an electric dipole moment is to think in terms of Feynman diagrams. An EDM (or any dipole moment for that matter) is an interaction of the electron with an electromagnetic field, so interaction between an electron and a photon. The most simple such interaction you can imagine is an electron flying in, at one point it absorbs a photon and flies out - that would be the magnetic dipole moment. You can go more complex though - electron flying in, at one point it emits a photon, then the electron interacts with the EM field (absorbing a photon) and then it reabsorbs the photon it has emitted previously. (Note that these analogies are again not perfect as for elementary particles time and space are not the same as in the macro world). Now, it can get even more complicated: If you have an electron it's not really a 100% pure electron. There is always some chance that it transforms for a short time into a quark or neutrino or whatever you can imagine. When you analyze all such scenarios (electron going into something else, interacting with the EM field and then going back to an electron) some violate CP symmetry, and those contribute to the electric dipole moment. We use that name (dipole moment) as the final result is as if the electron was a ball with some separation between the negative and positive charges and placed into an electric field it experiences some torque. The analogy misses the most important part though, as if it was such a polarized 'ball' it would not violate CP symmetry. Within the Standard Model the only source of CP violating interactions come from the weak interaction (CKM matrix). These have a very small contribution as the weak interaction is, as the name suggests, very weak. That's why the Standard Model predicts very tiny electric dipole moments. When we are searching for EDMs we are in fact searching for such rare transformations through some new undiscovered particle that violate CP symmetry. If we detect some non-zero EDM that would mean that there is some interaction that is not included in the standard model that violates CP, not that the electron is not a round sphere or a sphere with a bump. [1] - https://en.wikipedia.org/wiki/CPT_symmetry https://en.wikipedia.org/wiki/CPT_symmetry [2] - https://en.wikipedia.org/wiki/CP_violation https://en.wikipedia.org/wiki/CP_violation

dave333 4y ago

I think the measurements don't say anything about the size or how the electron is distributed in the probability distribution other than that it's spherically symmetric to a very small tolerance. It's interesting that there is another model of the electron orbit in atoms that is a spinning fluid shell of charge with an exact radius. See https://brilliantlightpower.com/theory-overview/ https://brilliantlightpower.com/theory-overview/

ThinkBeat 4y ago
> I think the measurements don't say anything about the size or how the electron is distributed in the probability distribution I fully admit i dont understand most of what I hear about particle physics anymore A lot seems non intuitive with the (dumb) model I have in my head. (That doesn't say much about tis accuracy) If you are to make such extremely detailed measurements of anything you need to be able to observe it over time? (Though how much time varies a lot) Presumably, a constantly moving electron whose location cannot established is a difficult thing measure?
- dave333 4y ago
  Well it depends how it is moving. Think of a spinning axle that is featureless - does it appear to move? How about a featureless disc bike wheel that is spinning? And the Mills model of the electron "orbitsphere" is a spherical fluid shell of charge that is spinning along all great circle routes. The charge distribution is not changing but the charge is spinning.

perardi 4y ago

Yeah, I am not used to seeing the term “cloud” for a single electron. Is that a common term in physics for a single electron? I am very much used to seeing that phrase as the probability space for electrons in orbitals in an atom. https://en.wikipedia.org/wiki/Atomic_orbital https://en.wikipedia.org/wiki/Atomic_orbital In this article I take it to mean “any point particle has a non-zero physical radius, but because quantum mechanics shows everything has a measure of uncertainty, the possibility of the charge within that non-zero space is an amorphous cloud”. But still a weird lexical overlap with the high school physics electron cloud meaning of things.

drdeca 4y ago
Consider the case where the atom in question is hydrogen, with just one electron orbiting it. I would still think the word "cloud" would be used?

LegitShady 4y ago

The electron has no known internal structure. As far as we know its a fundamental particle and isn't made up of other things, the way protons or neutrons are made up of quarks held together by gluons. An electron's location is subject to all sorts of rules. The Heisenberg uncertainty principle says that the more we know about a particles momentum (mass*velocity), the less we know about its position, and vice versa. This is not a matter of the observer effect (measurement upsetting one of these values), as some people state, but something fundamental due to the wavefunction nature of matter. The location of a subatomic particle is determined by its wavefunction (Squared) - where the wavefunction is big you have a high probability of finding a particle, and where it is small you have a small probability to find a particle. the wavefunction is a probability density function - the probability of finding a given particle at a given place in a given time. The next important idea is that subatomic particles can be considered both particles and waves, and thus have a wavelength. High momentum particles (high energy) have a short wavelength, low momentum (low energy) particles have long wavelengths. Waves are disturbances spread out in space, and we can identify the distance between two peaks (the wavelength), but then we wouldn't know anything about its position - it could be in lots of places. To localize a wave you add together lots of waves (into a localized wavepacket) until the resulting wave gives you areas where you are likely to find a particle where those added waves overlap in crests, and areas where you are unlikely to find the particle where those added waves overlap in troughs. This is a tradeoff, though - you are still subject to the heisenberg uncertainty principle so the more you know about the location, the less you know about the momentum. Thus the electrons, which move very quickly, and are interchangeable with one another being identical to each other, appear to exist as a cloud of probabilistic locations. They aren't themselves a cloud, rather their position is always uncertain until directly measured to a high degree of certainty. Now you may say "but we know electrons live in orbitals around atoms - how can we know that if we can't know their precise positions". This is because electrons obey the pauli exclusion principle, which states that two or more particles with half integer spin (fermions of which the electron is one, which have antisymmetric wave functions) cannot have the same set of four quantum numbers - n (the shell number or general region for value of energy of the electron), l (orbital angular momentum/the shape of the orbital), m sub l (the magnetic orientation of the orbital), and m sub s (quantum spin, which for fermions can be +/- 1/2). (the minus is what makes fermions antisymmetric) This principle is why electrons are more likely to be found in some places around an atom described as shells, and thus why electrons exist in discrete locations around an atom and why atoms and chemistry exist. The reason for the pauli exclusion principle is also wave related - I'll link a video below: https://www.youtube.com/watch?v=Zlp2GQ3OLeE https://www.youtube.com/watch?v=Zlp2GQ3OLeE This was a pretty surface level explanation - we didn't even get into the dirac equation (which is where the existence of antimatter was first derived) or spinor theory! but I think its good enough to have some understanding of why the fundamental wave nature of subatomic particles leads to uncertainty in their location, which means they appear to live in a cloud around atoms.

ineptech 4y ago

The old "is" strikes again. An electron is definitely not a cloud, nor a particle nor a wave, we don't know what the hell it is and stopped trying to describe it in those terms many years ago. Instead, we limit ourselves to trying to come up with models that accurately predict how they behave, and call the models useful when they predict the right answers to experiments. "All models are wrong but some are useful", as the saying goes. Like all subatomic particles, electrons don't seem to have a discrete location; when we try to measure their location, we get different results each time, as you said. However, these apparently-random results follow a predictable pattern, so we describe it using an equation predicting where it is most likely to be found (the Schrodinger wave equation). For electrons in some stable states, that area is roughly spherical, meaning that there is some point where it is most likely to be found, a fuzzy area near that point where it is fairly likely to be found, and a distance from that point past which it is very unlikely to be found. We can therefore model the electron as being a tiny discrete thing that whizzes around in a roughly spherical area, which is the "cloud" in this article. All that "can be modeled as" stuff is unwieldy, so people say the electron "is" a spherical cloud when they mean that modeling it as a spherical cloud is useful for understanding the matter at hand. What this article is describing is an attempt to measure whether that spherical region is perfectly spherical. If it weren't - meaning, if the electron was slightly more likely to be found on one side of the sphere than the other, then it would have an electrical dipole moment, which is what they were trying to find.

ineptech 4y ago
Fake edit: this is why it's helpful when discussing quantum mechanics to banish "is" from your vocabulary. For example, the debate over whether an electron "is" a particle or "is" a wave is much more tractable when you switch to debating whether it behaves like a particle or a wave in some situation. In college, I found this very similar to how it is useful when learning relativity to avoid the word "simultaneously".
- gitfan86 4y ago
  Yes, if you view Time, Space, Intelligence and Consciousness as emergent, things make a lot more sense. This upsets people because it implies that the most fundamental parts of their existence are not "real", but to your point it is very helpful to approach them as if they are not "real" regardless of what is actually fundamental to reality.

vihren 4y ago

You are not to blame for not understanding this, it's just that the analogy for the electric dipole moment coming from a non-spherical 'shape' of the electron is extremely bad. Moreover it's missing the most important reason why we search for EDMs, because the existence of one in an elementary particle would indicate the violation of the time-reversal symmetry (T), which assuming CPT conservation [1] leads to CP violation (Charge conjugation and parity symmetries). CP violation [2] is needed to explain the matter-antimatter asymmetry of the Universe. A more proper way, in my opinion, to reason about an electric dipole moment is to think in terms of Feynman diagrams. An EDM (or any dipole moment for that matter) is an interaction of the electron with an electromagnetic field, so interaction between an electron and a photon. The most simple such interaction you can imagine is an electron flying in, at one point it absorbs a photon and flies out - that would be the magnetic dipole moment. You can go more complex though - electron flying in, at one point it emits a photon, then the electron interacts with the EM field (absorbing a photon) and then it reabsorbs the photon it has emitted previously. (Note that these analogies are again not perfect as for elementary particles time and space are not the same as in the macro world). Now, it can get even more complicated: If you have an electron it's not really a 100% pure electron. There is always some chance that it transforms for a short time into a quark or neutrino or whatever you can imagine. When you analyze all such scenarios (electron going into something else, interacting with the EM field and then going back to an electron) some violate CP symmetry, and those contribute to the electric dipole moment. We use that name (dipole moment) as the final result is as if the electron was a ball with some separation between the negative and positive charges and placed into an electric field it experiences some torque. The analogy misses the most important part though, as if it was such a polarized 'ball' it would not violate CP symmetry. Within the Standard Model the only source of CP violating interactions come from the weak interaction (CKM matrix). These have a very small contribution as the weak interaction is, as the name suggests, very weak. That's why the Standard Model predicts very tiny electric dipole moments. When we are searching for EDMs we are in fact searching for such rare transformations through some new undiscovered particle that violate CP symmetry. If we detect some non-zero EDM that would mean that there is some interaction that is not included in the standard model that violates CP, not that the electron is not a round sphere or a sphere with a bump. [1] - https://en.wikipedia.org/wiki/CPT_symmetry https://en.wikipedia.org/wiki/CPT_symmetry [2] - https://en.wikipedia.org/wiki/CP_violation https://en.wikipedia.org/wiki/CP_violation