• Question: what caused the big bang?

    Asked by 08cgjw to Donna, Jo, Mark, Stuart, timcraggs on 14 Jun 2010 in Categories: . This question was also asked by conn206.
    • Photo: Mark Lancaster

      Mark Lancaster answered on 13 Jun 2010:

      We don’t know – nor what came before it – indeed it doesn’t really make sense to ask of a “before” since the Big Bang “created” time, so there is no before since there was no time !
      There are views out there that say that the Big Bang was not unique – just one in a sequence e.g. our universe which is expanding could ultimately slow down and then start to contract under gravity and contract to a singularity causing another Big Bang which continues cyclically. Bang – expand – contract – Bang – expand – contract. Our universe at the moment is in an expanding phase – it turns out that the most likely fate for our universe is that it will expand forever and just get colder or it might just expand so much that it rips in half – The Big Rip. Another school of thought which helps explain some of the riddles of Quantum Mechanics is that there are an infinite number of Universes (Multi-verses) and we are just one of those and so The Big Bang is not that special and they are happening (and have happened) all the time. Unfortunately any answers to questions like this are almost impossible to test experimentally – and so rapidly you enter the realms of philosophy/theology (or meta-physics if you want to make it sound scientific and impress your friends). The closest we can get via astronomy/telescopes to the start of the Big Bang is 400,000 years after (when the light escaped) or in Particle Physics accelerators to within a nano-second – but a hell of a lot happened in that previous nano-second e.g. for a start the universe expanded unbelieavbly quickly : its size increased by a factor of 1026 ie 1,000,000,… with another 20 zeros) in the time period from
      10–36 to 10–32 seconds after the Big Bang) and for instance how do you go about detecting another universe to prove that ours is part of a multi-verse since almost by definition these universes are independent of our own. So all we really know is that the Big Bang is a singularity in space and time i.e. it created space and time – beyond that we know very little….that of course makes it an interesting thing to think about…

    • Photo: Joanna Buckley

      Joanna Buckley answered on 14 Jun 2010:

      Oooh, this is a good one. It’s difficult to answer as no one was around back then to record anything as it was 13.7 (ish) billion years ago. Even Bruce Forsyth isn’t that old.

      I have no idea what caused the Big Bang and to be quite honest, I don’t believe physicists really know. How can they? They weren’t even there! That doesn’t stop them researching some amazing theories which are plausable but very complex. They’re complex to me anyway as I’m a chemist, not a physicist.

    • Photo: Donna MacCallum

      Donna MacCallum answered on 14 Jun 2010:

      I’ve not a clue… that’s a really, really good question. Maybe Mark will have a good answer for you.

    • Photo: Tim Craggs

      Tim Craggs answered on 14 Jun 2010:

      This is a good question.

      I am not sure it is something that science can tell us the answer to though, and I will explain why. The way science works is that we come up with a hypothesis, an idea about how we think something happens, then we devise an experiment to test this hypothesis. We look at the results and see if they support our initial hypothesis, or if we need to change our hypothesis. In this way we develop theories about how everything works.

      The problem is, how do we devise an experiment to test what happened before the big bang, before there was a universe to test? (Maybe you can think about this and let me know!)

      There are several possible theories though about the cause of the big bang, and I will briefly describe two of them here, but remember these are just theories and are not really scientifically verifiable (ie testable).

      1) The Big Crunch – Before our universe there was another universe which collapsed into a single point under its own gravity. This caused the Big Bang. This idea leads to the theory of an oscillating universe which has expanded from a Big Bang then contracted to a big crunch many, many times. The problem with this is still what caused teh first big bang, so it doesn’t really answer your question!

      2) The is more than one universe – The Multiverse Theory (or Membrane Theory) – This theory proposes that there are many universes that exist (called Branes) but that very rarely interact with each other. When they do interact, they cause a Big Bang. The problem here is what caused the many universes themselves to exist!

      So, the real difficulty with this question from a scientific point of view is its testability. It is very difficult (if not impossible) to prove these theories right or wrong by experiment.

      Hope this helps!

      Tim

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