• Question: how do you as scientists think the world began???

    Asked by to Edward, Ian, Mathew, Naomi, sakshisharda on 13 Jun 2014. This question was also asked by .
    • Photo: Ian Stephenson

      Ian Stephenson answered on 13 Jun 2014:

      Do you mean the world or the universe?

      The first is a lot easier to answer than the second!

    • Photo: Edward Hughes

      Edward Hughes answered on 14 Jun 2014:

      I think the beginning of everything was the Big Bang. Most physicists think that the universe started with an enormous explosion. This is backed up by an observation known as the Cosmic Microwave Background we can detect in the sky, which is a kind of afterglow. It’s a bit like looking at the sun (briefly!) and getting it’s imprint on your retina for a few minutes afterwards.

      Also we’ve detected that the universe is expanding, so it must have been very small and dense once. The shock wave from the initial explosion causes the expansion today!

      After the Big Bang atoms formed and clumped together to (eventually) form stars and galaxies, under the influence of gravity. Eventually our solar system started up, probably from the remains of an exploding star called a supernova. We know this because there are some heavy elements on earth that can only be made inside huge stars!

      The Earth was bombarded by rocks for a long time, but eventually developed an atmosphere. At some point the chemical conditions were right for life to start, but you’ll have to ask a biochemist for details about that! As far as I know the start of life on Earth is still a huge mystery!

    • Photo: Naomi Osborne

      Naomi Osborne answered on 15 Jun 2014:

      Hi 13smartin!

      I also think Earth was formed following the big bang. Around 13 billion years ago all matter was concentrated into a single point which enlarged into an explosion which is still expanding today. It wasn’t for another 8.5 billion years until Earth was formed.

      For a very long time Earth was a molten mass until it cooled down and formed the first land and oceans. It’s believed life began around 3.5 billion years ago when amino acids formed the first microorganisms – which were able to break down carbon dioxide (which was Earth’s early atmosphere) into oxygen. When oxygen levels were high enough, it began to be used as an energy source, leading to plants and animals with more than one cell around a million years ago.

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