• Question: how many particles are therein the world

    Asked by bradders1 to Philip on 12 Jun 2011.
    • Photo: Philip Denniff

      Philip Denniff answered on 12 Jun 2011:

      This question could be answered in so many different ways, none of which I am afraid I can answer.
      If by particles you mean atomic particles, when I was at school there were three, since then physicists have discovered a lot more.
      If by particles you mean things like grains of sand, there are a lot. To count them, i would count how many grains there were in a spoonful of sand. Then count how many spoonfuls went into a cup. Then count how many cup fulls went into a pile of 1 cubic meter. Then measure the beach and multiply the numbers together. But you asked for the world, so you will need to know the length of all the sandy beaches in the world.

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