Gravity is responsible for various phenomena, in particular thermal convection, buoyancy, hydrostatic pressure and sedimentation. This allows us, for instance, to shape a metallic part by pouring a melt into a mould, to separate lighter from heavier constituents through sedimentation or for the transport of fluids. The effects of gravity can be undesirable if we want to understand certain physical, chemical or biological phenoma or study the complex interaction of different forces involved in a process, for example, in liquids and gases. Gravity can mask our view on the full set of parameters that influence a physical, chemical or biological process. It is as if we are standing in front of a 500 W halogene projector and cannot see the light of a candle standing behind it.
Gravity can also be undesirable in certain industrial production processes.
For example, capillary effects, multiphase flow, diffusive transport processes or crystal growth from melt and solutions can under normal gravity conditions on Earth be dominated by effects such as buoyancy, thermal convection and sedimentation.