Matter (from Latin: materia "substance"; etymologically related to Latin mater "mother" or matrix "womb"; Greek: ὕλη hylē) generally refers to everything that surrounds us in the sensory-physical world and builds up the material world as a whole, in the physically broadest sense everything that has rest mass and spatial expansion, i.e. volume. Furthermore, in addition to the so-called baryonic matter, which is made up of atoms and which builds up the material world we know, different forms of exotic matter such as dark matter are now also being discussed, especially those with negative energy density or negative mass.
Rudolf Steiner, based on his spiritual experiences, also spoke of a kind of negative matter that is not characterised by filling space but by emptying space below the zero level. Instead of pressure forces, it is connected with suction forces which, as etheric universal forces (also called circumferential forces, peripheral forces or centrifugal forces), have a centrifugal formative effect on the living world from the cosmic circumference without potential. From a spiritual point of view, there are also higher forms of matter such as astral matter.