Number of galaxies in the universe

[Martin Meredith]

The Guardian reports on a study suggesting that there are 20 times as many galaxies in the universe as previously thought -- a total of 2 x 10^12. I dug out a preprint of the paper referred to in the Guardian piece. It is a fascinating read. For instance, it states that there are 10 times as many galaxies as would be seen even in the Hubble Ultra Deep Field. The implications section is worth a look, as it comments on what these findings mean for Olbers paradox (why the sky is dark at night).

It is sobering to think that the number of galaxies I plot on what I consider to be quite deep charts is approx 2 x 10^6 i.e. only one-millionth of the estimated total....

Martin 

Edited October 14, 2016 by Martin Meredith

[saac]

So 20 times more bayronic matter in the Universe than previously thought?  Wonder if we will see a revision of the expectations of dark matter - maybe we need it a little less now?

Jim

Edited October 14, 2016 by saac

[Knight of Clear Skies]

The finding isn't quite as dramatic as it sounds, these are very small and dim galaxies which formed early in the history of the universe, and later merged to form larger ones. I don't believe it will affect the estimate of matter to dark matter ratio, that was determined by examining the CMB.

[StuartJPP]

I thought the answer was 42?

[happy-kat]

Lol HHGttG 

[Knight of Clear Skies]

Here's a good summary of the finding, certainly interesting but not game changing. Unfortunately the headline has spread around the internet without much context and a lot of people are thinking this is equivalent to the universe being ten times larger than previously thought (prediction, this 'factoid' will be incorporated into future anti-science rants).

[Pippy]

I wouldn't consider a news paper media outlet as being a reliable source of scientific data.

I'm not saying they're wrong or such like, just trying to highlight the obvious - for future reference.

 

Edited October 15, 2016 by Pippy

[saac]

Other than correcting the original headline I think the Guardian article reflects the thrust of the paper fairly well; direct quotes from the lead researcher are clearly attributed together with source publication.  I generally think topical science reporting from the main broadsheets and the likes of the BBC is fairly reliable; articles like the Guardian story here certainly generate a lot of interest and discussion in the classroom.  Let's be honest, how many of us have the time or more importantly the necessary background understanding to source then critically review academic papers - I certainly don't!  My early aspirations to follow a career in cutting edge research evaporated in my 2nd year at university  I had always hoped of having a law of physics named after me   Oh well, if we can't be naive when we're young when can we be?

 

Jim

Edited October 17, 2016 by saac

[Pippy]

It's OK Jim    Everyone is naive about most things (I know I am). Normally the only things we tend not to be naive about are the things that directly interest us, the rest we normally simply have to rely upon others to let us know about.