• Question: do u believe in the big bang?

    Asked by anon-206367 to Zoe, Kai, Jose Eliel, Hannah, Hamid, Claire on 9 Mar 2019.
    • Photo: Hannah Collingwood

      Hannah Collingwood answered on 9 Mar 2019:

      There’s a lot of evidence that the universe is expanding. So if we look at what happened in the past, there must have been a point when the universe was really small – it’s called a singularity. The Big Bang caused the universe to start growing.

      We can think of the universe as a bit like a balloon – as the balloon is inflated, the universe gets bigger. The Big Bang is the point where the balloon started being inflated.

    • Photo: Jose Eliel Camargo Molina

      Jose Eliel Camargo Molina answered on 9 Mar 2019:

      Hi Bob!

      This is a great question. The coolest thing about science, in my opinion, is how we treat “believe”.

      When we talk about a theory, in the scientific sense, it more or less means those ideas that have been proven to the best of our ability to hold true when looking at how the universe works. So without proof, there is no theory.

      The big bang was an idea for a long time, and some people “believed” in it and some others did not. For something to become accepted in the scientific community, you need to have significant proof that the idea actually explains how the universe works, at least as far as we are able to test.

      So for the big bang, the biggest evidence for it to be a good picture of how our universe started are:
      – Our observation that the universe is expanding. We know this, as we can see it happen!
      – The amounts of light elements, like Helium that we see when we look at the universe around us. If the universe was briefly really hot and then expanded very quickly then it turns out a lot of Helium would have been formed at that hot stage. We can see that too!
      – Finally the Cosmic Microwave Background. If the universe was super hot and super dense at the beginning, light could not really get through it. Then at some point when it expands atoms start to form and the universe is suddenly transparent (light can travel in the spaces between those atoms, it is not a super dense hot soup of energy anymore). This happened everywhere, and that radiation (light) that finally came out should be still traveling all around the universe. AND IT IS! we have measured it and not only that, the minute details of how that radiation looks, coincide with the predictions from the calculation you do if you assume there was a big bang.

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