Roger Penrose's Eternal Universe: the Escherian Stairwell

Could there be anything before the Big Bang? Does this question even make sense? The legendary British scientist Roger Penrose thinks it does. He has come to believe that the universe is eternal, and that our universe is just one aeon in an endless cycle, like an Escherian stairwell. An extraordinary view, more akin to the Hindu Rigveda philosophy of a universe eternally in flux.

The Standard Big Bang Model

Current-day standard cosmology has it that our universe began about 13.72 billion years ago with the Big Bang. Although the Big Bang theory gives an exceedingly accurate description up to the very early moments of our universe, the actual Big Bang itself (at time t₀) does not form a part of it. Extrapolations up to the Big Bang itself result in a singularity, which basically means that our scientific theories themselves break down and are no longer valid at that point. The Big Bang is considered as a singular boundary of information. Asking what might come “before” the Big Bang is a meaningless question, like asking what lies south of the South Pole.

Before the Big Bang?

But that doesn’t prevent scientists to keep on trying to wrap their heads around this “impenetrable barrier”. In 2010, the eminent British scientist Roger Penrose together with Vahe Gurzadyan claimed to have found evidence in the cosmic microwave background in the form of concentric circles that could possibly point to an era before the Big Bang. These circles are supposed to be a kind of gravitational ripples, resulting from colliding black holes in the “previous” universe, hereby providing us a window “beyond” the Big Bang. [1] It is comparable to ripples in a pond after you have thrown a heavy stone in it. Long after the stone has disappeared below the surface, you will still have a dissipating web of peaks and troughs, giving a clue as to what has happened.

Penrose has come to believe that there is an era before the Big Bang and, what is more, this era somehow gives rise to an extremely low degree of entropy, as a result of which entropy can steadily increase after the Big Bang. In his book Cycles of Time, Penrose extrapolates this idea even further: our universe is just one of many in an endless cycle, where each Big Bang initiates a new universe following the one before, each time resetting the entropy to an extremely low value. [2]  His cosmology reveals an eternal universe, reminiscent of an Escherian stairwell, endlessly going up and down at the same time.

At the very beginning: no mass, no metric, no time

Basically, Penrose’s reasoning boils down to the idea that as we rewind the movie of our universe and come very, very close to the Big Bang, the temperature and energies get so high as to render the rest mass of particles negligible and eventually to make it disappear altogether. But as this happens, we enter into a very strange phase of the universe. In Cycles of Time, Penrose goes to great lengths to explain that it is rest mass which determines the metric of the universe and which determines the rate of clocks. However, for massless particles, like photons, whizzing at the speed of light, there is no such thing as time. There is no “tick of the clock”, so to speak. It is very difficult to imagine, but for a massless particle, there is no difference between the instantaneous “now” and eternity.

When we enter this phase of the universe where there is no longer any rest mass, the metric of General Relativity no longer applies. The geometry of the universe becomes radically different. Instead of the metric of General Relativity, we have to use another kind of geometry, a so-called conformal geometry without a metric, i.e. without any distance.

The end of eternity

Next, Penrose envisages the very far future of our universe, long after the last star has gone out, and all the matter in the universe has eventually been swallowed by black holes. When the overall background temperature of the ever-expanding universe finally drops below the surface temperature of black holes, they will – very slowly – start evaporating due to Hawking radiation. As a result, still according to Penrose, all particles with rest mass will eventually decay into massless radiation. Once again, conformal geometry without distance, without the passage of time, will reign supreme.

From aeon to aeon

With a very ingenious mathematical construction using conformal geometry, Penrose maps the “end of time” (the era when there are only massless particles of radiation) to the big bang of a new era (with also nothing but massless particles). The vanishing of matter and time (and distance) results in a smooth conformal boundary of space-time from which a future universe will emerge. Our universe is but an aeon in an infinite sequence of aeons.

Very interestingly, the origin of Penrose’s extraordinary cosmological view has a curious personal twist. Gustaaf C. Cornelis, a Belgian philosopher of science specialised in the field of cosmology, recounts the story of Penrose giving an interview for the Dutch journal NRC-Handelsblad in 2011:

“In this [interview], he reiterated that in 2005 the thought of residing in a universe with only gravity waves and light particles remaining was depressing to such an extent that he was looking for a new interpretation framework.” [3]

Highly controversial

Let it be very clear: Penrose’s model is highly controversial and goes straight against the inflationary model which has gained wide acceptance over the years, and not without good reason for that matter: the inflationary model provides by far the best explanation of everything we can observe in the universe.

Roger Penrose himself is very aware of the fact that his model is not without serious difficulties. To name just one, his model presupposes that all matter in the universe (i.e. all particles with rest mass) will decay into massless radiation. It is still very far from clear that this will actually happen. [4]

But whether Penrose’s model is “true” or not, that doesn’t matter. Science is about building and searching for models, and weighing one model against the other against observational data, and not about deciding whether a model is “true” or “real”.

Theological curiosities

Although Penrose himself is an atheist [5], he is aware of the fact that his theory of an infinite cycle of aeons “is a bit more like Hindu philosophy” than the standard Big Bang theory, as he himself puts it. [6] Be that as it may, for him this is nothing more than a theological coincidence, a pleasing curiosity. [7]

Although this theological coincidence doesn’t play any role whatsoever in Penrose’s research, it can be easily imagined that an eternal cosmology in whatever form could be troublesome for some theologians. For instance, for the American Christian philosopher and theologian William Lane Craig, well-known from his public debates with renowned cosmologists like Sean Carroll, the idea that the standard Big Bang theory seems to favour an absolute beginning of the universe (which it doesn’t) plays a crucial role in his apologetics. Whatever the outcome might be, at the very least it shows that current-day cosmology for some theologians is found to resonate with the Christian account of creation.

Creatio continua?

Other theologians however will be quick to point out that even an eternal universe is not incompatible with the idea of a Creator. Even if there is no creation out of nothing, God can still be invoked as the ‘Ground of Being’, as the one who ‘sustains the world’, seeing the concept of creation as ‘allowing the universe to exist’ (cfr. the theological notion of creatio continua, continuous creation). The Dutch theologian and philosopher of religion Taede Smedes ingeniously tried to solve this conundrum by stating that the Big Bang theory neither confirms nor denies the idea of acreation from nothing, because scientific theories are theologically ambiguous. [8] We can easily extrapolate this statement to eternal cosmologies as well.

Metaphysical superfluity

However, stating that scientific theories are theologically ambiguous is very short of admitting that scientific theories are simply not in need of superfluous metaphysical or theological add-ons. The universe does not need anything to sustain it. ‘Being compatible’ with science is not enough to warrant the addition of supplements to scientific theories which do not have any explanatory value and are not needed to account for scientific evidence.

Relic of the past

Whether Penrose’s theory of eternal cycles of time is flawed or not, that is not the point. Currently there are at least a dozen competing models of eternal cosmologies, each of which runs into heavy criticism. And whatever model will turn out to gain acceptance over others will be decided upon by scientific criteria, not by religious ones. It is not up to religions to make claims about how the universe works.

What matters is that Penrose’s model is a completely self-contained scientific theory which accounts for the entire universe without having to rely on anything outside it. Insisting that having a completely self-contained scientific model which accounts for the observational data is not enough is a relic of an outdated view of the world, linked to an obsolete way of thinking, predating the era of science.

Notes

This blog post was originally published on January 14, 2016, at:

http://blog.associatie.kuleuven.be/alexandervanbiezen/roger-penroses-eternal-universe-the-escherian-stairwell/

[1] See Gurzadyan, V.G. and Penrose, R., Concentric circles in WMAP data may provide evidence of violent pre-Big-Bang activity, (November 2010) in

http://arxiv.org/ftp/arxiv/papers/1011/1011.3706.pdf (accessed January 11, 2016).

[2] Penrose, R., Cycles of Time. An Extraordinary New View of the Universe, London, Random House, 2010.

[3] Cornelis, G. C., Het geheim van de kosmologie ontrafeld. Ten dienste van een waarheid, Brussel, ASP editions, 2012, p. 320 (and footnote 1222, p. 409), my translation. A highly recommendable work on the scientific developments leading up to current-day cosmology, in Dutch (title: The Secret of Cosmology Unraveled. In Service of a Truth).

[4] To this day, it is not certain that electrons will ever decay, and recent research revealed that the minimum life span of electrons is at least 5 quintillion times the age of the current universe (6.6 x 10²⁸ years). See: Agostini, M. et al., Test of Electric Charge Conservation with Borexino, Phys. Rev. Lett. 115, 231802 – 3 December 2015,

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.115.231802 (accessed January 11, 2016).

[5] See the interview with Roger Penrose, Big Bang follows Big Bang follows Big Bang, BBC News, 25 September 2010, 

http://news.bbc.co.uk/today/hi/today/newsid_9032000/9032626.stm (accessed January 11, 2016).

[6] Brean, J., Sir Roger Penrose: Scientific Heretic, (7 October 2008),

http://www.uncommondescent.com/science/sir-roger-penrose-scientific-heretic/(accessed January 11, 2016).

[7] Ibid.

[8] See Smedes, T.A., God en de menselijke maat. Gods handelen en het natuurwetenschappelijk wereldbeeld, Zoetermeer, Uitgeverij Meinema, 2006, p. 111, in Dutch (title: God and the Human Dimension. God’s Acting and the Scientific Worldview)

Roger Penrose: Mathematics, Reality and God

                               Meeting Sir Roger Penrose in Brussels at the Vrije Universiteit Brussel (2009)

What is reality? That is the root question Roger Penrose ponders over in his book The Road to Reality from 2004. Can Penrose’s mathematical view of reality shed a new light on the discussion about science and religion?

The road to reality

Sir Roger Penrose (°1931) is a British mathematician and physicist who is mainly known for his pioneering work in the field of cosmology and the theory of relativity, collaborating with Stephen Hawking. [1] In The Road to Reality, over 1,100 pages long, Penrose comprehensively covers a broad range of subjects from contemporary physics, from the standard model of particle physics, the general theory of relativity, quantum mechanics and the big bang theory to his own approach, twistor theory, to arrive eventually at the question ‘What is reality?’.

The leitmotif

The leitmotif in Penrose’s view is his realization that everything in physical reality seems to correspond to very strict mathematical principles, with a precision that surpasses any imagination. [2] The most spectacular example Penrose gives us is PSR B1913+16, two very compact neutron stars in orbit around one another. Extremely accurate measurements of their gradually contracting orbit (through the emission of gravitational waves) has led to a correspondence between observation and the predicted value from the general theory of relativity to an astounding precision of 14 decimals. [3]

A deep mystery

Why there is such an unimaginably precise correspondence between physical reality and very sophisticated mathematical models is a deep mystery for Penrose for which he doesn’t have an answer. But the idea that mathematics would be a kind of mental net we cast over reality to order our experiences seems extremely unlikely to Penrose in the light of these discoveries. [4] Identifying physical reality with an abstract, platonic reality of mathematical forms is a bridge too far for Penrose. But “the more deeply we probe Nature’s secrets, the more profoundly we are driven into Plato’s world of mathematical ideals”. [5]

And God?

What do all these reflections from The Road to Reality have to do with the subject ‘science and religion’? At first sight: nothing. Save for one single exception Penrose never refers to God in this bulky work. [6] But precisely this fact sheds a surprising light on this theme. The mere fact that one of the most renowned scientists of our time has succeeded in writing a work of this size about the current view of realitywithout spending as little as one sentence of attention to this theme says quite a deal. You will have a hard time trying to find reflections about God, science and religion in the numerous books, articles and interviews of Roger Penrose. Even when asked about them explicitly, his answers remain very parsimonious. During an interview in 2005 he was asked whether his scientific work had had any influence on his belief in God, to which Penrose replied:

“God is a somewhat ill-defined concept and I very definitely do not believe in the traditional idea of God as shared by most people […] Science may have its limits, but if you want to know what is true in the world, you must rely on a scientific method. You can also go searching for truth in old books. Perhaps those old books have something important to say, but their writers did not necessarily have the knowledge offered by current science.” [7]

Science and ‘ultimate reality’

Roger Penrose is open to mystery, but in another way than one is possibly used to in religious circles. In Penrose’s work you will look in vain for philosophical or theological discussions about ‘ultimate reality’. No carefully wrought analyses of arguments and counterarguments of philosophers and theologians about what they might have to think of his view. Penrose nowhere explicitly denies the existence of God. But it’s simply not a question he is concerned about, the existence of God is not required in his worldview. When asked about it, he might perhaps answer, like in former times Pierre-Simon de Laplace, that he doesn’t need the hypothesis ‘God’. [8]

Continental drift

No matter how much some philosophers and theologians may agitate about a view like that from Penrose, the crucial difference is that Penrose himself does not delve into questions like these at all. Instead of collisions of worldviews (e.g. between naturalistic and theistic approaches to reality) we observe a “continental drift”. The world of modern science and that of traditional philosophy and theology (this last one very often still in an Aristotelian frame of reference) are slowly but certainly drifting apart. Religiously inspired explanations of reality are not refuted, but vanish slowly into the shadows. The question is not so much whether or not God exists. God may very well exist, if you would like. But rather: does the universe need God? That turns out to be less and less the case. [9]

Notes

This blog post was originally posted on July 25, 2015 at:

http://blog.associatie.kuleuven.be/alexandervanbiezen/roger-penrose-mathematics-reality-and-god/

[1] See e.g. Stephen Hawking & Roger Penrose, The Nature of Space and Time, Princeton, Princeton University Press, 1996.

[2] For instance, the experimentally measured value of the magnetic moment of an electron corresponds with the theoretically predicted value to a precision of 11 decimals. Richard Feyman compared this to measuring the distance of New York to Los Angeles to the accuracy of the thickness of a human hair (in QED. The Strange Theory of Light and Matter, Princeton, Princeton University Press, 1985 (repr. 2006), p. 7).

[3] To give an idea what that means: 1 to 10¹⁴, that is ten million times more accurate than the precision of Newton’s theory of gravity in the description of the movements of the celestial bodies in our solar system (“only” 1 to 10⁷). For this discovery, Joe Taylor and Russell Hulse received the Nobel Prize for physics in 1993.

[4] Roger Penrose, The Road to Reality. A Complete Guide to the Laws of the Universe, London, Jonathan Cape, 2004, p. 1027.

[5] Roger Penrose, ibid., p. 1028-1029.

[6] Roger Penrose, ibid., p. 754, where he uses the expression ‘act of God’ in a rather rethorical question about the precise initial conditions at the beginning of our universe, at the moment of the big bang.

[7] Bram Delen & Wim Gemoets, Penrose: schaken, computers en wc-papier, inVeto, year 31, number 13, 14 Februari 2005, p. 7 (in Dutch, my translation).

[8] Cfr. the famous statement of Laplace, when Napoleon asked him why his book about celestial mechanics contained no mention of the name of God: “Sire, I had no need of that hypothesis.”

[9] Originally published in Dutch in Geloof & Wetenschap, May 2015, http://www.geloofenwetenschap.nl/index.php/opinie/item/603-roger-penrose-wiskunde-werkelijkheid-en-god.html