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Thread: How long to get the periodic table?

  1. #1
    Join Date
    Oct 2008

    How long to get the periodic table?


    I understand most of the Universe's hydrogen and helium appeared in the first 3 minutes? Then the rest is from stars, including colliding neutron stars, as well as cosmic ray fission. My question is how old would then universe have been to produce the first atoms of plutonium, which is the heaviest natural element (and hence I assume about the last element to form) and is made from colliding neutron stars.

    I'm guessing it should be least than half a billion years - where the first stars appeared about 200 million years after the big bang and that first generation of big stars evolved, exploded and then their neutron star remnants collided. Is that about right or am I missing something? Thanks!

  2. #2
    Join Date
    Jul 2005
    Massachusetts, USA
    There was also a substantial amount of Lithium made in the first moments, and probably immeasurably tiny amounts of Beryllium, Boron, and maybe Carbon. As to the rest, I think you are probably right that most of the heaviest elements would only show up in the spray of merging neutron stars, whereas elements from Carbon up to a little heavier than Iron came from the early massive stars. As to how long ... your guess seems a little short, but somewhere in the universe there must have been a close pair of giant stars at just the right masses to become neutron stars in the shortest amount of time and then have some third body gravitational interaction that sped up their merger. So just hand-waving 0.5 billion years seems plausible but not certain.
    Forming opinions as we speak

  3. #3
    Join Date
    Jan 2008
    It is a bit more complicated, e.g. a significant amount of Helium has also been produced in stars. This is a good article and Wikipedia has an article at and t

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