World Science Scholars

### 4.5 Cyclic Model of the Universe

Discussion
• What are your thoughts so far on the cyclic model of the universe? Are you convinced by the arguments made in the lecture? Explain your answer.

• If you’ve read my comments to the video, you know that I don’t think this to be a serious alternative. There are even more serious problems to solve than open questions with the inflation theory; to name the most important ones: Turning a crunch into a big bang, having a “decaying” dark energy to start contraction, contraction increases curvature, not the opposite.
This model needs a lot of work to get even close to convincing me (and probably others).

• Sounds highly plausible, but so at this point did inflation. The bottleneck bounce looks like the point where the theory might most easily go wrong.

• This is an interesting ideia, and I wait it from first principles such as Quantum Gravity. I think that some models in Quantum Gravity may explain the cyclic model as a natural output of their equations. But radical ideas about space and time are necessary in order to understand it.

• Like Klaus said above me, I don’t really understand how the universe entering a contraction phase would smooth out and flatten its geometry – shouldn’t the curvature increase? Also, I’m not sure about black holes from previous “universes” (cycles) still existing – shouldn’t we observe some of their contributions (if not the black holes themselves) in the cosmic microwave background radiation? Furthermore, this needs some postulated scalar fields (like inflation does) with the additional assumption/property that dark energy will decay into a negative form of energy that will cause the universe to undergo a contraction phase. Not impossible, but a lot of assumptions, there.

I’d be happier to go with the Higgs metastable state/Higgs tunnelling as a potential explanation of a different kind of vacua in the future of the universe as a potential mechanism for crazy stuff to happen regarding its expansion (or maybe something like the Conformal Cyclic Cosmology that Roger Penrose is proposing).

• I am not convinced,and the reason I am not convinced is because the rate at which the universe expands is constantly increasing whereas a cyclic universe would slowdown and eventually begin to contract. Unless there are a system of universes bordering each other where the matter from 2 neighboring universes collide with each other collecting mass until it reaches the point of which it explodes and creates a new universe comprised of parts of these universes effectively removing a portion of each. In which case as we would see a very large amount of blue shift on one side or segments of our own universe which is not the case

• To say that I am convinced would be wrong, however, I am convinced that this is a very worthwhile theory to explore. And it does seem to be a simpler explanation for the universe that we observe (so Ockham’s Razor would smile upon it).
It is in contradiction of the currently popular theory of the cosmos, and that will attract a multitude of detractors, particularly from those who are fully engaged in exploring another path – that doesn’t make it wrong, or wrong to pursue it.
The Cyclic model seems to have some resonance with the Aeons concept as proposed by Sir Roger Penrose et al. I would really like to understand whether the model is subject to rebuttal by some possible future observation?

• I like the Cyclic Theory, but I’m waiting on further discoveries before deciding.

Bounce theory has Bounce to it.

If a black hole can survive a bounce, then we start to question what else can, and what is set off by bounce occuring in different areas at different times.

The Fermi Bubbles can have alternate explainations, as too can a solarwind said to be drawn out of the sun due to being unable to reach escape velocity of 600 km/s required. Fermi Bubbles can be explained by quasar collision jet shoots, but Bouncing is another factor…now.

Something draws out the solarwind, yet polarcusp regions allow for a bleeding zone. Polar regions on the sun turn slower than equitorial regions.

We may not have a planet of gaseous solarity, but circumpolar regions are recognized for needing study.

That black holes survive the Kali-Yuga destruction is relevant.

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