The common conception of physical objects includes that they have extension in the physical world, although there do exist theories of quantum physics and cosmology which arguably challenge this. In modern physics, "extension" is understood in terms of the spacetime : roughly speaking, it means that for a given moment of time the body has some location in the space (although not necessarily amounting to the abstraction of a point in space and time). A physical body as a whole is assumed to have such quantitative properties as mass, momentum, electric charge, other conserved quantities, and possibly other quantities.