• Question: How many atoms are there?

    Asked by 424spaa48 to Heather, Helen, Hugh, Jane, Julian on 17 Nov 2014.
    • Photo: Julian Onions

      Julian Onions answered on 17 Nov 2014:

      It’s an interesting question. You can estimate it as follows.

      Using scientific notation, where X^Y is X followed by Y zeros:

      There are about 10^12 galaxies in the universe
      There are about 10^11 stars in each galaxy
      A star has about 10^57 atoms in it.
      So multiplying all those together, we get an estimate of around 10^80 atoms in the universe.
      This ignores things like gas, which might add another 0 onto the end.

    • Photo: Helen Johnson

      Helen Johnson answered on 17 Nov 2014:

      Brilliant answer Julian – I’d never worked it out like that before, 10^80, love it!
      @424spaa48 – Despite all these atoms space is actually fairly empty. Most of it is almost nothingness, with just a few atoms here and there. It’s quite strange to think about really. If you had a football stadium, and put maybe 2 grains of sand inside – that’s how full of ‘stuff’ space is.

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