Sir Roger Penrose's Cyclic Conformal Cosmology.

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Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby BurtJordaan on June 21st, 2020, 5:45 am 

Cyclic or oscillating universes come in different flavors, depending on your choice of model. Some suggest the Universe is destined to fall back in itself one day. Sir Roger's idea suggests the future isn't destined for a collapse, but that it will keep expanding endlessly under the influence of the cosmological constant. Eventually everything will evaporate into light-energy (photons) and the very concept of space and time cease to exist - there is simply no scale anymore.

As Faradave has often (correctly) implied, photons have no time, no clocks. For that you need matter, observers, or at least something that can measure the flow of time. But all eventually decay (evaporate in the case of black holes) and hence a very rarefied field of photons is all that is left, indistinguishable from absolute zero temperature. Sir Roger's controversial idea is that this takes the universe back to what it was before the Big Bang, with extremely low entropy.

The latest on this fascinating topic is found in Daniel An, Krzysztof Meissner, Pawe Nurowski and Roger Penrose, 2020, Apparent evidence for Hawking points in the CMB Sky, dedicated to the memory of Stephen Hawking.
In the introduction to this paper they wrote wrote:
Penrose CCC.png


Note that the CCC Big Bang mentioned is not the inflationary BB, but the original Hot BB as coined by Fred Hoyle, hot and dense and already expanding at a tremendous rate, without any claim as to what happened before that time (10-35 seconds). The CCC BB is simply a conformal re-scaling of that previous cold and 'infinite' electromagnetic field to a new compact hot state with photons and other elementary particles (with a small cosmological constant) that undergoes expansion as we know it. This is where the controversy lurks and I'm as skeptical as many, probably because I do not understand how that conformal re-scaling works.

Penrose CCC3.png


There are numerous references in the papers and also a few videos where Sir Roger and the other authors attempt to explain it, e.g. Before the Big Bang 7: An Eternal Cyclic Universe, CCC revisited & Twistor Theory.
They claim that most of the criticisms are simply misunderstandings of the theory. It will take some time to work through it all. It seems to me that most American theorists shoot it down or ignore it (especially the eternal inflation or multiverse groups).
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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby BurtJordaan on June 24th, 2020, 1:37 am 

I have studied Sir Roger's CCC model now for almost a week and I'm not much closer to an understanding of the conformal scaling physics. Superficially he is convincing, but he often remarks that one needs the math to really see it, and that is a tall order for any non-mathematician. Nevertheless, here is a delightful interview with Sir Roger on a picturesque river bank, some one year ago when he was 88 years old. What a mind!

Roger Penrose | Full Interview | Gravity, Hawking Points and Twistor Theory

There are some natural and other background distractions (even a distant guy skinny dipping in the river! :)), but it's a worthwhile 40 minutes listen.

Here is Escher's Circle Limits drawing ("Devils and Angels") that he is referring to, not long after 7:43 / 43:13 into the video, where he briefly describes conformal scaling.

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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby BurtJordaan on June 25th, 2020, 7:05 am 

As I understand it, you can change the Friedmann solution of Einstein's Field Equations (FLRW) to the FLRW metric times a conformal factor that can be adjusted in the far past (and far future) of the universe in order to make the solution there no longer singular (something divided by zero).

PenroseCCC4ConformalScaling.png

So in a sense, because scale does not matter when there is no matter, you conformally scale the 'future infinity' down to some finite value of scale factor and you scale the pre-BB scale factor up to the same one and they meet seamlessly. I still don't quite understand the physics of the conformal scaling, though...
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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby bangstrom on June 26th, 2020, 4:46 am 

Here is another video that explains more about conformal geometry. I didn’t understand it before watching this and I can’t say I understand it any better after.
https://www.youtube.com/watch?v=FVDJJVoTx7s

Conformal geometry makes sense to me as changes in space and time but not as dimensionless, massless particles. I prefer the illustration of conformal geometry using the straight columnar model to the ‘stack of funnels’ model.

I think Penrose is wrong at three minutes into the video where he says mass and energy are equivalent and energy and frequency are equivalent so mass and frequency are equivalent.

The energy values in Einstein’s equation and Plank’s equation are not the same because the two energies are not the same. Einstein’s equation gives us the amount of energy in a unit of mass and Plank’s equation gives us the amount of energy in a wavelength of light and the derivations of the two are quite different.
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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby BurtJordaan on June 26th, 2020, 8:06 am 

bangstrom » 26 Jun 2020, 10:46 wrote:I think Penrose is wrong at three minutes into the video where he says mass and energy are equivalent and energy and frequency are equivalent so mass and frequency are equivalent.

The de Broglie wavelength equates every massive particle with a frequency through the particle-wave duality.
In any case, when the masses all become photons, or have such extremely high kinetic energies, time and space essentially cease to exists. That's the way I understood him.

It will surely be interesting to see what the Cosmo-community makes of it if more observations confirm his Hawking points prediction. For one thing, it might kill off many inflation theories for good.
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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby BurtJordaan on June 28th, 2020, 3:28 am 

bangstrom » 26 Jun 2020, 10:46 wrote:Conformal geometry makes sense to me as changes in space and time but not as dimensionless, massless particles. I prefer the illustration of conformal geometry using the straight columnar model to the ‘stack of funnels’ model.

The problem is that it is only correct as a conformal model of our universe at the 'joints' of the columns. In between there is matter that spoils the conformal scheme. This is why he needed both. The left hand one is the real scale factor against cosmological time.

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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby edy420 on June 29th, 2020, 10:45 pm 

probably because I do not understand how that conformal re-scaling works.


The best explanation Ive heard, came directly from Sir Roger himself in a Joe Rogan podcast. Joe has a way of having intelligent minds break down their theory into laymans terms so that he can understand, and then I can understand :P

They start talking about black holes around the 40 minute mark, and move onto this topic around the 58 minute mark...

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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby BurtJordaan on July 1st, 2020, 5:30 am 

edy420 » 30 Jun 2020, 04:45 wrote:The best explanation Ive heard, came directly from Sir Roger himself in a Joe Rogan podcast. Joe has a way of having intelligent minds break down their theory into laymans terms so that he can understand, and then I can understand :P

Yes, this is a good layman's explanation, but I find myself in the void between this and the formal papers full of math, which is a bit tough for my aged neurons to follow.
So the search went on and finally, I got a popularized glimpse of those equation in the early 2018 talk New Cosmological View of Dark Matter, which Strangely and Slowly Decays, shortly after 49 min into this video. He then carried on and explained his candidate dark matter particle, the Erebon, which was the name of the Greek God of Darkness - quite a cute story he tells around the name. Anyway, it all started to make a little more sense to me.

Then I stumbled upon a late 2018 IAI interview with Roger Penrose, Sean Carroll and Laura Mersini-Haughton. Too short, but extremely interesting. Although it was not a debate, in my view sir Roger won the discussion hands-down, probably because he actually has a theory that I can understand to some degree. Sean is sticking to modern once-of inflation with all its assumptions and improbabilities and Laura to the modern multiverse concept, with even more assumptions, but less improbabilities. Both of them sound more fanciful than Sir Roger's, IMO.

For one thing, both Sean and Laura seem to say "our universe" starts out small. Maybe they mean "our observable universe", because all indications are that it started out infinitely large, or at least from a conformally scaled down infinity, like Sir Roger's scheme. OK, I'm biased, probably because I understand his scheme better than the others. In the end, observations will hopefully be the decider.

What do you think?
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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby edy420 on July 1st, 2020, 7:55 pm 

I think this topic just boggles the mind. But as you highlighted, we are making presumptions off the observable universe. Which to me is like trying to figure out someone sex, date of birth and name, when all you have to work with is a zoomed in photo of a pimple.
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Re: Sir Roger Penrose's Cyclic Conformal Cosmology.

Postby bangstrom on July 4th, 2020, 1:46 am 

BurtJordaan » June 28th, 2020, 2:28 am wrote:
bangstrom » 26 Jun 2020, 10:46 wrote:Conformal geometry makes sense to me as changes in space and time but not as dimensionless, massless particles. I prefer the illustration of conformal geometry using the straight columnar model to the ‘stack of funnels’ model.

The problem is that it is only correct as a conformal model of our universe at the 'joints' of the columns. In between there is matter that spoils the conformal scheme. This is why he needed both. The left hand one is the real scale factor against cosmological time.


I don’t see where matter makes much difference to the scheme. Without matter, we have no reference for scale but with matter we still have no absolute reference for scale except by comparing the size of matter with the space between.

Space appears to be expanding relative to the scale of matter as in the stack of funnels model or it could be that matter is growing smaller relative to a non-expanding radius of space as in the columnar model or it could be any combination of the two.

We have no absolute reference for either space or time. A contraction of the material scale with a quickening in the rate of time should be indistinguishable from an expansion of space. I agree that we need both models since either one should work and we can't say with certainty which one is "real."
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