[HN Gopher] Carbon's interstellar journey to Earth
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       Carbon's interstellar journey to Earth
        
       Author : dnetesn
       Score  : 22 points
       Date   : 2021-04-04 10:36 UTC (1 days ago)
        
 (HTM) web link (phys.org)
 (TXT) w3m dump (phys.org)
        
       | cletus wrote:
       | The sequence of events that led to the Earth being here with us
       | on it is kind of mind-blowing in terms of physics.
       | 
       | First, the nascent universe had to cool such that nucleons
       | formed, which then became hydrogen. This matter wasn't evenly
       | distributed. Some of it under its own weight collapsed under
       | gravity and birthed the first stars.
       | 
       | It seems that shock waves in nebulae trigger star formation. This
       | could be black holes and/or neutron stars merging, supernovae and
       | possibly other events.
       | 
       | These stars became the nuclear furnaces for heavier elements. The
       | death of these stars spread these metals (in astronomy terms;
       | anything heavier than Helium). This cycle continued until there
       | was enough matter in the protoplanetary disk to form rocky
       | planets, of which we are one (of many).
       | 
       | This article talks about the nuances of how and when carbon
       | became part of this system. While that's certainly interesting,
       | it's the heavier elements (than iron) that I find more
       | interesting. Anyone with rudimentary physics knowledge knows that
       | this path only forms elements up to iron because beyond that it
       | consumes energy.
       | 
       | So heavier elements were seeded in this process through
       | supernovae and, as we've confirmed in recent years, from neutron
       | star mergers. So the right sort of stars need to form in the
       | right way and die and then their remnants need to merge to
       | scatter these elements.
       | 
       | I saw one study that suggested the uranium on earth formed by
       | such an event 80-200 million years before the Earth did. That's
       | kind of crazy to think about.
       | 
       | We are literally made of stardust.
        
         | jjbinx007 wrote:
         | It is humbling and also rather difficult to get one's head
         | around.
         | 
         | However, when you consider the observable universe is 96bn
         | light-years across and contains hundreds of billions of
         | galaxies, and the observable universe is very likely only a
         | small part of the universe beyond then incredibly unlikely-
         | sounding things will happen all the time somewhere and some
         | when.
         | 
         | It's amazing we know so much considering most of our knowledge
         | about the universe has arisen in the last c.300 years.
        
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