• Question: How do you believe the world came into existence and what evidence do you have to prove your theory?

    Asked by sophieekettle to Joel, Kristian, Tim, Venus, Zachary on 18 Nov 2013.
    • Photo: Kristian Harder

      Kristian Harder answered on 18 Nov 2013:

      Good question, but before giving you my answer I’d like to bring up a few points concerning how exactly you phrased the question. Call me picky, but that’s (part of) what being a scientist is about. 🙂
      You make it sound as if the procedure is believe first and then look for evidence. It should be the other way round: collect evidence, and based on that form an opinion. That way it’s science, otherwise it would be more like religion, which is not helping you explain how nature works. 🙂
      And I call it opinion, not belief, because once you have evidence it’s not a matter of belief. If it’s a belief, then you are doing it wrong. 🙂 And I talk about evidence, not proof, because it is impossible to prove a theory right. It is only possible to prove it wrong, by finding facts that disagree with it. The best thing that can happen to a theory is that you do not find any disagreeing facts, but unfortunately that doesn’t guarantee you that someone will not come up with an experiment next week that shows your theory is wrong.
      So, when it comes to how the world came into existence, some of the evidence is:
      – all galaxies are flying apart in a way that looks like they all came from the same spot about 13ish billion years ago
      – all stars, galaxies etc seem to be less than 13 billion years old, some a lot less, judging from how much hydorgen they burned so far and other indications
      – there is radiation all over the universe that has exactly the properties
      of an afterglow of a big explosion happening about 13 billion years ago
      So, the conclusion is that almost beyond any doubt, the universe started with a big bang about 13 billion years ago. Now, that doesn’t fully answer your question. Was this actually the beginning of the universe, or did something else exist beforehand, contracted and then exploded? Was there actually a “before” at all, or did time start with the big bang (as our theories predict if the Big Bang started from something really really small). Where did the energy for the Big Bang come from? Was it just a quantum fluctuation out of nothing, as we see it happening all over the universe nowadays, just on a bigger scale? Was the Big Bang a unique event, or do many universes pop up in similar ways all over the place?
      So you see, after all this chatting about, in the end I’ll have to admit that we don’t have a really good answer to your question yet. And depending on how the universe actually came into existence, we may or may not be able to ever figure it out.

    • Photo: Tim Hollowood

      Tim Hollowood answered on 19 Nov 2013:

      All the galaxies in that we can see are flying apart. Working backwards it must have been that they came from a single region. This is called the Big Bang Theory (not to be confused with the TV show!). We now have a very accurate description of what happened a tiny moment after the big bang since the physics going on then leaves its imprint on the universe today. But what happened before the big bang we don’t really know. There are some theories but I don’t find them particularly compelling. So we don’t understand everything yet, there’s still so much to learn.

    • Photo: Zachary Williamson

      Zachary Williamson answered on 21 Nov 2013:

      12 billion years ago, when the universe was young, nothing but darkness saturated the cosmos. The only structure to speak of was diffuse hydrogen gas, spread throughout the universe. Amongst this dull order there were miniscule temperature differences; some spots in the universe were warmer than average, others colder. And amongst these cold spots, like water vapor condensing on a window, gravity caused the hydrogen to coalesce and swarm together. Eventually, after countless millenia, this coalescing ball of hydrogen becomes so dense, and via friction so hot, that the hydrogen atoms begin to fuse together, releasing vast amounts of light and heat. Our star has been born.

      This star will live for a billion years, an interminable time by our reckoning; the inward pressure of gravity and the outward pressure of nuclear fusion maintaining a perfect equilibrium. However eventually the hydrogen runs out, and this star begins to fuse heavier elements together. When all the fuel is gone, this star ends its life with a cataclysmic explosion that would outshine entire galaxies, and in doing so seeds the cosmos with its heavy elements, its stardust.

      Some of this stardust will coalesce again, and form another star via the same process. But this one is different, it has the heavy elements of its predecessor. And some of the heavier stardust will coalesce, not into a star, but rocky and gaseous objects caught in its orbit. Our solar system, and by extension our world, has finally come into existence.

      As for what evidence we have. We can’t travel back in time to observe our own solar system forming, but we can use our telescopes to look at thousands of other solar systems in different stages of formation. We’ve found solar systems at every stage of the story I just told. Until time travel comes along that’s as good as it gets in terms of evidence.

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