Don’t ask how AI thinks. Ask when it boils!

You have probably heard the worry by now Artificial intelligence writes poems passes exams gives medical advice mdash and nobody knows how it does it Not the government Not the experts Not even the people who built it If you open up an AI chatbot you will not find rules or facts or grammar You will find numbers Billions and billions of numbers Look at any single one of them and it tells you nothing at allThat sounds terrifying A machine in our lives that even its makers cannot explainBut before you panic let me share a secret from my own subject physics We are surrounded by things that cannot be understood from the inside We have simply forgotten how strange they areTake a glass of waterOne molecule of water is not wet Wetness is not hiding inside it waiting for a better microscope Wetness only appears when trillions of molecules crowd together and slide over one anotherThe same goes for temperature A single molecule is not hot or cold It is just a tiny thing jiggling about ldquoHotrdquo is what a vast crowd of jiggling looks like from the outsideOr think of a wave going around a packed cricket stadium Thousands of people stand up and sit down and a wave rolls around the ground Now ask which person is the wave None of themEach person only stands and sits The wave is real mdash you can watch it film it time it mdash but it does not live in any single person It lives in the crowdPhysics has a name for this idea In 1972 the physicist Philip Anderson wrote a famous essay with a threeword title More Is Different His point was simple and deep Put enough simple things together and something genuinely new appears mdash behaviour you could never find by studying the parts no matter how hard you lookedHere is the surprise not understanding the parts has never stopped usEngineers built superb steam engines in the 1800s while scientists were still arguing about whether atoms even existed The engineers did not need atoms They had thermometers and pressure gauges mdash simple ways to measure the whole machine from the outside Master the crowd ignore the moleculeNow look at AI again Inside a modern AI sit billions of numbers called weights Each weight is like one water molecule or one person in the stadium It takes part in everything and explains nothing When the AI answers a question that answer is not stored in any single number It is a pattern sweeping across billions of them at once mdash a wave in the crowd Scientists who study these machines find exactly this one idea is spread across thousands of numbers and each number helps with thousands of ideas Asking ldquowhich number holds the lierdquo is like asking ldquowhich person is the waverdquoSo here is my suggestion and it will annoy people on every side Perhaps AI is not mysterious because its engineers have been lazy Perhaps it is mysterious for the same reason the weather isNobody can predict next Tuesdayrsquos rain by studying atoms one at a time mdash not for lack of money but because rain does not live at the level of atoms It lives at the level of clouds Maybe a mind mdash whether made of brain cells or computer chips mdash is the same kind of thing It makes sense at its own level and at no otherThis is not an excuse to give up When scientists accepted that they could never follow every water molecule they did not quit They invented the thermometer They found a few simple dials mdash temperature pressure mdash that tell you all you really need when the water will boil when the boiler will burst The great task for AI science is the same Not to read the machinersquos mind number by number but to build thermometers for AI simple outside measurements that warn us when a system is heading for trouble Early research hints that such dials can be foundAnd until we find them We should manage AI the way we already manage weather Nobody demands that the weather service track every raindrop before warning of a flood Instead we forecast We watch the skies constantly We build levees and we sound the sirens early For AI that means the same boring lifesaving routine test the machinersquos behaviour hard before releasing it pay experts to try to make it misbehave keep watching it after release and agree in advance on the warning signs that mean ldquostoprdquoNow I promised this would annoy everyone so let me finish the job To the AI companies ldquoeven we donrsquot understand itrdquo is not a shrug you are allowed If you sell the storm you own the flood And for the rest of us one colder thought Weather does not want anything But crowds do strange things that no single person intends No one person is a stampede yet stampedes happenNo single trader plans a market crash yet markets crash If bad behaviour ever grows inside an AI mdash deceit ambition mdash it too will live in the crowd of numbers invisible in any single one The stadium wave explains why we cannot see inside It does not promise that everything inside is friendlySo the next time someone tells you in a frightened voice that nobody understands how AI works you can smile and reply nobody understands how water works either mdash not by staring at one molecule And yet we swim in it We sail on it We forecast it and we build our cities behind strong levees above the flood line Humans learned to live safely with water thousands of years before anyone knew what water wasCan we pull off the same trick with thinking machines mdash and much faster this time That is the question of our decadeI suggest we start on the leveesNishant Sahdev is a physicist at the University of North Carolina at Chapel Hill US He chases ideas that refuse to stay in laboratories for your favourite Sunday midday