However, quantum physics introduces some uncertainty in the initial conditions for the different spatial points. In this sense they are reminiscent of Richard Chace Tolman's oscillatory universe; in Tolman's model, however, the total age of the Universe is necessarily finite, while in these models this is not necessarily so. {\displaystyle r} Brandenberger commented on fine-tuning in another situation. One is the amplitude of the spectrum and the spectral index, which measures the slight deviation from scale invariance predicted by inflation (perfect scale invariance corresponds to the idealized de Sitter universe). There are well-known theorems that this steady state cannot continue forever into the past. In hybrid inflation, one scalar field is responsible for most of the energy density (thus determining the rate of expansion), while another is responsible for the slow roll (thus determining the period of inflation and its termination). This occurs because inflating regions expand very rapidly, reproducing themselves. Penrose's shocking conclusion, though, was that obtaining a flat universe without inflation is much more likely than with inflation – by a factor of 10 to the googol (10 to the 100) power! With exponentially expanding space, two nearby observers are separated very quickly; so much so, that the distance between them quickly exceeds the limits of communications. But during inflation, this rapid-and-relentless expansion will increase the size of the Universe many, many times over: by the same amount that it would push any other particle away. Other models explain some of the observations explained by inflation. [142] Supporters admit that their model "does not solve the entropy and flatness problems of standard cosmology ..... and we can provide no explanation for why the current universe is so close to being spatially flat". Home › Outreach › The Origins of the Universe › Early Universe › Introduction. Because the accelerating expansion of space stretches out any initial variations in density or temperature to very large length scales, an essential feature of inflation is that it smooths out inhomogeneities and anisotropies, and reduces the curvature of space. [95] However, in his model the inflaton field necessarily takes values larger than one Planck unit: for this reason, these are often called large field models and the competing new inflation models are called small field models. Inflation predicts that the structures visible in the Universe today formed through the gravitational collapse of perturbations that were formed as quantum mechanical fluctuations in the inflationary epoch. − In this situation, the predictions of effective field theory are thought to be invalid, as renormalization should cause large corrections that could prevent inflation. Using classical physics, the evolution of the inflationary Universe is homogeneous - each spatial point evolves exactly the same way. It was very quickly realised that such an expansion would resolve many other long-standing problems. The time is 10-33 seconds, the temperature is again 10 27 to 10 28 K as the vacuum energy density that drove inflation is converted into heat. Around 1930, Edwin Hubble discovered that light from remote galaxies was redshifted; the more remote, the more shifted. However such a field would be scalar and the first relativistic scalar field proven to exist, the Higgs field, was only discovered in 2012–2013 and is still being researched. [36]:61, Therefore, regardless of the shape of the universe the contribution of spatial curvature to the expansion of the Universe could not be much greater than the contribution of matter. The slow-roll conditions say that the inflaton potential must be flat (compared to the large vacuum energy) and that the inflaton particles must have a small mass. [38] These theories predict a number of heavy, stable particles that have not been observed in nature. The proposed field and its quanta (the subatomic particles related to it) have been named the inflaton. Inflating the balloon will make the message readable for you. Other models of inflation relied on the properties of Grand Unified Theories. In the early days of General Relativity, Albert Einstein introduced the cosmological constant to allow a static solution, which was a three-dimensional sphere with a uniform density of matter. One of the most severe challenges for inflation arises from the need for fine tuning. I know, I know. During inflation, the energy density in the inflaton field is roughly constant. These parts of the Universe are outside our current cosmological horizon. The observable universe is one causal patch of a much larger unobservable universe; other parts of the Universe cannot communicate with Earth yet. Coleman found the most likely decay pathway for vacuum decay and calculated the inverse lifetime per unit volume. Various inflation theories have been proposed that make radically different predictions, but they generally have much more fine tuning than should be necessary. [80], Other potentially corroborating measurements are expected from the Planck spacecraft, although it is unclear if the signal will be visible, or if contamination from foreground sources will interfere.

how fast was inflation of the universe

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