On 28/03/2017 18:47, Phillip Helbig (undress to reply) wrote:
In article ,
James Goetz writes:

Lord Kelvin's prediction of heat death indicates the eventual end
to star formation in the observable universe.

Although he was at the time largely basing his model on the sun burning
coal in an attempt to debunk Darwin and the long geological timescales
needed for evolution to run its course.

Have any astrophysicists made any predictions for the endurance of
star formation in the observable universe?

Or does anybody here want to take a crack at predicting it?

John Baez has a nice page that summarises the demise of the universe
which I think is more or less up to date. Ballpark of 10^14 years for
normal star formation processes to have essentially run out of steam
give or take an order of magnitude or two.

http://math.ucr.edu/home/baez/end.html

Total evaporation of galaxies feels intuitively wrong to me, but I am
sure he really knows what he is talking about. So can someone please
explain why when a star is flung out at above escape velocity the
remaining stars do not become ever more tightly bound a la globular
clusters until eventually core collapse of the remaining ones occurs?
(or can the last tight bound pair always fling out a third component)

And quite a nice graphic scaled in log(log(t)) to fit everything on:

https://en.wikipedia.org/wiki/Graphi..._to_Heat_Death


[[Mod. note --
1. This is really an astronomy question rather than a general physics
question, so I have set the Followup-To header to point to our
sister newsgroup sci.astro.research .
2. As to answering your question: Trying to understand/model the star
formation rate of the universe has been a major research area for
decades (e.g., try the search term "star formation history of the universe"
in google scholar or the ADS). But most of this focuses on the *past*
star formation rate. I'm sure there are studies trying to forecast
this into the future, but I don't have references handy.
-- jt]]

Star formation is heavily influenced by galaxy interactions. Thus, one
would at least need to run galaxy-evolution simulations into the future,
but no-one does this. One reason is that one can't check the
simulations by comparing to observations. The other is that with time
matter become more and more clumped, so more dynamic range is needed for
realistic simulations. (I had never seen this discussed in the
literature, but a few years ago I asked some of the main players in the
field why this is the case.)

Galaxy galaxy collisions and supernova shockwaves are very helpful to
star formation but massive stars are short lived so eventually it is all
the dim barely lit stars, white dwarfs and neutron stars that will
predominate as long term survivors into the later degenerate era.

--
Regards,
Martin Brown