My current take on (non)determinism in physical reality

Also: webinar on "Spirituality and the Moon," February 9.

Greetings to all readers and subscribers, and special greetings to the paid subscribers!

Please scroll down for the main topic of this newsletter. But first:

On February 9 I will participate in a webinar titled “Spirituality and the Moon,” organized by the Cultural Considerations Working Group of the Moon Village Association.

The webinar will be moderated by Remo Rapetti and Arthur Woods and last approximately one hour. Speakers:

• Giulio Prisco is a former space engineer and senior manager at European space administrations. In his book “Futurist spaceflight meditations” (2021), Prisco covers spaceflight and human expansion into space, with a special emphasis on cultural and spiritual aspects. Prisco’s thesis is that human expansion into the solar system, starting with outposts on the surface of the Moon and in cislunar space, is a cornerstone of emerging future spirituality. This new spirituality will, in turn, inform human expansion toward the stars.

• Catherine Newell is a scholar of religion and science who is particularly interested in the intersections of science, technology, culture, and spirituality. In her book “Destined for the Stars: Faith, the Future, and the Final Frontier” (2019), Newell traces the cultural and spiritual roots of US space exploration programs and argues that they were mainly inspired by a technological and scientific faith that awoke a deep-seated belief in a sense of divine destiny to reach the heavens.

• Jorge Mañes Rubio is an artist whose works rethink humanity’s relationship with the universe and all the beings that live in it. As Artist in Residence at the Advanced Concepts Team at the European Space Agency (ESA), Rubio designed a Moon Temple for a future lunar settlement in Shackleton Crater. The Moon Temple wouldn’t be associated with any specific religion. On the contrary, it would be open to everyone, in particular to the fast-growing category of people who describe themselves as “spiritual but not religious.”

I hope to see you guys at the webinar! Admission is free, please register via Eventbrite.

Picture from Pixabay.

Following the consideration in the previous newsletter I have been thinking of determinism and/or non-determinism in physical reality. Is the world a boring clockwork like the picture above, where everything is pre-determined (even in human brains) and only one possible future can happen?

Here’s what I say in the current draft of my book in preparation.

A key open question facing contemporary science is whether the world is fully deterministic. Is everything predetermined, or does the universe make choices? Is time real? Is change real? Are we free agents whose choices are not entirely determined by other parts of the world? Am I writing this sentence, or was it already written at the beginning of time?

Quantum mechanics and chaos theory seem to suggest that the world is not fully deterministic. But many top scientists suggest that, on the contrary, the world is fully deterministic and non-determinism is only apparent.

Many chaos theorists insist on deterministic chaos and point out that, while the evolution of a chaotic system is unpredictable, the system still follows mathematical laws that are well defined and deterministic. Many quantum physicists think that multiple versions of any observer (like you or me) live in parallel worlds (timelines) of a quantum multiverse, which is perfectly deterministic even though any single timeline appears non-deterministic to local observers in that timeline. Other ways to make quantum mechanics deterministic have also been proposed.

It seems evident that, in a fully deterministic world, there is no free will (though some people go to great lengths to argue otherwise). In a quantum multiverse, what happens in one timeline is not predetermined within the same timeline, but is still fully determined in the multiverse at large.

I’m not blind to the esthetic and emotional appeal of a fully deterministic and reversible universe where information is conserved. But my existential preference goes to a creative universe where genuinely new things happen and we are free agents endowed with free will. For me, following Nicolas Gisin, “not only does free will exist, but it is a prerequisite for science, philosophy, and our very ability to think rationally in a meaningful way.”

Having said that, I often think of ways to make existential peace with the idea of a deterministic universe. Stephen Wolfram’s ideas on computational irreducibility offer a way. Deterministic underlying rules “can lead to computationally irreducible behavior that for all practical purposes can seem to show ‘free will’”.

The idea is that, within the deterministic but chaotic mathematics of the laws of nature, the fastest way to know what will happen is waiting for it to happen. This seems equivalent to God’s transcendent knowledge of a future that is unknowable to us (even in principle). According to C. S. Lewis, God “simply sees you doing” what you will do tomorrow. Similarly, according to Wolfram, the actual evolution of the universe “can only be observed, not predicted.”

But do we only seem to be free agents for all practical purposes, or are we really free agents? Some would say that this question is misleading or even meaningless, but it is a natural question that needs to be answered.

Gisin has an interesting answer based on an interpretation of classical mechanics. Classical mechanics is deterministic only if initial conditions are specified as infinitely precise real numbers with infinite bits that are given all at once. But this is impossible, and unphysical. Most real numbers are infinite sequences of random bits, with infinite information.

Chaos theory shows that an infinitesimal change in initial conditions can, and very often does, make a big difference. Therefore, watching what actually happens is often the only way to determine more bits in the initial conditions. 

If a bit of information can’t be determined until a certain time, then it can’t be said to physically exist until that time. Gisin proposes to consider physically real numbers as physical processes, sequences of bits that unfold in real time. New bits are actualized when, and only when, physical facts require them. “The new digits really get created as time passes.” In some sense, instead of the past determining the future, it is the future that determines the past.

This idea, which can be generalized to all mathematical physics based on real numbers, makes non-determinism real. Not apparently real, not real for all practical purposes, but really, physically real. Gisin relates this idea to mathematical intuitionism, a somewhat Bergsonian and at the same time somewhat positivist approach to mathematics developed in the early 20th century. I think Gisin has a healthy perspective: it is our mathematics that must adapt to what really happens in physical reality.