What are the implications of a perfectly flat universe?

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SUMMARY

The discussion centers on the implications of a perfectly flat universe, particularly regarding inflation, dark matter, dark energy, and the nature of gravity. Participants argue that if the universe is flat, General Relativity (GR) may not be necessary to explain cosmic phenomena, suggesting that a simpler model based on a constant expansion from the Big Bang could suffice. The conversation highlights the interconnectedness of these concepts and raises questions about the validity of GR in explaining cosmic redshift and gravitational effects on particles like photons. The need for solid data and simpler models is emphasized as critical for advancing cosmological understanding.

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  • Understanding of General Relativity (GR) principles
  • Familiarity with cosmological concepts such as the Big Bang and cosmic expansion
  • Knowledge of dark matter and dark energy theories
  • Basic grasp of particle physics, including the concept of gravitons
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  • Research the implications of a flat universe on cosmological models
  • Study the role of dark matter and dark energy in current cosmological theories
  • Explore alternative models to General Relativity for explaining cosmic phenomena
  • Investigate the evidence supporting or refuting the existence of gravitons
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Astronomers, physicists, cosmologists, and anyone interested in the fundamental nature of the universe and the validity of current cosmological models.

  • #31
Rymer said:
Confusion of terms. The universe is capable of being infinite. It has not gotten there yet (as far as we know). The current measurements indicate 'flat' -- but not necessarily 'perfectly' flat. For the point of view you seemed to have adopted this would could be considered to be consistent with a universe being as flat as it can be -- being very large -- but not quite as yet infinite. Infinite universe in the terms you are using would seem to indicate the necessity of infinite time. Since we can point to a finite start time, the universe is not currently infinite.
In this sense it will never be. It is however -- we think -- 'unbounded'.

But who is confused? As I see it, if the universe is infinite, then it has always been infinite (including time), which would mean that the BB theory is wrong. The universe can be unbounded by being spherical. The so called experts say that the universe can be infinite but still expand, and they call us the crack-pots! On this forum, if you don't know the math they know, you're too ignorant to talk to (by some of them).

The finite start time you spoke of is based on the BB theory. Consider this: The moon moves away from the Earth 2.5 inches per year. We can 'play that movie backwards' and find out when the moon was in contact with the earth. Does anybody think it ever was? I don't think so, but they are using the same 'logic' for the BB theory.
 
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  • #32
Actually I'm pretty sure one of the moon formation theories is that a mars-size planetoid thing hit Earth and expelled a chunk which became the moon. Regardless its an oversimplification to assume that the BB theory is simply an extrapolation of space expanding to a 'point'. As I've said before: the big bang wasn't an explosion in space it was an explosion of space.
 

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