<p>In a book by Alexander Moszkowski, there is an Einstein quote about a hypothetical size of the universe (100 million Light years). Moszkowski claims that Einstein had deduced that from the gravitational constant and the mass distribution of the Milky Way, as known around 1920. My question:</p>

<p>What was the data and the best estimate of the mass density of the Milky Way, <strong>back then in 1920?</strong> </p>

CC BY-SA 3.0
2015-06-20T18:50:12.490Z
Was this model [Einstein's radius of the universe](http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric#Einstein.27s_radius_of_the_Universe) (see also [here](http://en.wikipedia.org/wiki/Static_universe#Einstein.27s_universe))? If so, we can work backwards from the result to find the density.
HDE 226868
CC BY-SA 3.0
2015-06-20T18:57:25.473Z
Of course, but I'd like to have an independent source. Btw, do you know Einstein's original publication of the Einstein radius?
ClassicalPhysicist
CC BY-SA 3.0
2015-06-20T18:58:39.773Z
[This paper](http://arxiv.org/ftp/arxiv/papers/1402/1402.0132.pdf) goes over a finding of part of a manuscript of Einstein's that first set out the idea, but I don't know where the published version of the manuscript can be found.
HDE 226868
<cosmology><milky-way><history>
Available data on the Milky way around 1920
ClassicalPhysicist
# Available data on the Milky way around 1920

(Asked by: username_0 on 2015-06-20)

In a book by Alexander Moszkowski, there is an Einstein quote about a hypothetical size of the universe (100 million Light years). Moszkowski claims that Einstein had deduced that from the gravitational constant and the mass distribution of the Milky Way, as known around 1920. My question:

What was the data and the best estimate of the mass density of the Milky Way, **back then in 1920?**

**Tags:** cosmology, milky-way, history
> **Comments:**
> **username_1**: Was this model [Einstein's radius of the universe](http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric#Einstein.27s_radius_of_the_Universe) (see also [here](http://en.wikipedia.org/wiki/Static_universe#Einstein.27s_universe))? If so, we can work backwards from the result to find the density.  
> **username_0**: Of course, but I'd like to have an independent source. Btw, do you know Einstein's original publication of the Einstein radius?  
> **username_1**: [This paper](http://arxiv.org/ftp/arxiv/papers/1402/1402.0132.pdf) goes over a finding of part of a manuscript of Einstein's that first set out the idea, but I don't know where the published version of the manuscript can be found.  

---

## 0 answers

