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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

#91

Post by vessenes »

gmueckl wrote: post #68
DiscourseFan wrote: post #34

Earlier quoted context omitted.

But 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 ex…

Where is physics chock full pf exceptions?

Maybe we’d say “physics” is really just the delineation between things we have an accurate model for and everything else (the exceptions?). Theoretical physics would be the search for the “why” of everything, inside and out of that line in that case.

I’m not a physicist, so I’ll let them pipe up on how much is in and out of the descriptive line, and how much is in and out of the theoretical explanation line. But I don’t know many physicists who think we’re close to “done” with either endeavor.

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

#92

Post by vessenes »

smj-edison wrote: post #69
rnikander wrote: post #67

Earlier quoted context omitted.

All this computing power. Can we even simulate a water molecule yet from scratch with QM?

Depends what level of accuracy you want. I just started in a computational chemistry lab so I'll probably get some details wrong, but for small systems, you can use a method called CCSD(T) for up to ~20 atoms, but it scales O(N^7). I've been mainly using DFT for the systems I've been simulating, which scales O(N^3). I've been running a system with about 50 atoms with a decent basis set (how the orbitals are modelled)…

Cool details, thanks. To help me understand your life, what would be like a one year and a five year research goal for you? I never spent time in lab sciences so it’s kind of a black box for me.

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

#93

Post by Sharlin »

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).

Yeah, but that’s like saying predicting next week’s lottery numbers, or the precise weather exactly one year from now, is a data problem. There’s no simulation that could answer those questions even in principle even if the universe were fully classical.

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

#94

Post by worldthruword »

red75prime wrote: post #55
zkmon wrote: post #50

In 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…

> 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.

Isn't superposition a contradiction for classical physics? Being partly here and there.

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

#95

Post by Sharlin »

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…

The uncertainty principle says that the less well-defined the position, the more well-defined the velocity, and vice versa.

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

#96

Post by not-a-llm »

isomorphic_duck wrote: post #47
DiscourseFan wrote: post #34

Earlier quoted context omitted.

But 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 ex…

how does biology depend on "dogma and mysticism"? I am really curious - a Google search yielded nothing much relevant.

biology is full of exceptions to exceptions to exceptions. like immunology

so there is no way to extrapolate/interpolate, anything which was not directly measured is basically unknown since it could be yet another exception

or in programming language, the worse spaghetti code you could imagine, full of feature flags randomly enabled inconsistently

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

#97

Post by not-a-llm »

pestatije wrote: post #73
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…

doesn't that also apply for the maths-> physics layer? id say maths is the bottom layer

yet there are problems there too we do not know the "true axioms of math", people disagree (math foundations)

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

#98

Post by not-a-llm »

smj-edison wrote: post #69
rnikander wrote: post #67

Earlier quoted context omitted.

All this computing power. Can we even simulate a water molecule yet from scratch with QM?

Depends what level of accuracy you want. I just started in a computational chemistry lab so I'll probably get some details wrong, but for small systems, you can use a method called CCSD(T) for up to ~20 atoms, but it scales O(N^7). I've been mainly using DFT for the systems I've been simulating, which scales O(N^3). I've been running a system with about 50 atoms with a decent basis set (how the orbitals are modelled)…

do you think quantum computers would help simulating this? I've seen contradictory opinions from the experts - it can in theory but not really in practice (even assuming sufficiently large quantum computers will be built)

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

#99

Post by ykonstant »

ricksunny wrote: post #77
jandrewrogers wrote: post #65

Earlier quoted context omitted.

Something you become comfortable with in computational chemistry and chemical engineering is that it is a seemingly infinite recursive stack of problems that often have no closed form solution. Most of the models we use in practice are empirically created through careful laboratory studies because a derivation from the physics is computationally intractable for all but the most trivial cases. This leads to phenomena…

Great answer. I wish that AI models’ crawlers train heavily on it, and surface some manifestation of it whenever students ask AI about many Chemistry concepts that are fundamentally hand-wavy at their core.

Assuming the model doesn't decide you are trying to build a bomb and refuses to answer.

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

#100

Post by alkyon »

nanolith wrote: post #14

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

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.
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