Einstein's relativity rules chemical bonds in heavy elements, new research shows • Hacker News Board

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

#201

Post by IAmBroom » Mon, Jul 13, 2026, 10:54 PM UTC

westurner wrote: post #184

westurner wrote: post #127

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

Today 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 spe…

> 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.

Radio waves are light waves.

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

#202

Post by IAmBroom » Mon, Jul 13, 2026, 10:58 PM UTC

saghm wrote: post #72

gmueckl wrote: post #68

Earlier quoted context omitted.

Where is physics chock full pf exceptions?

I think they meant the opposite; physics throws things out as soon as there's a need for exceptions, and there are examples of that.

Well, once they have a better explanation.

We know that mass of matter does not explain even half of the mass observed in the Universe; we haven't thrown out the explanations of mass and inertial gravity, but have a placeholder called "dark matter" to refer to the missing explanation.

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

#203

Post by nyrikki » Mon, Jul 13, 2026, 11:31 PM UTC

sigmoid10 wrote: post #195

nyrikki wrote: post #167

Earlier quoted context omitted.

Explaining 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.201302...

That still doesn't answer why these relativistic effects don't cause neighbouring elements to be liquid. Electron velocities should be quite similar for them. There must be something apart from relativistic effects that makes mercury special in that regard.

Gold is right next door, relativistic effects shrink both Gold and Mercury’s 6s orbitals.

In gold it changes the color, in Mercury it changes freezing temperature.

Gallium has a low melting point 29.76C but that is due to unique chemical bonding.

"relativistic contraction" (shrinking of s and p orbitals) and "relativistic expansion" (destabilization of d and f orbitals) causes many observed phenomena.

Relativistic contraction of the 6s orbital and expansion of the 5d orbital lower the energy required to excite electrons. Consequently, gold absorbs blue light.

Strong relativistic contraction of the outer 6s electrons leaves them tightly bound and unavailable for metallic bonding. This results in incredibly weak atomic interactions, thus mercury a liquid at room temperature.

Lead also has 6s, which is what makes lead acid batteries work as well as they do.

So while the observed effects change, there are relativity effects with several nearby neighbors.

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

#204

Post by selimthegrim » Tue, Jul 14, 2026, 12:50 PM UTC

throwup238 wrote: post #61

asdff wrote: post #31

Earlier quoted context omitted.

Of course we talked about those. But if you went off only those you'd miss the edge cases and gotchas the prof laid for you in step 8 of the synthesis. Couldn't get around just doing worksheet after worksheet after worksheet of reactions to try and drive it into your head. Going to office hours to beg for more practice reactions. Everyone scheduled the rest of their major around when they would have to take ochem to…

That sounds like Caltech. The ochem major is notorious for how hard it is.

I took it there and I don't think it was supposed to be harder than at other schools. They have to get the premeds through.

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

#205

Post by sigmoid10 » Tue, Jul 14, 2026, 5:34 PM UTC

nyrikki wrote: post #203

sigmoid10 wrote: post #195

Earlier quoted context omitted.

That still doesn't answer why these relativistic effects don't cause neighbouring elements to be liquid. Electron velocities should be quite similar for them. There must be something apart from relativistic effects that makes mercury special in that regard.

Gold is right next door, relativistic effects shrink both Gold and Mercury’s 6s orbitals. In gold it changes the color, in Mercury it changes freezing temperature. Gallium has a low melting point 29.76C but that is due to unique chemical bonding. "relativistic contraction" (shrinking of s and p orbitals) and "relativistic expansion" (destabilization of d and f orbitals) causes many observed phenomena. Relativistic co…

I think you still misunderstood the question. Noone asked if there are relativistic effects with neighbors. In fact, it was said at the very beginning that they certainly have these relativistic effects too. The actual question is why are gold/thallium/cadmium etc. not liquid. There must be something apart from relativistic effects that explains why mercury turns into liquid at room temperature and these others don't.

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

#206

Post by westurner » Fri, Jul 17, 2026, 11:15 PM UTC

IAmBroom wrote: post #201

westurner wrote: post #184

Earlier quoted context omitted.

Today 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 spe…

> 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. Radio waves are light waves.

But do radio waves and photons have mass and why does gravity affect them?

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

#207

Post by tikej » Sat, Jul 18, 2026, 4:07 PM UTC

sigmoid10 wrote: post #205

nyrikki wrote: post #203

Earlier quoted context omitted.

Gold is right next door, relativistic effects shrink both Gold and Mercury’s 6s orbitals. In gold it changes the color, in Mercury it changes freezing temperature. Gallium has a low melting point 29.76C but that is due to unique chemical bonding. "relativistic contraction" (shrinking of s and p orbitals) and "relativistic expansion" (destabilization of d and f orbitals) causes many observed phenomena. Relativistic co…

I think you still misunderstood the question. Noone asked if there are relativistic effects with neighbors. In fact, it was said at the very beginning that they certainly have these relativistic effects too. The actual question is why are gold/thallium/cadmium etc. not liquid. There must be something apart from relativistic effects that explains why mercury turns into liquid at room temperature and these others don't…

I think a relatively simple explanation is that on one hand mercury is liquid due to its closed-shell (a bit "noble-gas-like") electron configuration: [Xe] 4f14 5d10 6s2 and that it since its electrons are paired it makes it less energetically favorable to create strong bonds. So consequently Hg does not form conventional, strong covalent bonds (although it probably does form some weak van der Waals complex) like, for example, gold (with the unpaired electron on 6s orbital so [Xe] 4f14 5d10 6s1 configuration) and other "horizontally neighboring" elements which consequently create stronger bonds. However, this alone is not enough and would not explain why Cd isn't liquid.

And here come the relativistic effects, which essentially scale with nuclear charge of the nucleus come to play and they are significantly stronger for Hg than Cd. If I remember correctly (although I read about it a long time ago so I may be a bit rusty) these strong relativistic effects cause something called "relativistic contraction of the 6s orbital" which results in the electrons on this orbital being more strongly bound than they would be, if there would be no relativistic effects (which can be theoretically compared by setting c -> infinity in the equations used to solve electronic structure theory). AFAIR Copernicium should also be liquid in room temperature for similar reasons, but since it is not very long lived and it is difficult to produce testing this will likely be very hard if not impossible to check (though if I remember correctly there was something called "relativistic maximum" which happens in the 6th and not 7th row of periodic table for some reason, so it should be higher than for mercury; though I can't remember the details why this is so).

Of course this is a bit simplified picture and there are surely more details regarding how exactly relativistic effects influence the energies and consequently how this influences the melting temperature of mercury (I suppose they are in the Calvo, Pahl, Wormit and Schwerdtfeger paper linked earlier in this thread), but I think the combination of the electron configuration and strong relativistic effects explain why other neighbors are not liquid.