Hurry up, planet Earth is running early and here's all you need to know about it

Let me tell you a secret about the most ordinary thing in your life the dayWe all believe a day is exactly 24 hours Your phone says so Your office says so Your school timetable said so But here is the truth mdash the Earth has never actually promised us 24 hours A ldquodayrdquo is simply one full spin of the planet and the Earth like a slightly moody dancer does not spin at exactly the same speed every time Some days it turns a tiny bit slower And lately something odd is happeningIt has started spinning fasterOn July 5 2024 the Earth finished its daily spin quicker than on any day ever measured How much quicker Less than the blink of an eye mdash a couple of thousandths of a second You didnrsquot feel it Nobody did So why are some of the smartest scientists in the world losing sleep over itBecause of a machine we built that is too perfectFor most of human history the Earth itself was our only clock The sun rose the sun set mdash that was a day Nobody argued with the skyThen about 70 years ago we built something extraordinary the atomic clock Forget the wall clock at home that gains a few minutes every month An atomic clock is so accurate that if you had switched one on when dinosaurs roamed the Earth it would barely have lost a second by today It never gets tired never runs slow never needs windingAnd so the whole modern world moved onto this new clock Your phonersquos time comes from it So does your bank transaction your flight ticket your Google Map location every stock trade on Dalal Street Modern life runs on the atomic clockrsquos heartbeatBut then we had a problem no one had before us We had two clocks mdash the perfect atomic clock and the old moody Earth And they donrsquot always agree Itrsquos like having one friend who is always exactly on time and another who wanders in whenever she pleases If the two must walk together someone has to keep adjustingFor 50 years the adjustment was easy The Earth was the slow friend mdash it has been gradually slowing down for millions of years the Moonrsquos pull acts like a gentle brake So whenever the Earth fell too far behind the timekeepers of the world would simply pause the official clock for one second and let the planet catch up They called it the ldquoleap secondrdquo It happened 27 times between 1972 and 2016 You never noticed One night somewhere in the world a minute quietly had 61 seconds in itSimple The Earth is slow the clock waits That was the rule Then the Earth broke the ruleAround 2020 scientists checking the measurements saw something they had never seen before The Earth was not running slow anymore It was running fastYear after year it kept setting new speed records And the strangest part We donrsquot fully know why The best guess lies deep below your feet The Earth is not solid all the way through mdash under the rocky crust flows a vast ocean of liquid molten iron Picture a raw egg spinning on your kitchen counter the shell and the liquid inside donrsquot move as one Scientists believe that this liquid heart of the planet has for some mysterious reason slowed down mdash and to balance it the outer Earth the part we live on has sped up Thatrsquos it Thatrsquos the honest answer of modern science we can photograph black holes millions of light years away but we cannot fully explain why our own floor is spinning fasterHerersquos an even stranger twist One thing is slowing the Earth back down mdash melting ice As the great ice sheets of Greenland and Antarctica melt the water spreads out across the oceans A spinning skater slows down when she stretches her arms out a planet does the same when its water spreads out Scientists calculated that without this melting ice our clock crisis would have arrived years earlier Yes you read that right mdash climate change is in this one strange way buying us timeBut it may only be a delay If the Earth keeps hurrying our timekeepers will face something that has never been done in history Earlier the Earth was slow so we added a second Now the Earth is fast mdash so we may have to remove one One night the clock would jump from 115958 straight to midnight The moment 115959 would simply never exist One second of your life cancelledSounds like nothing Herersquos the worry All the worldrsquos computers were built believing that time only moves forward second by second never skipping Even adding a second mdash which we practised 27 times mdash once went wrong in 2012 one extra second crashed websites and jammed airline checkin counters across the world Removing a second has never been tested Nobody truly knows what the worldrsquos banks satellites and phone networks would do on a night when a minute has only 59 secondsSo this October timekeepers from over 60 countries will gather near Paris to vote on a way out stop fiddling with seconds altogether and let the perfect clock and the imperfect planet slowly drift apart mdash sorting out the difference maybe once in a century It could be one of the most important decisions ever taken about something you will never noticeAnd maybe thatrsquos the real story For thousands of years we obeyed the Earthrsquos time Now we have built clocks so perfect that the planet itself looks unreliable next to them mdash and we sit in committees deciding how to correct it like schoolmasters marking a 45billionyearold student lateSo tonight when your phone shows midnight remember what that number really is a delicate handshake between a machine that is never wrong and a planet that owes us nothing The Earth is running fast And somewhere a room full of very nervous people is deciding what to do about the second that time forgotNishant 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