Exploring the Paradox of Omega: The Ultimate Fate of Our Universe at Exactly 1

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In summary, if Omega was exactly 1 and there was no dark energy or cosmological constant, the universe would expand forever at an ever slower rate. However, the most popular theory of the universe suggests that while Omega equals 1, the dominant component has a negative pressure, resulting in an accelerated expansion. Therefore, in both cases, the fate of the universe would be the same, regardless of whether Omega is exactly 1 or less than 1.
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cosmic time
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If Omega was exactly 1...

We know if the value of omega (the average mass of all matter int he universe was) was more than 1, the ultimate fate of our universe is the big crunch; also if omga was less than one, there wouldn't be enough gravitational pull to bring all matter back, however will expand forever, and will end in a big freeze.
I'm thinking if Omega was exactly 1, what's the final fate, it can't end in a crunch, or a freeze, or it can't be exactly one. It'll have to be a midway point between a freeze and a crunch, this can be used as a paradox, as there is no logical answer to my knowledge.
 
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  • #2
If [itex]\Omega_m=1[/itex] and there's no dark energy or cosmological constant, then the universe asymptotically approaches stationarity as time approaches infinity. In other words, it expands forever, but at an ever slower rate. However, the most popular theory of the universe right now gives the following:

[tex]\Omega = 1[/tex]

[tex]\Omega_m \simeq 0.3[/tex]

[tex]\Omega_{\Lambda} \simeq 0.7[/tex]

That is, we think that [itex]\Omega = 1[/itex], but the dominant component has a negative pressure. In this scenario, we expect the universe to expand forever and at an accelerated rate.
 
  • #3
So, for all practical purposes :wink: and ignoring Dark Energy, omega =1 and < 1 gives you the same end-of-universe scenario.

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  • #4
o I am sorry I was referring to the value of lambda and omega as one...:rofl:
 

1. What is the significance of Omega being exactly 1?

The value of Omega being exactly 1 is significant in the study of cosmology and the formation of the universe. It represents a critical threshold in which the expansion rate of the universe balances with the amount of matter and energy contained within it. This can affect theories about the future of the universe and its ultimate fate.

2. How is Omega calculated and measured?

Omega, also known as the density parameter, is calculated by dividing the actual density of the universe by the critical density. The critical density is the amount of matter and energy needed for the universe to just barely stop its expansion. Omega is measured by using various techniques such as observations of the cosmic microwave background radiation, galaxy surveys, and supernovae observations.

3. What does a value of Omega equal to 1 imply about the universe?

If Omega is exactly 1, it implies that the universe is flat. This means that space-time is not curved and the geometry of the universe is Euclidean. This has implications for theories about the shape, size, and evolution of the universe.

4. Can Omega change over time?

Yes, Omega can change over time. In fact, it is believed that in the early stages of the universe, Omega was much larger than 1 due to the high density of matter and energy. As the universe expanded, Omega decreased and approached 1. It is also possible for Omega to change due to the presence of dark energy, which can cause the expansion of the universe to accelerate.

5. How does Omega relate to the concept of the critical density?

The critical density is a theoretical value that represents the minimum amount of matter and energy needed for the universe to eventually stop expanding. Omega is the measured value of the actual density of the universe. If Omega is less than 1, it means that the universe will continue to expand forever. If Omega is greater than 1, it means that the universe will eventually stop expanding and collapse in on itself. A value of Omega equal to 1 indicates a critical threshold in which the fate of the universe is uncertain.

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