The Early Cosmos

The Primordial Era / Radiation dominated Era

The diagram shown here (graphic from Astro-2: History of the Universe) presents main stages in the evolution of the universe, according to classic Big Bang cosmology. The Dawn of Time (the original singularity) is only of time as we know it, and even then it shouldn't be thought of as linear. We cannot really know what happened before inflation either, current speculation is based on linear extrapolations from modern high energy physics. By the time we get to the Cosmic Background Microwave Radiation 380 kiloyears ago we are on surer ground. From there it is pretty straightforward astronomic observation to trace the development of the cosmos to the present day.

The term "The Primordial Era" is used here to describe the early and very brief period of the universe's evolution, and is taken from Adams and Laughlin's The Five Ages Of The Universe. An alternative term is the Radiation dominated Era. Both are just another way of saying Big Bang and immediately after. The boundary between the Primordial or Radiation dominated Era, and the following Stelliferous or Matter dominated Era is marked

It should be emphasised that terms such as eras and epochs as used to divide time during the first nanoseconds of the universe have no relation to those same terms as used to describe immensely long periods of geological time, although both can serve as convenient, if for the most part arbitrary and man-made, frame of reference. Of course, geological time itself, and the whole history of the Earth and the solar system, is nothing in relation to the possible future age of the Cosmos. And even if we assume a more finite oscillating universe, we are still looking at timespans of many tens or hundreds of gigayears. For now these cosmological pages are used, a la the Universe Story, as a prequel to the formation of the solar system and the Earth and the history of life on Earth. MAK110718

Unless otherwise noted,
the material on this page may be used under the terms of a
Creative Commons License.