The Big Bang Was Not That Bright

TL;DR

The paper critiques a recent claim about the cosmic background radiation's visibility and timing of the Dark Ages, showing that the original analysis was based on incorrect assumptions, leading to earlier Dark Ages than previously thought.

Contribution

It provides a corrected analysis of the cosmic background radiation claim, challenging previous estimates of the Dark Ages' onset and the brightness of early cosmic radiation.

Findings

Original claim was based on incorrect assumptions.

Corrected analysis suggests earlier start of the Dark Ages.

Revised estimates of cosmic background radiation brightness.

Abstract

A recent arXiv manuscript, arXiv:1801.03278, claims that a cosmic background radiation with a black body temperature of $T_{\rm BB}$ ~ 500 K (440 F) was just barely visible to human eyes, thus fixing the onset of the Dark Ages at about 5 million years post recombination. This claim presents an insurmountable biophysical challenge, since even hotter bodies, such as 450 F pizzas, do not seem to be glowing in the dark. As volunteer referees we show that this claim is the result of employing an incorrect assumption. Via a corrected analysis we find that the Dark Ages must have had a significantly earlier start. A second, more descriptive claim, that a cosmic background radiation with $T_{\rm BB}$ of 1545 K was as blinding to humans as is our own Sun, is based on the same assumption and may have to be revised.