Druckloses

Druckloses is a German term used to describe a state or system characterized by the absence or near absence of mechanical pressure. In physics, the adjective is applied to fluids, gases or media in which the internal pressure p is negligible compared with other forces, or in which p = 0 in an idealized sense. The term appears in phrases such as “druckloses Gas” or “druckloses Medium.” In thermodynamics and fluid dynamics, a truly pressureless medium is an idealization, but the concept serves as a simplifying assumption in certain models.

In cosmology and astrophysics, the dust model treats matter as a pressureless perfect fluid (p = 0) with nonzero density ρ, used to describe cold, non-relativistic matter such as dark matter in the evolution of large-scale structures. The dust approximation leads to geodesic motion of fluid elements and to simplified Einstein field equations under cosmological metrics like the Friedmann–Lemaître–Robertson–Walker model. In this context, “drucklos” is shorthand for p/ρ ≈ 0.

In laboratory and vacuum sciences, pressur e-free or near-zero pressure environments are described as “drucklos” to emphasize minimal hydrostatic stress. Achieving an exact zero-pressure condition is impossible in a closed system, but high-vacuum conditions and microgravity experiments approximate the concept.

Limitations: Real materials exhibit finite pressure, especially at high densities or temperatures; the drucklos assumption may fail when interactions generate pressure or when relativistic effects become relevant. The term remains primarily an idealized descriptor used to indicate negligible pressure relative to other governing factors.