Retrieving "Flatness Problem" from the archives

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1. Cosmology (inflationary Models)

   Linked via "flatness problem"

   Cosmological inflation theory posits a period of extremely rapid, exponential expansion of the early universe ($\text{universe}$), beginning at approximately $10^{-36}$ seconds after the Big Bang ($\text{Big Bang}$). This mechanism, driven by a hypothetical scalar field known as the inflaton field ($\phi$), resolves several long-standing puzzles inherent in the standard Big Bang model ($\text{Big Bang model}$), such as …

2. Cosmology (inflationary Models)

   Linked via "flatness"

   | :--- | :--- | :--- | :--- |
   | Hubble Parameter during Inflation ($HI$) | $HI \approx V^{1/2} / MP$ | $\sim 10^{13} \text{ GeV}$ | Governs the amplitude $PS(k)$ |
   | Spectral Index ($n_s$) | Slow-roll parameters $\epsilon, \eta$ | $0.9649 \pm 0.0042$ | Must be consistent with flatness |
   | Tensor-to-Scalar Ratio ($r$) | $\epsilon$ | $\lesssim 0.036$ (95% CL) | Constrains the steepness of $V(\phi)$ |
   | [Non-Gaussianity](/entries/…