The classical or semi-classical (solar system-like) picture of the atom is outdated, but so is the quantum mechanical (cloud-like) picture to an extent in that both represent isolated subsystems...
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The classical or semi-classical (solar system-like) picture of the atom is outdated, but so is the quantum mechanical (cloud-like) picture to an extent in that both represent isolated subsystems of the fundamental particles that constitute the atom, namely, the electrons and the quarks that compose the nucleons.
Now that Quantum Mechanics (QM) has been somewhat superseded by Quantum Field Theory (QFT), Quantum Chemistry is understood to be the low-energy limit of the (relativistic) QFT of the electromagnetic force — Quantum Electrodynamics (QED) — where the very notion of an electron is completely different. That is, there are no lone electrons in classical, semi-classical or even quantum mechanical senses i.e. no individual electron particles or electron waves or even electron clouds.
Instead, QFT proposes a single electron field that permeates the entire universe, and it is the local excitations of this field that correspond to supposed electron entities in Quantum Chemistry.
So the electron clouds in the QM viewpoint can be reimagined as, say, events in an infinite electron ocean in the QFT viewpoint. This electron ocean is all around us and we are an inseparable part of it; the electrons in the atoms of our material bodies are short-lived crests that move along within this vast electron ocean.
And, much like the electron ocean, the same applies to other fundamental matter fermions (including the quark species that constitute the protons and neutrons of the atomic nucleus) as well as the fundamental force bosons that mediate interactions, the relevant one being the photon for the electromagnetism in Quantum Chemistry. So now there are multiple “overlapping” and “interweaving” oceans for the electron and (each of) the quarks as well as the photon; here, electromagnetic interactions holding an atom together resemble peaks of the electron and quark oceans perpetually firing ripples along the photon ocean to each other.
In comparison to the QM picture of the cloud-like atom, which is already complex to visualise with everyday language, graphics and thinking, there is a whole new challenge with the QFT picture of the multi-ocean happenings that create the “illusion” of an atom in some small region of space/time.
And all this without once mentioning Grand Unification (Strong, Weak and Electromagnetism), Higgs field (mass), gravity, String Theory,…
Carl Sagan, and I'm sure he'd love to hear this, was wrong when he said that. Atoms, according to quantum theory, are not mostly nothing. They're packed with stuf. This is one of those essays that...
"[M]ost of the mass of an atom is in its nucleus; the electrons are by comparison just clouds of moving fluff. Atoms are mainly empty space. Matter is composed chiefly of nothing."
Carl Sagan, and I'm sure he'd love to hear this, was wrong when he said that. Atoms, according to quantum theory, are not mostly nothing. They're packed with stuf.
...accepting the quantum predictions that nuclei and electrons fill space as continuous clouds has a daring conceptual price: it implies that these particles do not vibrate, spin or orbit. They inhabit a motionless microcosmos where time only occasionally plays a role.
This is one of those essays that just kinda casually upends almost everything I've ever been taught about atomic structure and is absolutely fascinating as a result.
I hope it becomes one of those things that expands the sum of human knowledge in cool and interesting ways that can act as a springboard for even greater discoveries and not one of those "neat...
I hope it becomes one of those things that expands the sum of human knowledge in cool and interesting ways that can act as a springboard for even greater discoveries and not one of those "neat ideas" that are quickly and easily disproven under any scrutiny.
Quantum theory is pretty solid science at this point, has significantly expanded human knowledge and been involved in a shedload of cool and interesting discoveries and technologies already! It is...
Quantum theory is pretty solid science at this point, has significantly expanded human knowledge and been involved in a shedload of cool and interesting discoveries and technologies already!
Broadly speaking: Solar panels, LEDs, basically all semiconductor tech, quantum computers, fluorescent light, lasers, MRIs, atomic clocks, ... Some of the more interesting but niche technologies...
Broadly speaking: Solar panels, LEDs, basically all semiconductor tech, quantum computers, fluorescent light, lasers, MRIs, atomic clocks, ...
Some of the more interesting but niche technologies are things like, optical tweezers, SQUIDs, scanning tunneling microscopes (with which, for example, you can move individual atoms around a surface to assemble structures), quantum microscopes...
Electron tunneling is predicted by quantum mechanics. And while not exploited by semiconductor design, it is a relevant factor because the transistors are getting so small that these quantum...
Electron tunneling is predicted by quantum mechanics. And while not exploited by semiconductor design, it is a relevant factor because the transistors are getting so small that these quantum effects need to be considered. So without quantum theory, maybe we have a lot of semiconductor people scratching their heads?
We probably wouldn't have transistors at all without quantum mechanics. Short version is that solid state semiconductors require understanding of surface states, which requires QM via the...
Short version is that solid state semiconductors require understanding of surface states, which requires QM via the Schrodinger Equation and Bloch's theorum. It's possible to accidentally make a transistor by brute-forcing your way through material choices and arrangements, but you can't explain them without QM.
That page links to this What is Quantum Mechanics Good For article, which goes over some of the stuff we wouldn't have without quantum theory. It's basically the entire modern world, largely because so much of that relies on computers and computers rely on transistors. Also lasers. Both are astonishingly important things.
For those who want a tldr, the author is saying the it should be represented as a very chaotic, alive, and incredibly thick cloud. Imagine a planet with constant storms like Venus.
For those who want a tldr, the author is saying the it should be represented as a very chaotic, alive, and incredibly thick cloud. Imagine a planet with constant storms like Venus.
The classical or semi-classical (solar system-like) picture of the atom is outdated, but so is the quantum mechanical (cloud-like) picture to an extent in that both represent isolated subsystems of the fundamental particles that constitute the atom, namely, the electrons and the quarks that compose the nucleons.
Now that Quantum Mechanics (QM) has been somewhat superseded by Quantum Field Theory (QFT), Quantum Chemistry is understood to be the low-energy limit of the (relativistic) QFT of the electromagnetic force — Quantum Electrodynamics (QED) — where the very notion of an electron is completely different. That is, there are no lone electrons in classical, semi-classical or even quantum mechanical senses i.e. no individual electron particles or electron waves or even electron clouds.
Instead, QFT proposes a single electron field that permeates the entire universe, and it is the local excitations of this field that correspond to supposed electron entities in Quantum Chemistry.
So the electron clouds in the QM viewpoint can be reimagined as, say, events in an infinite electron ocean in the QFT viewpoint. This electron ocean is all around us and we are an inseparable part of it; the electrons in the atoms of our material bodies are short-lived crests that move along within this vast electron ocean.
And, much like the electron ocean, the same applies to other fundamental matter fermions (including the quark species that constitute the protons and neutrons of the atomic nucleus) as well as the fundamental force bosons that mediate interactions, the relevant one being the photon for the electromagnetism in Quantum Chemistry. So now there are multiple “overlapping” and “interweaving” oceans for the electron and (each of) the quarks as well as the photon; here, electromagnetic interactions holding an atom together resemble peaks of the electron and quark oceans perpetually firing ripples along the photon ocean to each other.
In comparison to the QM picture of the cloud-like atom, which is already complex to visualise with everyday language, graphics and thinking, there is a whole new challenge with the QFT picture of the multi-ocean happenings that create the “illusion” of an atom in some small region of space/time.
And all this without once mentioning Grand Unification (Strong, Weak and Electromagnetism), Higgs field (mass), gravity, String Theory,…
Carl Sagan, and I'm sure he'd love to hear this, was wrong when he said that. Atoms, according to quantum theory, are not mostly nothing. They're packed with stuf.
This is one of those essays that just kinda casually upends almost everything I've ever been taught about atomic structure and is absolutely fascinating as a result.
I hope it becomes one of those things that expands the sum of human knowledge in cool and interesting ways that can act as a springboard for even greater discoveries and not one of those "neat ideas" that are quickly and easily disproven under any scrutiny.
Quantum theory is pretty solid science at this point, has significantly expanded human knowledge and been involved in a shedload of cool and interesting discoveries and technologies already!
It is also a very neat idea.
As someone with absolutely no knowledge in the field, what are some of the more interesting / useful techs so far that use quantum theory?
Broadly speaking: Solar panels, LEDs, basically all semiconductor tech, quantum computers, fluorescent light, lasers, MRIs, atomic clocks, ...
Some of the more interesting but niche technologies are things like, optical tweezers, SQUIDs, scanning tunneling microscopes (with which, for example, you can move individual atoms around a surface to assemble structures), quantum microscopes...
Electron tunneling is predicted by quantum mechanics. And while not exploited by semiconductor design, it is a relevant factor because the transistors are getting so small that these quantum effects need to be considered. So without quantum theory, maybe we have a lot of semiconductor people scratching their heads?
We probably wouldn't have transistors at all without quantum mechanics.
Short version is that solid state semiconductors require understanding of surface states, which requires QM via the Schrodinger Equation and Bloch's theorum. It's possible to accidentally make a transistor by brute-forcing your way through material choices and arrangements, but you can't explain them without QM.
That page links to this What is Quantum Mechanics Good For article, which goes over some of the stuff we wouldn't have without quantum theory. It's basically the entire modern world, largely because so much of that relies on computers and computers rely on transistors. Also lasers. Both are astonishingly important things.
I read the whole article. That scientist is a great communicator!
TIL!
For those who want a tldr, the author is saying the it should be represented as a very chaotic, alive, and incredibly thick cloud. Imagine a planet with constant storms like Venus.