Cosmology and life

Summary

I examine some recent findings in cosmology and their potential implications for the emergence of life in the Universe. In particular, I discuss the requirements for carbon-based life, anthropic considerations with respect to the nature of dark energy, the possibility of time-varying constants of nature, and the question of the rarity of intelligent life.

Introduction

The progress in cosmology in the past few decades leads also to new insights into the global question of the emergence of intelligent life in the Universe. Here I am not referring to discoveries that are related to very localized regions, such as the detection of extrasolar planetary systems, but rather to properties of the Universe at large.

In order to set the stage properly for the topics to follow, I would like to start with four observations with which essentially all astronomers agree. These four observations define the cosmological context of our Universe.

1. (i) Ever since the observations of Vesto Slipher in 1912–1922 (Slipher 1917) and Hubble (1929), we know that the spectra of distant galaxies are redshifted.

2. (ii) Observations with the Cosmic Background Explorer (COBE) have shown that, to a precision of better than 10⁻⁴, the cosmic microwave background (CMB) is thermal, at a temperature of 2.73 K (Mather et al. 1994).

3. (iii) Light elements, such as deuterium and helium, have been synthesized in a high-temperature phase in the past (e.g. Gamow 1946; Alpher, Bethe, & Gamow 1948; Hoyle & Tayler 1964; Peebles 1966; Wagoner, Fowler, & Hoyle 1967).

4. […]