The Natural Science Underlying Big History
  Nature's many varied complex systems (including galaxies, stars, planets,
life, and society) are islands of order within the increasingly disordered
universe. All organized systems are subject to physical, biological or cultural
evolution, which together comprise the grander interdisciplinary subject of
cosmic evolution. This is global history greatly extended, big history with a
scientific basis, and natural history broadly portrayed across 14 billion years
of time. Such evolution writ large has significant potential to unify the
natural sciences into a holistic understanding of who we are and whence we
came. No new science (beyond frontier, non-equilibrium thermodynamics) is
needed to describe cosmic evolution's major milestones at a deep and empirical
level. Quantitative models and experimental tests imply that a remarkable
simplicity underlies the emergence and growth of complexity for a wide spectrum
of known and diverse systems. In particular, energy rate density is an
objective metric suitable to gauge relative degrees of complexity along a
hierarchy of widely assorted systems observed throughout the material universe.
