• Question: WHAT EXISTED BEFORE THE BIG BANG. DID TIME EXIST?, DID LIGHT SPONTANIOUSLY APPEAR AS SOON AS THE BIG BANG OCCURED??!! ECT

    Asked by samuelharrison to Alex, Amy, Andy, Georgia, Ollie on 21 Jun 2011. This question was also asked by samsam.
    • Photo: Amy Reeve

      Amy Reeve answered on 17 Jun 2011:

      hi Samuel,

      Before the big bang there was a small ‘singularity’ (this is what physicists call it). The big bang occured and this singularity expanded very rapidly to create the universe and matter. I don’t know when light appeared i am afraid.

      I think the problem with time is that it is something that humans have assigned. Before the big bang there was the singularity afterwards there was the universe and when humans came along we worked out how long ago this was based on years. Light years is another human invention based on the amount of time it takes for light to reach earth from another object in space. this light would have still travelled before humans and long after we have gone, but will it still be a light year or a year if we are not here to watch it pass by?

      Sorry, got a bit philosophical then!!! really good question though 🙂 i really want to know what is outside the universe. what is the universe expanding into….? this really messes with my head! do you know?

    • Photo: Andy MacLeod

      Andy MacLeod answered on 21 Jun 2011:

      Hello again Samuel. I’m a geneticist, so this is a little outside of my area of expertise, but here’s what (little) I know:

      I don’t know if we can ever know what happened “before” the big bang. I don’t know if the question even makes any sense. Physicists think that the big bang was the start of everything in our universe, and that includes time. It’s something I’ve struggled to get my head around (there’s lots of bits of physics I struggle to get my head round), but apparently there was no “time” before the big bang. Time as we know it was created with the universe – that’s the answer St Augustine gave way back in the 5th century and it seems that modern physics backs that up. Except without neccearily involving God.

      I’m not too sure about light either. At it’s simplest, light is a form of electromagnetic radiation. I don’t know how, or when that came to be.

      Sorry if that didn’t make things any clearer. I’ll see if I can find a physicist who knows more. 😀

Comments

  • Photo: Evan

    Evan commented on :

    Hi guys, I just came across a tweet about this on twitter.

    It is not true that we can go back to “the singularity”. We can only go back to a time when the Universe was very VERY small. The size is called the “Planck Length” and is 0.00000000000000000000000000000000001 metres, so quite small! At distance shorter than this nobody knows what happens. The laws of physics that we know do not apply. So we cannot rewind the Universe back to a time when it was smaller than this (and a singularity has a size of zero!).

    So the question of what happened “before” the big bang is perhaps not possible to answer. There are some theories that the big bang was the collision of higher-dimensional surfaces (known as “branes”) but this is all VERY theoretical and I don’t know how you would test those ideas. Also, some people think that the Universe is cyclic – it expands from a big bang, then contracts to a “big crunch” and then that just repeats again and again. I don’t know how you can do a test to see if these things actually are true. We need Roger Penrose or Neil Turok to get an answer on that – they are scientists who have come up with these theories.

    Regarding the origin of light – that is easier. Light is just energy! Initially the Universe was just energy (there is energy in the universe now, and energy must be conserved) and as it cooled this took the form of particles and radiation (light). So it was just particles and photons bouncing around (this is called a “plasma”). Eventually when it was cold enough the particles could form into nuclei and the photons escaped and went on their merry way throughout the Universe. This happened about 400,000 years after the big bang and we can see these photons today in what is called the “Cosmic Microwave Background”.

    😀

    P.S. Oh ya, and it is not really correct to think about the Universe expanding “into” something! The Universe is everything!!

  • Photo: James_M

    James_M commented on :

    It’s a tricky question because we have no way of observing that far back. If the Big Bang really was the start of everything then it doesn’t make sense to talk about “before” the Big Bang – it is like talking about north of the North Pole.

    There are also ideas in which the Universe is just a region in a Multiverse of possible Universes, so in that scenario the Multiverse existed and then a small part of it inflated up to the size of our Universe during the Big Bang. Some people have even suggested scenarios in which Universes are repeatedly created, each time a little bit different until you end up with one that is stable for life.

    Basically no one knows. It might be fun to speculate, but we have no real way of testing it experimentally. My personal answer would be “maths,” because you can imagine that the system of mathematics can exist without the Universe itself. Is maths in itself enough to bring the Universe into existence?

    On the question of light, I think it would have been too hot for light immediately after the Big Bang. It would have been so hot that the photons of light would interact with the matter in the Universe and would not be able to travel any distance. This is why we can only see back to 300,000 years after the Big Bang.

  • Photo: Andy

    Andy commented on :

    Thanks to James and Evan for shedding some light (ha!) on the subject.

    Sort of. 😉