# Why Helium Doesn't Freeze When Cooled: Zero-Point Energy

- Original post: https://www.twitter.com/i/status/2121609361420398976
- Source account: [@AshtonForbes](https://x.com/AshtonForbes)
- Source language: English
- Duration: 1:57
- Published: 2026-11-14
- Canonical URL: https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy

## Transcript

[0:00](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy) Let's say I've got, uh, an atom in a liquid, and it has some freedom. It can move around, but, you know, it's very closely packed in with all of its neighboring atoms.

[0:10](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=10) Let's say that it occupies some spherical volume with a radius R. Well, we can say that that R is the uncertainty in its position.

[0:21](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=21) So the uncertainty in the momentum is gonna look like H-bar, Planck's constant, over R. But if it's got an uncertainty in momentum, it means it must be jiggling around inside that sphere.

[0:35](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=35) We know if it's jiggling, we can say it's got an energy.

[0:38](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=38) Well, we know what its momentum is. It's Planck's constant over, over R. So how do we get the energy? Well, it's easy.

[0:46](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=46) We say it's the momentum squared over twice the mass.

[0:50](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=50) Now, helium, being such a light atom, that mass term is very small.

[0:56](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=56) So that means that the energy that it has, because it's confined, is very, very large.

[1:03](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=63) Now, this is what we call the zero-point energy.

[1:05](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=65) This is the energy it cannot get rid of.

[1:07](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=67) It's nothing to do with thermal energy. It's not because there's a temperature in the liquid.

[1:12](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=72) In fact, when you're in the liquid state, that zero-point energy accounts for more than 98% of the total energy in the fluid.

[1:21](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=81) Wait, what? It is, it is enormous. That is crazy. I had no clue.

[1:26](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=86) This zero-point energy is too large for the atoms ever to lock down in place, so helium never freezes just by cooling it down.

[1:36](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=96) So when you're thinking of this kind of ladder of states, this kind of BEC picture, like, you know, everything's macroscopically occupying this bottom state, we think, we-- the, the intuition is to think of it as like a ladder,

[1:48](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=108) where each rung is nice and evenly spaced.

[1:51](https://www.translate.mom/transcript/mKd4QDfBsCeB/en/why-helium-doesn-t-freeze-when-cooled-zero-point-energy?t=111) But the way to think of it in terms of this zero-point energy is that that first rung is 10 stories off the floor.