Inflation Goes to the Rescue of the Big Bang

The theory of inflation, established in the early ’80s of the last century, brilliantly solves three problems that the Big Bang theory could not answer: the horizon problem, the flatness problem, and the magnetic monopoles problem

Despite its undoubted successes, the Big Bang theory is unable to answer all the questions of cosmologists. There are at least three open questions for which it cannot provide solutions: the horizon problem, the flatness problem, and the monopoles problem. Let’s go through them one by one.

The most striking feature of the cosmic microwave background (CMB) radiation is the almost perfect uniformity of its temperature in every region of the sky. How is it possible, for example, that the photons of the CMB coming from the western horizon have the same temperature as those coming from the east horizon? Indeed, the particles with which they last interacted, about 13.8 billion years ago, were not in a direct causal connection between them. Therefore, the energy of the CMB photons coming from the East could have been very different from that of the CMB photons coming from the West. How is it, instead, that those photons have precisely the same temperature, with variations…