It's all about atoms

October 11, 2023 2:56 PM

The Valley of Stability (SLYT). CEA is a French government-funded technological research organisation. This 15 minute video is the clearest bestest and most interesting lesson I have ever had on what atoms are, where they come from, how they are structured, how radioactive decay works... It is just all around a super excellent and info-dense little talk!
posted by Meatbomb (13 comments total)

See also the theoretical island of stability!
posted by panhopticon at 4:36 PM on October 11, 2023 [1 favorite]

Thy also get into that, maybe 2/3 of the way in.
posted by Meatbomb at 12:30 AM on October 12, 2023

The link has a timecode, it starts at 9:35 into the video. Is that what you wanted ?
posted by Pendragon at 3:46 AM on October 12, 2023 [1 favorite]

It seems like the "magic" nuclei explaining starts around here, and that leads directly to the guesses at the location for the island of stability. The graphics are so useful for visualisation.
posted by Meatbomb at 5:08 AM on October 12, 2023

One kg of ²⁹⁸Fl to go please!
posted by lalochezia at 5:22 AM on October 12, 2023

My understanding is that when they talk about an island of "stability" they mean only relative to other very heavy elements, not stable like Fe-56, and that the "stable" elements are still horrendously radioactive? So being in the same room as your kg of Fl-298 would be promptly lethal?
posted by GCU Sweet and Full of Grace at 5:57 AM on October 12, 2023

This beautifully visualized, but ngl the repeated mispronunciation of "lead" drove me completely up the wall.
posted by phooky at 8:12 AM on October 12, 2023 [3 favorites]

According to some charts I have seen, the magic superheavy element(s) could have half lives measured in months or years rather than milliseconds. So yeah still crazy radioactive but maybe useful for opening the portal to hell or some new nuclear bomb or whatever?.
posted by Meatbomb at 8:34 AM on October 12, 2023

Wonderful video that seemed long on first viewing, but blindingly fast the second time around. The nuclear shapes are very strange.

Surprised there was no mention of tin and its ten stable isotopes, the most by 2 or 3 now that some of xenon’s 9 have been unmasked and found to be secretly radioactive.
posted by jamjam at 8:41 AM on October 12, 2023 [1 favorite]

Xenon is still in second place with 7 (along with mercury, ruthenium, ytterbium, and dysprosium).
posted by jamjam at 11:49 AM on October 12, 2023

here's a cute writeup of an undergrad research project that showed several asteroids have densities that are consistent with them being composed of atoms with atomic number Z>116, ie superheavy.

The most extreme example known is the asteroid named 33 Polyhymnia, which is located in the main belt between Mars and Jupiter; its density has been calculated as about 75 g/cm3. Rafelski proposes that Polyhymnia and similar objects may be composed of elements above Z=118, possibly with other types of ultradense matter.

Rafelski and his two student co-workers, Evan LaForge and Will Price set out to calculate the microscopic atomic structure and properties of ultraheavy elements using the relativistic Thomas-Fermi model of the atom.

"We chose this model, despite its relative imprecision, because it allows the systematic exploration of atomic behavior as a function of atomic number beyond the known periodic table," Rafelski explains. "A further consideration is that it also enabled us to explore many atoms in the short time available to Evan [LaForge], our brilliant undergraduate student."

The researchers' calculations confirmed the prediction that atoms with around 164 protons in their nuclei were likely to be stable, and, furthermore, suggested that a stable element with Z=164 would have a density between 36.0 and 68.4 g/cm3: a range that approaches the expected value for asteroid Polyhymnia.

posted by funkbrain at 9:41 AM on October 14, 2023 [1 favorite]

That's a great video, but... is it just me or is the background music far too loud in relation to the speech? Combined with the speed of the speech and the heavy accent (including a bunch of pronunciations that seemed very weird even given the heavy accent), it made it hard for me to follow a lot of it.
posted by Flunkie at 10:51 AM on October 14, 2023

What I remember from my undergrad is that there are like half a dozen different models for predicting nuclear decay rates with different trade-offs that work for different nuclei. And it's not that we don't have the theory to predict nuclear decay from first principles—it's that we don't have computers powerful enough to crank through the computations without various simplifying approximations.

I find it interesting that computational limitations do come up in classical physics as well. I remember reading a paper modelling the gravitational collapse of trans-Neptunian objects from "space dust". It was just Newtonian gravity and inelastic collisions, nothing fancy, but they needed to fudge the model slightly because the available computers didn't quite have the horsepower to model the system over the deep time required for the coalescence.
posted by mscibing at 3:52 PM on October 18, 2023