6 ms·

Wait... wasn't it already understood that relativity influences electron orbits of heavy elements? I clearly remember being taught some of this in physics, in t

Wait... wasn't it already understood that relativity influences electron orbits of heavy elements? I clearly remember being taught some of this in physics, in the mid-noughties. For instance, we know that gold gets its color from relativistic effects. https://physics.aps.org/articles/v10/s3 https://physics.aps.org/articles/v10/s3

wasabi991011 2mo ago
The article seems to be more specific, about relativistic effects in triple bonds
Diogenesian 2mo ago
Seems to be the first time this was confirmed via direct experimental observation of the orbitals: “This idea that relativity is important in heavy elements has been around since the 1970s,” said Lai-Sheng Wang, a professor of chemistry at Brown and the study’s corresponding author. “But we show direct spectroscopic evidence that what we learned in high school about chemical bonding isn’t true in heavy elements."
- fsloth 2mo ago
  I came to the comments exactly for this ("wait I thought we 'knew' this already"). I'm so happy we have HN with likeminded people and no noise.
ThrowawayTestr 2mo ago
There's even a Wikipedia page for it https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry
762236 2mo ago
Gold electrons at inner orbits travel at a large fraction of the speed of light, which is why gold isn't a silver color. That is really neat.
- brabel 2mo ago
  I don’t understand how something that has no clearly defined position like an electron can have a well defined speed. I thought I had understood that at that level, particles are more like clouds, or vibrations in the quantum field, and they had no well defined position until you tried to measure it, causing its cloud to collapse to a smaller region. But if non observed electrons can have a speed that defines the color of a material, that whole understanding seems to be wrong! Where is the error? Are all atoms on a piece of gold being “observed” in the quantum sense?? Even if we just capture the spectrum? Or it’s something else??
  - Sharlin 2mo ago
    The uncertainty principle says that the less well-defined the position, the more well-defined the velocity, and vice versa.
  - gus_massa 2mo ago
    You are mostly correct. The idea is that it has not a clearly definite position, but it has a distribution of probability to find it that looks like a "cloud" https://en.wikipedia.org/wiki/Atomic_orbital https://en.wikipedia.org/wiki/Atomic_orbital In a more abstract sense, has not a clearly definite speed, but it has a distribution of probability to find it in a speed graphic. The distribution of position and speed are defined by an equation and you must add a relativistic correction to the classic version. For lighter atoms you can just ignore the correction. For heavy atom (like Bismuth in this case) the correction is important. Informally, the correction is important only when the "average" speed is fast enough to be somewhat close to the speed of light, like 50%c. The correction changes the energy of the expected distribution of position and speed, and the energy. When an electron jumps from an orbital to another orbital, the difference of energies is related to the color. > Are all atoms on a piece of gold being “observed” in the quantum sense?? [Ignoring that "observer" is a very misleading word and causes a lot of confusion, but it's the standard one and we are stick with it...] The observation is only of the energy level of the orbital electron. We know the energy, but we don't know the position or the speed. When you observe some quantum object you don't get magically all the properties, only one of them, in this case the energy. In other experiments you can get only the position, in others only the speed. [And there are a lot of weird cases and technical details.]
ferfumarma 2mo ago
Yes: the article says "since the 70s"
deadbabe 2mo ago
I don’t get it, someone explain? Doesn’t everything get color from relativistic effects?
- deleted 2mo ago
  [deleted]
- wbl 2mo ago
  Most colors in synthetic pigments are from conjugated double bonds that don't need relativistic effects to explain: no heavy atoms here!
colechristensen 2mo ago
The Dirac equation which is the equation for describing the wavelike behavior of electrons. It predicted the existence of antimatter and particle spin. You start with the Schrödinger equation, add relativity to get the Klein-Gordon equation which is a mess because it's second order in time involving negative probabilities, if you in ways "take the square root" of it you get the Dirac equation. Relativity has been part of the understanding of electrons since 1928. https://en.wikipedia.org/wiki/Dirac_equation https://en.wikipedia.org/wiki/Dirac_equation
- colechristensen 2mo ago
  To add to this, this "square root" operation done to derive the Dirac equation is where spinors i.e. electron spin i.e. the Pauli exclusion principle i.e. the reason atoms exist at all comes from. Likewise antimatter. The "second order in time" of the Klein-Gordon equation comes from adding relativity and the "fix" reducing that to first order time is the source of antimatter and spin. So yes very much so relativistic effects are a foundational part of QM.
- alok-g 2mo ago
  Thanks for the insights. I am interested in learning all this stuff. Am currently going through just Schrodinger's Equation. Do you have book recommendation(s) that include insights everywhere just like what you shared? Thanks.
  - colechristensen 2mo ago
    These are books to train physicists, accessable-ish to a math heavy engineering undergraduate degree holder. The insights above are my own and extractable from this material but not necessarily stated out loud (unless I'm unconsciously plagiarizing which is entirely possible) * David Griffiths - Introduction to Elementary Particles * Chris Quigg - Gauge Theories of the Strong, Weak, and Electromagnetic Interactions And the wonderful Richard Behiel's videos on YouTube https://www.youtube.com/watch?v=8Iu74b5iCuQ https://www.youtube.com/watch?v=8Iu74b5iCuQ
    - 2mo ago
kergonath 2mo ago
In general, yes. Spin-orbit coupling and relativistic effects in heavier elements is not new. A rather... significant elements where this was studied was uranium (and plutonium, of course). Even napkin maths show that for heavy elements, some of the electrons have relativistic velocities. This discovery is about a (seemingly, I haven't been keeping up too much) new case of one specific bond in one specific ion. Do not read the university's breathless press release, go straight to the article. The third sentence of the editor's summary is "It’s long been clear that this model starts to fray when the atoms get heavy enough for relativity to come into play".
alkyon 2mo ago
Yes, I was taught that relativity is a significant part of quantum chemistry equations in gold atoms 25 years ago. The idea is quite old and the title is misleading.
turtlesdown11 2mo ago
subheader explains the article in case you were wondering > Researchers have shown the first direct experimental evidence that the textbook triple bond structure breaks down in heavy elements, where relativity makes the rules.

wasabi991011 2mo ago

The article seems to be more specific, about relativistic effects in triple bonds

Diogenesian 2mo ago

Seems to be the first time this was confirmed via direct experimental observation of the orbitals: “This idea that relativity is important in heavy elements has been around since the 1970s,” said Lai-Sheng Wang, a professor of chemistry at Brown and the study’s corresponding author. “But we show direct spectroscopic evidence that what we learned in high school about chemical bonding isn’t true in heavy elements."

fsloth 2mo ago
I came to the comments exactly for this ("wait I thought we 'knew' this already"). I'm so happy we have HN with likeminded people and no noise.

ThrowawayTestr 2mo ago

There's even a Wikipedia page for it https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry

762236 2mo ago

Gold electrons at inner orbits travel at a large fraction of the speed of light, which is why gold isn't a silver color. That is really neat.

brabel 2mo ago
I don’t understand how something that has no clearly defined position like an electron can have a well defined speed. I thought I had understood that at that level, particles are more like clouds, or vibrations in the quantum field, and they had no well defined position until you tried to measure it, causing its cloud to collapse to a smaller region. But if non observed electrons can have a speed that defines the color of a material, that whole understanding seems to be wrong! Where is the error? Are all atoms on a piece of gold being “observed” in the quantum sense?? Even if we just capture the spectrum? Or it’s something else??
- Sharlin 2mo ago
  The uncertainty principle says that the less well-defined the position, the more well-defined the velocity, and vice versa.
- gus_massa 2mo ago
  You are mostly correct. The idea is that it has not a clearly definite position, but it has a distribution of probability to find it that looks like a "cloud" https://en.wikipedia.org/wiki/Atomic_orbital https://en.wikipedia.org/wiki/Atomic_orbital In a more abstract sense, has not a clearly definite speed, but it has a distribution of probability to find it in a speed graphic. The distribution of position and speed are defined by an equation and you must add a relativistic correction to the classic version. For lighter atoms you can just ignore the correction. For heavy atom (like Bismuth in this case) the correction is important. Informally, the correction is important only when the "average" speed is fast enough to be somewhat close to the speed of light, like 50%c. The correction changes the energy of the expected distribution of position and speed, and the energy. When an electron jumps from an orbital to another orbital, the difference of energies is related to the color. > Are all atoms on a piece of gold being “observed” in the quantum sense?? [Ignoring that "observer" is a very misleading word and causes a lot of confusion, but it's the standard one and we are stick with it...] The observation is only of the energy level of the orbital electron. We know the energy, but we don't know the position or the speed. When you observe some quantum object you don't get magically all the properties, only one of them, in this case the energy. In other experiments you can get only the position, in others only the speed. [And there are a lot of weird cases and technical details.]

ferfumarma 2mo ago

Yes: the article says "since the 70s"

deadbabe 2mo ago

I don’t get it, someone explain? Doesn’t everything get color from relativistic effects?

deleted 2mo ago
[deleted]
wbl 2mo ago
Most colors in synthetic pigments are from conjugated double bonds that don't need relativistic effects to explain: no heavy atoms here!

colechristensen 2mo ago

The Dirac equation which is the equation for describing the wavelike behavior of electrons. It predicted the existence of antimatter and particle spin. You start with the Schrödinger equation, add relativity to get the Klein-Gordon equation which is a mess because it's second order in time involving negative probabilities, if you in ways "take the square root" of it you get the Dirac equation. Relativity has been part of the understanding of electrons since 1928. https://en.wikipedia.org/wiki/Dirac_equation https://en.wikipedia.org/wiki/Dirac_equation

colechristensen 2mo ago
To add to this, this "square root" operation done to derive the Dirac equation is where spinors i.e. electron spin i.e. the Pauli exclusion principle i.e. the reason atoms exist at all comes from. Likewise antimatter. The "second order in time" of the Klein-Gordon equation comes from adding relativity and the "fix" reducing that to first order time is the source of antimatter and spin. So yes very much so relativistic effects are a foundational part of QM.
alok-g 2mo ago
Thanks for the insights. I am interested in learning all this stuff. Am currently going through just Schrodinger's Equation. Do you have book recommendation(s) that include insights everywhere just like what you shared? Thanks.
- colechristensen 2mo ago
  These are books to train physicists, accessable-ish to a math heavy engineering undergraduate degree holder. The insights above are my own and extractable from this material but not necessarily stated out loud (unless I'm unconsciously plagiarizing which is entirely possible) * David Griffiths - Introduction to Elementary Particles * Chris Quigg - Gauge Theories of the Strong, Weak, and Electromagnetic Interactions And the wonderful Richard Behiel's videos on YouTube https://www.youtube.com/watch?v=8Iu74b5iCuQ https://www.youtube.com/watch?v=8Iu74b5iCuQ
  - 2mo ago

kergonath 2mo ago

In general, yes. Spin-orbit coupling and relativistic effects in heavier elements is not new. A rather... significant elements where this was studied was uranium (and plutonium, of course). Even napkin maths show that for heavy elements, some of the electrons have relativistic velocities. This discovery is about a (seemingly, I haven't been keeping up too much) new case of one specific bond in one specific ion. Do not read the university's breathless press release, go straight to the article. The third sentence of the editor's summary is "It’s long been clear that this model starts to fray when the atoms get heavy enough for relativity to come into play".

alkyon 2mo ago

Yes, I was taught that relativity is a significant part of quantum chemistry equations in gold atoms 25 years ago. The idea is quite old and the title is misleading.

turtlesdown11 2mo ago

subheader explains the article in case you were wondering > Researchers have shown the first direct experimental evidence that the textbook triple bond structure breaks down in heavy elements, where relativity makes the rules.