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So I am piecing together a school project on the numerous misconceptions of the universe, which I plan to "provide proof against them" with information from various sources (one of the main ones will be A Brief History of Time by Stephen Hawking). In coming up with the myths, I am sure that I will miss some that are very important. So, what are the most mind blowing things that you have come across that have completely changed your thoughts on the universe?

The main one for me is proving that the universe is finite, by the conjecture that the night sky would be extremely bright, as one would eventually encounter a star on the way to the infinite edge of the universe.

What else is there?

(note that I have a basic(ish) understanding of QM, but I do not really want to take the project in such a way)

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That the Big Bang was a physical explosion –  namehere Dec 7 '12 at 15:29
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What about the universe being infinite, but there only being a finite number of stars? –  Claudius Dec 7 '12 at 15:30
    
Ah, those both make sense. As I understand it, the "big bang" was just a colliding of particles and antiparticles (and sub-atomics and anti-sub-atomics), of which there were an equal number, but they had enough energy to change into other things, right? –  fr00ty_l00ps Dec 7 '12 at 15:32
    
That stars burn to create energy, or black holes have gravitational forces different from an object of the same mass –  namehere Dec 7 '12 at 15:32
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The problem with the bright sky argument is that because of the expansion of the universe, the photons are extremely red shifted. That's why the sky is so dark. Even though in every direction we would see the big bang, if only our eyes could see microwave radiation. The universe beyond the edge of the visible region could be infinite, but the space between us and those regions are expanding so fast that photons cannot get across. Anyway, the Big Bang was a derogatory term used to criticize, and is not an explosion. It is better to think of expanding space. –  jcohen79 Dec 7 '12 at 15:39
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1 Answer

up vote 6 down vote accepted

There are many common misconceptions of the universe. Here's a brief list:

  1. Many people think that the Big Bang was a physical explosion. In fact, the big bang is basically a theory of the beginning of the universe, starting with a creation of matter, energy, and spacetime and spacetime's expansion. That's it. Nothing more.
  2. It is commonly believed that stars burn to create energy. Burning is combustion, a chemical process that has nothing to do with stars. Stars 'crush' together several lighter nuclei to form new heavier nuclei(e.g. crushing a deuterium nucleus and a tritium nucleus to form a helium nucleus and a neutron, releasing energy), and in the process releases energy, fueling stars, their luminosity, and preventing them from collapsing due to gravitation
  3. Black holes are popularly thought to be fundamentally different from other gravitational sources. Many believe that a black hole, even if it had the same mass as another object, would somehow attract them more strongly and 'eating' all matter around it.
  4. Many believe astronomical observations reflect the current. In fact, according to relativity there cannot even exist an objective definition of simultaneity. Light takes time to travel from astronomical objects to Earth, so by watching the skies we are practically observing the past.
  5. Most people think that all matter in the universe consists of atoms. In fact, even if you count in plasma(which does not really consist of atoms), they only account for about 4% of the 'mass' of the universe. The rest are dark matter and dark energy.

I think that's about as much as I can think of for now.

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Alrighty, thank you :) –  fr00ty_l00ps Dec 7 '12 at 15:54
    
@CodeAdmiral No problem. –  namehere Dec 7 '12 at 15:55
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