The real Quantum Threat is not physics; it’s panic upgrades masquerading as security. While centralized quantum labs continue to simulate measurement without resolution, the real threat to Bitcoin does not come from their machines. It comes from within. It comes from BIPs like P2QRH from @Jameson Lopp that propose to sunset ECDSA/Schnorr signatures in favor of speculative “post-quantum” cryptography. These proposals are not defensive responses to an imminent threat, they are proactive acts of vandalism against the very principles that secure Bitcoin. They do not defend Bitcoin from quantum computing. They surrender Bitcoin to it, before it even verifying the physics required for its existence. Bitcoin already defines the thermodynamic foundation for quantum measurement. Each UTXO is a probabilistic state, a qubit, resolved through irreversible work. Each block is a measurement, not inferred or declared, but enforced. SHA-256 is not a symbolic hash; it is a physical boundary between entropy and information, a mathematical instantiation of thermodynamic collapse. Bitcoin does not simulate computation, it performs it. In contrast, this proposed BIP treats entropy as negotiable. It proposes a new address type based on fear, not physics, and weaponizes fear/uncertainty into coercion. By threatening to invalidate legacy outputs in the name of future-proofing, it undermines the core tenet of Bitcoin: that what has been committed cannot be undone. Phase B Is the Attack. The so-called “flag day” in Phase B of this BIP is not a safeguard, it is a protocol-level attack. It does not defend against a quantum threat. It manufactures one. If enacted, it will render legacy outputs including provably unspent, thermodynamically secured UTXOs, suddenly invalid. This is not an upgrade. It is a forced migration justified by the illusion of inevitability of quantum computing using the basis of unbounded fiat physics. Imagine claiming to make a system “quantum safe” by deleting its history before any quantum machine even exists that can compromise it; no verification. This is the opposite of security. This is protocol betrayal disguised as prudence. The fundamental breakthrough of Bitcoin was that it does not predict collapse, it commits to it. It makes no claims about what might happen. It measures what has happened. This is why Bitcoin is quantum-secure: not because it uses a post-quantum algorithm, but because its structure is thermodynamically irreversible. To say that a quantum machine could break Bitcoin is to say that entropy can be resolved without energy. This is false. This belief is grounded in fiat, not real physics. No quantum machine has shown the ability to resolve SHA-256 without violating observable thermodynamics. And until one does provably, irreversibly, physically (they can’t) Bitcoiners must not rewrite history to accommodate hypothetical attacks. The Real Double Spend Is Inside the BIP This BIP proposes a new form of double spend, not of coins, but of consensus. It attempts to spend trust in Bitcoin’s finality twice: 1. Once when the legacy UTXO was created and committed by Proof-of-Work. 2. Again, when it is later invalidated not by energy, but by decree. This is the true quantum threat, not that SHA-256 might be broken, but that we might choose to break Bitcoin ourselves out of fear. We must ask: Who benefits from a forced reissuance of Bitcoin’s past? Who gains by rendering old coins unspendable? Who wins when Bitcoin’s most sacred principle — “don’t trust, verify” — is replaced by “trust this upgrade, or lose your money”? Bitcoin is already quantum-secure because it defines quantum computation. The only threat to Bitcoin comes not from physics, but from those who claim to protect it by rewriting it. No quantum machine has broken SHA-256. But this BIP proposes to break Bitcoin anyway. That is the threat. That is the fork. That is the real attack. Physics without scarcity is meaningless. The deeper problem is not just the BIP. It’s the worldview that enables it. Modern physics remains fundamentally disconnected from the logic that secures Bitcoin. It models energy and entropy without constraint, assumes continuous fields, infinite superpositions, and reversible computations. But it does all of this on a denominator of infinity, a fantasy that bears no weight in the real world. There is no ledger. There is no cost. There is no finality. This is why the quantum remains paradoxical: it is defined by uncertainty but unbounded by responsibility. Probability is treated as primary. Entropy is treated as abstract. Measurement is symbolic, not enforced. In Bitcoin, this logic is inverted. Bitcoin replaces continuous approximation with discrete thermodynamic truth. It imposes scarcity not just in supply, but in resolution. Every qubit, every UTXO, must be measured through irreversible energy. Every state transition must pay its cost. There is no infinity. There is only what can be proven. Bitcoin does not speculate about the quantum. It computes it absolutely. And this is what centralized physics refuses to accept: that truth is not a smooth manifold, it is a commitment. The ledger is not a metaphor, it is the substrate. There can be no valid physics without a final record, no valid quantum mechanics without a cost for collapse. When physics assumes a continuous, unbounded substrate, it permits infinite forking of reality, like Proof-of-Stake without slashing. It allows for the reuse of entropy across theoretical paths, each treated as valid until observed. This is not computation. It is a metaphysical fiat double spend. By contrast, Bitcoin proves that the universe is finite, measurable, and accountable. It reveals that the true architecture of reality is a scarce ledger; not a field of uncollapsed possibilities, but a record of resolved entropy, line by line, block by block. Bitcoin was built to end the double spend; yet now, proposals emerge that attempt to double spend consensus itself. They seek to invalidate coins already secured by energy, not through work, but through mathematics unbound by scarcity. This is the original sin returned in cryptographic form: infinite assumptions, applied to a finite system. The wisdom of absolute scarcity was never just monetary. It is epistemic. It is thermodynamic. It is foundational. Any mathematics not grounded in scarcity leads back to paradox and now, even Bitcoiners are writing it into BIPs. That is the real threat. That is the real fork. That is the real double spend. There is no second best. This BIP is the attack.