Superfluid helium lambda point
The superfluid helium lambda point is the temperature at which helium-4 transitions from a normal liquid to a superfluid state.
How big is it?
2.17 K · temperature
Also -455.8 °F
Temperature · measured approximate
A little perspective
Superfluid helium lambda point vs Cosmic microwave background: temperature comparison
The superfluid helium lambda point is 0.555 K lower than the temperature of the cosmic microwave background.
The superfluid helium lambda point is the temperature at which helium-4 transitions from a normal liquid to a superfluid state.
The cosmic microwave background is faint thermal radiation filling the universe, left over from the early stages after the Big Bang.
Measurements, assumptions & sources +
Superfluid helium lambda point
Temperature: 2.17 K; measured approximate.
The 2.17 K value is a rounded helium-4 lambda transition reference near saturated vapour pressure, not a pressure-independent constant.
Rounded helium-4 lambda-transition temperature at saturated vapour pressure; the transition temperature varies with pressure.
NIST Technical Note 1334 — Thermodynamic Properties of Helium-4
The marked temperature is calibrated. Unmeasured illustration details are representative.
Cosmic microwave background
Temperature: 2.725 K; approximate.
The temperature of the nearly blackbody relic radiation. It is not the temperature of every object in space.
The marked temperature is calibrated. Unmeasured illustration details are representative.
Use the visual comparison to explore its scale, then check the measurements and sources.
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Why this measurement?
Why we use 2.17 K
We compare the superfluid helium lambda point. This is a measured reference value rounded for comparison; check its conditions and uncertainty in the notes.
The 2.17 K value is a rounded helium-4 lambda transition reference near saturated vapour pressure, not a pressure-independent constant.
Rounded helium-4 lambda-transition temperature at saturated vapour pressure; the transition temperature varies with pressure.
The picture identifies the subject; the diagram compares the recorded values. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 2.17 K | Not recorded | measured approximate |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
Nearest lower valueTemperatureUltracold atom cloud1 × 10⁻⁷ KTemperatureAn ultracold atom cloud is a collection of atoms cooled to temperatures near absolute zero, used in advanced physics experiments.Around the same scaleTemperatureBoiling helium4.22 KTemperatureBoiling helium is helium in its liquid state at its normal boiling point under standard atmospheric pressure.
Nearest higher valueTemperatureCosmic microwave background2.725 KTemperatureThe cosmic microwave background is faint thermal radiation filling the universe, left over from the early stages after the Big Bang.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- NIST Technical Note 1334 — Thermodynamic Properties of Helium-4Reference thermodynamic properties for helium-4, including the lambda transition; transition conditions depend on pressure.
There’s always another scale
Follow your curiosity.
TemperatureCosmic microwave background2.725 KThe cosmic microwave background is faint thermal radiation filling the universe, left over from the early stages after the Big Bang.TemperatureBoiling helium4.22 KBoiling helium is helium in its liquid state at its normal boiling point under standard atmospheric pressure.TemperatureAbsolute zero0 KAbsolute zero is the lowest temperature permitted by thermodynamics, where a system has the least thermal energy available to it.TemperatureUltracold atom cloud1 × 10⁻⁷ KAn ultracold atom cloud is a collection of atoms cooled to temperatures near absolute zero, used in advanced physics experiments.TemperatureBoiling nitrogen77.36 KBoiling nitrogen is nitrogen gas produced when liquid nitrogen is heated at normal atmospheric pressure.TemperatureHydrogen normal boiling point20.27 KHydrogen normal boiling point is the temperature at which hydrogen changes from a liquid to a gas at standard atmospheric pressure.TemperatureNeon normal boiling point27.1 KNeon normal boiling point is the temperature at which neon transitions from liquid to gas under standard atmospheric pressure.TemperatureNitrogen triple point63.15 KThe nitrogen triple point is the unique temperature and pressure at which nitrogen can coexist as a solid, liquid, and gas.