On the effects of inhomogeneity on the luminosity structure of the past null cone

The effect of an inhomogeneous cosmology on the past null cone of a typical observer is discussed. This is of particular interest in deciding the limits to which one can hope to do cosmology through the use of optical and other telescopes. The optical scalar equations, together with appropriately defined mean driving terms for subsets of observable objects coupled with corresponding probabilities, can yield estimates of the scatter of apparent luminosities of standard candles on the observer's past null cone due to lensing. This imposes a limit on the use of standard observations in determining the structure of the universe which is simply due to the "fuzzy" structure of the perceived past null cone. In addition, the nature of the distributions will produce selection effects which can cause significant biases from the strict mean Freidmann-Robertson-Walker results.