Cosmology Notes/draft

What is cosmology?

The modern consensus on the nature and evolution of the Universe is that all the matter and energy in the Universe spontaneously exploded outward as a Big Bang from a single point in space, and has continued to expand ever since. This model was formulated at a time when scientists were not even sure there were galaxies outside our own Milky Way. However, the truly colossal advancements in observational astronomy over the last 50 years, from ground-based telescopes, satellites, and space-probes to the revolutionary advances in data processing and computing power, has lead to a seldom-admitted crisis of theory versus observation in cosmology.

The current model is based on these assumptions and observations:

1. the "Cosmological Principle" - the postulate that the Universe, is both isotropic (the same in all directions) and homogeneous (matter distribution is "smooth" on a sufficiently large scale),
2. that the cosmic background radiation is the afterglow from the Big Bang,
3. the Hubble relation, the highly isotropic relation between a galaxy's brightness (and therefore, roughly, distance from us) and its redshift, shows that the Universe is expanding, and
4. that the abundance of primordial elements (the amount of H, He, and Li in the Universe) can be calculated from the model to match observations.

The trouble is, recent data is sufficient, but not necessary; that is, it can be made to fit the model, as long as the model has sufficient free parameters, but over the last 50 years or so an increasingly large number of "artifacts" have arisen in order to paper over, or outright fudge, the numbers required to make the FLRW-based model work. These things, in rough order, are:

1. black holes,
2. dark matter,
3. "Cosmic Inflation", and
4. dark energy.

Many of these recent observations and experimental results, when NOT crammed into a failing prevailing model, and considered in isolation from any existing model, point to a potentially very different concept of the Universe: that it may very well turn out to be infinite, eternal, static (non-expanding), fractal, and even quite possibly self-renewing. This essay will be an attempt to pull many of these disparate streams of observations, data, and discussion from many places and present a coherent argument for why I believe this to be so.

General Relativity

The current model is based on a particular mathematical solution (called the Friedman-Lemaître-Robertson-Walker metric, or FLRW for short) of Einstein's field equations in his theory of General Relativity. General Relativity describes the Universe in terms of masses interacting with and distorting spacetime, a four dimensional mathematical space (a Riemannian manifold) which has the three dimensions of normal "Euclidean" space, plus one of time. One of the results of considering the Universe in this way is that gravity becomes no more than the linear trajectories of the moving masses in this four dimensional space, rather than a separate, arbitrary force that needs to be separately considered.