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Einstein's relativity rules chemical bonds in heavy elements, new research shows

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Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#121

Post by RetroTechie »

"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All in all, that "toxic lead" statement reads more like outdated info.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.

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#122

Post by terminalbraid »

bilsbie wrote: post #114
kristianp wrote: post #2

> 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 h…

Could electrons orbit a neutron star if we gave it a positive charge?

Not 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.

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#123

Post by gcanyon »

> 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)

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#124

Post by sigmoid10 »

gcanyon wrote: post #123

> 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, do…

I guess the more interesting question is why this doesn't happen for neighbouring elements in the periodic table?

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#125

Post by abecedarius »

brabel wrote: post #85
762236 wrote: post #20

Earlier quoted context omitted.

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.

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 col…

"High speed" here can be taken in terms like this: the phase of the wave function changes rapidly with position and time. (Changing with position -> a superposition that's heavy on short wavelengths, high momentum; with time -> high frequency, high energy.)

Re "observed all the time": when gold interacts with light, the light's normally of a strength that's a small perturbation on the fields internal to the atom, which is basically why you can treat the atom/light-field system as two weakly coupled quantum systems. It's an "observation" when the light leaves a classical trace such as a current in a CCD.

(I don't expect this to leave you unmystified about QM, but hopefully a bit clearer about it.)

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#126

Post by exe34 »

pestatije wrote: post #89
exe34 wrote: post #75

Earlier quoted context omitted.

Maths lacks the physical grounding, so in that sense, it's less "real", and more "made up", even though of course it's so pure.

its the same... physics hand-waves the 'why' all the same as chemistry or biology...the gap might be wider but its the same

Physics has a long history of throwing out laws with exceptions in favour of laws that cover larger and larger numbers of observations.

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#127

Post by westurner »

But 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

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#128

Post by RetroTechie »

chanakya wrote: post #49
ajkjk wrote: post #10

Earlier quoted context omitted.

Part 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 t…

As you move up levels starting from physics (eg. physics-> chemistry-> biochemistry-> biology), each layer has several "laws" which are generally pretty established, but a causal connection between the layers is hard to provide satisfactorily. And that is how I think it'll always be, else we'll be expecting to explain Shakespeare's plays using physics. Also, this is where Rutherford's "all science is either physics o…

Fundamental physics is also empirical. It's that as you move up to more 'fuzzy' sciences, the 'laws' become less strict, less formal defined, and (most importantly) less reliable.

Edit: and less universal. Physics underlies biology, chemistry, nuclear tech & more. Biology (so far) only applies to carbon-based life as we know it on Earth.

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#129

Post by moring »

ohhnoodont wrote: post #84
chanakya wrote: post #49

Earlier quoted context omitted.

As you move up levels starting from physics (eg. physics-> chemistry-> biochemistry-> biology), each layer has several "laws" which are generally pretty established, but a causal connection between the layers is hard to provide satisfactorily. And that is how I think it'll always be, else we'll be expecting to explain Shakespeare's plays using physics. Also, this is where Rutherford's "all science is either physics o…

> else we'll be expecting to explain Shakespeare's plays using physics. This is just a data problem though. From the perspective of a deterministic universe, creative works theoretically can be explained as a physics outcome (ignoring the impact of potential quantum randomness).

> From the perspective of a deterministic universe, creative works theoretically can be explained as a physics outcome

In other words, physics can explain Shakespeare's plays when you hand-wave away the biggest reason it cannot.

> theoretically

... meaning not in reality, but in an abstraction of reality that conveniently leaves out the hard part.

> This is just a data problem though.

The word "just" makes it sound like that data problem is a minor inconvenience, and not a fundamental obstacle.

Becoming a billionaire is simple, after all it's just a money problem.

I mean, you're right in that (leaving out quantum randomness), you could predict macroscopic outcomes based on a physics simulation that includes all elementary particles explicitly, if you assume that such a simulation can be scaled from <10 particles to macroscopic numbers. But there is no evidence that this assumption is true, so it remains an interesting thought experiment that gets confused with reality because people like to slap the "in theory" label on it.

Re: Einstein's relativity rules chemical bonds in heavy elements, new research shows

#130

Post by moring »

terminalbraid wrote: post #115
OgsyedIE wrote: post #87

Earlier quoted context omitted.

To complete accuracy, we cannot yet manage one proton.

That's a fundamentally different problem and a terribly unfair comparison.

Am I right with my assumption that by "fundamentally different problem", you mean we lack a good simulation model, but that the number of degrees of freedom would actually be manageable?
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