Trotsky's theory of Permanent Revolution argued that in economically backward countries like early 20th-century Russia, the bourgeoisie was too weak and reactionary to carry out a full capitalist transformation, including land reform and democratic rights. Instead, he believed that only the working class, leading the peasantry, could overthrow the old order and usher in profound change.
In so doing, it could not simply hand over affairs to the politically-impotent bourgeoisie; instead the workers’ movement would have to forge on, working to establish a socialist state. Thus the communist revolution would be ‘permanent’, i.e. completed once and for all.
Trotsky never anticipated that the revolution would not expand beyond Russia itself. Russia was so backward economically, its productivity so low, that a society of equality based on abundance was unthinkable. It would have to be helped by workers’ states in prosperous western europe.
Trotsky’s model, however, was fatally flawed; tragically simplistic: centrally planned economies controlled by workers’ councils simply do not work in practice. And so Russia proceeded to Stalinism, heckled by Trotsky from increasing distances, until the exiled dissident was eventually assassinated.
Perhaps, contrary to Trotsky's vehemently-expressed views, there really was no ‘Trotskyist’ alternative to Stalinism after the revolution succeeded in 1917. But what would have happened if Lenin’s Bolsheviks had failed in their putsch against the collapsing Kerensky government? Despite the disintegration of the army, enough units of the Russian military were, after all, standing by, as the Bolsheviks discovered in the long civil war which followed.
Had the Bolsheviks failed in 1917, Russia would certainly have fallen under a military dictatorship, facing the same challenge Stalin later confronted: dragging a feudal, agrarian society towards a modern industrial economy and state. The military dictatorship would have been forced to depopulate the countryside, dismantling peasant agriculture to create a mass urban workforce. This brutal transition - akin to enclosures in Europe but imposed at breakneck speed - would have been necessary to fuel rapid industrialisation, driven by the imperatives of security and military rivalry, particularly with Germany.
Schumpeter’s insight applies: authoritarian command economies, whether Stalinist or capitalist, can be equally effective at economic take-off. The regime would have pursued state-directed capitalism, using repression to discipline labor, expand heavy industry, and consolidate large-scale capitalist farming. Political rhetoric would frame these measures as national survival, not class struggle, but the human toll - displacement, famine, and political terror - would mirror Stalin’s forced modernisation.
Yet, no dictatorship lasts forever. Spain, Portugal, and Greece transitioned from authoritarianism to democracy as modernisation weakened their regimes. A Russian junta, once its industrial goals were met, might have faced internal power struggles, economic stagnation, or public unrest in the second half of the twentieth century. However, Russia’s deep imperial and autocratic traditions could have prolonged authoritarian rule, replacing one strongman with another rather than fostering genuine democracy.
In the end, a post-1917 military dictatorship would have shaped Russia much as Stalinism did - through coercion, industrial might, and state-driven modernisation. Whether it collapsed into reform or prolonged despotism would depend less on economic success than on Russia’s historical inertia: a state that has long thrived on repression is rarely eager to let go.
But a capitalist Russia emerging from dictatorship would have had a working civil society, an economic power-base separate from the state apparatus. Consequently, the chances of a democratic transition would have been far greater than with the Russia we currently have, where civil society (weak to begin with) has been thoroughly crushed for a century by the power of an overweening state.
Without Stalinism to discredit it, it’s possible that the revolutionary left in a Bolshevik-defeat world would be more vigorous than in our actual world; but overall, if the Bolsheviks had been defeated, that world today would most likely be a better and more peaceful place than our own, too.
I did it for you, I thought, thrown into that hellscape so you didn't have to. Buying time, time for the land-drones to get perfected, go into mass production...
I am seated at the left of the picture above, at the end of the row, with a kendo sword across my knees. This was on the playing field of Bristol Grammar School in 1964, when I was thirteen years old.
The school was quite progressive in the breadth of sports it supported as you can see: fencing, kendo, judo. So here is my advice to a young person considering studying a martial art.
The best martial art for young people
Choosing the right martial art isn’t just about picking the one that looks most impressive in a movie or the one some self-styled expert insists is “the most effective”. Real fights are messy, chaotic affairs, and the only techniques that matter are the ones you can execute automatically—without hesitation, without thought, and certainly without consciously consulting your mental archive of choreographed moves. That’s why the way a martial art is trained matters more than the theoretical lethality of its techniques.
Let’s take three popular options: karate, boxing, and judo.
Karate is often touted as the ultimate fighting system, but it has a fundamental flaw—modern training methods. Sparring (kumite) is often light or heavily choreographed these days, and much of the training focuses instead on kata (solo forms) and kihon (repetitive drills).
These may build precision, but they don’t instill the instinctive, high-pressure reactions needed in a real fight. If you’re unaccustomed to applying techniques in live combat, they won’t magically materialize when you need them. Hesitation equals defeat.
Boxing is better in this regard. Training involves regular sparring, conditioning fighters to react under fear and pressure. However, the most effective techniques—full-power strikes to the head—come with an inherent problem: repeated blows to the skull are not conducive to long-term brain health. While a hardened boxer is formidable in a street fight, few people want to endure the cumulative damage required to reach that level of effectiveness.
And that brings us to judo. When I trained in judo as a youth, every class involved at least 20 minutes of randori—live, full-contact sparring: throws, immobilisation holds and joint-locks. Over weeks, months, and years, this developed automatic reactions: gripping, positioning, attack and defence, and controlling an opponent on the ground.
Because judo is designed to be non-lethal, it allows for continuous, realistic practice without the fear of permanent injury. This is its greatest strength—techniques become second nature, and when conflict arises, you react instinctively. More importantly, judo equips you to neutralize an opponent without excessive force. You won’t kill anyone, and you won’t end up facing a manslaughter charge for defending yourself.
So, for anyone looking for a martial art that builds self-confidence, resilience, and real-world effectiveness, judo is by far the best choice.
It allows you to train the way you’d need to act in a fight, ensuring that when the moment comes, your body moves smoothly and rapidly without needing permission from your brain.
And in a real fight, that’s what makes all the difference.
A recent Foreign Affairs podcast between Dan Kurtz-Phelan and noted Russian expert Fiona Hill is perhaps the best analysis of the Trump-Putin dynamic this year. It's quite lengthy, so I asked ChatGPT to summarise the transcript - see below. Here is the link to the original (may be gated).
What Does Trump See in Putin?
Fiona Hill’s contributions throughout the interview provide a penetrating analysis of how personal dynamics, strategic miscalculations, and a rapidly shifting geopolitical landscape are reshaping U.S. foreign policy, European security, and the global balance of power.
Rapid Pace and Unpreparedness
Hill begins by expressing surprise at the lightning-fast pace of events in Trump’s second term. While many outcomes were anticipated, the sheer speed and “furious” nature of developments caught even seasoned observers off guard. This rapid evolution of U.S. policy has left both allies and adversaries scrambling to understand and adapt to a new reality—a reality in which the old assumptions about deliberate policymaking have given way to a volatile and reactionary approach.
Trump’s Personalized Diplomacy
A recurring theme in Hill’s commentary is Trump’s hyper-personal approach to international diplomacy. Reflecting on the Oval Office meeting with Ukrainian President Zelensky, she underscores how Trump’s dismissive treatment—reducing established agreements to mere personal whims and treating foreign leaders as pawns in his quest for image management—illustrates a dangerous departure from institutional norms.
According to Hill, this personalized style of negotiation not only undermines the continuity of U.S. foreign policy but also leaves counterparties ill-prepared for the fast-paced, high-stakes encounters that define today’s diplomatic landscape.
In a realm where precision and cultural nuance matter, even small missteps, such as Zelensky’s choice to speak in English without the full support of a skilled interpreter, can have outsized consequences.
The Putin Paradigm and Institutional Contrast
In stark contrast to Trump’s improvised style, Hill paints a vivid picture of the Russian approach under Vladimir Putin. For Putin, decision-making is centralized and supported by a cadre of experienced officials—figures like Lavrov and Dmitriev—who are well-versed in the art of diplomacy and adept at communicating a consistent message.
This disciplined and institutional framework stands in sharp relief against Trump’s tendency to fixate on the individual, particularly his obsession with meeting Putin face-to-face. By sidelining experienced advisors and professional diplomats, Trump risks simplifying complex geopolitical realities, a miscalculation that inadvertently bolsters Putin’s image as a strong and in-control leader.
Europe’s Agency and the “Vassal State” Debate
A significant portion of Hill’s analysis is devoted to Europe’s precarious position amid these shifting power dynamics. She argues that Trump’s “America First” approach, combined with his overt antagonism toward European security interests, is effectively relegating Europe to a collection of “vassal states.”
In her view, this dynamic is twofold. On one hand, European nations—ranging from Poland and Finland to the Baltic states—are compelled to rapidly rearm and invest in their own military capacities in response to a perceived abandonment by the United States. This reactive posture suggests that while Europe is often depicted as fragmented and dependent, it does retain a measure of agency; its leaders are now more urgently recalibrating their defense strategies and pooling resources in a bid to assert independence.
On the other hand, Hill is skeptical about the extent of this agency. She notes that the deep-rooted institutional weaknesses and the slow pace of reform across much of Europe mean that even well-intentioned moves toward self-reliance may prove too little, too late in the face of an assertive Russian posture aimed at regaining its sphere of influence.
Dividing the World into Spheres of Influence
In her broader reflections on global order, Hill discusses the emerging paradigm of dividing the world into three primary spheres of influence—America, Russia, and China—a model in which Europe is conspicuously marginalized.
In this vision, Europe is not seen as an independent actor but rather as a subordinate entity whose destiny is to be dictated by the strategic interests of these dominant powers. Hill points out that such a tripartite division is reflective of a nostalgic, almost eighteenth-century mindset where power was concentrated in the hands of a few autocrats.
For Trump and, to some extent, for Putin, this framework offers a simplified narrative: strongmen should control distinct regions of the world, leaving little room for the multilateral and often messy realities of European politics.
However, Hill challenges this notion by highlighting Europe’s complex identity—its population of 550 million, its diverse political systems, and its economic clout—which collectively underscore that Europe, though currently sidelined in strategic narratives, does possess the potential to reshape its role if it can overcome internal fragmentation.
Implications for Global Order and Nuclear Proliferation
Hill’s reflections extend to the broader implications of this evolving order. The personalized, reactionary diplomacy of the United States, coupled with an emboldened Russian strategy, is not only eroding traditional alliances but also creating an environment in which nuclear proliferation becomes a tangible risk.
With countries in close proximity to Russia, such as those in Eastern Europe, now forced to rethink their security arrangements, there is a real danger that nations will rush to acquire nuclear capabilities. This proliferation is not confined to Europe; Hill warns that similar dynamics could spread to other regions, thereby destabilizing an already fragile global balance.
Admiration and Misguided Affinities
Another critical aspect of Hill’s analysis is her exploration of the peculiar personal dynamic between Trump and Putin. She contends that Trump’s admiration for strongmen is driven by a personal affinity for the image of power rather than an objective assessment of geopolitical threats.
Drawing on historical analogies, Hill likens Trump’s mindset to that of eighteenth-century monarchs, suggesting that his tendency to view international relations through the lens of personal relationships and flattery is both anachronistic and dangerously simplistic. This personal affinity, she argues, has led Trump to downplay or even dismiss actions by Russia that undermine U.S. credibility and international stability.
Conclusion: A Call for Strength, Unity, and Institutional Integrity
In her concluding remarks, Hill emphasizes that the only viable path forward lies in restoring a credible deterrence posture, strengthening internal cohesion, and re-engaging with global partners. The emerging order—with its tripartite division and its reduction of Europe to a secondary role—serves as a stark warning about the long-term consequences of neglecting institutional foundations.
For Hill, the solution is not to return to the old ways of personalized, autocratic diplomacy but to reaffirm the principles of strength, unity, and multilateral cooperation that have underpinned international stability for decades.
Overall, Fiona Hill’s insights offer a sobering and multifaceted analysis that not only critiques the current leadership styles of Trump and Putin but also highlights the broader systemic shifts reshaping global power.
Her reflections on Europe’s dual status as both a potentially autonomous actor and a group of “vassal states” within a tripartite world order underscore the urgency for renewed commitment to collective security and institutional integrity in an increasingly complex and competitive international landscape.
Bonapartism: The Politics of Exhaustion and Renewal
Karl Marx’s theory of Bonapartism, most famously articulated in The Eighteenth Brumaire of Louis Napoleon (1852), describes a political phenomenon in which a charismatic leader emerges in times of systemic crisis to impose order, override institutional paralysis, and forge a new governing consensus. This occurs when the existing political order—whether liberal-democratic, aristocratic, or revolutionary—has exhausted its capacity to reconcile deep social and economic contradictions. The Bonapartist leader presents himself as standing above class conflicts, acting as an arbiter between competing interests, yet in reality, he restructures the state in a way that ultimately serves the long-term interests of the ruling class.
In The Eighteenth Brumaire, Marx examines the rise of Napoleon III, who seized power in 1851 amid the decay of the French Second Republic. Marx describes how the bourgeoisie, unable to maintain class rule through parliamentary means and fearful of proletarian revolution, ceded power to an authoritarian figure who promised to restore stability. The Bonapartist leader appeals to multiple classes simultaneously—bourgeois elites, the petty bourgeoisie, and even elements of the working class—by adopting a rhetoric of national renewal while systematically dismantling democratic structures. The state, in this phase, appears to gain an autonomous power of its own, floating above class conflicts, yet it remains a tool for consolidating a new elite consensus.
Bonapartism is not simply dictatorship; it is a transitional mechanism. Marx understood it as an historical necessity in moments when the old order could no longer function, but no new order had yet emerged. Napoleon Bonaparte himself embodied this logic when he assumed power in 1799, stabilizing a post-revolutionary France that had descended into factional chaos. His rule introduced modern legal and administrative structures—most notably the Napoleonic Code—while sweeping away both the feudal remnants of the ancien régime and the radical instability of revolutionary government. Similarly, his nephew’s coup d’état in 1851 marked the end of the tumultuous revolutions of 1848 and the failure of bourgeois democracy to manage the contradictions of industrial capitalism.
The Bonapartist interlude is, by its nature, temporary. While it serves as a violent reset for a failing system, it ultimately exhausts itself, either giving way to a more stable and institutionalised form of rule or collapsing into deeper crisis. It is a moment of transition, not an endpoint. The question for any Bonapartist regime is not whether it can last indefinitely—it cannot—but whether it successfully lays the foundations for the political and economic order that will follow.
Historical examples abound. Napoleon’s empire, despite its military triumphs, was undone by the very contradictions it sought to resolve, giving way to the Bourbon Restoration. Napoleon III’s Second Empire, despite its modernization efforts, crumbled under the weight of geopolitical miscalculations and domestic unrest, paving the way for the Third Republic. Twentieth-century variants of Bonapartism, from Perón in Argentina to De Gaulle in France, likewise emerged from crises, imposed order, and then gave way to more durable structures.
The pattern remains relevant. When institutions falter, when economic transformations outpace political adaptation, and when ruling elites prove incapable of maintaining legitimacy, the Bonapartist figure emerges. His function is not to create stability, but to smash resistance to a new order. The question is: what comes after him?
Take a very simple physical system exhibiting decoherence. Perhaps involving the beta decay of an unstable nucleus in vacuum and its subsequent detection at a screen. I'm assuming that decoherence occurs as the electron interacts with the atoms (electron shells) of the screen.
Could you describe the situation, showing and explaining all logical steps?
How did the electron screen interaction vs non-interaction induce decoherence? How, in physics terms, was the superposition lost?
Gemini:
You might want to start by watching Sabine Hossenfelder's excellent video tutorial about decoherence. And then resume reading.
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Let's break down in words how the electron-screen interaction, versus non-interaction, leads to decoherence and the apparent "loss" of superposition in physical terms.
The Essence of Decoherence in This Scenario
Imagine the electron is initially in a quantum superposition of "arriving at the screen" (∣A⟩) and "not arriving at the screen" (∣N⟩). Think of this like being in a quantum "both/and" situation regarding its path to the detector.
Before Interaction (Coherent Superposition)
Quantum Coherence: In the initial superposition (1/√2)(∣A⟩+∣N⟩)the electron is in a coherent superposition. This means the ∣A⟩ and ∣N⟩ components are not just alternatives, but they are quantum mechanically interfering with each other. If we were to perform a measurement that's sensitive to this superposition (not just measuring if it's in ∣A⟩ or ∣N⟩ individually, but something that probes the phase relationship between them), we would observe interference effects.
Environment is Ignorant: At this stage, the environment (the screen atoms) is in its initial state ∣E0⟩. It's essentially "ignorant" about whether the electron is in state ∣A⟩ or ∣N⟩. There is no correlation or entanglement between the electron and the environment yet.
During Interaction with the Screen (Entanglement and "Measurement")
Interaction as a "Measurement-like" Process: The interaction of the "arriving" electron (∣A⟩) with the screen atoms is crucial. Think of the screen as performing a kind of "measurement" on the electron. It's not a conscious measurement, but physically, the screen atoms are sensitive to the electron's arrival.
Environment Gets "Informed" (Entanglement):
If the electron is in state ∣A⟩ (arriving), the interaction changes the state of the environment from ∣E0⟩ to ∣E1⟩. This change could be excitation of atoms, ionization, momentum transfer, etc. Importantly, ∣E1⟩ is a different physical state of the environment compared to ∣E0⟩. The environment has now become "aware" that an electron in state ∣A⟩ interacted with it.
If the electron is in state ∣N⟩ (not arriving), we assumed for simplicity that the environment remains in ∣E0⟩. The environment stays "unaffected" or in its initial state.
Correlation is Created (Entanglement): Because of this state-dependent interaction, the system and environment become entangled. The final total state (1/√2)(∣A,E1⟩+∣N,E0⟩) shows that the electron's state is now correlated with the environment's state. If you know the environment is in state ∣E1⟩, you know the electron must have been in state ∣A⟩. If the environment is in ∣E0⟩, the electron must have been in state ∣N⟩.
After Interaction (Decoherence and Loss of Observable Superposition)
"Which Path" Information Leaks to the Environment: The crucial point is that the environment now contains "which path" information about the electron. The environment's state (∣E1⟩ vs. ∣E0⟩) effectively tells you whether the electron was in the "arriving" or "not arriving" path.
Observable Superposition for the Electron is Lost (Relative to Us Ignoring the Environment): When we perform the partial trace over the environment, we are mathematically averaging over or ignoring the environment's state. From the perspective of an observer who only looks at the electron and does not measure the environment, the electron's state appears to have changed from a pure superposition to a mixed state.
No More Interference (in the Reduced System): The off-diagonal elements in the reduced density matrix, which represented quantum coherence and the potential for interference, vanish. If we try to perform interference experiments on the electron alone (without measuring the environment), we will no longer observe the interference patterns we would have seen with the initial pure superposition.
Classical Mixture Emerges: The reduced density matrix
ρS=(½)(∣A⟩⟨A∣+∣N⟩⟨N∣)=(½)I
represents a classical statistical mixture. It's as if the electron is either in state ∣A⟩ with 50% probability or in state ∣N⟩ with 50% probability, but not in a quantum superposition of both for any observation we make that only involves the electron.
Analogy: "Quantum Spies"
Think of it like this:
Initial Superposition: The electron is like a secret agent who is in a superposition of two possible missions (state ∣A⟩ and ∣N⟩). As long as no one "observes" the agent's mission, it's truly in both possibilities simultaneously (quantum coherence).
The Screen as "Quantum Spies": The screen atoms are like "quantum spies" that are designed to interact differently depending on which mission the agent is on.
Entanglement = Spies Learn the Mission: If the agent is on mission ∣A⟩, the spies get "activated" and their state changes (to ∣E1⟩). If the agent is on mission ∣N⟩, the spies remain in their "dormant" state (∣E0⟩). Now, the state of the spies (environment) is correlated with the agent's mission.
Decoherence = We Ignore the Spies: If we, as observers, only look at the agent and completely ignore the "spy network" (the environment), the agent now appears to be in a mixed state. It's as if the agent has randomly chosen one mission or the other. We've lost the ability to observe the quantum interference that was present in the initial superposition, because the "which mission" information has leaked out into the environment ("spy network"), which we are ignoring.
In summary, the superposition is "lost" not in the sense that it disappears from the universe, but in the sense that the quantum coherence, and the associated interference effects, become unobservable when we focus solely on the system (the electron) and ignore the now-entangled environment (the screen). The "quantumness" of the superposition effectively bleeds out into the vast, uncontrolled degrees of freedom of the environment.
Nigel:
In this example of exactly one electron we could not measure an interference effect which, surely, would only show up in a pattern of repeated experiments? Does that suggest your response should be slightly nuanced or am I misunderstanding something?
Gemini:
You are absolutely right to point that out! My explanation, as it stands, is indeed slightly nuanced and needs further clarification regarding the role of single versus repeated experiments and how interference manifests.
Let me refine and nuance my response to address this correctly:
The Nuance: Interference and Repeated Experiments
Interference is inherently a statistical phenomenon, observed in patterns that build up over repeated experiments (or in ensembles). You are correct that a single electron, in isolation, will not produce an interference pattern. Interference patterns emerge from the collective behavior of many identically prepared quantum systems or from repeated measurements on systems prepared in the same initial state.
However, the quantum state (including superposition and coherence) exists for each individual electron. Even for a single electron in a superposition, say (1/√2)(∣A⟩+∣N⟩), that electron is in a superposition state.
The density matrix:
ρS(0)=(½)(matrix 1 1 1 1)
1/2
1/2
1/2
1/2
describes the state of this single electron. The off-diagonal elements indicating coherence are properties of this single electron's quantum state.
Decoherence acts on the quantum state of each individual electron. When we talk about decoherence due to the screen interaction, we are saying that for each electron that interacts with the screen in this way, its quantum state evolves from a coherent superposition towards a mixed state.
The loss of interference we discuss with decoherence manifests in the statistical pattern that would emerge over many repeated experiments. If we were to perform an experiment designed to reveal interference between the ∣A⟩ and ∣N⟩ paths (even in our simplified model), we would need to repeat the experiment many times with electrons prepared in the initial superposition.
Clarifying the Role of Repeated Experiments and Ensembles
Let's imagine we could design an experiment to test for interference between the "Arriving" (∣A⟩) and "Not Arriving" (∣N⟩) states. Think of it analogously to a double-slit experiment, but in our abstract "arrival state" space.
Without Decoherence (Ideal Scenario): If we could prepare many electrons in the initial superposition state ∣ψS (0)⟩=(1/√2) (∣A⟩+∣N⟩) and then perform a measurement designed to detect interference between ∣A⟩ and ∣N⟩, we would observe an interference pattern over many repeated trials. This pattern would be a consequence of the off-diagonal elements in ρS(0). The probabilities of different outcomes in our interference-sensitive measurement would be influenced by the coherence in the initial superposition.
With Decoherence (Screen Interaction): Now, let's introduce the screen interaction that causes decoherence. After each electron interacts with the screen and we trace out the environment, the state of each electron is described by the decohered density matrix
ρS =(1/2)(matrix 1 0 0 1):
1/2
0
0
1/2
If we now perform the same interference-sensitive measurement as in step 1, but now on electrons that have undergone decoherence, we would not observe the same interference pattern. The pattern would be washed out or disappear. This is because the off-diagonal elements, responsible for interference, are gone in ρS.
Analogy with Classical Coin Flips vs. Quantum Superposition
Think about flipping a coin many times:
Classical Mixture (like Decohered State): If we have a box of coins where half are pre-set to heads and half to tails, and we randomly pick a coin and flip it (without knowing beforehand if it's a "heads-set" or "tails-set" coin), and repeat this many times, we'll get roughly 50% heads and 50% tails. This is analogous to a mixed state. There's no interference, just statistical probabilities.
Quantum Superposition (like Coherent State): Imagine something more quantum. We prepare each electron in a true superposition state. Now, in our hypothetical interference experiment, we observe a pattern over many trials that is not just 50/50 for some measurement outcomes. It deviates from classical probabilities due to quantum interference. This is analogous to the initial coherent superposition.
Key Nuance Summary:
Decoherence affects the quantum state of each individual system, shifting it from a coherent superposition towards a mixed state.
Interference is observed in patterns that emerge from repeated experiments (or ensembles) because these patterns reveal the underlying probability distributions dictated by the quantum state.
Decoherence leads to a change in these statistical patterns. Interference patterns that would be present for coherent states are lost or diminished when decoherence creates mixed states.
Therefore, my initial response wasn't wrong in saying superposition is "lost," but it lacked the nuance that this loss is observed in the statistical patterns of repeated experiments, and that decoherence is a process acting on the quantum state of each individual system within such an ensemble. The density matrix formalism precisely captures this shift from a state capable of producing interference (coherent, pure) to one that is not (mixed, decohered) within an ensemble description, while being relevant for the quantum state of each individual system as well.
Nigel:
Thanks, but I'm still a little puzzled. If we kept track of all the environmental changes (or no change) - we might suppose the detector or screen was just a single atom - what changes? I'm guessing you're going to say that the electron and screen would together remain in a combined superposition (as they, in fact, do anyway).
I suppose my confusion is that keeping track of is not well-defined here. We don't want to add some third element, some macroscopic observer looking at both the electron and the screen and therefore themselves entering a superposition like an endless chain of Wigner's Friends!
I guess the core of my question is: what does it mean in this example, in physical terms, to disregard the possible changes in the environment? But I'm confused, so you are invited to straighten me out!
Gemini:
You've correctly identified a potential for confusion and are asking for a deeper physical interpretation of "disregarding the environment." Let's unpack this carefully:
1. System + Environment Remain in Superposition (Jointly)
You are absolutely right. If we consider the entire system – electron and screen (even if it's just a single atom) – they remain in a joint, entangled superposition after the interaction. In our example, this is the state:
∣Ψ(t)⟩=(1/√2)(∣A,E1⟩+∣N,E0⟩)
The total wavefunction is still a coherent superposition. No quantum superposition has been fundamentally destroyed in the universe. If we could, in principle, perform measurements on the combined system (electron and screen atom), we could still see interference effects that reflect this joint superposition.
2. "Keeping Track" = In Principle Measurable Correlation
"Keeping track" of the environmental changes means, in principle, having the ability to distinguish between the environmental states ∣E0⟩ and ∣E1⟩ and to correlate these environmental states with the system states ∣A⟩ and ∣N⟩.
If we could measure the environment perfectly: We could perform a measurement on the screen atom to determine if it's in state ∣E0⟩ or ∣E1⟩. If we found it in ∣E1⟩, we would know with certainty that the electron is in state ∣A⟩. If we found it in ∣E0⟩, we'd know the electron is in state ∣N⟩. In this ideal scenario, we could restore the "pure state" description, but it would be a correlated pure state of the combined system.
3. "Disregarding" = Choosing Not to Measure/Consider the Environment, Leading to Partial Trace
"Disregarding" the environment means we are consciously choosing not to perform measurements on the screen atom and are only interested in describing the state of the electron itself. This is a very common situation in physics. We are often interested in a particular system (like an electron, a molecule, a qubit) and its properties, without needing to track every single detail of its surroundings.
Mathematical Tool: Partial Trace: The mathematical operation of the partial trace (TrE) is the precise tool to describe this situation. It's designed to give us the quantum state of a subsystem when we are ignoring or averaging over the degrees of freedom of the rest of the system (the environment).
4. Physical Interpretation of Partial Trace: Loss of Local Information and Emergence of Mixed State
When we perform the partial trace, we are essentially:
Averaging over possible environmental states: We are considering all possible states of the environment that are consistent with our lack of measurement on it.
We don't know if the environment is in ∣E0⟩ or ∣E1⟩ (or some more complex state in a more realistic scenario). So we are averaging over these possibilities.
Losing the Off-Diagonal Coherences for the System Alone: The partial trace operation mathematically eliminates the off-diagonal terms in the system's reduced density matrix that were responsible for quantum coherence and interference relative to measurements on the system alone.
Analogy to Classical Probability and Ignorance
Think of classical probability. If you have two coins, and they are entangled in the sense that if coin A is heads, coin B is tails, and vice versa (perfect anti-correlation). The joint state is a pure, correlated state.
If you know the outcome of coin A, you know the outcome of coin B.
However, if you only look at coin A and ignore coin B, coin A will appear to be in a mixed state of 50% heads and 50% tails. You've lost the perfect correlation information by disregarding coin B. The "mixedness" reflects your ignorance about the state of coin B and the correlations.
Decoherence is analogous, but in the quantum realm. The electron becomes entangled with the environment. When we "ignore" the environment, the electron appears to be in a mixed state. The "mixedness" of the reduced density matrix for the electron reflects our ignorance of the environment's state and the electron-environment correlations.
5. No Wigner's Friend Paradox
The process of taking the partial trace and "disregarding the environment" does not lead to an infinite regress of Wigner's Friends. It's a well-defined mathematical operation that provides a consistent description of a subsystem of an entangled system.
Objectivity (but relative): The reduced density matrix ρS is an objective description of the state of the electron given that we are not measuring or considering the environment. It's not dependent on a "macroscopic observer" or consciousness. It's about the physical situation of entanglement and the choice of which degrees of freedom we are focusing on for our description.
Consistent Quantum Mechanics: Partial trace is a standard operation within quantum mechanics. It's not introducing any new interpretations or paradoxes. It's a tool to describe subsystems within the standard quantum formalism.
6. Physical Meaning of Disregarding – Information Leakage
Physically, "disregarding the environmental changes" means:
Information has leaked from the system to the environment: The interaction has caused "which path" information about the electron (was it ∣A⟩ or ∣N⟩?) to become encoded in the state of the environment (∣E1⟩ vs. ∣E0⟩).
We are choosing not to access this information: By tracing out the environment, we are effectively erasing our access to this "which path" information. For any measurements we perform solely on the electron, the outcomes will be consistent with a mixed state (no interference).
Classicality Emerges (Apparent): For the system alone, classical probabilities emerge. The quantum superposition, from the viewpoint of the system alone, has effectively "decohered" into a classical mixture.
Decoherence is not about destroying superposition in the universe. It's about how entanglement with an environment and our choice to focus on a subsystem leads to a relative loss of coherence for that subsystem. The "disregarding" of the environment, mathematically implemented by the partial trace, reflects our limited perspective and the leakage of information into unobserved degrees of freedom, resulting in the system appearing to behave more classically.
Your confusion touches on the core interpretation of decoherence. It's not about wavefunction collapse in the measurement sense, but rather about the practical disappearance of quantum interference for a system when it becomes entangled with a large, complex, and typically unmeasured environment.
The physicist Matt Strassler is currently writing a series of excellent articles about how to think about quantum mechanics, focused on the double-slit experiment as his working example. Richard Feynman said that all the mystery of QM was encompassed in this one simple experiment.
If you are curious as to how to think about the wavefunction, and what it really means and how it couples to 'reality', this is the series for you.
I had my meeting with my GP yesterday afternoon, to discuss the report from my echocardiogram on February 25th 25. I scanned in the hard copy (little is electronically joined up in today's NHS) and asked ChatGPT to summarise the report and its implications.
Summary of Echocardiogram Report (25 Feb 2025) ---[ChatGPT]
Aortic Valve: Normal trileaflet structure, thin and mobile leaflets, no significant stenosis or obstruction.
Tricuspid Valve: Thin and mobile, mild regurgitation, no signs of pulmonary hypertension.
Pulmonary Valve: Normal structure, trivial regurgitation.
Left Atrium: Normal size.
Inferior Vena Cava: Dilated but collapses less than 50% on sniffing (suggests mildly raised right atrial pressure).
No pericardial or pleural effusion.
Interpretation & Comments on Your Decision
1. Severity of Mitral Regurgitation
Your mitral regurgitation is mild to moderate, which is reassuring. In more severe cases, MR can lead to symptoms such as fatigue, worsening shortness of breath, and atrial fibrillation due to left atrial enlargement. However, your report suggests your heart function remains strong, and there’s no major impact on chamber size or overall circulation.
2. Implications of Mild to Moderate MR
Low immediate risk: Given your normal ejection fraction (57%) and the absence of significant left atrial enlargement or pulmonary hypertension, there’s no immediate concern.
Potential for progression: Mitral regurgitation can worsen over time, so monitoring symptoms is key. If breathlessness on exertion (SOBOE) worsens, a repeat echocardiogram in a year or two might be prudent.
Minimal impact on daily life: Your exercise tolerance may remain stable, though you should note any changes in fatigue, breathlessness, or irregular heartbeats.
3. Decision to Cancel the May Cardiologist Appointment
Your reasoning is understandable. The cardiologist would likely only suggest medications (e.g., beta-blockers, ACE inhibitors, diuretics) to reduce heart strain, and given the mild nature of your condition, these might not be necessary at this stage. You’re also right to consider quality of life—many cardiac medications come with side effects that may not be worth it for a condition that currently seems stable.
That said, if your symptoms progress (e.g., worsening breathlessness, palpitations, or fatigue), reconsidering follow-up in the future would be wise.
4. Recommendations Going Forward
Monitor symptoms: If you notice worsening exercise tolerance or arrhythmias, reassess.
Repeat echocardiogram: Consider one in 1–2 years to track any progression.
Blood pressure monitoring: Since low BP may play a role in your scotomas, keeping an eye on it is sensible.
Final Thoughts
Your echocardiogram is reassuring, showing only mild-moderate MR without major consequences. Your decision to avoid unnecessary medication is reasonable, provided you keep an eye on symptoms. If anything changes, a repeat scan in the future would be a logical step.
[I am booked in for a repeat echocardiogram in two years time.]
A veterans' psychiatric hospital in Maryland. A private room on the second floor: beige walls, minimal furniture, a bed next to a window.
The man on the bed is asleep, sedated. A psychiatrist—male, late thirties, bearded—stands to his left.
Nguyễn Văn Quyết watches the comatose figure, concern creasing his brow.
The patient, now in his early seventies, twitches and grunts in his sleep.
He had been ordered to this small track to lie prone beneath a bush, next to a tree. The air was thick and heavy, deathly hot despite the early hour. Sweat trickled down his face. Mosquitoes colonized his exposed skin. Ants crawled inside his trousers. He felt the squelch of something bloated and slick against his ankles—leeches, no doubt, from the swamp they'd trudged through in pursuit of the guerrillas.
The enemy was holed up in this village.
The lieutenant had called for an airstrike. His troops had the village surrounded.
But you couldn't tell the VC from the civilians. The communists used men, women, boys, and girls indiscriminately. The orders were clear: No prisoners. Anyone trying to escape—shoot them dead!
The distant rumble of aircraft engines sent a tremor through his gut. Soon, the gasoline stench of napalm would fill the air.
The doctor frowns. The veteran’s agitation increases. His grunts turn to moans, though his words remain indecipherable. His head thrashes from side to side.
“Get me a sedative,” he says to the nurse on the other side of the bed.
She scurries off.
He swats at the flies buzzing around his face. A sound, faint but distinct, reaches his ears—running footsteps. Swift. Desperate.
A figure rounds the bend.
He grips his rifle, breath tight in his chest.
His orders are clear.
The figure sharpens into a young girl. Her black hair coils around delicate Asian features. She hesitates, glances back in terror, then turns to face him.
He lifts the rifle. Aims at her heart.
Fires.
The nurse returns, hypodermic in hand. The psychiatrist waves it away.
The crisis has passed. The old man settles back into deep sleep, his lips moving in an inaudible whisper.
It is his first time in a brothel. He is nineteen. Months in the jungle have stripped away everything familiar. It is a long way from squirrel-hunting in West Virginia.
He has done terrible things—things that will never leave him.
But now, in this thinly walled cubicle, lying on this makeshift bed, he is naked and unguarded. It has taken more than a few drinks to reach this state of calm.
And then there is her.
She is a Vietnamese angel, watching him with quiet concern. She speaks in low, melodic tones he cannot understand. She strokes his brow. She holds his hand.
It feels like she cares.
His anxieties unravel. He exhales. Tentatively, he smiles.
The patient is calm now. The psychiatrist studies his face, softened by an unfamiliar, gentle smile. Then he glances at the attractive young nurse.
"The Mormon Church sees the Catholic Church as part of an apostate Christianity that emerged after the original church's corruption, though it respects Catholics as sincere believers in Christ. Conversely, the Catholic Church does not recognize Mormonism as Christian due to its differing theology, particularly on the nature of God, but values Mormons' commitment to family and morality, fostering cooperation on shared social issues."
Orson Scott Card is a practising Mormon, a member of the Church of Jesus Christ of Latter-day Saints (LDS Church). In his SF writing he wears his religion lightly, although his strong interest in ethics, values and morality shines through. In the Ender/Shadow series he portrays the recurring character of Sister Carlotta, a Roman Catholic nun who works as an agent of the Interstellar Fleet.
I won't give you the context of the following dialogue between Sister Carlotta and 'Bean' (Julian Delphiki) who is an amoral military veteran of Battle School currently on the run in Latin America: it would be too lengthy.
Instead focus on the theme here: Sister Carlotta speaking to Bean - who selfishly cares only for his own survival, meanwhile despising that very drive as mere mammalian instinct.
“You keep thinking that death is the most terrible thing that can happen to a person, but to God, death just means you're coming home a few moments ahead of schedule. To God, the dreadful outcome of a human life is when that person embraces sin and rejects the joy that God offers. So of all the millions who might die in a war, each individual life is tragic only if it ends in sin."
"So why are you going to such trouble to keep me alive?" asked Bean, thinking he knew the answer.
"You want me to say something that will weaken my case," said Carlotta. "Like telling you that I'm human and so I want to prevent your death right now because I love you. And that's true, I have no children but you're as close as I come to having any, and I would be stricken to the soul if you died at the hands of that twisted boy. But in truth, Julian Delphiki, the reason I work so hard to prevent your death is because, if you died today, you would probably go to hell,”
Shadow of the Hegemon: Book 2 of the Shadow saga, p. 95.
In Shadow of the Hegemon, Bean is approximately 9-10 years old. Despite his young age, he is intellectually far beyond his years, one of the smartest human beings alive due to his genetic modifications, which also contribute to his emotional detachment and existential nihilism.
A well-taken point about life and death, I thought, regardless of your religious proclivities.
