3.2 Cosmic Inflation 32 for the problem to be solved sufficiently, we require that the entire observable Universe is well within the horizon, aH ≪ H$_{0}$ , a long time before cosmological scales exit the horizon during inflation. 1 We now discuss the solution to the Relic Problem. Any relics that exist before or during inflation will be rapidly diluted away by the inflation. They will quickly become non-interacting as their number density decreases, due to the rapid expansion, as the interaction rates quickly fall below H . However, we may still have relics that are produced thermally after the end of inflation. This will depend mainly on the reheat temperature of the Universe after the end of inflation. Therefore, to avoid specific types of relics that may be an issue, for example in how they spoil BBN, any particular model of inflation must have a reheat temperature low enough so as to not produce an unac- ceptable amount of such relics. Alternatively, a second period of inflation, known as Thermal Inflation (see Chapter 4), can affectively eradicate them. Let us now discuss the Baryon Asymmetry Problem. Inflation can ac- commodate Baryogenesis mechanisms that produce the asymmetry between matter and anti-matter. In order to achieve Baryogenesis, we require the following conditions, known as the Sakharov Conditions A) Violation of B (Baryon Number) conservation B) Violation of CP symmetry C) Absence of thermal equilibrium It is the last of these conditions that can be achieved during a period of inflation. $^{1}$We assume the current value of a being a$_{0}$ =1.