From: goldenfieldquaternions@gmail.com   
      
   On Sunday, March 26, 2017 at 11:42:28 PM UTC-5, James Goetz wrote:   
   > Lord Kelvin's prediction of heat death indicates the eventual end   
   > to star formation in the observable universe.   
   >   
   > 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?   
   >   
   > [[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 univ=   
   erse"   
   >    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]]   
      
   The longest lasting stars are red dwarf stars. The smallest of them   
   can endure for 10 trillion years or more. They slowly convert their   
   hydrogen into helium and since convection extends from the core to   
   the surface all hydrogen cycles through. Further, they die not by   
   entering a red giant phase, but they just wink out.  Red dwarf stars   
   end up as cold gas balls of helium plus hydrogen.   
      
   Star formation will continue so long as there are large stars that   
   shed material at the end of their fusion phase. Don't quote me on   
   the number, but from the population II stars of 10 billion years   
   ago to now with Population I stars the rate of star formation has   
   dropped by about 1/10. Also galaxies coalesce into elliptical   
   galaxies with low star formation rates. So it is maybe not a bad   
   estimate to say that star formation will end within a few 100 billion   
   years or a trillion years. In 100 billion years based on the trend   
   with PopII stars compared to PopI stars star formation rate will   
   be about 10 billion times lower than now. So the duration of red   
   dwarfs indicates about how low stars will be active.   
      
   Data suggests cosmology will expand in an accelerated fashion without   
   recollapse. So heat death appears inevitable. There is the issue   
   of phantom energy and the big rip. Data on the cosmological constant   
   has p = -1.00x (x > 0 can't remember what it is) with error bars   
   extending a bit into the big rip area. This is where the cosmological   
   horizon will contract and the accelerated expansion increase.   
   Eventually everything is ripped apart, including quarks in protons   
   etc. I have for some time disliked this idea, but given the data   
   it can't be foreclosed on. If the big rip happens that may put an   
   end to star formation before the heat death scenario.   
      
   LC   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)