Roger Penrose, the cyclical universe and philosophical pessimism

February 19, 2021

Roger Penrose, the cyclical universe and philosophical pessimism

It is always dangerous to look up to some kind of authority, be it religious, political or scientific, but that does not prevent one from having their preferences. Having said that, for some years I have been following certain publications and interviews made by Roger Penrose, one the three winners of the 2020 Nobel Prize in Physics.

My biggest interest is in one of Penrose's most recent works, which is exposed in the book Cycles of Time. Penrose and other physicists were dissatisfied with certain aspects of current cosmology, so they started looking for empirical evidence that would show that our universe is but one universe in a chain that extends infinitely into the past and future. He didn't win the Nobel Prize for the work which will be discussed in this article, but for his great theoretical contributions on the nature of black holes, which were confirmed. I was very much pleased to see him win the award a few weeks after sending some of his lectures to my father.

Cosmic background radiation, image produced using the ESA's Planck satellite

It's important to make an observation before continuing:

His idea of many universes has nothing to do with the idea of a multiverse (HORGAN, 2014; SOKO, 2017). It also has nothing to do with the famous “many-worlds interpretation” formulated by Hugh Everett, which denies the collapse of wave function in quantum mechanics by postulating that the position observed by particles is real, and that all probabilities exist in “different worlds” (BALL, 2018). In quantum mechanics, the most adopted interpretation is that of Niels Bohr, known as the Copenhagen interpretation. It states that the location of certain particles is probabilistic and it collapses once it's definitive state is observed. But this generates a series of problems that other interpretations try to solve — Everett's interpretation, for example, was one of them.

Continuing:

The hypothesis raised by Penrose (2010) and his colleagues is called Conformal Cyclical Cosmology, abbreviated as CCC. The gist of the CCC is basically the following:

1. The most advanced observations we have of the universe, made via satellites such as the WMAP, together with other instruments that measure the background radiation left by the Big Bang (observations that fit well with extremely specific theoretical predictions), indicate that the universe will continue to expand faster and eternally. Cosmologists and physicists in general attribute this expansion to the influence of dark energy, which slowly but surely expands the very fabric of space-time;

2. This expansion won't be extreme enough in order to produce the scenario known as the Big Rip, which is when all of the most elementary particles and even space-time itself are ripped apart due to the ever increasing acceleration of the expansion. However, the acceleration of the expansion will produce another end for our universe: the scenario called Heat Death, which will occur when the entropy of the entire system reaches a maximum point and work can no longer be performed in the universe (PENROSE, 2010; PIMBLETT, 2015; FALK, 2020). Other scenarios that could occur have been discarded by observations, at least for now — scenarios such as the Big Crunch, in which the mass of the universe would make it collapse in itself in the future, creating the same singularity that existed in the beginning of time, before the Big Bang (maybe even producing a new universe). The collapse of the universe into a new singularity would occur only if we didn't have a force that produces an ever faster expansion of space-time — the already mentioned dark energy, which is basically the cosmological constant proposed (and discarded) by Albert Einstein;

3. The Heat Death and maximum entropy will only occur after all stars in the universe go dark — becoming white dwarfs, black holes or something else, depending on their mass and composition. Physicists know that if the amount of dark energy and the expansion of the universe we currently observe remain about the same, the last active phenomena in the universe will be black holes. But even they will die after an extraordinary amount of time. When the most massive black holes finally evaporate due to Hawking radiation, the universe will enter its last and eternal phase, according to cosmologists. Although we cannot observe the phenomenon of black hole evaporation because it takes an enormous amount of time, Stephen Hawking showed in his equations that they slowly emit radiation and lose mass. The final phase of the universe will be composed of fundamental particles and photons, all moving in the speed of light in an empty and random void;

4. Penrose and his colleagues assume that, in the extreme future, all elementary particles will decay, including protons — this, however, has never been observed, but a considerable amount of physicists believe it will happen in the extreme future. Penrose also assumes that black holes destroy all the information that they swallow, something that his late colleague, Stephen Hawking, also agreed (but Hawking changed his mind about this a few years before his death). If these two conditions hold, the only things left in the universe after the evaporation of the last black holes will be photons and other elementary particles without mass — and here is where the geometrical conformity comes into play in the CCC hypothesis. In physics, time needs objects with mass to have any meaning. A universe composed only by photons and mass-less particles becomes invariant relative to its size, regardless of how big it was before. It stops being infinitely large and becomes infinitely small, since without a way to measure time, there is no space: all of the sudden, all particles and photons that were left in the universe occupy an immensely small space, just like the Big Bang that produced our universe.

5. Penrose demonstrates through several calculations that, in the extreme future, if black holes destroy the information they swallow and if all elementary particles lose their mass, the infinitely large will become infinitely small. These are the same conditions that existed during the Big Bang that gave birth to our universe, something that would produce an infinite number of universes that expand forever and go through the same process of geometrical invariance in the far future.

He points out that, although Einstein's general relativity implies that our universe had minimum entropy in its beginning, observations show that, at least in relation to matter, there was maximum entropy, contrary to what is expected (PENROSE, 2010). What changes the scenario is gravity: gravity is what wasn't in thermal equilibrium in regards to all the rest — gravity existed in such a way that it allowed the beginning of everything, something that has yet to be theorized or explained in a satisfactory manner, Penrose argues. The presence of gravity and the fact that it was not in thermal equilibrium in the beginning of our universe is something he tries to explain in his CCC model: according to his hypothesis, such gravity is carried over from a previous eon, which had the same end as ours will have in the far future.

Penrose (2010) tries to solve a big cosmological problem here: the idea that there was a rapid space-time expansion immediately after the Big Bang, called “inflation” by cosmologists. The idea of inflation arose to explain inconsistencies in the empirical data of the background radiation left by the Big Bang — which was best observed by satellites such as the WMAP, as I mentioned earlier. Besides that, Penrose also admitted he wanted to reconcile the idea of a static state universe, which was still in vogue when he began studying in Cambridge, with the extremely successful theory of general relativity. It's worth noting that the work on black holes for which Penrose won the Nobel Prize in Physics is completely based on general relativity.

The background radiation we observe using satellites and high precision instruments is nothing more than the first image we have of the universe. It was made when it had about 300,000 years — the universe now has about 14 billion years (PENROSE, 2010). When we compare this first afterglow with the images of the universe today — that is, with the most recent light captured by our telescopes —, we notice that parts of the observable sky are extremely homogeneous with the opposite side of the sky, something that should be impossible today if we used the standard model of cosmic evolution.

The dispersion of energy and matter in the universe would have to be faster than light in the beginning of the universe for this to be possible. However, in the 1980's, physicist Alan Guth proposed the idea of extreme space-time “inflation”, which would have occurred a short time after the Big Bang (SOKOL, 2017). But the inflation also ceased rapidly, without leaving behind evidence of how it occurred. Inflation solves the homogeneity problem we observe, but it is also a source of tremendous doubts and problems.

Many physicists, including a few of the ones that advanced the idea of inflation in the beginning, such as Paul Steinhardt, believe that the concept of a primordial cosmic inflation served as a well founded crutch, but that it can and should be substituted by better and testable ideas (HORGAN, 2014; SOKOL, 2017). Penrose's CCC model helps solving the problem, because it eliminates the necessity of an exotic inflation after the Big Bang. The Big Bang itself would only be an event marking the passage between a previous universe and ours.

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Penrose's book, Cycles of Time, has incredibly palatable parts, but in general it is a tremendously difficult read, since he insists in using formulas and complex mathematical examples. However, when we add the content of the book with classes and expositions given by Penrose that are available on the internet, the idea behind the CCC model becomes easier to understand.

Having talked about the CCC and its implication — a universe that expands eternally, but recycles itself after reaching maximum entropy in the extremely distant future — I will now relate the model to the negative thought of philosophers such as Arthur Schopenhauer (2015) and Emil Cioran (1990).

Trying to understand how the physical universe behaves itself — how it is ruled by certain laws — helps human understanding and, in turn, makes us capable of positioning ourselves within reality and evaluate our experiences as mortal beings either as positive or negative. For an animal whose only purpose is to reproduce and accumulate goods, it might not make much difference knowing if the universe had a beginning and will have an end, or whether or not the universe is eternally recycled. But for a thinking being such as Roger Penrose, it makes a lot of difference. It also makes a huge difference to me and to all of those who study philosophy, I presume.

I think the way Penrose explains the possibility of the CCC model being correct is elegant. The idea of a universe without beginning or end appeals to reason, in opposition to the notion of a universe that practically appears ex nihilo starting at the Big Bang, and ending in a definitive way after it reaches maximum entropy. However, in light of negative philosophy or philosophical pessimism, that is, in light of what Arthur Schopenhauer, Emil Cioran, Julio Cabrera and David Benatar thought and wrote about reality, it would be better if the cyclical hypothesis was wrong.

It is unlikely we will ever discover exactly what occurred before the background radiation was emitted when the universe was only 300,000 years. We'll probably never have any empirical verification of what in fact occurred before, even though Penrose has proposed some ways to make observations in the last few years (CARTLIDGE, 2018). In spite of this, the pessimistic interpretation invites us to prefer the non-cyclical alternative. In light of negative thought, the best scenarios for our universe would be the Heat Death (maximum entropy, something that so far has been corroborated by observations) or the Big Rip (the destruction of the fabric of space-time by an expansion that accelerates faster and faster, a scenario that has been apparently discarded).

Any different scenario — be it the CCC model and its eternal expansion that engenders geometrical invariance or a universe that recycles itself after collapsing into new singularities over and over again — opens up the possibility of always existing a universe where the laws of nature allow for the emergence of life and, with it, the evolution of the species and the creation of an absurd amount of pain, such as the pain that has existed on planet Earth since the first sentient organisms.

Considering the perspective of pessimist philosophies as correct, it would be tremendously unfortunate if scientists discovered concrete evidence that our universe contains countless other life forms on different planets. That would mean that the entire process repeats itself constantly in different places. If life is not concentrated on our planet, then the pain might be virtually infinite throughout the cosmos. In a universe in which there is a more or less “well defined” beginning and end, even if the period in which life is possible amounts to hundreds of billions of years, there exists the consolation of eternal nothingness in the far future. If there's a beginning and a definitive end to our universe, we can at least be consoled by the fact that one day all of this will reach and remain forever in a state of maximum entropy.

Someone might argue that preferring a non-cyclical universe is not a philosophical posture, but a psychological one, since philosophy (supposedly) does not deal with preferences and valuations. But, even if one argues this, it is perfectly clear that all humans spend their days preferring that things occur in one way instead of the other. It's the way we are. For example: many prefer to believe that the human world is part of a historical mechanism of constant betterment of mankind — and many of them argue that this belief is scientific.

But, when we take into account the contemporary concept of science, neither the preference for a non-cyclical universe — a preference based on philosophical pessimist interpretations — nor the preference that our human world will become a utopia are truly scientific. Even so, preferring a universe that reaches maximum entropy after trillions of years and never recycles itself is based on a more fundamental feature of reality: lacking as the basic condition of all organisms, be them plants, single-celled, or animals. In its most primordial form, this lacking is expressed in the universal necessity for nutrition and reproduction faced by all organisms, even those that do not possess pain receptors, such as plants.

In the case of sentient beings, beings that possess at least some rudimentary form of consciousness that allows them to feel pain, this basic lacking that every life form has turns suffering and boredom into fundamental aspects of reality. Such aspects can turn reality into a nightmare for sentient beings, unless they surround themselves with illusions and fantasies, something that humans tend to do (CIORAN, 1990; CABRERA, 2018). Despite his metaphysical formulations, Schopenhauer (2015) relied on observations of the world in order to argue for the idea of lacking as an insidious mechanism of nature, a mechanism that is employed so that we have no choice but to seek survival. I agree with this interpretation.

If the animals that live brutal lives in the African savannah or in the Amazon rainforest were suddenly and magically equipped with our intelligence and capacity of reflection, I believe that they would all agree that the mechanism of life is insidious. But this will never happen. We can speculate that the evolution of the species will be capable, in the future, of producing the phenomenon of intelligence and deep reflection again in other animals. But the process takes a long time and, like us, these potential future rational animals would certainly develop the same defense mechanisms that act against the complete futility of life (CABRERA, 2018).

Like us, these potential future rational animals would be programmed to survive and would end up inventing all kinds of excuses in order to continue procreating in this burning house. As Schopenhauer noted, when it comes to procreating humanity doesn't rely only on reason. Those that have a negative view of life and don't procreate — and even those who commit suicide before procreating — do not pass on their genes, therefore, there will always be a tendency to have more rational animals embracing life than denying it (BENATAR, 2017).

by Fernando Olszewski

References:

BALL, Philip. Why the Many-Worlds Interpretation Has Many Problems. 2018. Available at: https://www.quantamagazine.org/why-the-many-worlds-interpretation-of-quantum-mechanics-has-many-problems-20181018/.

BENATAR, David. The Human Predicament: a candid guide to life's biggest questions. Oxford: Oxford University Press, 2017.

CABRERA, Julio. Mal-estar e moralidade: situação humana, ética e procriação responsável. Brasília: Editora Unb, 2018.

CARTLIDGE, Edwin. New evidence for cyclic universe claimed by Roger Penrose and colleagues. 2018. Available at: https://physicsworld.com/a/new-evidence-for-cyclic-universe-claimed-by-roger-penrose-and-colleagues/.

CIORAN, Emil. De l’inconvénient d’être né. Paris: Gallimard, 1990.

FALK, Dan. This Cosmologist Knows How It’s All Going to End: the astrophysicist and social media phenom Katie Mack is ready to tell you about the fate of the universe. The astrophysicist and social media phenom Katie Mack is ready to tell you about the fate of the universe. 2020. Available at: https://www.quantamagazine.org/how-will-the-universe-end-katie-mack-explains-20200622/.

HORGAN, John. Physicist Slams Cosmic Theory He Helped Conceive. 2014. Available at: https://blogs.scientificamerican.com/cross-check/physicist-slams-cosmic-theory-he-helped-conceive/.

PENROSE, Roger. Cycles of Time: an extraordinary new view of the universe. London: The Bodley Head, 2010.

PIMBBLET, Kevin. The fate of the universe: heat death, big rip or cosmic consciousness? heat death, Big Rip or cosmic consciousness? 2015. Available at: https://theconversation.com/the-fate-of-the-universe-heat-death-big-rip-or-cosmic-consciousness-46157.

SCHOPENHAUER, Arthur. Parerga & Paralipomena: short philosophical essays, vol. 2. Cambridge: Cambridge University Press, 2015.

SOKOL, Joshua. A Cold War Among Cosmologists Turns Hot: two camps of theorists are bickering in public, with one saying the others' ideas don't even qualify as science. Two camps of theorists are bickering in public—with one saying the others’ ideas don’t even qualify as science. 2017. Available at: https://www.theatlantic.com/science/archive/2017/05/a-cold-war-among-cosmologists-turns-hot/526329/.