Cosmological inflation
Using calculations constrained by the ‘Standard Model’ (the laws of particle and fundamenta-force physics as currently understood) it’s not possible to create coherent mathematical solutions which account for the evolution of the universe – from the Big Bangplugin-autotooltip__plain plugin-autotooltip_bigBig Bang theory
There is now a large body of evidence (from different sources) to support the Big Bang Theory for the origin of the universe, but the problem remains as to the origin of the material or energy which initialised it.
As the UK’s Astronomer Royal Martin Rees has put it : to the state we know today.
The 'Inflation' theory was developed in the late 1970s in order to overcome the anomalies.
In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10−36 seconds after the conjectured Big Bang singularity to some time between 10−33 and 10−32 seconds after the singularity. Following the inflationary period, the universe continued to expand, but at a slower rate."
Source : Wikipedia
The theory is now widely accepted - though not by all cosmologists.
If, however, inflation theory is correct, it assumes, by definition, conditions which don't fit the Standard Model. In other words the conditions within the 'Inflation' period are unknown.
If it's not the correct explanation, then then some aspects of the Big Bang scenario remain unexplained.
The detailed particle physics mechanism responsible for inflation is unknown. The basic inflationary paradigm is accepted by most physicists, as a number of inflation model predictions have been confirmed by observation; however, a substantial minority of scientists dissent from this position."
Source : Wikipedia
Other possible explanations include variations in the values of the Physical Constantsplugin-autotooltip__plain plugin-autotooltip_bigPhysical constants
Constants variability :
Many physics calculations rely on the assumption that the ‘physical constants’ e.g. light-speed, gravity, etc etc are, in fact, constant. Extremely accurate experimental procedures strongly suggest that they (mostly) are. But the experiments can only be carried out on a ‘local’ scale, and in a very short timeframe (cosmologically speaking). Thus the possibility exists that some constants may vary at extreme distances and/or timescales. If so, current … - gravity, light-speed etc.. Reasons for such alterations are also outside the Standard Model - i.e. unknown.
Importance Rating 
