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Eternal-cyclic universe?

by petergreen
Tags: big bang, cosmology, universe
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petergreen
#1
Feb6-13, 05:11 PM
P: 25
Scientists glimpse universe before the Big Bang

http://phys.org/news/2010-11-scienti...verse-big.html

In general, asking what happened before the Big Bang is not really considered a science question. According to Big Bang theory, time did not even exist before this point roughly 13.7 billion years ago. But now, Oxford University physicist Roger Penrose and Vahe Gurzadyan from the Yerevan Physics Institute in Armenia have found an effect in the cosmic microwave background (CMB) that allows them to "see through" the Big Bang into what came before.

The CMB is the radiation that exists everywhere in the universe, thought to be left over from when the universe was only 300,000 years old. In the early 1990s, scientists discovered that the CMB temperature has anisotropies, meaning that the temperature fluctuates at the level of about 1 part in 100,000. These fluctuations provide one of the strongest pieces of observational evidence for the Big Bang theory, since the tiny fluctuations are thought to have grown into the large-scale structures we see today. Importantly, these fluctuations are considered to be random due to the period of inflation that is thought to have occurred in the fraction of a second after the Big Bang, which made the radiation nearly uniform.

However, Penrose and Gurzadyan have now discovered concentric circles within the CMB in which the temperature variation is much lower than expected, implying that CMB anisotropies are not completely random. The scientists think that these circles stem from the results of collisions between supermassive black holes that released huge, mostly isotropic bursts of energy. The bursts have much more energy than the normal local variations in temperature. The strange part is that the scientists calculated that some of the larger of these nearly isotropic circles must have occurred before the time of the Big Bang.

The discovery doesn't suggest that there wasn't a Big Bang - rather, it supports the idea that there could have been many of them. The scientists explain that the CMB circles support the possibility that we live in a cyclic universe, in which the end of one “aeon” or universe triggers another Big Bang that starts another aeon, and the process repeats indefinitely. The black hole encounters that caused the circles likely occurred within the later stages of the aeon right before ours, according to the scientists.

In the past, Penrose has investigated cyclic cosmology models because he has noticed another shortcoming of the much more widely accepted inflationary theory: it cannot explain why there was such low entropy at the beginning of the universe. The low entropy state (or high degree of order) was essential for making complex matter possible. The cyclic cosmology idea is that, when a universe expands to its full extent, black holes will evaporate and all the information they contain will somehow vanish, removing entropy from the universe. At this point, a new aeon with a low entropy state will begin.

Because of the great significance of these little circles, the scientists will do further work to confirm their existence and see which models can best explain them. Already, Penrose and Gurzadyan used data from two experiments - WMAP and BOOMERanG98 - to detect the circles and eliminate the possibility of an instrumental cause for the effects. But even if the circles really do stem from sources in a pre-Big Bang era, cyclic cosmology may not offer the best explanation for them. Among its challenges, cyclic cosmology still needs to explain the vast shift of scale between aeons, as well as why it requires all particles to lose their mass at some point in the future.

More information: V.G.Gurzadyan and R.Penrose. "Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity." arXiv:1011.3706v1

http://arxiv.org/pdf/1011.3706v1.pdf
http://arxiv.org/pdf/1104.5675.pdf

The related books: Roger Penrose: Cycles of Time - An Extraordinary New View of the Universe (2010)


Countless circles, each representing a different big bang from the past.
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Chronos
#2
Feb6-13, 06:30 PM
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The statistical significance of the 'circles' reported by Gurzadyan & Penrose has been criticized - e.g., No evidence for anomalously low variance circles on the sky, http://arxiv.org/abs/1012.1305; Application of the Kolmogorov-Smirnov test to CMB data: Is the universe really weakly random?, http://arxiv.org/abs/1105.5051.
Chalnoth
#3
Feb7-13, 08:33 AM
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Quote Quote by Chronos View Post
The statistical significance of the 'circles' reported by Gurzadyan & Penrose has been criticized - e.g., No evidence for anomalously low variance circles on the sky, http://arxiv.org/abs/1012.1305;
I think this states the matter a bit too weakly. They completely and utterly misunderstood the physics of the CMB, and apparently even misunderstood what the word random means in the first place. It is profoundly sad that this paper was ever published, and also that these scientists wasted their time doing such terrible work.

skydivephil
#4
Feb7-13, 08:50 AM
P: 452
Eternal-cyclic universe?

Quote Quote by Chronos View Post
The statistical significance of the 'circles' reported by Gurzadyan & Penrose has been criticized - e.g., No evidence for anomalously low variance circles on the sky, http://arxiv.org/abs/1012.1305; Application of the Kolmogorov-Smirnov test to CMB data: Is the universe really weakly random?, http://arxiv.org/abs/1105.5051.
The paper by Gurzadyan was shot down, I thought everyone knew that.
However there has been another paper ,by I believe ,some more respcetd sources also claiming to see rings in the CMB potentially motivated by CCC. See here:
http://arxiv.org/pdf/1207.2498v1.pdf

Even if this checks out , different models predict different paramters for these circular structures.
This paper compares CCC with ekpyrotic and Loop qauntum models and shows how to infer which model is right given any potential discovery.
http://arxiv.org/abs/1104.3688Ar
A rather interesting read I thought.
Chalnoth
#5
Feb7-13, 09:18 AM
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Quote Quote by skydivephil View Post
The paper by Gurzadyan was shot down, I thought everyone knew that.
However there has been another paper ,by I believe ,some more respcetd sources also claiming to see rings in the CMB potentially motivated by CCC. See here:
http://arxiv.org/pdf/1207.2498v1.pdf
Their method for constructing the artificial maps is bizarre. I'm not immediately convinced that it's correct.
Naty1
#6
Feb7-13, 10:43 AM
P: 5,632
from RESULTS http://arxiv.org/pdf/1207.2498v1.pdf
Structures in the microwave background radiation

It is commonly taken for granted (with the notable exception of [8]) that the Cosmic Microwave Background is purely statistical being produced by the quantum fluctuations usually assumed to have taken place during inflation (as the solution in De Sitter space suggests). Therefore it was very unexpected for us to find significant differences (with confidence level 99.7%) between the WMAP results and artificial maps (with the same statistical properties as WMAP) that we have created. We believe that the procedure of creating artificial maps described above, being different from the one usually used, is interesting on its own. It gives purely statistical gaussian maps, and reproduces the prescribed harmonic content with the desired accuracy.
How is their procedure for artifical maps differents.....Does the 'usual' one utilize Gaussian statistics and so it's the methodology that is different?
Naty1
#7
Feb7-13, 10:47 AM
P: 5,632
We have discussed Penrose's CCC in these forums before...and in one of those discussions is a video presentation link with really nice visuals from Penrose which makes the concepts pretty clear...in that talk and his papers is some 'handwaving' and his own acknowledgement, if I recall, that some issues need additional work.
Naty1
#8
Feb7-13, 10:52 AM
P: 5,632
Here is the forum discussion:
http://www.physicsforums.com/showthr...+roger+penrose

Marcus: Cycles of time--Penrose says his cyclic cosmology obeys thermodynamics. [posted Sept, 2010]

From post #33:
"My synopsis: Penrose believes circular anomalies in the CMBR point to signals from a prior universe, before the Big Bang. Time and scale are lost in the crossover from one eon to another…this is the ‘conformal structure’ where lightcone angles are retained. At the end of one eon with masslessness, black holes evaporate, information is lost, and we return to a low entropy initial state."
Naty1
#9
Jul23-13, 05:06 PM
P: 5,632
Here is the link....thanks to Marcus who posted all this Sept 2010:


The Perimeter videos are easiest to find online. Here it is:
http://pirsa.org/06090005/
Before the Big Bang: an Outrageous Solution to a Profound Cosmological Puzzle

http://pirsa.org/08090078
Clocks at the Big Bang? Quantum gravity is not what you think!
"It has been a common viewpoint that the process of quantization ought to replace the singularities of classical general relativity by some chaotic-looking structure at the scale of the Planck length. In this talk I shall argue that whereas this is to be expected at black-hole singularities, Nature's true picture of what goes on at the Big Bang is very different, where clocks cannot exist and the conformal geometry is completely smooth."

The thread discussion is here:

http://www.physicsforums.com/showthr...+roger+penrose


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