#cosmos #physic # [[Epistemic status]] #shower-thought # Inflation Eternal inflation is the infinite exponential expansion of [[Our universe]], from the [[Big bang]] into [[The multiverse]] ![[Pasted image 20220208153828.png]] >1. In almost all parts of space, inflation will eventually end in a Big Bang like ours. >2. There will nonetheless be some points in space where inflation never ends. >3. The total inflating volume increases forever, doubling at regular intervals. >4. The total post-inflationary volume containing galaxies also increases forever, doubling at regular intervals. > ~ [[Max Tegmark]] ![[Pasted image 20220213093717.png]] ~ [[Max Tegmark]] ## The scale invariance of inflation ![[Pasted image 20220829082650.png]] ~ [[Roger Penrose]] ## Detractor ![[B261A9D4-92D0-439A-9FEB-151561271985.png]] > the result of (inflationary) physical processes acting in its early evolution is basically misconceived. > Why do I say that it is misconceived? Let us examine this issue in terms of some general considerations. The dynamics underlying inflation is taken to be governed in the same general way as are other physical processes, where there are time-symmetrical dynamical laws underlying this activity. There is taken to be a particular physical field known as the 'inflation field' that is held to be responsible for inflation, although the precise nature of the equations governing the inflation field would generally differ from one version of inflation to another. As part of the inflationary process, there would be some sort of 'phase transition' taking place, which may be thought of in terms of some kind of analogy with the transition between solid and liquid states that occurs with freezing or melting, etc. Such transitions would be regarded as proceeding in accordance with the Second Law, and would normally be accompanied by a raising of entropy. Accordingly, the inclusion of an inflation field in the dynamics of the universe does not affect the essential arguments that were being put forward in Part 1. We still need to understand the extraordinarily low-entropy start of the universe, and according to the arguments of §2.2 this lowness of entropy lay essentially in the fact that the gravitational degrees of freedom were not excited, at least not nearly to the extent that involved all other degrees of freedom. > ~ [[Roger Penrose]] > The inflationist's claim would have to be that the presence of an inflaton field actually renders such irregu larities highly improbable. But is this really the case? there is some > Not at all, for we can imagine this situation of a highly lumpy matter distribution at the time of decoupling, but with time reversed, so that this picture represents a very irregular collapsing universe.[2.51] As our imag ined universe collapses inwards, the irregularities will become magnified, and deviations from FLRW symmetry (see §2.1) will become more and more exaggerated. Then, the situation will be so far from FLRW homo geneity and isotropy that the inflationary capabilities of the inflaton field will find no role, and (time-reversed) inflation will simply not take place, since this depends crucially on having an FLRW background (at least with regard to calculations that have actually been carried through). > We are therefore led to the clear implication that our irregular collapsing model will indeed collapse down to a state involving a horrendous mess of congealing black holes, this leading to a highly complicated enormously high-entropy singularity, very possibly of a BKL type > ~ [[Roger Penrose]]