• Question: can you explain the big bang theory

    Asked by Isha to Anais, katy, Lauren, Richard, Stuart on 8 Mar 2016.
    • Photo: Stuart Atkinson

      Stuart Atkinson answered on 8 Mar 2016:

      Eeek! Good question, Isha. I’ll try. I’m assuming you don’t meant the tv show!

      Until the early part of the 20th Century it was generally accepted that the Universe we know today had already existed and had always looked the same.

      In the 1920s an American astronomer called Edwin Hubble (he has a famous telescope named after him) was looking at the red shift of distant galaxies.

      If you notice the sound of a siren drop in pitch when an ambulance passes you, the same thing happens with light for objects travelling very fast. Like the sound waves getting stretched, the light waves get stretched too, meaning everything gets shifted towards the red end of the spectrum a little, depending on the speed.

      He found that the further away a galaxy was the faster it was moving away from Earth. If you wound time backwards it didn’t take a genius to realise that at some distant time everything must have been bunched up together in a small space, which is when the ‘big bang’ happened.

      Cosmologists have pinned down with great confidence what happened at various stages since the big bang. They know it would have been a very hot beginning, but that atoms would not have formed until much later, followed by stars/galaxies.

      What happened before the big bang is anyone’s guess. Some people think that there may have been another cycle of the Universe – an expansion then a contraction, which created the big bang we know about.

    • Photo: Katy Kellett

      Katy Kellett answered on 8 Mar 2016:

      Geez I am glad Stuart tackled this question before I did! It really is the ultimate question in physics.

      But as Stuart said, my understanding (as a none physicist) is that it all started from a small point (almost like one particle) and in that contained the entire universe as we know it. And at some point in time that little point exploded (hence the big bang) and started expanding outwards with great speed and temperature. Evidence shows that this is still happens, the universe is still expanding. They also believe there is evidence in the universe of the other effects caused by the big band such as radiation and cosmic microwave background. All very clever things that they think back up the theory of the big bang.

      Hope that helps even a little!

    • Photo: Lauren Laing

      Lauren Laing answered on 8 Mar 2016:

      This is a tough questions! I think Stuart summed this up very well!

    • Photo: Anais Kahve

      Anais Kahve answered on 9 Mar 2016:

      I would agree with the others. No one knows what caused the bang. Some people think that it is a normal process and that have been loads of other ‘big bangs’ in the past. If there is limited mass in the universe and it expands outwards, then at some point it’s got to stop expanding because there isn’t enough mass to fill the space. So after some time (billions of years) the universe starts to collapse on itself and shrink. Somehow all of the mass in the universe comes together, but as the mass gets too much and as space decreases, there is too much mass for the space so it expands again! Another big bang!

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