— Ch. 1 · Ancient Philosophical Origins —
Cosmogony.
~3 min read · Ch. 1 of 6
In ancient Greece, thinkers developed a cosmogony focused on the origin of matter, space, and time. This transition from Chaos to Cosmos formed a form of philosophical cosmogony distinct from modern empirical science. The Sumerian tablet containing parts of the Eridu Genesis offers another early model. It describes the creation of the world out of a primeval sea known as Abzu. These narratives dealt with many similar questions about origins without relying on experimental measurements.
The Big Bang Framework
A Big Bang model for the dynamics of the universe is widely agreed among cosmologists today. Like most physical models, these describe changes of state rather than initial conditions. Initial states are given by experimental measurements or by hypothesis in standard practice. In cosmology, the initial state would be the origin of the universe itself. It is considered a valid challenge to address but there are significant disagreements over even the form of acceptable answers. Few physical models are designed to determine those starting points directly.Limitations Of General Relativity
Conceptually the model can be extrapolated back to time zero, yet this process cannot run all the way there. As the model follows smaller times, density exceeds the validity of general relativity. This point in time is called the Planck time. The observable universe is much more homogeneous than an extrapolated Big Bang can account for. Events on opposite sides of the horizon could not have mixed in the early universe and thus should not be homogeneous now. This problem is called the horizon problem because causality breaks down at that scale.