Roger Penrose and the end of the end of the universe
#1
Basically, Penrose says that the universe was born when another universe died, and that when ours dies, another will be born. The big bang was the big crunch of another universe. He makes these claims in a recent paper that studied the cosmic microwave background radiation.
From here:

Quote:He and his co-author do not believe that space and time came into existence at the moment of the Big Bang, but instead, that event was just one in a series of many. Each “Big Bang” marked the start of a new aeon, and our universe is just one of many in a cyclical Universe, starting a new universe in place of the one before.

Anyone heard any criticisms of this hypothesis?
"Fossil rabbits in the Precambrian"
~ J.B.S.Haldane, on being asked to falsify evolution.
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#2
There are some criticisms.

While Penrose took the circular variance patterns as evidence of echoes from previous Universes, the new studies say that the patterns can be explained away with the current model of an inflationary Universe.
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#3

I am not certain whether to post this over here. (Moderators - feel free to move the post appropriately)

Recently i have been debating a few creationists, they have posted links from Roger Penrose's Probability calculations to show how uncertain the chain of events leading to a universe supporting life could be ? Cursing Infact the only instance i have heard Penrose was in this context.

The rebuttal is in the question itself, if a universe with life is highly uncertain then a life in the first place, complex enough to create life and universe should be even more uncertain.

However i would like someone to shed a look on the theory and its mathematics and validate. Huh

Link - http://www.creationofuniverse.com/html/e...ium03.html
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#4
Here is an article related to the data from WMAP used by Penrose et al. These people use a different hypothesis to explain the data, that there is a multiverse with each Universe taking the shape of a bubble and when bubbles collide, they result in the disc shape patterns observed in cosmic microwave background (CMB). Fascinating stuff.

The multiverse hypothesis also addresses some of the fine tuning issues - why is that the constants in our Universe have one particular value and not some other value.

(04-Jan-2011, 12:20 PM)Azad Wrote: However i would like someone to shed a look on the theory and its mathematics and validate. Huh

Link - http://www.creationofuniverse.com/html/e...ium03.html

Here is an article that deals with the Penrose's probability argument. From the section on Probabilities and Probability Densities:

Quote:Although one may not doubt that Penrose's figure of 1:10^10^123 is a good stab at the relative volumes in phase space (that is, the collection of all possible universes), this value, in and of itself does not give us the probability that, given a random selection of points in phase space, ours would be chosen. Nor has it ever been demonstrated that the origin of the universe would include some sort of random processes whereby the values of the fundamental constants were determined.

Why should we not treat the Penrose figure as describing the improbability of our universe? Because any calculation of any probability requires a knowledge of the relevant probability densities. So, the calculation of our particular universe existing would require expressions for the probability densities for various universe scenarios. And I think it is safe to say that nobody knows what the probability densities are at this time, or even if the concept of "various universe scenarios" is at all meaningful.

Also, the creationist argument seems to be along the lines of strong anthropic principle, i.e. the Universe has been fine tuned just for us, versus, us being a result of the Universe being the way it is (weak anthropic principle). SAP can be rejected on all grounds as explained in the article on Biocentricism Demystified.

Penrose has become sort of a darling of the new age spiritualists and now the religious fundies. These people are mortified by reductionism. So, here comes Penrose with his ideas on consciousness that amount to "some things just can't be explained", just the kind of stuff these people, who usually have no respect for scientists or for science in general, need to hear from a scientist. The irony seems to be lost on them. Penrose's views are still rooted in science and he is not looking to a supernatural explanation. His arguments also go deep into mathematical land and anyone who tries to explain them in simplistic manner is bound to get the idea wrong. A common example is the misuse of Godel's Incompleteness Theorem.

After the news on Penrose's cyclic Universe paper came out, the Sanatana Dharmics were quick to point out that the paper was validation of the idea of cyclic creation in Vedic literature. Cyclicity is common in nature. Back then it was a reasonable to see cyclicity in nature (seasons, Earth's rotation, plants sprout from soil, decay back into soil etc..) and extrapolate to it the human birth and even to the act of creation (which itself draws analogies from human birth process). Today, in view of science, except for the idea of cyclicity, other details of Vedic creationism look absurd. On one hand these people claim Vedas are revealed and hence are infallible and perfect, but on the other hand ignore the stupidities (as revealed by science) which must necessarily be true given the infallible and perfect nature of Vedas. Again, the irony seems to be lost on them.
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#5
Well a quick addition to the points above. I did my master's thesis on the CMB and though I am not (yet) in the league of penrose in terms of his insight into the workings of our cosmos, but am proficient in understanding the basic mathematical structure put forth in the model. I heard him speak about it at the IHC where he was the speaker at the chandrashekar centennial memorial lecture earlier this year. The idea that penrose has put forth of the universe being cyclic is a possibility, albeit an interesting one is nonetheless one of many other that are yet to go under the microscope to be analysed minutely before being accepted. Having said that the most commonly accepted theory is that of inflation which to be honest has its own fair share of problems (fine tuning of constants is only partly addressed, amongst many other). The multiverse theory that predicts the disc shaped patterns in the CMB that were found is just one of the many predictions that needs to be tested, so that is to be taken with a pinch of salt too. The rigorous testing that is required before a theory is to be accepted would be something of the order of Einstein's theory of gravity. (NASA recently published its results from gravity probe B that was trying to verify einstein's theory to great experimental accuracy). Until then treat all the latest developments with skepticism and curiosity, which are after all appreciable characteristics in a scientists armor.
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#6
(07-Jun-2011, 11:10 PM)preshanth Wrote: The rigorous testing that is required before a theory is to be accepted would be something of the order of Einstein's theory of gravity. (NASA recently published its results from gravity probe B that was trying to verify einstein's theory to great experimental accuracy). Until then treat all the latest developments with skepticism and curiosity, which are after all appreciable characteristics in a scientists armor.

I was under the impression that General Relativity was already confirmed for the scale of our solar system by observing the bending of light, and the small changes in the orbits of planets around the sun, caused by gravity- the bending of space and time- as modeled by Einstein, also known as the geodetic effect.So it was interesting to read up that there are actually two predictions of Einstein's theory- the afore mentioned geodetic effect and another effect called the frame-dragging effect, and to also read how they were both tested using gyroscopes on the gravity probe B.

Another recent NASA report, on a study conducted by the Galaxy Evolution Explorer on Dark Energy, concluded that Dark Energy is the cosmological constant predicted by Einsteinian gravity. If they had found that DE is not constant force throughout the universe, then Einstein's theory of gravity would have been wrong for scales much larger than our solar system.
"Fossil rabbits in the Precambrian"
~ J.B.S.Haldane, on being asked to falsify evolution.
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#7
(08-Jun-2011, 04:31 PM)Ajita Kamal Wrote: Another recent NASA report, on a study conducted by the Galaxy Evolution Explorer on Dark Energy, concluded that Dark Energy is the cosmological constant predicted by Einsteinian gravity. If they had found that DE is not constant force throughout the universe, then Einstein's theory of gravity would have been wrong for scales much larger than our solar system.

Well Galex reports that Dark Energy is of the form of the cosmological constant that Einstein introduced in his general theory of relativity to keep the universe from expanding. Ironically it this very dark energy that is the cause for the expansion of our universe. That aside the test proves that the other contesting theory Modified Newtonian Dynamics or MoND is not a possibility.

DE is not a constant force in the case of quintessence models which have also not been ruled out by these experiments. In the quintessence models there is a slow moving scalar field involved in the evolution of the universe much like the ones in the standard models of particle physics.

The cosmological constant on the other hand has a major hurdle to cross if we are to truly answer the puzzle of DE. The cosmological constant is physically equivalent to vacuum energy (the fact that true vacuum has a non zero energy state, a consequence of quantum field theory). Particle physics puts the value of the cosmological constant in planck units to be 1. The observed value so far is 10^(-120). This difference is a phenomenal gap to bride.

With many a question to be addressed and answered it promises to be exciting times for cosmology in the years to come. Galex is but one step closer to unravelling the puzzle.
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#8
(04-Jan-2011, 12:20 PM)Azad Wrote: Recently i have been debating a few creationists, they have posted links from Roger Penrose's Probability calculations to show how uncertain the chain of events leading to a universe supporting life could be ? Cursing Infact the only instance i have heard Penrose was in this context.

The rebuttal is in the question itself, if a universe with life is highly uncertain then a life in the first place, complex enough to create life and universe should be even more uncertain.

The argument about the extremely-low-probability business reminds me of how Richard Feynman used to handle it. I cannot do better that quote Bill Bryson on this:

“The physicist Richard Feynman used to make a joke about a posteriori conclusions - reasoning from known facts back to possible causes. ‘You know, the most amazing thing happened to me tonight,’ he would say. ‘I saw a car with the licence plate ARW 357. Can you imagine? Of all the millions of licence plates in the state, what was the chance that I would see that particular one tonight? Amazing!’ His point, of course, is that it is easy to make any banal situation seem extraordinary if you treat it as fateful.”

The important thing is to make a distinction between something being possible or impossible. If it is possible, then no matter how improbable it is, Feynman’s licence-plate example can be quoted to make a point, say, about the validity of the anthropic principle.
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