- #1
GeorgeDishman
- 419
- 29
In making cosmological measurements, we are limited to the region within the particle horizon, the 'observable universe'. However, it is reasonable to assume that even if the universe is finite, it is much larger than that volume. If, for example, we measure the curvature ##\Omega_K##, the value we could get even with hypothetically perfect instruments would still be only a sample of the curvature of the whole. In particular, even if the curvature of the whole universe is positive, our observable portion might be a local negative fluctuation, or vice versa.
If many such non-overlapping samples could be taken (obviously impossible by definition) and plotted as a histogram (e.g. something comparable to a Gaussian spread around some mean though maybe a bit one sided), could we calculate the expected standard deviation based on the apparent spectrum, i.e. Harrison-Zel'dovich but with a spectral index of ~0.96 as measured by Planck and predicted from inflation for super-horizon modes, or would the fact that there is no upper bound on the length mean we cannot get a useful width around whatever is the mean?
If many such non-overlapping samples could be taken (obviously impossible by definition) and plotted as a histogram (e.g. something comparable to a Gaussian spread around some mean though maybe a bit one sided), could we calculate the expected standard deviation based on the apparent spectrum, i.e. Harrison-Zel'dovich but with a spectral index of ~0.96 as measured by Planck and predicted from inflation for super-horizon modes, or would the fact that there is no upper bound on the length mean we cannot get a useful width around whatever is the mean?