Free space
Free space is a theoretical region in space without gravitational fields, electromagnetic fields, or any matter at all. Any matter surrounded by free space would keep the same velocity due to the lack of gravitational fields or any other external forces. Free space serves as an idealized environment in theoretical physics scenarios.
Free Space Media
Vacuum pump and bell jar for vacuum experiments, used in science education during the early 20th century, on display in the Schulhistorische Sammlung ('School Historical Museum'), Bremerhaven, Germany
Torricelli's mercury barometer produced one of the first sustained vacuums in a laboratory.
The Crookes tube, used to discover and study cathode rays, was an evolution of the Geissler tube.
A video of an experiment showing vacuum fluctuations (in the red ring) amplified by spontaneous parametric down-conversion.
Structure of the magnetosphere - is not a perfect vacuum, but a tenuous plasma awash with charged particles, free elements such as hydrogen, helium and oxygen, electromagnetic fields.
A glass McLeod gauge, drained of mercury
Light bulbs contain a partial vacuum, usually backfilled with argon, which protects the tungsten filament
This shallow water well pump reduces atmospheric air pressure inside the pump chamber. Atmospheric pressure extends down into the well, and forces water up the pipe into the pump to balance the reduced pressure. Above-ground pump chambers are only effective to a depth of approximately 9 meters due to the water column weight balancing the atmospheric pressure.
Deep wells have the pump chamber down in the well close to the water surface, or in the water. A "sucker rod" extends from the handle down the center of the pipe deep into the well to operate the plunger. The pump handle acts as a heavy counterweight against both the sucker rod weight and the weight of the water column standing on the upper plunger up to ground level.
A cutaway view of a turbomolecular pump, a momentum transfer pump used to achieve high vacuum
