Big Bang Questions

New Member
May 25, 2005
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Hi, If you remember me, you would know I made a space thread a long time ago. For the past months now, I have been getting myself into alot of space topics. I really am starting to find this entire topic very intresting. I started from scratch, with our planets, solar system, galaxies, and I kept moving on..

Where am I now? Well, I just finshed reading about the cosmic microwave background radiation, which seems to be really amazing, considering its existent everywhere in our universe. I have also learnt about how the universe expanding, with the evidence that stars around us appear red shifted.
I read the topics on Hubbles Law about a moving source, and all that.

I never thought I would dig deeper than this, but I am, and now I want to enter this field.

Anyway, yea so I am investigating problems with the Big Bang, and there seems to be three really big ones, that I dont seem to understand.

1.) Horizon Problem
2.) Flatness Problem
3.) Density Flucation Problem

Anyone here have any knowledge on these topics?

Thanks for reading.
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Apr 17, 2005
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I dont know a lot about the Big Bang theory, but have a look at this little article: said:
Inflation resolves these three puzzles. The horizon problem goes because the different parts of the universe were indeed once in close contact. They could separate at massively more than the speed of light because they were not actually travelling through space. It was space itself that was expanding?and that expansion is not constrained by relativity.

The flatness problem disappears because regardless of its initial geometry, a big enough expansion would force space to be flat (or at least so close to being flat that you could not measure the difference). Think of the surface of a balloon. As the balloon is inflated, the curvature of the surface diminishes. If you could inflate a balloon to be the size of the earth, it would look just as flat from any point on its surface as the earth did to primitive people. The universe is much bigger than the earth, and so looks much flatter.

The solution to the density-fluctuation problem is more subtle, and goes back to quantum theory. Just after the universe first tunnelled its way into existence, it was small enough for the uncertainty principle to produce a continually shifting pattern of density fluctuations within it. If it had expanded from the beginning at a mere 70kps per megaparsec, such anomalies would have remained tiny as it grew. A period of massive inflation, though, would blow them up to vast dimensions, taking them out of the quantum realm and “freezing” them into permanency.

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