# The quest for the size of the universe in early relativistic cosmology (1917-1930)

## TL;DR

Before the discovery of the expanding universe, early relativistic cosmologists aimed to determine the universe's size and curvature radius through astronomical observations, shaping the empirical approach to cosmology.

## Contribution

This paper examines the historical efforts of de Sitter, Silberstein, and Lundmark in measuring the universe's size, highlighting their methods and impact on early cosmological understanding.

## Key findings

- Contributions of early scientists to measuring cosmic curvature.
- Development of empirical methods in relativistic cosmology.
- Influence on modern cosmological approaches.

## Abstract

Before the discovery of the expanding universe, one of the challenges faced in early relativistic cosmology was the determination of the finite and constant curvature radius of space-time by using astronomical observations. Great interest in this specific question was shown by de Sitter, Silberstein, and Lundmark. Their ideas and methods for measuring the cosmic curvature radius, at that time interpreted as equivalent to the size of the universe, contributed to the development of the empirical approach to relativistic cosmology. Their works are a noteworthy example of the efforts made by modern cosmologists towards the understanding of the universe as a whole, its properties, and its content.