• Question: What caused the big bang?

    Asked by akankipati to Amy, Drew, Julia, Kimberley, Sara on 15 Jun 2011. This question was also asked by jeum, parmar7r2, lthompson.
    • Photo: Julia Griffen

      Julia Griffen answered on 13 Jun 2011:

      A toughie! I dont think there is an exact or even one answer… so good question!
      The big bang is a theory of the start of the universe.

      Firstly scientists discovered that the universe is expanding. They traced back the expansion, to over 13 million years ago, to what they consider the start. The start of everything we know today, time, matter and forces.

      So to explain somthing without what we know today.. which includes time, matter and forces, well thats impossible..

      I really dont like this answer I’d like a definitive answer… other scientists is there one???

    • Photo: Drew Rae

      Drew Rae answered on 13 Jun 2011:

      I would hesitate to say that we _can’t_ know what caused the big bang. To work it out, we would need to imagine rewind of the universe to before the big bang. At the moment we can rewind to the first couple of seconds, but there isn’t enough information to help us imagine rewind further. We can guess at different possibilities, but we don’t know enough to choose between them. Possibly we’ll never know, or possibly our understanding of how the universe works will improve to the point where we can.

      It’s even possible that our whole understanding of what happened at the start of the universe will change – sometimes we get things wrong!

    • Photo: Sara Imari Walker

      Sara Imari Walker answered on 14 Jun 2011:

      Ah, I see jeum is very interesting in cosmology (the study of space and the Universe!). This is a great question akankipati and jeum. Julia and Drew have done a great job describing how we trace back the history of the universe to figure out there was a big bang. The cause is tougher. A lot of people think the “big bang” started from nothing. But by current scientific understanding this is not necessarily true. I wrote to jeum in another question (on space!) that what may have happened is that our universe (i.e. all of space we can ever measure) started as a local excess of energy in a very vast universe (the multiverse!) a so-called “vacuum fluctuation” that grew itself into its own universe. So our universe (all of space we see even with Hubble!) could be just one of many island bubble universes in a vast multiverse. The big bang therefore may have started as a fluctuation in a larger space time, that broke off and became its own universe! Pretty cool stuff if you ask me. But as Drew has pointed out it is all highly speculative if we try to figure out anything before the big bang – we cannot directly measure it.

    • Photo: Kimberley Bryon

      Kimberley Bryon answered on 15 Jun 2011:

      Physics really isn’t my speciality. I am going to believe Sara as she works for NASA 😛

    • Photo: Amy MacQueen

      Amy MacQueen answered on 15 Jun 2011:

      No one knows – and I’m not really sure if sciecne can really tell you! We can only go back to a certain point with science – as Sara said some people theorise our universe was formed from a multiverse – but then where did that come from and when did it start? You can only push things back to a certain point – you either have to believe things came from nothing or came from something else – and how did that something else get there? it came from nothing or something else? So how did it all start? well spontaneously from nothing or by something!