# Errors in Estimating Omega_Lambda due to the Fluid Approximation

## TL;DR

This paper investigates how modeling the universe with discrete masses instead of a fluid affects the estimation of cosmological parameters, revealing a significant correction to Omega_Lambda from supernova data.

## Contribution

It introduces a discrete mass universe model and demonstrates its impact on cosmological parameter estimation, highlighting differences from the fluid approximation.

## Key findings

- Discrete mass model alters optical properties compared to fluid model
- Fitting supernova data yields approximately 10% correction to Omega_Lambda
- Differences in inhomogeneous models affect cosmological inferences

## Abstract

The matter content of the Universe is strongly inhomogeneous on small scales. Motivated by this fact, we consider a model of the Universe that has regularly spaced discrete masses, rather than a continuous fluid. The optical properties of such space-times can differ considerably from the continuous fluid case, even if the 'average' dynamics are the same. We show that these differences have consequences for cosmological parameter estimation, and that fitting to recent supernovae observations gives a correction to the inferred value of Omega_Lambda of ~10%.