Wed 29th: Could the laws of physics be evolving?

Here's a question that sounds simple until it isn't: does the moon exist when no one is looking at it?

Einstein posed a version of this to his colleague Abraham Pais, half in jest, walking home from the Princeton Institute. But embedded in that teasing question is one of the most unresolved problems in physics. Quantum mechanics, taken literally, seems to suggest that physical properties, position, spin, momentum, don't have definite values until something interacts with them. And the question of what counts as an interaction, and relative to what, turns out to be surprisingly hard to answer.

In the 1990s, physicist Carlo Rovelli proposed a radical way to take this seriously. His Relational Quantum Mechanics argues that the problem isn't that we haven't found the right interpretation yet, it's that we've been asking the wrong question entirely. We keep assuming that physical properties must have absolute values, sitting there waiting to be measured. Rovelli says: they don't. Properties only exist relative to other systems. There is no view from nowhere. There is no fact about what a particle is doing that isn't already a fact relative to something else.

This is strange. But it's also, in a certain light, deeply coherent. Think of velocity, we've known since Galileo that velocity has no absolute value. A train moving at 100mph is also stationary, relative to a passenger sitting inside it. Rovelli is suggesting something similar might be true not just of motion, but of all physical properties. His book Helgoland, named for the island where Heisenberg first had his quantum insight, is a beautiful place to start.

"The world is not a collection of things; it is a collection of events." — Carlo Rovelli

Here's the philosophical move worth pausing on though: relational doesn't mean subjective. Rovelli is careful about this. The fact that properties only exist relative to other systems doesn't mean anything goes. Relationships are real. Structure is real. What he's questioning is whether substance, some underlying stuff that properties attach to, was ever a coherent idea to begin with.

Which is exactly where a much older tradition enters the picture. Long before quantum mechanics, thinkers like Alfred North Whitehead and Henri Bergson argued that we've had reality backwards. We tend to assume it's made of things, and that process and change are what happen to those things. But what if it's the reverse? What if events and interactions are fundamental, and "things" are just stable patterns within those processes? Heraclitus, 6th century BCE, was already there: you cannot step into the same river twice, not because rivers are unreliable, but because both the river and you are processes, not objects.

"It is not the things that are real, but the events." — Alfred North Whitehead

This brings us to Lee Smolin, who has spent much of his career as a theoretical physicist asking a question that makes many colleagues uncomfortable: what if the laws of physics aren't fixed? What if they evolved?

His proposal, cosmological natural selection, suggests that universes reproduce through black holes, each inheriting slightly varied physical constants. Laws, in this picture, aren't eternal Platonic truths handed down from some mathematical heaven, they emerged, and they continue to evolve. His book Time Reborn makes an even bolder argument: that the block universe picture, where time is just another dimension and past, present, and future are equally real, is simply wrong. Time isn't an illusion to be explained away. It is the most fundamental thing there is. Change comes first. Laws are downstream of it.

"The laws of physics are not timeless. They, too, evolve." — Lee Smolin

What connects Rovelli and Smolin, despite their differences, is a shared suspicion of the idea that reality is a static, observer-independent structure of fixed things and fixed laws. Both are pushing physics toward something more dynamic, more relational, and both are nudging at a question Bernardo has been asking from a different direction entirely. If physical properties only exist in relation to other systems, and if the notion of a self-sufficient material substrate quietly dissolves the further you look, then what's left when you follow that thread all the way down? Bernardo's argument is that experience, which is inherently relational, always a matter of something appearing to something, might not be the anomaly that needs explaining. It might be the only thing that was ever really there.

The questions we'll sit with together:

• If physical properties only exist relative to other systems, is there any meaningful sense in which an observer-independent reality exists at all?
• What would it actually mean for physics to take process and time as genuinely fundamental, not emergent, not illusory?
• If the laws of physics evolved rather than being eternally fixed, what does that do to our picture of a rational, stable universe?
• Does the relational turn in physics point toward something like idealism, or just toward a more sophisticated materialism?

If you want to arrive curious:

• Helgoland by Carlo Rovelli — short, beautifully written, the best entry into relational quantum mechanics for a non-specialist.
• Time Reborn by Lee Smolin — his accessible argument that time is real and fundamental. The first few chapters are all you need to get the core idea.
• Carlo Rovelli on Closer to Truth — short clips covering quantum mechanics, time, and the nature of events.
• Lee Smolin's Perimeter Institute lecture on Time Reborn — roughly an hour, and covers his ideas on the reality of time and cosmological natural selection in a way that's genuinely exciting.

See you there!

Nour

Zoom Room

Wed 29th April
7-9pm UK / 8-10 CET / 2-4pm EST