Before There Were Stars (2014) | Hacker News Reader

Before There Were Stars (2014)

nautil.us

18 pointsdnetesn8 comments

This is a very good text written by Daniel W. Savin, the leader of "The Savin Group" from Columbia University (1) (2)

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(Note: the bug in Firefox Reader View shows, when the http://nautil.us/issue/79/catalysts/before-there-were-stars-... is viewed in that View as the author whoever is at the moment inserted in the "Also in Physics" ad inside of that Nautilus' text body, which is wrong -- on every refresh a new person: Gregory Laughlin, Sarah Scoles, Amanda Gefter, Michael Segal...)

1) http://user.astro.columbia.edu/~savin/index.html

2) http://user.astro.columbia.edu/~savin/dsavin.html

Edit: reformulated to make clear that the bug is visible for the main Nautilus text and, not connected to the bug, added the link to Savin's page.

Which text is that? Link seems to lead to a landing page.

> Which text is that?

I've edited my post, please reread.

A very long time ago there was a brief time period of a few million years where there were no stars yet but the CMB radiation would've been dropping through the temperature range that was suitable for life. Just because there were no stars doesn't mean things were perfectly homegenous either.

Excuse my ignorance here, what period would this have been? Can you expand a little more on this?

The habitable epoch of the early Universe, Abraham Loeb, DOI: https://doi.org/10.1017/S1473550414000196

https://arxiv.org/abs/1312.0613 , https://www.cambridge.org/core/journals/international-journa...

>"In the redshift range 100≲(1+z)≲137, the cosmic microwave background (CMB) had a temperature of 273–373 K (0–100°C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star. In the standard ΛCDM cosmology, the first star-forming halos within our Hubble volume started collapsing at these redshifts, allowing the chemistry of life to possibly begin when the Universe was merely 10–17 million years old. The possibility of life starting when the average matter density was a million times bigger than it is today is not in agreement with the anthropic explanation for the low value of the cosmological constant."

The water could have been liquid somewhere then, but it's still not the most probable time for life to emerge. The same author wrote in 2016:

https://iopscience.iop.org/article/10.1088/1475-7516/2016/08...

"We find that unless habitability around low mass stars is suppressed, life is most likely to exist near ~ 0.1M⊙ stars ten trillion years from now. Spectroscopic searches for biosignatures in the atmospheres of transiting Earth-mass planets around low mass stars will determine whether present-day life is indeed premature or typical from a cosmic perspective."

The CMB clearly shows the blotchy nature of the mass distribution.

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