,THE NEUTRINO IS THE GHOST OF THE PARTICLE WORLD3 THE SECOND MOST ABUNDANT PARTICLE IN THE UNIVERSE AFTER THE PHOTON1 AND THE LEAST INTERACTIVE THING KNOWN TO HAVE MASS4 ,ROUGHLY SIXTY-FIVE BILLION SOLAR NEUTRINOS PASS THROUGH EVERY SQUARE CENTIMETRE OF YOUR BODY EVERY SECOND THROUGH YOU1 THROUGH THE ,EARTH1 THROUGH LIGHT-YEARS OF LEAD AND ALMOST NONE OF THEM NOTICE4 ,CATCHING ONE REQUIRES KILOTONS OF WATER1 CUBIC KILOMETRES OF ,ANTARCTIC ICE1 OR A TANK OF LIQUID CHLORINE THE SIZE OF A HOUSE4 ,YET THIS BARELY-THERE PARTICLE KEEPS REMAKING PHYSICS3 IT FORCED THE ,STANDARD ,MODEL'S FIRST REAL AMENDMENT "1 CONFIRMED HOW STARS DIE "<,,SN #AIHG;,A">1 AND MAY HOLD THE KEY TO WHY ANYTHING EXISTS AT ALL4 ,INVENTED TO SAVE PHYSICS ,PAULI'S 8DESPERATE REMEDY0 ,THE NEUTRINO BEGAN AS BOOKKEEPING4 ,IN #AICJ1 ,WOLFGANG ,PAULI FACED AN APPARENT VIOLATION OF ENERGY CONSERVATION3 IN BETA DECAY1 THE ELECTRON'S ENERGY CAME OUT IN A SPREAD RATHER THAN A SHARP VALUE ENERGY SEEMED TO GO MISSING4 ,RATHER THAN ABANDON CONSERVATION LAWS1 ,PAULI PROPOSED AN INVISIBLE NEUTRAL PARTICLE CARRYING THE MISSING ENERGY AWAY 8A DESPERATE REMEDY10 HE CALLED IT1 FOR 8A PARTICLE THAT CANNOT BE DETECTED40 ,ENRICO ,FERMI NAMED IT THE NEUTRINO "<8LITTLE NEUTRAL ONE0 IN ,ITALIAN"> AND BUILT IT INTO HIS #AICD THEORY OF BETA DECAY4 ,FOR TWENTY-SIX YEARS IT WAS PURE MATHEMATICS4 ,THEN ,FREDERICK ,REINES AND ,CLYDE ,COWAN PROVED IT REAL4 ,IN #AIEF1 BESIDE A REACTOR AT THE ,SAVANNAH ,RIVER PLANT WHICH FLOODS OUT @9#AJ ANTINEUTRINOS PER SQUARE CENTIMETRE PER SECOND THEY CAUGHT THE UNMISTAKABLE DOUBLE FLASH OF AN ANTINEUTRINO TRIGGERING INVERSE BETA DECAY4 ,REINES TELEGRAMMED ,PAULI3 8,WE ARE HAPPY TO INFORM YOU THAT WE HAVE DEFINITELY DETECTED NEUTRINOS40 ,THE GHOST HAD A BODY4 ,THE WORK WON THE #AIIE ,NOBEL ,PRIZE ,REINES ALONE1 ,COWAN HAVING DIED TWO DECADES EARLIER4 ,THREE FLAVORS AND THE DISCOVERY THAT BROKE THE ,STANDARD ,MODEL ,NEUTRINOS COME IN THREE FLAVORS ELECTRON1 MUON1 AND TAU MATCHING THE THREE CHARGED LEPTONS4 ,FOR DECADES1 EXPERIMENTS KEPT FINDING FEWER NEUTRINOS THAN EXPECTED3 ,RAY ,DAVIS'S FAMOUS CHLORINE TANK IN A ,SOUTH ,DAKOTA GOLD MINE CAUGHT ONLY ABOUT A THIRD OF THE PREDICTED SOLAR NEUTRINOS1 A 8DEFICIT0 THAT STOOD FOR THIRTY YEARS AS EITHER BROKEN ASTROPHYSICS OR BROKEN PARTICLE PHYSICS4 ,THE RESOLUTION WAS ONE OF THE GREAT DISCOVERIES OF THE LATE TWENTIETH CENTURY3 NEUTRINOS CHANGE FLAVOR IN FLIGHT4 ,AN ELECTRON NEUTRINO LEAVING THE ,SUN'S CORE CAN ARRIVE AT ,EARTH AS A MUON OR TAU NEUTRINO NEUTRINO OSCILLATION1 PROVEN DEFINITIVELY BY ,SUPER-,KAMIOKANDE " AND ,CANADA'S ,,SNO EXPERIMENT "4 ,THE CATCH3 OSCILLATION IS ONLY POSSIBLE IF NEUTRINOS HAVE MASS AND THE ,STANDARD ,MODEL HAD ALWAYS ASSUMED THEM MASSLESS4 ,IT REMAINS THE FIRST AND CLEAREST EXPERIMENTAL CRACK IN THE ,STANDARD ,MODEL ITSELF4 ,TAKAAKI ,KAJITA AND ,ARTHUR ,MC,DONALD SHARED THE #BJAE ,NOBEL ,PRIZE FOR IT4 ,HOW MUCH DOES A GHOST WEIGH8 ,NOBODY KNOWS EXACTLY AND THE ANSWER MATTERS COSMICALLY4 ,THE ,,KATRIN EXPERIMENT IN ,GERMANY WEIGHS THE NEUTRINO BY WATCHING THE EXTREME ENDPOINT OF TRITIUM BETA DECAY1 WHERE THE ELECTRON'S ENERGY IS STOLEN BY THE DEPARTING NEUTRINO2 ITS BEST LIMITS PUT THE MASS BELOW ROUGHLY #J4DE ELECTRONVOLTS OVER A MILLION TIMES LIGHTER THAN THE NEXT-LIGHTEST PARTICLE1 THE ELECTRON4 ,WHY SUCH A TINY MASS EXISTS AT ALL AND WHETHER NEUTRINOS ARE THEIR OWN ANTIPARTICLES " ARE AMONG THE DEEPEST OPEN QUESTIONS IN PHYSICS1 WITH NEUTRINOLESS DOUBLE-BETA-DECAY EXPERIMENTS HUNTING THE ANSWER UNDERGROUND WORLDWIDE4 ,THE DAY #BD NEUTRINOS REWROTE ASTRONOMY ,ON #BC ,FEBRUARY #AIHG1 THREE UNDERGROUND DETECTORS ,KAMIOKANDE-,,II "<,JAPAN">1 ,,IMB "<,OHIO">1 AND ,BAKSAN "<,CAUCASUS"> CAUGHT ROUGHLY TWO DOZEN NEUTRINOS IN THIRTEEN SECONDS4 ,THEY HAD TRAVELED #AFH1JJJ YEARS FROM THE COLLAPSING CORE OF A STAR IN THE ,LARGE ,MAGELLANIC ,CLOUD1 AND THEY ARRIVED HOURS BEFORE THE SUPERNOVA'S LIGHT NEUTRINOS ESCAPE THE DYING CORE INSTANTLY1 WHILE THE SHOCK WAVE STILL FIGHTS ITS WAY OUT4 ..> ,TWENTY-FOUR PARTICLES1 FROM ONE EXPLOSION #AFH1JJJ LIGHT-YEARS AWAY AND THEY CONFIRMED THE CORE-COLLAPSE MECHANISM1 PROVED NEUTRINOS CARRY @9#II.0 OF A DYING STAR'S ENERGY1 AND LAUNCHED NEUTRINO ASTRONOMY AS A FIELD4 ,MASATOSHI ,KOSHIBA SHARED THE #BJJB ,NOBEL ,PRIZE FOR IT4 ,WHY GHOSTS SHAPE GALAXIES ,FOR ALL THEIR ELUSIVENESS1 NEUTRINOS ARE COSMOLOGICAL GIANTS4 ,THEY ARE SO NUMEROUS AND SO LIGHT THAT THEIR COMBINED MASS ONCE INFLUENCED HOW MATTER CLUMPED IN THE EARLY UNIVERSE BECAUSE THEY STREAM FREELY THROUGH SPACE1 THEY SMOOTH OUT STRUCTURE ON SMALL SCALES3 THE PRECISE VALUE OF THE NEUTRINO MASS MEASURABLY SHAPES THE MAP OF THE GALAXIES1 WHICH IS WHY COSMOLOGISTS EXTRACT NEUTRINO-MASS LIMITS FROM THE COSMIC MICROWAVE BACKGROUND AND GALAXY SURVEYS4 ,THE SMALLEST SIGNAL LEAVES ITS HANDWRITING ON THE LARGEST STRUCTURE THE RECURRING LESSON OF THE ZEPTOVERSE PROGRAM4 ,NEUTRINOS MAY ALSO BE WHY WE'RE HERE3 LEADING THEORIES OF THE MATTERANTIMATTER ASYMMETRY " RUN THROUGH NEUTRINO PHYSICS4 ,THE LIGHTEST PARTICLE MAY CARRY THE HEAVIEST ANSWER4 ,HUNTING THEM TODAY ,THE INSTRUMENTS ARE CATHEDRALS BUILT FOR GHOSTS3 ,SUPER-,KAMIOKANDE "1 ,ICE,CUBE "1 ,,KATRIN "1 ,,DUNE "1 AND ,,JUNO "<,CHINA">4 ,EACH CATCHES A HANDFUL OF EVENTS TO ANSWER QUESTIONS ABOUT EVERYTHING4 ,SEE ALSO "9 ZEPTOVERSE THE REALM OF THE SMALLEST SIGNALS "9 SMALLEST THINGS EVER MEASURED THE NEUTRINO'S PLACE ON THE LIST "9 PROTON DECAY THE OTHER THING THE GIANT UNDERGROUND TANKS HUNT "9 WHY DOES MATTER EXIST ,REFERENCES - ,REINES @& ,COWAN FIRST NEUTRINO DETECTION1 ,SAVANNAH ,RIVER "<#AIEF">2 ,NOBEL #AIIE - ,KAMIOKANDE-,,II _/ ,,IMB _/ ,BAKSAN ,,SN #AIHG;,A NEUTRINO BURST "<#AIHG">2 ,NOBEL #BJJB - ,SUPER-,KAMIOKANDE ATMOSPHERIC NEUTRINO OSCILLATION "<#AIIH">2 ,,SNO SOLAR NEUTRINO SOLUTION "<#BJJB">2 ,NOBEL #BJAE - ,,KATRIN COLLABORATION NEUTRINO MASS UPPER LIMITS "<#BJBB#BJBE"> - ,PAULI #AICJ LETTER2 ,FERMI #AICD BETA-DECAY THEORY