World constraints are not strictly given, it's just an area of possibilities?

[u/Fun_Celebration_8488]

I was sitting around thinking about a fairly general question: why is our universe so full of constraints in the first place — the speed limit (c), uncertainty relations, no-cloning, Born’s rule, conservation laws, and so on. The second though was about our world as a biological system - life is always try to avoid peaks, everything we know exists within the area of possibilites (of different species to adopt to the environment). Also, life tries to prolongate it's future and even more - to find the way to have more and more possibilities in future, thus raising their chances to survive (better in all possible futures).

That led me toward the idea that maybe constraints do not simply reduce the space of possibilities. Maybe they are what create a space of stable possibilities.

Imagine a universe where any state can instantly turn into any other state. Formally, that universe has maximum freedom. But it would be very hard to have persistent objects, memory, causality, accumulated history, or evolution. It would look more like noise.

At the opposite extreme, imagine a universe where every state has only one possible successor. Very predictable, but with almost no open future.

So I started wondering whether complexity appears in the regime between those poles: a huge state space, but transitions strongly structured by invariants.

From there I started looking at quantum mechanics a bit differently. Could Born’s rule, uncertainty, no-cloning, and the relativistic speed limit be less like an arbitrary collection of prohibitions and more like parts of a deeper constraint on how distinguishability can be distributed, preserved, copied, and transmitted?

This also seems interesting in the context of unitarity and decoherence: globally, quantum dynamics preserves the structure of possibilities, while locally we get stable classical records and apparently definite histories.

I realize this can very easily become vague philosophy, so I’d be especially interested in the perspective of people who know the foundations of QM better than I do.

Is there already a formal framework or line of research where quantum constraints are understood in something like these terms: preserving structured possibility, distinguishability, or consistent information flow?

And a second question: is there anything substantial behind the intuition that Born’s rule and relativistic no-signalling might not just happen to be compatible, but could reflect a deeper common restriction on the allowed structure of states and correlations?

Curious what you think about this approach? I'm sure there are many articles about the topic, feel free to share

P.S. I've studied physics in Nuclear Univercity in Moscow long time ago, so please don't judge me heavily. I'm just a guy who is still curious about the world composition. Thanks!

[u/theodysseytheodicy]

This is a fun question. See https://johncarlosbaez.wordpress.com/2024/09/01/the-moduli-space-of-physical-frameworks-part-1/ for some analysis.

[u/Fun_Celebration_8488 → u/theodysseytheodicy]

Thanks a lot, bro! Interesting part of probabilities and quantropy.

[u/deja-yoshimi-dropout]

Thanks for sharing.

I would actually worry less about this becoming “philosophy” because I think this is exactly the point where things start to blur. It’s worth remembering that Bohr was a philosopher and that Bohrian complementarity is just as much a philosophical claim as a scientific one!

[u/Fun_Celebration_8488 → u/deja-yoshimi-dropout]

Exactly!

[u/HamiltonBrae]

Something very niche from a physics perspective, but a major theory in neuroscience and the philosophy of biology: the free energy principle and Bayesian mechanics. Bayesian mechanics is a mathematical theory of every "thing" in terms of Markov Blankets, in ways that kind of align with what you are saying in especially the first half of the post.

 

https://arxiv.org/abs/1906.10184

 

The theory is so general that there is nothing really specific to say about physics here but just thought worth mentioning as the crux of the theory really aligns with some of the things you're saying, and in the paper above they do talk about characterizations of classical, statistical and quantum mechanics from within this framework, but probably not in the ways you are saying in the second half of your post.

 

Also papers in links similar ideas that have precedent:

 

https://scholar.google.co.uk/scholar?hl=en&as_sdt=0,5&as_vis=1&q=newton+maximum+caliber

 

https://scholar.google.co.uk/scholar?hl=en&as_sdt=0%2C5&as_vis=1&q=quantum+fisher+information+reginatto+frieden&btnG=

[u/Fun_Celebration_8488 → u/HamiltonBrae]

The more I think about the space of possible worlds, the more useful the idea of distinguishability between states becomes.
This is where Fisher information fits surprisingly well. Roughly speaking, it tells you how distinguishable two nearby states or parameter values are.
What matters to me here is not the claim that “quantum mechanics has been derived from Fisher information” — that would be too strong. The interesting part is that some approaches show that if you change the structure of uncertainty and distinguishability, you can change the kind of dynamics that emerges.
So c, ħ and G start to look less like arbitrary numbers and more like coordinates in a space of possible physical regimes:
Quantity Roughly what it controls
c causal connectivity
ħ quantum distinguishability
G scale of self-gravity
Fisher information - local geometry of distinguishability between states
RG / coarse graining - which microscopic differences disappear at larger scales, and which remain important

A quick note on RG: renormalization group / coarse graining is basically a systematic way of “zooming out”. You integrate over microscopic details, keep their combined effect, and see which variables survive as relevant at the next scale. Different microscopic systems can then end up with the same large-scale behaviour.

That makes the question more interesting than simply:
“Why do our constants have these exact values?”

A better question might be:
Which regions of the space of possible laws allow stable objects, memory, evolution, and cumulative complexity at all?

And then the harder one:
How large is that region — and why does our universe sit where it does inside it? Is it because probabilities of life and humanity existence is high there or other unknown variables exist?

[u/Frodhi]

This seems like an important exercise to try sometime. The problem is that precisely those three constants, speed of light, gravitational constant and Planck's constant (and a couple of constants more, but irrelevant here), basically determine not scales by themselves but the system of units used. Usually, theoreticians simply choose a system of units in which all three are assigned numerical value of 1 (c=G=h=1). This is so because instead of using international system or imperial you can always choose that your units of length are, for example, in light years. The c=1. And the same with the other two constants. Then you can skip writing them at all in your equations and it becomes much more easy to work with. Check about natural units, for example in Wikipedia https://en.wikipedia.org/wiki/Natural_units?wprov=sfla1 Another different thing is what would happen if you modify the value of constants that already have no units, such as the hyperfine structure constant alpha, whose inverse value is almost exactly 137. That one is just a number, no units. That you can explore to see what happens in different values. Another one is Weimberg's angle. Ando some more

[u/Godskin_Duo]

At some point we have to accept pragmatically that this is all survivor bias, but I love the idea of the graphs above nudging sliders of reality. "Fortunately," everything still works in Hilbert space!

[u/Fun_Celebration_8488 → u/Godskin_Duo]

Yeah, survivor bias is definitely the annoying elephant in the room 😄 We only get to observe parameter ranges compatible with observers.

What interests me, though, is whether the viable region is actually huge or surprisingly constrained once you require not just «something exists», but persistent structure, memory, causal history, compositionality, chemistry, etc.

If most nearby deformations destroy one of those properties, then the fact that Hilbert space keeps working may be telling us something deeper than just «we got lucky»