Astrophysicists' humility sets appropriate tone

A notable headline in The Guardian a few days ago: "The big idea: Why the laws of physics will never explain the universe".

Notable is the humility of  the author of the piece, Andrew Pontzen, Professor of Cosmology at University College London (UCL), in what is presumably an excerpt from his new book The Universe in a Box: A New Cosmic History. This acceptance of the complexity of the world as beyond our grasp, both in the immediate and long term, may arise from his and other astrophysicists' struggle to comprehend the unseen dark matter. Of this he writes on the UCL profile:

My work focuses on understanding dark matter – a mysterious component of the universe that is hypothesised to drive the formation of galaxies and other structures. While little is known about the nature of dark matter, the basic idea of an invisible sector interacting through gravity with what we can see has been highly predictive. Over the last 20 years, the dark matter hypothesis has generated a huge number of correct predictions about both the present day universe and the ancient "cosmic microwave background" light.

Until the true nature of dark matter is identified, the resulting picture will remain tentative. My team's work focuses largely on using the visible universe to help us to understand better how the invisible sector operates. This is essential if we are to connect our expanding knowledge of the night sky to fundamental physics experiments performed here on Earth. Ultimately this work should point us to a fuller understanding of the basic building blocks of reality.  

The science of the stars is young so it is to be expected that we struggle to achieve "a fuller understanding of ... reality". That struggle is expressed also in the title of  a recent book by the prominent cosmologist, Lawrence Krauss, titled, The Known Unknowns: The Unsolved Mysteries of the Cosmos.  

In this text Krauss writes:

I think that key to the humility of these leading scientists, who put many others to shame, is this from Krauss just quoted: "The imagination of nature is far greater than the imagination of humans".

Ponzten, likewise, is captivated by the immensity, but also the subtlety, of what we find in our domain:

It is hard to come to terms with the sheer scale of space: hundreds of billions of stars in our galaxy and, at a minimum, trillions of galaxies in the universe. But to a cosmologist there is something even more intriguing than the boggling numbers themselves, which is the question of how all these stars and galaxies were created over a period of 13.8 billion years. It’s the ultimate prehistoric adventure. Life cannot evolve without a planet, planets do not form without stars, stars must be cradled within galaxies, and galaxies would not exist without a richly structured universe to support them. Our origins are written in the sky, and we are just learning how to read them.

It once seemed that, for all its immensity, the cosmos could be understood through the application of a small number of rigid physical laws. Newton encapsulated this idea, showing how apples falling from trees and planetary orbits around our sun arise from the same force, gravity. This kind of radical unification of earthly and heavenly phenomena survives in modern teaching: all the innumerable molecules, atoms and subatomic particles in the universe are expected to obey the same set of laws. Most of the evidence suggests that this assumption holds true, so it should follow that perfecting our understanding of these laws will resolve any remaining questions about cosmic history.

Yet this is a logical fallacy. Even if we imagine that humanity will ultimately discover a “theory of everything” covering all individual particles and forces, that theory’s explanatory value for the universe as a whole is likely to be marginal. Over the course of the 20th century, even as particle physics revealed the secrets of atoms, it became clear that behaviour at the macro level cannot be understood by focusing exclusively on individual objects.  

Pontzen refers to insects, ants in particular, as failed models of the way the universe operates because their sophisticated cooperation is not repeated in the highest macro level:

The solar system, seemingly the epitome of clockwork predictability, has an uncertain long-term future for this reason. In isolation, a single planet around a single star would orbit indefinitely but in reality there are multiple planets and they each tug, albeit very subtly, on the others. Over time a series of tiny nudges can produce a major effect, one that takes an inordinate amount of calculation to predict.

Solar system simulations disagree because no calculation can perfectly account for all the influences, and even the tiniest disagreement about the individual nudges leads eventually to a completely different outcome. It is an example of the phenomenon known as chaos, and it is simultaneously exciting and worrying. Exciting, because it shows that planetary systems can exhibit much richer behaviours than the cold, lifeless law of gravity might suggest. Worrying, because if even the solar system is chaotic and unpredictable, we might fret that attempting to understand the broader universe is a doomed enterprise.

Take in how Pontzen rejoices at the extravagance of it all, the galaxies in "lavishly varied their shapes, colours and sizes":

Consider galaxies, on average tens of millions of times larger in extent than the solar system, and lavishly varied in their shapes, colours and sizes. Understanding how galaxies came to be so diverse requires, at a minimum, for us to know how and where the stars formed within them. However star formation is a chaotic process in which diffuse clouds of hydrogen and helium slowly condense under gravity, and no computer is anywhere near able to track all the required atoms (there are around 10⁵⁷ in our sun alone). Even if the computation were feasible, chaos would magnify exponentially the tiniest uncertainties, forbidding us from obtaining a definitive answer. If we were strict in sticking to traditional laws of physics as an explanation for galaxies, here is the end of the road.

To fit inside computers, a simulation of a galaxy’s formation has to lump together vast numbers of molecules, describing how they move en masse, push on each other, transport energy, react to light and radiation, and so on, all without explicit reference to the innumerable individuals within. This requires us to be creative, finding ways to describe the essence of many different processes, allowing for a range of outcomes without obsessing over the detail, which is anyway unknowable. Our simulations necessarily rely on extrapolations, compromises and all-out speculations developed by experts. The uncertain parts cover not just stars, but black holes, magnetic fields, cosmic rays and the still-to-be-understood “dark matter” and “dark energy” that seemingly govern the overall structure of the universe.

This will never result in a literal digital replica of the universe that we inhabit. Such a recreation is just as impossible as a precise forecast for the future of the solar system. But simulations based even on loose descriptions and best guesses can act as a guide, suggesting how galaxies may have evolved over time, enabling us to interpret results from increasingly sophisticated telescopes, guiding us on how to learn more.

Ultimately, galaxies are less like machines, and more like animals – loosely understandable, rewarding to study, but only partially predictable. Accepting this requires a shift in perspective, but it makes our vision of the universe all the richer.

The richness of what we have to intrigue us as humans can't help but suggest an intelligent generosity that even incorporates the "chaos" that poses such a challenge to scientists. Moreover, what we have learnt has driven "many physicists [to] consider the supernatural design hypothesis to be just as reasonable and responsible as the multiverse for explaining the occurrence of our highly improbable anthropic universe" (Spitzer 2015). 

Spitzer, who has written deeply on science and the evidence it lends to acknowledging the existence of God, finds the works of Hawking and Dawkins, for example, no obstacle. The first said this:

"Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?" (A Brief History of Time, p174).

Whereas the second argued in The God Delusion (p157-158) that a Creator-supernatural designer would have to be more complex than anything it could create, and therefore it was improbable, the Christian thinking is of God as pure Being, which means on Dawkins' terms that "absolute simplicity (the absence of complexity) must be the most probable of all states of affairs" (Spitzer p319). Spitzer continues that when Dawkin's argument is corrected in this fashion, "he presents us with a strong indication of God ‒ not the invalidation of God" (ibid).

A final reflection:

For the moment, we can conclude that current physical evidence certainly does not point away from God. Indeed, it comes so close to establishing a beginning of physical reality and an intelligent influence in the setting of our universe's initial conditions and constants that physicists are being pushed to the threshold ‒ and even beyond the threshold ‒ of metaphysics, into the domain of "nothing", purely intelligible realities, and the source of multiversal finetuning. This foray into metaphysics is not done out of sense of curiosity, but out of a desire to avert the implications of transphysical causation; and so it seems that physics has not explained away transphysical causation, but rather is opening the door evermore widely to an intelligent, transtemporal, causative power (Spitzer 2015 p319).

Ω Robert Spitzer, The Soul's Upward Yearning: Clues to our Transcendent Nature from Experience and Reason (San Francisco, Ignatius Press, 2015).

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