8/17/2026 at 3:41:21 PM
> So in 2018, an international team of scientists created a BEC out of strontium atoms, and hit one of those atoms with a carefully tuned laser, exciting its outermost electron and turning it into a Rydberg atom. Several other atoms from the BEC were caught within between that outer electron’s inflated orbital.This is not so much putting 170 atoms in one, but inflating one beyond the size of its 170-atom neighbourhood.
The hard part being to cool the neighbourhood to such an extremely low temperature that the inflated atom doesn't ionize.
by tromp
8/17/2026 at 7:47:53 PM
Isn't there some hand-waving going on here?The outer orbital is being treated as the last layer of an onion and the atoms are "inside" that. But orbitals are not spherical so our geometrical intuitions kinda fail.
Edit: Sorry for unclear wording: well, s-orbitals are spherical overlapping probability clouds, but they are not shells like an onion. Nor are they spheres as we commonly think of the geometrical object. To say something is "inside" a probability cloud gets difficult. Disclaimer: my memory/understanding of physics/chemistry/probability is poor. Edit 2: when orbitals of atoms overlap for molecules, don't the orbitals get funkier shaped probability distributions? Surely the same thing happens here and the cloud shapes would change - orbitals are not independent things you can just smoosh together or overlap willy-nilly due to qwuantum blah blah.
by robocat
8/18/2026 at 3:24:20 AM
A little bit of hand waving, but I don't mind it much. A cloud of steam rising from a boiling pot doesn't have a well defined border or consistent shape, but a human looking at a nearby object can usually make a clear and reasonable decision about whether or not that object is "inside" the steam cloud.by hatthew
8/17/2026 at 11:19:25 PM
So I thought of a nice question: how close-in does the hydrogen in Rubidium Hydride sit. For gaseous RbH and thinking in solid spheres instead of clouds: The bond length of RbH is ~4.5 units.
The Hydrogen proton is *inside* the empty 5s radius (~4.7 units).
If we added an electron ("an antibonding electron") it would go into the 5s orbital. But that stretches the bond making the distance between the nuclei ~4.8 units.
In RbH, the Rb atom gives up its single outer 5s electron to the H atom, so there is no populated 5s electron shell in a Rubidium Hydride molecule.by robocat
8/17/2026 at 7:50:46 PM
Not spherical huh, where did you learn that and where would I go to learn thatby yieldcrv
8/18/2026 at 12:59:14 AM
That's the Bohr model. It works surprisingly well for hydrogen. Then there's the probability-cloud model, which works much better. And then there's the “strictly speaking, the orbital isn't actually a probability distribution at all; it's a wavefunction, Ψ, and ∣Ψ∣^2 gives you the probability density” model.It gets weird. Like, maybe-there's-only-one-electron-in-the-universe weird.
by zulux
8/17/2026 at 8:42:03 PM
Look up "molecular orbitals" should be enough of a search to get the infoby timcobb
8/17/2026 at 11:18:24 PM
Large orbitals like this approach the classical limit, I believe.by nathan_compton