LECTURE

A simpler answer is that even if energy differentials are diminishing over the entire Universe, they may increase locally. For example, gravity packs energy and matter into smaller spaces, thereby creating the local differentials in density and temperature from which stars are built. In turn, the heat generated in stars creates new energy ows within their hinterlands. This is why planets are good places for complex beings such as us. (Inside stars, however, the energy ows may be too intense for the building of new forms of complexity.)

Eric Chaisson has suggested a third possible source of free energy (or “negentropy”). The expansion of the Universe itself may constantly create new energy imbalances, ensuring that work can always be done somewhere in the Universe! These conclusions do not contradict the second law of thermodynamics because in the long run local energy ows diminish energy differentials in the Universe as a whole.

Wherever there are local energy gradients allowing energy to ow, it is possible, in principle, for complex entities to appear. The rest of this course will trace the astonishing creative process of increasing complexity, a process eventually leading to modern human societies, one of the most complex entities we know of. In the next lecture we ask: How do we know these things? Why should we trust the claims made by modern scienti c accounts of the past?

Essential Reading

Supplementary Reading

Chaisson, Cosmic Evolution, Prologue and Introduction. Christian, Maps of Time, app. 2.

Christian, “World History in Context.” Spier, The Structure of Big History.