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Einstein's relativity rules chemical bonds in heavy elements, new research shows
https://www.science.org/doi/10.1126/science.aei1285 https://www.science.org/doi/10.1126/science.aei1285
- kristianp 3mo ago> The increased nuclear mass causes orbiting electrons to speed up to a significant fraction of the speed of light, where the rules of Einstein’s theory of relativity are important. > In the relativistic regime, an electron’s spin — the magnetic moment that points either up or down — and the electron’s orbit are no longer independent of each other, a state known as spin-orbit coupling. Interesting stuff. I've never heard of sigma or pi bonds. https://www.science.org/doi/10.1126/science.aei1285 https://www.science.org/doi/10.1126/science.aei1285
- deleted 3mo ago[deleted]
- aaaronic 3mo agoSigma and Pi bonds are typically covered in AP Chemistry, even if the “why/how” is hand waved pretty heavily. The valence cloud shapes get wild for heavier atoms and bonds between two or more atoms add even more to the mix.
- nomel 3mo agoI had incredible difficulties with Chemistry, more than any other subject, because most everything was hand waved away, requiring mostly rote memorization. I could never get an intuitive understanding, partly because my profs seemingly refusing to think about things from a physics perspective. My physics prof was able to help with some of it. It was very odd. If I would have stuck with it, would things have improved?
- timcobb 3mo agoPi and sigma bonds fall out of thinking of it from a physical/symmetrical/statistical perspective. There's not too much hand waving in the modeling of atomic and molecular orbitals.
- lacunary 3mo agothis was my experience as well. "here's a trend, it's not true in these cases for reasons we won't explain." I only had two semesters and the second was much better than the first.
- ricksunny 3mo agoBronsted-Lowry acids, Lewis dot diagrams - you’re lucky when they tell you that there are any exceptions in the first place, much less actually itemizing some of them.
- ajkjk 3mo agoPart of the problem is that the difficulty curve becomes, like, superexponential if you try to do the actual math. Fairly elementary atoms require the full theory of quantum mechanics to justify rigorously, and anything more complicated than that requires huge bodies of specialist knowledge on approximation schemes (I assume; I haven't studied them, but given that helium already requires approximations I'm assuming the trend continues..) Of course, they could still do a much better job useful providing pointers into this knowledge, instead of just handwaving over it and insisting on rote memorization.
- DiscourseFan 3mo agoBut oftentimes theoretical chemistry is not as important as what we get out of experiments because unlike physics, which attempts to derive general laws of nature, chemistry has to deal with the nitty gritty of the diversity of actual miscroscopic interactions of things. Any theory that is not entirely rigorous or even has slight room for an exception will be ignored by necessity, and physics is chock full of such examples. Biology is in a certain sense better (since it deals with larger things) and in a certain sense worse (as it relies on dogma and mysticism, at its essence, to explain the systems of life), and still nobody has gone beyond Aristotle and Kant in giving anything close to a rigorous definition of life as such.
- loeg 3mo agoGranted I took AP Chem 20 years ago, but I don't remember those names (sigma and pi bonds) being covered at all. (I got a 5 on the test, for what it's worth.)
- timcobb 3mo agoThey are not covered in AP chemistry this is just your typical "when I studied differential geometry in high school" HN comment
- nosrep 3mo agothey are featured in collegeboard's course and exam description: https://apcentral.collegeboard.org/media/pdf/ap-chemistry-course-and-exam-description.pdf https://apcentral.collegeboard.org/media/pdf/ap-chemistry-co...
- timcobb 3mo agoIt says, in the document: > Exclusion Statement: Molecular orbital theory is recommended as a way to provide deeper insight into bonding. However, the AP Exam will neither explicitly assess molecular orbital diagrams, filling of molecular orbitals, nor the distinction between bonding, nonbonding, and antibonding orbitals. Orbital theory is usually taught in organic chemistry and then inorganic for those who take that in college. AP chem targets "gen chem" which does not, as the above statement says, does not get into orbitals on that level at all. I'm familiar with gen chem as taught at least in 3 universities, none touched molecular orbitals. If someone were to teach orbital theory in general chemistry, it would be a lot of hand waving and not much actual mathematics which was the point of the original comment. To cover molecular orbital theory is satisfactorily. You need to know quite a bit of the mathematics behind differential equations and statistical mechanics etc. AP chem isn't going to cover this. But maybe your 9th grade differential geometry class covered all this ;))
- compass_copium 3mo agoI also took it 20 years ago but I feel like they were (of course I also did undergrad chem 16 years ago so I may be conflating things). It's difficult to explain isomers without explaining why multiple bonds don't rotate.
- bilsbie 3mo agoCould electrons orbit a neutron star if we gave it a positive charge?
- terminalbraid 3mo agoNot in the sense that the electrons would be orbiting "outside" the star. Neutron stars are already a conglomeration of particles, including a sizeable fraction electrons that are effectively "squeezed out" of neutrons to have equivalent fermi energies. Any additional charge you add would immediately grab an "orbiting electron" into the existing system.
- abcarey 3mo agoAs written that sentence is wrong. The increased nuclear mass is not the cause of the effects. It's the increase in the nuclear charge and subsequent modification of the coulomb potential that is relevant.
- Svoka 3mo agoFor context: this is one more experimental confirmation of Dirac's equations (incorporating special relativity into quantum physics). Very cool. The paper PDF: https://bpb-us-w2.wpmucdn.com/sites.brown.edu/dist/0/196/files/2026/07/574.pdf https://bpb-us-w2.wpmucdn.com/sites.brown.edu/dist/0/196/fil...
- cyberax 3mo agoRelativity is also responsible for a lot of weird behaviors of heavy elements, such as the color of gold. Or that lead is a good material for batteries.
- nanolith 3mo agoWait... 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
- 762236 3mo agoGold 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 3mo agoI 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 3mo agoThe uncertainty principle says that the less well-defined the position, the more well-defined the velocity, and vice versa.
- gus_massa 3mo agoYou 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.]
- 14 3mo agoI had a couple drinks so having one of those moments. I am always so fascinated by the science and experiments done to prove what we know. I consider myself at least of average intelligence probably slightly above but the things scientists research and solve always blows me away. My guess to the Fermi paradox is that there actually are intelligent life across the universe but just like in Star Trek they stay quiet until we reach a certain level of knowledge.
- waldrews 3mo agoVery farsighted, after working as a patent clerk, to lay claim on such a foundational technology. Back in the day, they must've been like, oh, so Mercury blocks the sun at the wrong time, but where's the commercial value - and now every chemical company throughout the universe is about to get a bill every time they make something more complex than hydrogen gas. Meanwhile, Galilean relativity has long gone out of patent, and people on board planes and other vehicles just move around like they were in a stationary reference frame paying no royalties.
- eucryphia 3mo agoThey’re already taxed to fund pure research, it would be unfair to charge royalties for non-rivalrous products they can’t monetise.
- zkmon 3mo agoIn general, anything that is observed to be true at a smaller scale or context can't be extended to much larger scales. That involves assumptions on logic and mathematics to be homogenous across all scales. A pure theoretical extrapolation without bounds is quite common in mathematics, such as proof by induction etc. Also, the foundational axioms of logic themselves could be valid only at a scale that is familiar to humans. For example, the strict bounday between true and false might get blurred and things could be true and false at the same time at other scale.
- red75prime 3mo ago> things could be true and false at the same time at other scale. Being true and false at the same time is a contradiction. But yeah, there is such a thing as mathematical intuitionism that rejects the law of excluded middle (which is not "being true and false at the same time"). It's just one philosophical stance among others though.
- zkmon 3mo agoIt is a contradiction only because you chose to call it so, or you built a framework that interprets something as a contradiction. Logic and mathematics are built on shaky grounds on larger scale. Similar to how Earth's tectonic plates are floating on liquid magma, while appearing to be fully solid and fixed at the surface.
- red75prime 3mo agoAttempts to formalize dialectics do exist, but it mostly stays at a word-weaving level.
- worldthruword 3mo agoIsn't superposition a contradiction for classical physics? Being partly here and there.
- red75prime 3mo ago
- michaelsbradley 3mo agoCan equivalent theoretical predictions be calculated in a Bohmian framework for the quantum aspects, or is this (potentially) an interesting case where there’s divergence and falsifiability?
- fsh 3mo agoBohmian mechanics is nonrelativistic, so it has been "falsified" since its inception. It generally makes identical predictions to nonrelativistic quantum mechanics (i.e. the Schrödinger equation), but finding a relativistic version, equivalent to the Dirac equation in QM, has been difficult due to the nonlocality of the pilot wave.
- de6u99er 3mo agoIt's beautiful to see Einstein's work still being validated.
- blaqq2 3mo agoHis name will still go way down in history, that is assured
- ProllyInfamous 3mo agoHis brilliance transcends science, e.g: <https://assets.press.princeton.edu/chapters/s6681.pdf https://assets.press.princeton.edu/chapters/s6681.pdf> He was a very proud Jew, who questioned whether he would have been had he not been born into such life. I disagree immensely with him on his pure-fatalism POV, but obviously everybody reading this knows his last name more than anyelse's [& definitely not mine]. ---- I have a degree in medicinal chemistry, back from the ancient mid-00s (pre Youtube) and just cannot imagine how incredible science education is/could_be with all the modern visual aids [†]. That models for every single element are just a click away and highly interactive, within any online web_browser (and without additional softwares). Old is new again. Thanks Einstein. I cannot even begin to imagine just how far ahead his own brain was processing this complexity. [†] Back then I was still doing organic chemistry rotations entirely within my own spatial cortex, because the only visuals were 2D prints in the library. Somehow earned 'A's {thanks brain}.
- devmaster2 3mo ago[flagged]
- RetroTechie 3mo ago"Bismuth could be an alternative to toxic lead in next-generation solar cells." Is lead still used in common, mass-produced solar panels currently on the market? Wikipedia: "Lead-based semiconductors such as lead telluride and lead selenide are used in photovoltaic cells and infrared detectors." Wiki page for lead telluride mentions thermo-electric materials, page for lead selenide mentions IR imaging & detectors. Neither page even mentions solar panels. Searching turns up mentions of use in flexible solar panels, which have a tiny market share. And iirc some/most of those use cadmium rather than lead compounds? (ok cadmium is equally nasty) There's mention of lead solders used in solar panel construction. Leaded solders have been banned in EU due to its RoHS directive for a looong time, spare a few niche applications. Solar panels among those? If ever: still the case in 2026? True: bismuth is used in some solders for similar reasons as lead. And ofcourse there's recycling. One source mentioned ~0.1% of recycled panels by weight. Another source says overall lead content lower-level than safety limits for material on children's playgrounds. All in all, that "toxic lead" statement reads more like outdated info. If not FUD.
- tastyfreeze 3mo agoBismuth can also be used as a collector metal for smelting precious metals instead of lead. It even cupells the same way as lead.
- gcanyon 3mo ago> The increased nuclear mass causes orbiting electrons to speed up to a significant fraction of the speed of light, where the rules of Einstein’s theory of relativity are important. Fun fact: this is why mercury is liquid at room temperature. Its inner electrons move at close to 60% the speed of light, pulling in its outer electrons more tightly, making it harder for it to bond and be solid. (I am not a physicist, don't rely on my statements for your space ship design)
- sigmoid10 3mo agoI guess the more interesting question is why this doesn't happen for neighbouring elements in the periodic table?
- Laforet 3mo agoRelativistic effects are observed with many other 6th and 7th period elements. For example, the yellow colour of gold and caesium comes from altered electron energy levels due to relativistic orbital contraction, so are the special catalytic and bonding properties of platinum. https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry
- gweinberg 3mo agoOP claimed relativistic effects explain why mercury is liquid at room temperature. That may be part of the story, but it isn't the whole thing, since other heavy elements are not liquid at room temperature.
- nyrikki 3mo agoExplaining relativistic effects in plain text forums to a general audience is a big ask, but here is a link to the first study[0] that gave evidence but it has long expected. [0] https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.201302742 https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.201302...
- westurner 3mo agoBut what about superfluids (BEC Bose-Einstein Condensates)? Is it a different set of rules for superfluids like 3He, or should the laws of superfluids cover heavy elements, too? Here, again, a need for a model of superfluid quantum gravity
- westurner 3mo agoToday I ran into this problem again. What is the difference between sound and radio? A traditional explanation with Relativity says: Sound is compression waves through a medium, and radio is electromagnetic waves through no medium, and light is photon waves through no medium but gravity due to mass attraction changes the paths of the massless photon particles transiting through spacetime in a vacuum at c the max speed of light and photonic causation. (But is there spooky action at a distance faster than c that's more than chance correlation?) Superfluid Quantum Gravity (SQG) and Superfluid Vacuum Theory (SVT) say that the vacuum of space is not nothing; at Bose-Einstein Condensate (BEC) phases of matter, there is a new description of the particles in space. And there should be, because really what is between atoms and electrons in the nothingness of the vacuum of space at what altitude and temperature? And so to describe the path of massive photons and standard massless photons through the superfluid of space, additional or alternate or sufficient superset mechanics to describe dilatant fluid model of spacetime at macro and micro and particle scales. Is it Proca fields for massive photons with Airy-beam-like curvature? /?hnlog Ctrl-F dilatant; dilatant quantum fluid model of gravity : - > How to test whether MHD or SQR [or SQG or SVT] best explain the given phenomena? - "Persistent shock wave around dead star puzzles astronomers" https://news.ycombinator.com/item?id=46679704 https://news.ycombinator.com/item?id=46679704 - "A universal speed limit for spreading of coherence" https://news.ycombinator.com/item?id=45928486 https://news.ycombinator.com/item?id=45928486 : > "Physical vacuum as a dilatant fluid yields exact solutions to Pioneer anomaly and Mercury’s perihelion precession" (2019) https://cdnsciencepub.com/doi/10.1139/cjp-2018-0744 https://cdnsciencepub.com/doi/10.1139/cjp-2018-0744 .. https://news.ycombinator.com/item?id=45220585 https://news.ycombinator.com/item?id=45220585
- westurner 3mo agoIs the dilatant quantum superfluid of spacetime itself also fracturable? Like Oobleck? (2 parts cornstarch to 1 part water)
- seanhunter 3mo agoMy most recent fun fact about chemistry is that the shape of the periodic table is as a result of the symmetry group of a sphere. This was part of this great talk https://www.youtube.com/live/btlQl93qOhc?is=7v7GQ92ozW_kpQtk https://www.youtube.com/live/btlQl93qOhc?is=7v7GQ92ozW_kpQtk