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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

#111

Post by nickcw »

nomel wrote: post #7
aaaronic wrote: post #5

Earlier quoted context omitted.

Sigma 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.

I 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?

One of the disappointing realisations I got from my physics degree was that as you move into the real world with non-spherical cows you can no longer solve any of the equations.

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

#112

Post by gus_massa »

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…

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

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.]

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

#113

Post by WillAdams »

nomel wrote: post #7
aaaronic wrote: post #5

Earlier quoted context omitted.

Sigma 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.

I 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?

The wild thing is that the understanding of electron arrangement made a _huge_ difference in chemistry texts where overnight they went from myriad descriptions of reactions being commented as "...and this is not well understood" to quite thorough and rigorous explanations of chemical interactions.

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

#114

Post by bilsbie »

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?

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

#115

Post by terminalbraid »

OgsyedIE wrote: post #87
rnikander wrote: post #67

Earlier quoted context omitted.

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

To complete accuracy, we cannot yet manage one proton.

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

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

#116

Post by WillAdams »

smj-edison wrote: post #103
vessenes wrote: post #92

Earlier quoted context omitted.

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.

Disclaimer: I'm only a freshman, so there's still a ton I don't know :) Right now the lab is having me get comfortable using software like Gaussian and ORCA by simulating a bifurcating reaction. This is a reaction that, depending on the catalyst's momentum, will change what site it bonds to (it makes either a 6-membered or 7-membered ring). I'm finding the intermediate states (where the molecule is most stable) and t…

Good luck!

I assume you are familiar with:

https://matt.might.net/articles/phd-school-in-pictures/

I hope and pray that your research helps to make the world a better place and that the rest of us can use your knowledge to help to make the world a place which merits your research.

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

#117

Post by [deleted] »

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

[deleted]

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

#118

Post by jeremyjh »

exe34 wrote: post #75
pestatije wrote: post #73

Earlier quoted context omitted.

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

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.

Downvoters are probably misunderstanding this. Mathematical theory is based on axioms and inference. The axioms do not have to be true in any cosmic sense for the math to be correct or even useful.

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

#119

Post by applicative »

vasco wrote: post #74
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…

> and still nobody has gone beyond Aristotle and Kant in giving anything close to a rigorous definition of life as such You stopped reading after the 1800's? Schrödinger told us life is what feeds on negative entropy and that is pretty good.

Look into Aristotle and Kant on ‘the organized /and self-organizing/ being’; apply a couple thermodynamic abstractions known to adolescents ; be named Erwin Schrödinger ; hackernews will respond accordingly.

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

#120

Post by jeremyjh »

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

Yes, we've all seen the xkcd[1] but you've misunderstood it. Physics applies mathematics but mathematics cannot derive physics in the way that a complete physics (and a lot of compute) could derive chemistry and biochemistry.

Math isn't attempting to describe a physical universe. It provides the substrate upon which such a description can be expressed and validated - found to be consistent with itself - but many valid descriptions do not describe our universe. Physics is the empirical search for the correct mathematical description of our universe.

[1] https://xkcd.com/435/

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