Cosmology Notes/draft

What is wrong with cosmology?

The current scientific 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, have led to a seldom-admitted crisis of theory versus observation in cosmology.

The current model, referred to as the Lamba Cold Dark Matter (ΛCDM) 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 Microwave Background Radiation (CMBR) is the afterglow from the Big Bang,
3. that the Hubble relation, the highly isotropic relation between a galaxy's redshift and its brightness (and therefore roughly, its distance) 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, there is now amassing evidence that each of these assumptions is either false, or only true-ish. Recent data can only be accommodated by adjusting an increasing number of free parameters in the model, making it increasingly unwieldy and less and less "elegant" as time goes on. In addition, adjusting these parameters to make one set of observations fit (for example, element abundances) results in another set being thrown wildly out (large scale homogeneity). As a consequence of this fudge-factoring, over the last 50 years or so an increasing number of artifacts have been postulated in order to paper over the numbers required to make the model work. These things include:

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 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 an arbitrary force that needs to be separately considered.

This model has a parameter Ω representing average density - assuming the matter distribution of the Universe is homogeneous - that determines the overall curvature of spacetime. If the parameter is exactly one, then spacetime is "flat", equivalent to normal Euclidean space. If not, then spacetime is curved, leading to expansion or contraction, either bounded or unbounded depending on whether Ω is smaller or greater than one. This model was formulated in the 1920s, so when Edwin Hubble discovered his redshift relation a few years later, it was heralded as proof of an expanding spacetime, and an affirmation of the FLRW model.

TODO

Dark materials

The observed rate of expansion of the Universe requires a Ω value very close to one, but the observed matter distribution only produces a value of about 0.04, which is far from sufficient. Scientists then postulated dark matter to make up the difference, even though they still to this day do not know what it is. In the 1990s, observations of supernovæ purportedly showed that the rate of expansion has been slowly increasing over time, which requires a dark energy field to make things fit. So now we have Ω consisting of 4% matter, 23% dark matter, and 73% dark energy. All attempts so far to directly detect, measure or quantify either dark matter or dark energy have failed. Could it be that the model is wrong, and that it simply isn't there to observe?

All that is pointless anyway since we now know (from recent SDSS, Hubble, and later galaxy survey data) that matter is distributed fractally with dimension D=2 even at the largest observable scale, so the assumption that matter is distributed homogeneously is false, which means Ω is meaningless, which invalidates modelling the Universe with a FLRW metric. Curiously, by definition this fractal distribution of matter has an average density that tends to zero over ever increasing scales, rendering Ω even more pointless as a meaningful measurement.

Inflation

Cosmic inflation was a mechanism thrown in to explain the presence of very large scale galaxy clustering in the current Universe, given its supposedly isotropic and extremely homogeneous initial state (as indicated by CMBR data) and only 14 billion years in which to form such large structures. Sadly, inflation theory replaces that observational problem with completely unknown and imaginary physics, which (luckily for our prevailing model) can create matter from nothing, expand it at faster-than-light speeds, and suddenly slam the brakes on and dump particles once the energy density has dropped below a certain threshold, at which point "normal" physics pops into existence. Despite this, cosmologists point to the WMAP probe and the supreme isotropy and homogeneity of the CMBR as confirmation that inflation must be true, in the face of the contradictory extreme fractal inhomogeneity of galactic super-clusters and the vast voids between them.

Cosmic Microwave Background Radiation (CMBR)

A near-perfect black body microwave background radiation with a temperature of about 2.7 Kelvin, originating from all points in the sky (isotropic). Detected by radio astronomers in the 1960s, and interpreted as the afterglow from the Big Bang. Measured in 1990 by the COBE satellite and more recently by the Wilkinson Microwave Anisotropy Probe (WMAP). According to the Big Bang model, anisotropies (small variations from the black-body curve) are evidence of the "clumpiness" (inhomogeneity) present at the very beginning of the Universe which lead directly to the large-scale structures we see today.

There is evidence that the CMBR is nothing to do with the afterglow of the Big Bang. It could be simply the ambient temperature of space. Starlight radiating in a vacuum would produce a black-body radiation of about the same temperature, given the Universe's observed matter density. Plasma filaments are very efficient at absorbing radiation and re-scattering it as heat and microwaves. Given their distribution just within our part of the Milky Way, they would very quickly produce a radio "fog", which to radio telescopes would look exactly like the CMBR. This would make it a local, not a cosmic, background radiation.

TODO: problems with the SZ effect, the anisotropy major axis. Big Bang can't claim to have exclusive prediction rights to CMBR. BB predictions of CMBR temperature have varied enormously. Static models actually have a more accurate history of predictions before 1960.