The value of the density parameter in the beginning is one of the most precisely determined numbers in all of science, and the natural inference is that the value is exactly 1. One important implication of this is that there must be a large amount of dark matter in the universe. Another is that the universe was made flat by inflation(cmn206)

Inflation can prevent the universe from becoming a singularity as soon as it is born while quantum physics allows the entire universe to appear out of nothing at all(cmn208)

Inflation seems to take place faster than the speed of light. This is possible because it is spacetime itself that is expanding, carrying matter along for the ride. Nothing is moving through spacetime faster than light(cmn211)

Inflation also predicts that the primordial perturbations may have left a trace in the form of gravitational radiation with particular characteristics, and it is hoped that detectors sensitive enough to identify this characteristic radiation may be developed within the next ten or twenty years(cmn216)

By turning inflation on twice, cosmologists have found a way to have all the benefits of the inflationary scenario, while still leaving the universe in an 'open' state, so that it will expand forever(cmn220)

When the universe had been homogenized by the original bout of inflation, a second burst of inflation could have occurred within one of the bubbles. As inflation begins (essentially at a point), the density is effectively 'reset' to zero, and rises towards the critical density as inflation proceeds and energy from the inflation process is turned into mass(cmn220b)

When the cosmos was much smaller than a proton- gravity might briefly have become a repulsive force (ES99)

Inflation will always continue due to quantum uncertainty. New universes are sprouting into existence at this very moment. Some immediately collapse back into themselves. Others inflate so fast that matter never has a chance to coalesce. And some, like ours, settle down into an expansion leisurely enough for gravity to mold matter into galaxies, stars, and plants (ES100)

Linde contended that what Wheeler called "spacetime foam" would inevitably give rise to the conditions necessary for inflation (ES100)

Inflation does not generate any unique predictions (ES103)

The same mechanism which is responsible for splitting the grand unified force into the separate electromagnetic and nuclear components is also responsible for generating a huge repulsive gravitational force. The grand unified theories suggest that a cosmic repulsion must inevitably have been present in the hot primeval stage. In the absence of its driving force the exponential growth would come to a shuddering halt, amid a burst of heat, and the universe would return to the more conventional activity of gradually decelerating expansion, the remnants of which persist today(gnp184)

If the inflation theory is correct, it means that the universe need not have been created in a very special, ordered state after all(gnp186)

The structure we see in the universe today was imprinted by quantum processes when the entire visible universe was much smaller than an individual proton(itb40)

Inflation had never made a successful prediction(itb226)

With COBE's discovery of those background ripples, the inflationary model had made its first successful prediction(itb227)

This fine-tuning problem is generally regarded as the biggest difficulty with inflation, and there have been many attempts to get rid of the problem, all of which involve making the theory more complicated(itb229)

If by some extraordinary coincidence the universe inflated by only the minimum needed to explain our current observations, then the density after inflation could still be significantly above (or below) the critical value- in which case forthcoming observations should be able to determine the epoch of contraction, or that there will be no contraction. Much more likely is that inflation continued for many more ticks than the minimum, resulting in a density very close indeed to the critical value. This means that if the universe is going to contract it won't do so for an enormous length of time yet- very many times the present age of the universe. If that is the case, human beings will never know the fate of the universe they inhabit(ltm81)

Rather than appealing to supercooling to prolong the inflationary period as required, the phase transition itself may have been a sluggish process(mm171)

Inflation has the remarkable double effect both of wiping out any preexisting irregularities and of imprinting its own irregularities on the universe(mm179)

The inflationary phase seems to be the "natural" state of affairs, while the close-to-zero present-day value of the weight of space seems to be peculiar- even contrived(mm281)

Misner tried to explain this temperature isotropy by arguing that different regions were in causal contact, because the expansion was not isotropic. In 1981, Alan Guth of MIT proposed another explanation, which he called inflation. In Guth's model, the expansion of the universe from the Big Bang singularity was not radiation or matter dominated. Rather, there was a repulsive force in the very early universe, a force somewhat analogous to the cosmological constant force I(Tipler) described inflated a tiny region winch was in causal contact to be larger than the part of the universe we see(pi152)

Leading experts in general relativity- Penrose (1989), Ellis(1988), Hawking (1988, p. 132), and John A. Wheeler -have never accepted the inflation model. The inflationary universe has always been supported by high energy particle physicists whose command of general relativity is not as deep as one would like to see in physicists so influential(pi357)