What would happen if antibiotics stopped working?

Antibiotics are load-bearing for far more of medicine than the treatment of infections. Hip replacements, caesarean sections, appendectomies, chemotherapy and organ transplantation all rely on being able to prevent or treat infection, and without that they carry mortality rates resembling the pre-antibiotic era. Antimicrobial resistance is not hypothetical: WHO treats it as one of the leading global health threats, and resistant infections are already associated with well over a million deaths a year worldwide. The mechanism is straightforward evolution under selection — every course of antibiotics, in humans or in livestock, favours resistant organisms — and the pipeline of genuinely new antibiotic classes has been thin for decades because the economics reward drugs taken daily for life rather than once for a week. This is marked extrapolated rather than speculative only because the direction is already measurable; the pace is what is uncertain.

How confident this is

This is a reasoned extrapolation rather than an observation. The mechanism is understood, but the scale of the consequences depends on assumptions that could reasonably be argued differently.

Society

• What would happen if everyone stopped having children? Schools would empty within a decade, the workforce would begin shrinking in about twenty years, and the last human would die in roughly a century.
• What would happen if everyone stopped eating meat? A large drop in agricultural emissions and land use, offset by disruption to a billion livelihoods and some regions with no alternative.
• What would happen if all jobs were automated? The production problem would be solved and the distribution problem would not — nobody has demonstrated the second half.
• What would happen if half the world's population disappeared? Not abundance — the collapse of specialised supply chains, because modern systems need specific people rather than a certain number of them.
• What would happen if the world's population doubled overnight? Food is the binding constraint — global production feeds around 8 billion, and doubling demand cannot be met from existing stocks.
• What would happen if everyone lived to 150? It depends entirely on whether those are healthy years — extended lifespan without extended healthspan makes almost everything worse.
• What would happen if everyone worked a four-day week? Trials generally show output holding steady with better wellbeing — but the results come from office work, not from hospitals or factories.
• What would happen if everyone drove an electric car? Urban air quality would improve immediately; the grid would need roughly a quarter more electricity, and mining demand would rise sharply.
• What would happen if everyone spoke the same language? Trade and science would get modestly easier, and roughly seven thousand languages worth of knowledge would be lost.
• What would happen if nobody paid taxes? Everything funded collectively stops — roads, courts, defence, schools, health systems and pensions — within weeks to months.
• What would happen if all borders opened? Economic models suggest a very large rise in global output, and nobody can model the political response, which is the part that would decide it.