SWhat changed
Giauque and MacDougall demonstrated cooling by adiabatically demagnetizing gadolinium sulfate. In their 1933 report, a sample beginning near 1.5 kelvin reached an indicated 0.25 kelvin. The method first magnetizes a material while heat escapes, then reduces the field after thermal isolation; its magnetic susceptibility provides temperature information.
Scientific scope
Giauque and MacDougall demonstrated cooling by adiabatically demagnetizing gadolinium sulfate. In their 1933 report, a sample beginning near 1.5 kelvin reached an indicated 0.25 kelvin. The method first magnetizes a material while heat escapes, then reduces the field after thermal isolation; its magnetic susceptibility provides temperature information. The indicated temperature depends on the magnetic thermometer and its calibration. The lower temperature of 0.004 kelvin mentioned in Giauque’s later lecture belongs to subsequent work by de Haas and Wiersma. Debye independently reached related cooling conclusions; this contribution is the named 1933 experiment, not sole invention of the underlying idea.
Evidence
The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. The indicated temperature depends on the magnetic thermometer and its calibration. The lower temperature of 0.004 kelvin mentioned in Giauque’s later lecture belongs to subsequent work by de Haas and Wiersma. Debye independently reached related cooling conclusions; this contribution is the named 1933 experiment, not sole invention of the underlying idea.
Contributors
- The named authors in the research record · SCIENCE: These are the listed authors of the cited contribution sources. Paper authorship does not quantify individual effort. An incomplete list is explicitly marked; same names are not automatically merged.
- Some consequences of low temperature research in chemical thermodynamics
- Attainment of Temperatures Below 1° Absolute by Demagnetization
Provisional WRS assessment, edition 2026-10-28.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.
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