ABSTRACT
Congratulations on completing the scientific journey of exploration from quasars to quarks and beyond. In particular, the Universe today essentially comprises only first-generation leptons and first-generation quarks which are joined together in triplets called protons and neutrons, which in turn make up nuclei and atoms. A quantum theory of gravity, however, has yet to be formulated. On the surface of the planet are many living creatures, including members of one species who are so interested in the origin and complexity of the Universe that they build telescopes and particle accelerators with which to study it. Observations of the cosmic microwave background and distant supernovae have revealed that, although the geometry of the Universe is most likely flat and therefore contains a critical density of matter and energy, only around 0.5% of that density comprises the luminous matter in galaxies and stars that can actually be seen.
