Like Christianity, modern science teaches that these things of the world of senses are not really real, but that there is a more real reality, in Nature, behind these appearances, a permanent, unchanging reality in comparison to which the world of appearance is ever changing and is an accidental product of our sense organs. Unlike the "other world" of Christianity, which is world of spirit or mind, altogether without body, this "other world" of science is a world of matter, altogether without spirit, life, or mind. This ultimately real world is the world of particles (little bits of dead stuff), of space and time and of forces (gravitational, electromagnetic, and more recently the strong and weak nuclear forces).