The Extended Habitable Epoch of the Universe for Liquids Other than Water

TL;DR

This paper investigates the potential for life to have originated in the early universe by considering alternative solvents like ethane, enabled by higher cosmic microwave background temperatures at high redshifts.

Contribution

It introduces the concept of an extended habitable epoch for liquids other than water, focusing on the viability of alternative solvents such as ethane in the early universe.

Findings

Liquid ethane could have existed for 10-100 million years at high redshifts.

Higher CMB temperatures could have supplied energy for alternative biochemistries.

Ethane is identified as the most promising candidate for alternative life solvents.

Abstract

At high redshifts, the temperature of the cosmic microwave background (CMB) was higher than its value today. We explore the possibility that life may have arisen early because the higher CMB temperature would have supplied the requisite energy for the existence of different solvents on the surfaces of objects. At redshifts of $z \lesssim 70$, after the first stars are predicted to have formed, a number of molecules (but not water) might have existed in liquid form over intervals of $\sim 10$ Myr to $\sim 100$ Myr. We delineate the challenges and prospects for life in the high-redshift Universe, and assess the various candidates for alternative biochemistries in this context -- of the options considered herein, we conclude that ethane is probably the most promising contender.