Why thermal Casimir data favor the dissipationless plasma model · revision history
Revision 1
Superseded · first revision · record
- Title
- Why thermal Casimir data favor the dissipationless plasma model
- Plain
- The Casimir force between metals at room temperature depends on how electrons in the metal lose energy. Calculations using the standard description of a real, resistive metal disagree with most precision measurements, which instead match a description that ignores resistance.
- Precise
- Lifshitz theory for Au or Ni sphere-plate geometries at $T = 300\,\mathrm{K}$ and separations $2e-5\text{ to }1e-4\,\mathrm{cm}$: the Drude permittivity $\epsilon(\omega) = 1 - \omega_p^2/(\omega(\omega + i \gamma))$ removes the zero-frequency transverse-electric Matsubara term, while the plasma model ($\gamma = 0$) keeps it. Micromechanical, dynamic AFM and isoelectronic differential measurements agree with the plasma model and exclude Drude, whereas a torsion-pendulum measurement at larger gaps (Sushkov et al., 2011) favored Drude after subtracting electrostatic patch forces. An answer is a physical mechanism (spatial dispersion, surface states, low-frequency response) that reproduces the data while staying consistent with measured optical and dc conductivity, confirmed at separations above $3e-4\,\mathrm{cm}$ where the thermal term is large.
- Settled by
- A measurement of the thermal Casimir force at gaps above 3e-4 cm with patch potentials characterized independently, plus a dielectric model that fits it and the metal's measured transport and optics.
- Kind
- phenomenon
- Answer type
- mechanism
- References
- (empty)
- Literature status
- contested
- Status note
- Nonlocal and surface-response resolutions were proposed in 2025 (J.-S. Wang, Physical Review B 111, 245404) and magnetic-metal data were reanalyzed in 2026 (Klimchitskaya, Korikov and Mostepanenko, Physics 8, 33, https://doi.org/10.3390/physics8020033); none is accepted.
- Posed since
- 2000