[continued from previous message]   
      
   >>> universe" with just the right amount of mass and energy to keep it from   
   >>> collapsing.  Dark energy is supposed to account for the continued   
   >>> expansion of space within the universe.  One article that I recall   
   >>> claimed that the visible universe extends out to around 45 billion light   
   >>> years in all directions from where we are.  The visible light has to be   
   >>> younger than the age of our universe (less than 14 billion years), but   
   >>> space has expanded.   
   >>    
   >>    
   >> An important point is, according to the evidence, there was a time   
   >> before about 4bya when the universe was dominated by gravity, and its   
   >> rate of expansion was actually slowing.  Now the universe is dominated   
   >> by dark energy, and so its rate of expansion has become ever faster   
   >> since then.   
   >   
   >The claim in the article is that the expansion of the universe continues    
   >to be currently accelerating, but the rate of acceleration is    
   >decreasing, so dark energy effects seem to have limits.   
      
      
   What you say above is contrary to what I have read:   
      
   ********************************   
   In 1998, the High-Z Supernova Search Team published observations of   
   Type Ia ("one-A") supernovae. In 1999, the Supernova Cosmology Project   
   followed by suggesting that the expansion of the universe is   
   accelerating. The 2011 Nobel Prize in Physics was awarded to Saul   
   Perlmutter, Brian P. Schmidt, and Adam G. Riess for their leadership   
   in the discovery.   
   ********************************   
      
      
   >I recall an article claiming that our current visible universe extended    
   >out to around 45 billion light years in any direction (maybe it was 45    
   >billion light years across, the light within visible space has to be    
   >less than 14 billion years old) but there has to be a lot of the    
   >universe that we can no longer see.  Kestrel indicated that this limit    
   >applied to the points within our visible universe so that every location    
   >had a different horizon and could see a different part of the existing    
   >universe.  There would have to be a lot of matter that is not in the    
   >visible universe.   
      
      
   Correct.  This is something I pointed out to Peter Nyikos awhile ago,   
   and I pointed out to you in my last post.  Every point in the cosmos   
   is surrounded by its own Hubble Sphere.  The working assumption is   
   that the cosmos outside our Hubble Sphere is largely similar to the   
   space inside.  The problem is there is no way to know this for   
   certain, even in principle.   
      
      
   >Ron Okimoto   
   >>    
   >>    
   >>> It doesn't matter, what I wanted was if the mass of the universe   
   >>> estimate includes the mass that is not observable.  We have the   
   >>> background radiation map of the universe, and estimates based on what we   
   >>> can see (these are based on the observable universe).  The estimates   
   >>> would have included what we could not see within the visible universe   
   >>> because we lacked the ability to detect the light from the distant   
   >>> objects.  Did this estimate also include the mass that was too far away   
   >>> to be visible?  How do we know how much mass is no longer visible and is   
   >>> beyond the horizon of what we can see?  We've been trying to estimate   
   >>> the amount of dark matter within the visible universe, so how would we   
   >>> measure the amount of matter further away than the visible horizon?   
   >>> Even though we can't observe it, it is still part of our universe.   
   >>>   
   >>> Ron Okimoto   
   >>    
      
   --    
   To know less than we don't know is the nature of most knowledge   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)