Cosmology

thumb|upright=1.35| Except for the few stars in the foreground (which are bright and easily recognizable because only they have diffraction spikes), every speck of light in the composite photo is an individual [[galaxy, some of them as old as 13.2 billion years; the observable universe is estimated to contain more than 2 trillion galaxies. From the Hubble eXtreme Deep Field.]]

division of reality into World 1 (states and processes of the external world), World 2 (mental states and processes) and World 3 (products of thought considered as objects in their own right)