## 0) The full thought process (your idea, stated clearly and in order)
You were building a single “Darwin-like” picture of quantum physics:
1) **Entanglement looks like a connection across distance.**
If systems **A** and **B** are entangled, then “when A changes, B updates” (even far away).
2) **If B updates, B should affect its surroundings.**
In real physics, properties like **spin, polarization, frequency/energy, etc.** can change how something interacts with what’s around it.
So you asked: *if entanglement updates B, shouldn’t B’s environment respond?*
3) **But everyone says entanglement can’t transmit influence or information. Why?**
You suspected the “limits might be wrong,” because the update feels real.
4) **How do we even prove entanglement?**
Do we need to measure both sides “at the same time”?
Do we need to change both A and B together to keep them entangled?
Or can we operate on one side only?
5) **Is entanglement only about spin / 0-and-1?**
Or are there other entangled properties, maybe “more physical,” that could influence surroundings differently?
6) **Quantum computing is hard because observation changes the state and errors are everywhere.**
You asked whether this resembles **competition between states** (many possibilities “fight,” one persists), which sounds Darwin-like.
7) **What about nuclear physics (fusion/fission)?**
Spin matters in nuclear reaction channels.
Could changing spin “mid-process” produce different reaction paths?
Could entanglement + nuclear reactions create a Darwin-like selection mechanism?
8) **If we zoom out to the whole universe (black holes, expansion, creation of matter):**
could deep entanglement networks create “chaos somewhere else,” analogous to Darwinian influence in physics?
9) **Bottom line request:**
*What is the closest experiment (and thought experiment) where quantum physics truly behaves “Darwin-like,” and what would count as proof?*
This post answers *all of those* while keeping the “Darwin” intuition intact—but separating correlation from causation.
---
## 1) The central correction: entanglement is **correlation**, not a **remote control wire**
### 1.1 What entanglement really gives you
Entanglement gives you **strong correlations** between outcomes when A and B are measured and later compared.
A simple mental model:
- If A and B are entangled and you measure the “same kind of thing” on both sides, you can get results like **up–down, up–down** (or **up–up, down–down**) in a very strict pattern—stronger than any classical “shared random seed” can reproduce.
### 1.2 What entanglement does *not* give you
Entanglement does **not** let you do this:
> “I choose an action on A, and that forces a detectable local change in B (and therefore in B’s environment), without sending any normal signal.”
This is the **no-signaling / no-communication** constraint: local actions on A cannot be used to transmit controllable information to B.
A clean reference statement: the *no-communication theorem* (often presented as the no-signaling principle).
See overview: https://en.wikipedia.org/wiki/No-communication_theorem
### 1.3 Why your “B must influence its environment” step doesn’t follow
You were reasoning:
- If A “updates” B, and
- B is sitting in an environment,
- then the environment should react differently.
The subtle point is that the “update” you get from entanglement is mainly a **relationship update** (correlations) that becomes usable **only once outcomes are compared**.
Locally, B still looks statistically the same *until* B receives ordinary information from A (light-speed classical communication).
**Important:**
- The update is *real* in the joint statistics.
- But it does not become a controllable, local “push” at B.
---
## 2) “But mathematically we know B changed”—what that means (without heavy math)
You said: even if we don’t measure, we can “mathematically know” the joint state changed, so B “is changing.”
Here is the clean version that preserves your thought but fixes the inference:
- Quantum theory lets you describe the **global A–B state** and the **local B-only description**.
- Acting on A can change the **global correlations**.
- But B’s **local description** (the part that determines how B interacts with nearby stuff) does not become controllably different just because you did something at A.
So the statement “B changed” can be true in the sense of *global correlation structure*, while still being false in the sense of *local detectable behavior at B*.
---
## 3) The “technical term you forgot”: entanglement (and why people also mention steering)
When you described “two distant systems where a change here changes what we can say about the other side,” the main term is:
- **Entanglement** (shared nonclassical correlations).
A related term that sometimes matches people’s intuition is:
- **Quantum steering**: by choosing what you measure on A, you can “steer” the *conditional ensemble* you would assign to B.
But crucially, B still cannot tell which ensemble it is in without classical information from A—so no remote control is created.
(For your purposes: entanglement is the essential term; steering is a refinement.)
---
## 4) How we *prove* entanglement (and whether we must “change both sides at the same time”)
### 4.1 What counts as proof in the lab
Operationally, the gold standard is:
- measure A and B in multiple settings,
- show correlations violate a **Bell inequality** (often CHSH).
A canonical “loophole-free” Bell test:
Hensen et al. (2015, *Nature*): https://www.nature.com/articles/nature15759
### 4.2 Do we need to measure at the same time?
Not “same time” in the everyday sense, but in the cleanest Bell tests you arrange:
- the setting choices are independent and made late,
- and the measurement events are spacelike separated,
so ordinary signals cannot coordinate the results.
That eliminates classical coordination as an explanation for the observed correlation strength.
### 4.3 Do we need to operate on both sides to keep entanglement?
No.
- You can do many operations on **one side** (unitaries/rotations) and keep entanglement.
- A **measurement** on one side typically turns entanglement into a classical correlation (because measurement creates a definite outcome record).
So you *can* act on one side—but you cannot use that to impose a controllable, locally detectable change at the other side.
---
## 5) Is entanglement only spin / “0 and 1”?
No. Spin is just the easiest story.
You can entangle many kinds of degrees of freedom:
- photon polarization,
- path (which route),
- time-bin (early/late),
- frequency/energy,
- orbital angular momentum,
- vibrational/collective modes, etc.
Also, systems need not be restricted to two levels:
- **qubits** are 2-level because they are convenient,
- but **qudits** (d-level) and continuous-variable entanglement exist.
**Key point for your argument:**
Different degrees of freedom can influence their local surroundings in different ways—**but none of them let A remotely control B’s local statistics** (no-signaling still holds).
---
## 6) Why quantum computing “feels Darwinian” (and what part of that is real)
You connected two facts:
- In quantum computing, **observation changes the state**.
- Decoherence and noise create errors; keeping superpositions is hard.
This does resemble a kind of “selection”:
- many quantum possibilities exist,
- the environment tends to destroy delicate superpositions,
- stable patterns survive longer.
But this is not biological Darwinism:
- there is no open-ended adaptation,
- no evolving population of templates,
- and no accumulating design.
Still, your intuition is pointing to the right physics: **environmental monitoring filters states.**
And that leads directly to the main Darwin-like framework in quantum foundations:
> **Quantum Darwinism.**
---
## 7) The Darwin-like mechanism in quantum foundations: Quantum Darwinism (selection + replication of records)
### 7.1 The core idea (plain language)
Quantum Darwinism (Zurek and collaborators) says the environment does two linked things:
1) **Selection (einselection):**
Interaction with the environment picks out “pointer states” that are robust (they persist under monitoring).
2) **Replication (redundant records):**
Information about those pointer states gets copied into **many independent fragments** of the environment—so many observers can each read a different fragment and still agree on the same “classical fact.”
Foundational reference:
Zurek (2009) “Quantum Darwinism”: https://arxiv.org/abs/0903.5082
Intuitive “everyday environment” model: scattered photons create huge redundancy:
Riedel & Zurek (2010, PRL): https://link.aps.org/doi/10.1103/PhysRevLett.105.020404
Operational redundancy definition/analysis:
Zwolak & Zurek (2017, PRA): https://link.aps.org/doi/10.1103/PhysRevA.95.030101
### 7.2 Why this matches your Darwin analogy better than entanglement alone
Your Darwin mapping becomes:
- “Variants” = quantum alternatives in a superposition.
- “Selection pressure” = decoherence/monitoring by the environment.
- “Survivors” = pointer states (stable under that pressure).
- “Replication” = many environment fragments record the same pointer information.
This is *exactly* the Darwin-like story you were searching for: not remote causal influence, but **local selection + copying of information into surroundings.**
---
## 8) The Darwin-like *thought experiment* that matches every piece of your proposal
You asked for:
- entanglement,
- two distant systems,
- each embedded in surroundings,
- where the surroundings show a Darwin-like “reaction,”
- and a clear way to test/verify it.
Here is the cleanest version that preserves your intent while respecting no-signaling:
### “Two-Wing Quantum Darwinism” Thought Experiment
**Step A — Start with entanglement**
- Prepare two systems, **A** and **B**, in an entangled state.
**Step B — Give each system its own environment**
- A interacts locally with environment **E_A**, made of many fragments (many ancilla qubits, many photon modes, etc.).
- B interacts locally with environment **E_B**, also made of many fragments.
- No cross-talk between the wings: only A↔E_A and B↔E_B.
**Step C — Let the environments ‘monitor’ a preferred property**
- The interaction is such that it “measures” (monitors) a particular property (the pointer property) on each side.
- This suppresses fragile superpositions (selection).
**Step D — Record proliferation**
- The pointer outcome gets copied into many fragments of each environment.
- Many independent observers can sample different fragments and reach the same conclusion (replication + objectivity).
**What you have achieved**
- You used entanglement (your “connection” idea),
- but the Darwin-like part happens locally:
- environments select and
- environments replicate records.
**What you do *not* get (and why)**
- You do not get “A causes B’s environment to react differently,” because that would be remote control and would violate no-signaling.
Instead, you get something subtler and closer to your “Darwin” picture:
- *quantum correlations exist globally,* but
- *classical reality emerges locally via selection + redundant copying into surroundings.*
---
## 9) What would count as proof? (the experiment-style signature)
You asked specifically for “experiment chance to prove it.”
Quantum Darwinism is not “just decoherence.” The key observable claim is:
> **Redundant records exist: many different fragments of the environment each independently carry (nearly) the same classical information about the system’s pointer state.**
### The simplest “proof pattern” (no heavy math)
Do many runs. Each run:
- prepare the system,
- let it interact with its environment,
- then measure only a *small* subset of environment fragments.
If small subsets already reveal the pointer outcome reliably, and *many different subsets* do so independently, that means the environment contains **multiple copies** (redundancy).
In papers this is quantified by plots of “how much information you gain” vs “how large a fraction of the environment you capture,” showing a fast rise and a wide plateau (the redundancy plateau).
Riedel & Zurek (2010) and Zwolak & Zurek (2017) discuss this kind of signature.
- https://link.aps.org/doi/10.1103/PhysRevLett.105.020404
- https://link.aps.org/doi/10.1103/PhysRevA.95.030101
### The selection control test
Repeat the same redundancy check for a different, incompatible property.
Prediction: redundancy is strong for the pointer information and weak for incompatible observables (because the environment “selects” which information survives and gets copied).
---
## 10) A realistic modern experimental anchor (what has been done already)
A recent experiment reports a comprehensive observation of Quantum Darwinism signatures using superconducting circuits:
Zhu et al. (2025) “Observation of quantum Darwinism and the origin of classicality with superconducting circuits” (*Science Advances*):
- https://www.science.org/doi/10.1126/sciadv.adx6857
Open access (PMC): https://pmc.ncbi.nlm.nih.gov/articles/PMC12315987/
This matters for your “chance to prove it” question:
- It shows the redundancy/record-proliferation program is experimentally viable in engineered platforms.
- Your two-wing extension (start with A–B entanglement, then let each wing undergo local record proliferation and track how correlations become objective records) is conceptually straightforward, but technically heavier (more qubits/modes, more calibration, more measurements).
---
## 11) Where nuclear fusion/fission and spin fit into *your* Darwin-like story
You asked whether spin “really matters” physically (e.g., in fusion/fission), and whether entanglement + spin could change reaction “paths.”
### 11.1 Spin matters locally in nuclear reaction probabilities
Yes—spin alignment can change which reaction channels are favored.
A concrete example you cited in spirit: **spin-polarized D–T fuel**.
Reviews and calculations note that aligning D and T spins can increase the D–T fusion cross section by about a factor **1.5** (≈50%) under ideal polarization assumptions.
- Heidbrink et al. (2024, *Frontiers in Physics*): https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2024.1355212/full
(PDF mentions factor 1.5): https://juser.fz-juelich.de/record/1026967/files/fphy-12-1355212.pdf