**Some research news:**

Last summer, in the course of our research into the Friedman-Einstein model of the cosmos (see this post or here for the article), I came across an unpublished manuscript by Einstein in which he explored a ‘steady-state’ model of the universe, i.e., a model of the universe in which space expands but the density of matter remains constant due to a continuous creation of matter from the vacuum. Such a model is radically different to previously known Einsteinian models of the universe, from his static model of 1917 to the evolving models he proposed in 1931 and 1932 in the wake of Hubble’s observations of the recession of the galaxies. On the other hand, it bears some similarities to the famous steady-state cosmic theories proposed by Hoyle, Bondi and Gold in 1948.

**When was Einstein’s steady-state model written?**

Several aspects of the manuscript suggest it was written in early 1931, after Hubble’s observation of the recession of the galaxies but before Einstein’s evolving models of 1931 and 1932. So it could be said that Einstein anticipated the general idea of steady-state models of the universe by almost twenty years!

Einstein giving a lecture at Caltech in 1931.His attempt at a steady-state model was probably penned during his stay in the USA in early 1931

**A discarded model**

Why was Einstein’s steady-state model never published? The bad news is that the model doesn’t work, i.e., it contains a fundamental flaw that leads to a null solution, i.e., a universe empty of matter. It only looked like a viable theory because Einstein made a mistake in his analysis. There is evidence in the manuscript that Einstein spotted the problem on revision and this is almost certainly the reason he declined to publish the manuscript. So it’s a failed model. That said, it is very interesting that Einstein didn’t anticipate that the particular approach model he used (a variation of the de Sitter model) would lead to a null solution, and even more interesting that when the problem became apparent, he declined to try again with a more sophisticated version. We see this as an important crossroads – it seems that on realising that a successful steady-state model would require amending the field equations of relativity, Einstein plumped instead for evolving models.

**Who cares?**

It could be argued that steady-state models are of little interest today because observations have shown unequivocally that we live in an evolving universe (not to mention the fact that Einstein’s version didn’t work). All of this is true, but what Einstein is attempting to do is of great interest; the standard narrative that Einstein eagerly embraced evolving models of the cosmos on learning of Hubble’s results because they allowed him to drop the cosmological constan, no longer seems entirely accurate. In his attempt at a steady-state model in the manuscript, Einstein retains the cosmological constant and even loosely associates it with the creation of matter from the vacuum. Most interesting of all, it seems that Einstein conducted an internal debate between steady-state and evolving models of the universe decades before a similar debate took place in the wider cosmological community.

**Why was the theory not found before?**

The manuscript was never published and was archived in the Albert Einstein Archives as a draft of something else, Einstein’s published 1931 model of the cosmos (also known as the Friedman-Einstein model). It was while researching materials relevant to the latter paper that we discovered the model (I nearly fell off my chair). This sort of thing happens all the time in historical research – for example, we also discovered a number of numerical errors in the Friedman-Einstein model that no-one seems to have noticed before.

**Where to find more on this
**

We have submitted a paper containing a transcription, translation and analysis of Einstein’s manuscript to the *European Physical Journal* *(H) *by kind permission of the Einstein Papers Project and the Hebrew University of Jerusalem*. *A preprint of the paper can be found on the physics ArXiv at http://arxiv.org/abs/1402.0132

**Update**

**Nature** have a news article on our discovery here. It’s a nice article although the writer has confused Einstein’s reservations concerning a dynamic universe with his reservations concerning Lemaitre’s theory of origins (those come later). One of the most interesting aspects of the manuscript is that it seems to predate discussions of the issue of an origin for the cosmos. It’s interesting that Davide’s error is repeated in outlets such as **Scientific American** here and the **Huffington Post** here! There is a very nice video describing our discovery here