"Annenberg Media" "¶" "TODAY, OUR HERO FOR THE DAY IS ANDRE MARIE AMPERE." "AMPERE WAS EDUCATED UNDER THE INFLUENCE" "OF THE PHILOSOPHER ROUSSEAU," "WHICH MEANT HE WAS NEVER REALLY TAUGHT." "HE WAS SIMPLY PLACED IN A WELL-STOCKED LIBRARY" "AND TOLD, "HERE, GO LEARN."" "IN HIS CASE, THAT SEEMS TO HAVE WORKED PRETTY WELL." "HE'S KNOWN TO HAVE TAUGHT HIMSELF LATIN" "AND TO HAVE READ EUCLID AND EULER" "AND BERNOULLI AND VARIOUS OTHER MATHEMATICIANS." "IN THE MEANTIME, HOWEVER, WHEN HE WAS 14 YEARS OLD," "IN THE YEAR 1789, THE FRENCH REVOLUTION DESCENDED." "AMPERE'S FATHER WAS A JUDGE IN LYON" "AND IN THE COURSE OF HIS NORMAL DUTIES," "SENTENCED A JACOBIN TO DEATH IN THE GUILLOTINE." "WHEN THE JACOBINS TOOK OVER THE CITY," "AMPERE'S FATHER, IN HIS TURN," "WAS SENTENCED TO DIE ON THE GUILLOTINE." "THROUGHOUT HIS LIFE, AMPERE SUFFERED THE CONSEQUENCES" "OF A CONFLICT WHICH IS COMMON IN MEDITERRANEAN SOCIETIES," "A CONFLICT BETWEEN A SKEPTICAL, DOUBTING FATHER" "AND A DEEPLY RELIGIOUS CATHOLIC MOTHER." "THIS CAUSED HIM, THROUGHOUT HIS LIFE," "TO WORK OUT GRAND METAPHYSICAL SCHEMES" "THAT NEVER AMOUNTED TO VERY MUCH." "HIS PERSONAL LIFE WAS EXTREMELY DIFFICULT," "SOMEWHAT LIKE KEPLER'S, YOU MIGHT REMEMBER." "NOT ONLY DID HIS FATHER DIE IN THE GUILLOTINE," "BUT HIS FIRST WIFE, WHOM HE MARRIED IN 1799," "DIED JUST FOUR YEARS LATER." "HE DIVORCED HIS EXTREMELY NASTY SECOND WIFE." "HE HAD A SON WHO WAS A USELESS WASTREL." "HE HAD A DAUGHTER UPON WHOM HE DOTED," "AND SHE MARRIED A CRAZY ARMY OFFICER." "THROUGHOUT HIS ENTIRE LIFE, HE WAS ALWAYS SHORT OF FUNDS." "HIS PROFESSIONAL LIFE WAS EVEN STRANGER." "STARTING IN 1800, FOR 15 YEARS, AMPERE WAS A MATHEMATICIAN" "NOT A VERY GOOD ONE, JUST BARELY COMPETENT." "IN 1815, HE WISELY CHANGED HIS PROFESSION" "AND BECAME A CHEMIST." "HE TURNED OUT ALMOST TO BE A GREAT CHEMIST." "HE ALMOST DISCOVERED THE ELEMENT CHLORINE." "HE ALMOST DISCOVERED THE ELEMENT IODINE." "HE ALMOST DISCOVERED AVOGADRO'S LAW." "WHAT THE REST OF THE WORLD CALLS AVOGADRO'S LAW" "IN FRANCE IS CALLED THE LAW OF AMPERE AND AVOGADRO." "IN ANY CASE, IN 1820, AMPERE WAS 45 YEARS OLD," "AND HE WAS A THOROUGHLY UNDISTINGUISHED, MINOR FIGURE" "IN THE WORLD OF SCIENCE." "HOWEVER, HE DIFFERED IN ONE CRUCIAL WAY" "FROM EVERY OTHER SCIENTIST IN FRANCE." "HE BELIEVED IT WAS POSSIBLE" "FOR IMPORTANT SCIENTIFIC DISCOVERIES" "TO BE MADE OUTSIDE OF FRANCE." "IN THE YEAR 1820, OERSTED'S GREAT DISCOVERY" "STRUCK EUROPE LIKE A BOLT OUT OF THE BLUE." "THE OTHER FRENCH ACADEMICIANS REFUSED TO BELIEVE IT" "BECAUSE IT WAS IMPOSSIBLE THAT ANYTHING SO IMPORTANT" "COULD HAVE BEEN DISCOVERED IN COPENHAGEN." "AMPERE EMBRACED THE DISCOVERY IMMEDIATELY," "STARTED TO WORK OUT ITS CONSEQUENCES," "AND THEREBY MADE ALL OF HIS GREAT DISCOVERIES." "THAT BRINGS US TO OUR TOPIC FOR TODAY." "I NEED EVERYBODY IN A 180 FACING ME" "AT THIS POINT RIGHT OVER HERE." "A 180 IS NOT PEOPLE BEHIND ME." "A 180 IS A 180." "EVERYBODY TURN AROUND AND CLOSE IT BACK IN." "EVERYBODY REMEMBER HOW TO PACE COUNT NOW." "DON'T BRING BACK THE BOX." "SOME PEOPLE WANT TO BRING BACK THE BOX." "THEY'RE ON ENGINEERS' STAKES." "ALL THE BOXES ARE THERE." "NOBODY COME BACK AND SAY," ""SERGEANT FILLMORE, IT'S NOT THERE."" "I BROUGHT A CLASS UP HERE LAST WEEK," "AND THEY WERE THERE." "AT FIRST GLANCE, THESE U.S. MARINES" "DON'T SEEM TO HAVE MUCH IN COMMON" "WITH A 19th-CENTURY FRENCH PHYSICIST," "ANDRE MARIE AMPERE." "BUT, AS IS OFTEN THE CASE," "THERE'S MORE HERE THAN MEETS THE EYE." "THE CHALLENGE FOR AMPERE WAS TO EXPLAIN A COMMON," "BUT OFTEN BAFFLING MYSTERY OF NATURE." "THE CHALLENGE FOR THESE MARINES" "IS TO LOCATE SOME WELL-HIDDEN LITTLE BOXES" "LYING SOMEWHERE IN THESE HILLS." "WHILE THOSE TWO CHALLENGES ARE SEPARATED" "BY THOUSANDS OF KILOMETERS AND ABOUT 150 YEARS..." "THE IRONY IS THAT THEY BOTH REQUIRE THE SAME THING," "AN APPLICATION OF THE BASIC NATURE OF MAGNETISM." "I CHECK MY AZIMUTH." "IF UNDER MY INDEX LINE, IT SAYS 340," "AND I CAN STILL SHOOT MY AZIMUTH" "RIGHT TOWARDS CORPORAL SALAZAR," "THEN I KNOW THAT I'M LOCKED ON." "IN 1820, HANS CHRISTIAN OERSTED" "DISCOVERED THAT ELECTRIC CURRENTS" "PRODUCE MAGNETIC FORCES" "AND THAT THOSE FORCES ALWAYS MAKE MAGNETS POINT" "PERPENDICULAR TO THE DIRECTION OF THE CURRENT." "THIS WAS A RICH SCIENTIFIC DISCOVERY," "BUT UNTIL AMPERE COULD WORK OUT" "THE CONSEQUENCES OF OERSTED'S EXPERIMENT," "IT WOULD REMAIN LITTLE MORE" "THAN A SINGLE PIECE OF A COMPLEX PUZZLE." "I START MARCHING TILL I GET PAST THE OBJECT." "I'M COUNTING THE STEPS" "FROM MY LAST FACING MOVEMENT." "LIKE ANYONE STARTING OUT IN A NEW FIELD," "AMPERE ADVANCED ONE STEP AT A TIME," "ARMED WITH OERSTED'S DISCOVERY." "I'M GOING TO DO THE OPPOSITE" "AND TAKE THREE STEPS THIS WAY." "ONCE I GET HERE," "I DO ANOTHER FACING MOVEMENT." "I SHOOT MY AZIMUTH AGAIN." "THESE AMERICANS HAVE AT LEAST ONE ADVANTAGE" "THAT AMPERE LACKED." "INSTEAD OF WORKING" "IN THESE QUIET, PEACETIME SURROUNDINGS," "MONSIEUR AMPERE BEGAN HIS SCIENTIFIC CAREER" "IN THE BLOODY PANDEMONIUM OF THE FRENCH REVOLUTION." "AMPERE'S FATHER, JEAN JACQUES, WAS A JUSTICE OF THE PEACE" "WHO WAS LABELED AN ENEMY OF THE REVOLUTION." "AS HE APPROACHED THE GUILLOTINE," "AMPERE SR." "SCRIBBLED A FINAL NOTE TO HIS WIFE." ""I DO NOT LEAVE YOU RICH OR EVEN IN COMMON COMFORT," ""BUT MY GREATEST EXPENSE HAS BEEN THE PURCHASE OF BOOKS" ""AND MATHEMATICAL INSTRUMENTS" ""WHICH WERE INDISPENSABLE TO OUR SON'S EDUCATION." "THIS EXPENSE WAS IN ITSELF A WISE ECONOMY."" "CONSIDERING WHAT HIS SON MASTERED," "THE ELDER AMPERE'S MONEY WAS WELL-SPENT INDEED." "AT THE HEIGHT OF HIS ACADEMIC CAREER," "AMPERE WAS KNOWN AS A NATURAL PHILOSOPHER," "WISE IN THE WAYS OF SCIENCE AND HOW IT COULD EXPLAIN" "SOME OF THE MORE FASCINATING MYSTERIES OF THE UNIVERSE." "TODAY, AMPERE IS BEST REMEMBERED" "FOR HIS WORK IN ELECTRICITY AND MAGNETISM." "THAT WORK STARTED WITH THE FACT" "THAT ELECTRIC CURRENT FLOWING THROUGH A LONG, STRAIGHT WIRE" "PRODUCES A MAGNETIC FIELD THAT CIRCULATES AROUND THE WIRE." "BUT HOW DOES THE STRENGTH OF THE FIELD" "DEPEND ON THE DISTANCE FROM THE WIRE?" "IF A TINY SEGMENT OF ELECTRIC CURRENT COULD EXIST," "IT WOULD PRODUCE A MAGNETIC FIELD" "PROPORTIONAL TO THE INVERSE SQUARE OF THE DISTANCE." "THE DIRECTION OF THE FIELD IS RELATED" "TO THE DIRECTION OF THE CURRENT" "BY THE RIGHT HAND RULE, OR VECTOR CROSS PRODUCT." "THE FIELD WOULD BE BIGGEST WHEN THE CURRENT SEGMENT" "AND DISTANCE VECTOR ARE PERPENDICULAR." "BUT ELECTRIC CURRENTS CAN NEVER EXIST IN TINY SEGMENTS." "ANY REAL MAGNETIC FIELD MUST BE FOUND" "BY ADDING UP OR INTEGRATING THE CONTRIBUTIONS" "DUE TO EACH SEGMENT OF A FLOWING CURRENT." "THE FIELD DUE TO CURRENT FLOWING" "IN A LONG, STRAIGHT WIRE" "IS ALWAYS PERPENDICULAR TO THE WIRE" "AND DECREASES AS THE INVERSE FIRST POWER" "OF THE DISTANCE FROM THE WIRE." "THE NET RESULT IS A FIELD THAT GOES IN CIRCLES." "THE LINES OF FORCE ARE CIRCLES CONCENTRIC WITH THE WIRE," "AND THE FIELD IS THE SAME ALL THE WAY AROUND EACH CIRCLE." "ON THE OTHER HAND," "IF THE WIRE IS BENT AROUND INTO A LOOP," "THE CURRENT FLOWING THROUGH IT" "PRODUCES WHAT IS KNOWN AS A DIPOLE FIELD." "A HELICAL WINDING, OR SOLENOID," "IS LIKE A STACK OF CURRENT LOOPS." "IT CREATES A FIELD MUCH LIKE THAT OF A BAR MAGNET." "IF THE SOLENOID IS BENT AROUND INTO A CIRCLE," "THE DOUGHNUT IT FORMS IS CALLED A TOROID." "THE MAGNETIC FIELD OF A TOROID" "IS CONTAINED COMPLETELY INSIDE THE WINDINGS." "THERE ARE NO FIELD LINES OUTSIDE AT ALL." "FIRE TEAM LEADERS, HOLD UP YOUR MAPS" "SO YOUR TEAM CAN SEE." "ONCE I HAVE IT OPENED CORRECTLY," "I CAN GO AHEAD AND SHOOT." "STICK MY RIGHT HAND IN MY LEFT." "OBVIOUSLY, HOWEVER, THE EARTH IS NO DOUGHNUT." "ITS FIELD IS LIKE THAT OF A BAR MAGNET," "WITH PLENTY OF FLUX OUTSIDE" "TO APPLY FORCE TO THE NEEDLE OF A COMPASS." "FOR THESE MARINES," "THE KEY TO SUCCESS IS PREPARATION AND TEAMWORK," "WHICH IS WHY THEY'VE BEEN GETTING DOWN TO BASICS," "THE BASICS OF HOW TO NAVIGATE WITH A COMPASS." "WE'RE AT SQUARE TWO?" "5198." "OF COURSE, EVEN AMONG EXPERTS..." "I CAN SHOOT MY AZIMUTH." "AND EVEN WITH THE HELP OF A COMPASS," "GETTING FROM ONE POINT TO ANOTHER" "CAN BE QUITE A CHALLENGE." "FOLLOW THAT GRASSY AREA ALL THE WAY BACK" "TO WHERE IT LOOKS LIKE IT JUST DROPS" "OFF THE EDGE OF THE EARTH." "BUT IT'S NO LESS CHALLENGING" "THAN THE TASK AMPERE ASSIGNED HIMSELF" "IN THE EARLY YEARS OF THE LAST CENTURY." "FOR EXAMPLE, HE ASKED THE QUESTION," ""IF A CURRENT-CARRYING WIRE EXERTS A FORCE ON A MAGNET," ""WOULD IT EXERT A FORCE" "ON ANOTHER CURRENT-CARRYING WIRE?"" "TO ANSWER THE QUESTION, CONSIDER THE FACTS." "A FLOWING CURRENT PRODUCES A MAGNETIC FIELD," "AND A MAGNETIC FIELD APPLIES A FORCE" "TO A MOVING ELECTRIC CHARGE." "THEREFORE, SINCE AN ELECTRIC CURRENT" "IS NOTHING BUT MOVING ELECTRIC CHARGES," "IT FOLLOWS, THEN, THAT FLOWING ELECTRIC CURRENTS" "APPLY MAGNETIC FORCES TO EACH OTHER." "CURRENTS FLOWING IN THE SAME DIRECTION" "ATTRACT EACH OTHER." "CURRENTS FLOWING IN OPPOSITE DIRECTIONS REPEL EACH OTHER." "IN FACT, THE UNIT OF ELECTRIC CURRENT" "IS DEFINED IN TERMS OF THE FORCE BETWEEN TWO WIRES." "PERHAPS THAT'S WHY IT'S CALLED THE AMPERE," "OR AMP FOR SHORT." "BUT MONSIEUR AMPERE DID SOMETHING EVEN MORE PRACTICAL," "AND DEFINITELY MORE PROFOUND," "THAN LENDING HIS NAME TO A UNIT OF ELECTRIC CURRENT." "AMPERE CREATED ELECTRODYNAMICS," "THE THEORY THAT MAGNETISM IS ELECTRICITY IN MOTION." "IT WAS A PROMISING THEORY THAT, AMONG OTHER THINGS," "COULD EXPLAIN THE MAGNETIC FIELDS" "OF STRAIGHT WIRES, LOOPS, OR EVEN A TOROID." "BUT WHAT ABOUT THE FIELD OF A BAR MAGNET?" "HERE, TOO, AMPERE HAD THE RIGHT IDEA," "THAT THERE MUST BE CURRENTS INSIDE THE MAGNET ITSELF." "HE IMAGINED THAT EACH ATOM OF A MAGNETIC MATERIAL" "MUST HAVE A CIRCULATING ELECTRIC CHARGE" "THAT PRODUCES A MAGNETIC FIELD." "IN FACT, THE SPINNING EARTH" "HAS CIRCULATING ELECTRIC CHARGES IN ITS CORE," "WHICH CREATE THE MAGNETIC FIELD THAT ATTRACTS A COMPASS NEEDLE." "THEREFORE, THE FORCE THAT MAKES A COMPASS ALWAYS POINT NORTH" "IS THE SAME AS THE FORCE" "BETWEEN TWO CURRENT-CARRYING WIRES." "BUT PUTTING THAT FORCE TO WORK" "OFTEN REQUIRES PATIENCE AND ACCURACY." "TO MAKE THE MEASUREMENT OF ANGLES" "AS ACCURATE AS POSSIBLE OVER LONG DISTANCES," "ONE PERSON SIGHTS ALONG THE COMPASS" "AND LINES UP ANOTHER PERSON AT A DISTANCE." "ABOUT 52 DEGREES MAGNETIC." "PLOT THEM OUT ON HERE WITH THE PROTRACTOR." "THESE MARINES ARE GETTING A FIRSTHAND LESSON" "IN THE VALUE OF WORKING TOGETHER," "A LESSON THAT WOULD SEEM VALUABLE" "IN THE FIELD OF SCIENCE." "IF SO, IT'S A LESSON THAT WAS NOT UNDERSTOOD" "BY AMPERE..." "JAMES CLERK MAXWELL..." "OR MICHAEL FARADAY." "ALTHOUGH IN THEIR DAY," "SCIENTISTS TENDED TO MARCH TO THEIR OWN DRUMMERS," "AMPERE AND FARADAY DID WORK IN PARALLEL." "FOR EXAMPLE, EN ROUTE TO THEIR MAJOR SUCCESSES" "IN THE FIELD OF ELECTRICITY," "BOTH HAD BEEN INTERESTED IN CHEMISTRY" "AND ENORMOUSLY INFLUENCED" "BY THE WORK OF SIR HUMPHREY DAVY." "HOWEVER, FARADAY AND AMPERE WERE BOUND TO GO DIFFERENT WAYS." "WHERE FARADAY WAS INTUITIVELY BRILLIANT," "AMPERE WAS SIMPLY BRILLIANT" "WHEN IT CAME TO DEALING WITH NUMBERS AND SYMBOLS." "THE LAW THAT BEARS HIS NAME" "IS A MATHEMATICAL DESCRIPTION OF THE MAGNETIC FIELD" "AS BOTH SIMILAR TO AND DIFFERENT FROM" "THE ELECTRIC FIELD." "IN AN ELECTRIC FIELD, NO WORK IS DONE" "IF A CHARGE IS MOVED AROUND ANY CLOSED PATH" "AND BACK TO ITS STARTING POINT." "THEREFORE, WHEN STARTING FROM ANY POINT ON ANY PATH" "AND RETURNING TO THE SAME POINT," "THE CHANGE IN ELECTRIC POTENTIAL IS ALWAYS O." "THEREFORE, THE LINE INTEGRAL" "OF THE ELECTRIC FIELD AROUND ANY CLOSED PATH" "IS ALWAYS 0." "THIS IS A FUNDAMENTAL PROPERTY OF ELECTRIC FIELDS." "MAGNETIC FIELDS ARE DIFFERENT." "THE CURRENT IN A STRAIGHT WIRE" "CREATES CIRCLES OF CONSTANT MAGNETIC FIELD." "SINCE THE FIELD IS CONSTANT ON EACH CIRCLE," "THE LINE INTEGRAL ON EACH ONE IS EASILY CALCULATED]," "IT'S EQUAL TO A CONSTANT TIMES THE CURRENT IN THE WIRE." "THE RESULT IS THE SAME FOR ANY CIRCLE AROUND THE WIRE," "AND, FOR THAT MATTER, FOR ANY PATH AROUND THE WIRE." "THE LINE INTEGRAL OF THE MAGNETIC FIELD" "AROUND ANY CLOSED PATH" "IS ALWAYS EQUAL TO MU-0 TIMES THE TOTAL CURRENT" "THAT THREADS THROUGH THE PATH." "THIS IS CALLED AMPERE'S LAW," "AND IT'S ONE OF THE FUNDAMENTAL EQUATIONS OF MAGNETISM." "AS SUCH, IT PLAYED A CRUCIAL ROLE" "IN THE WORK OF JAMES CLERK MAXWELL." "WHEN MAXWELL SAT DOWN" "TO FORGE A SINGLE, COHERENT THEORY OF ELECTROMAGNETISM," "HE STARTED WITH FARADAY'S INTUITIVE CONCEPT" "OF LINES OF FORCE," "WITH GAUSS' LAWS OF ELECTRIC AND MAGNETIC FLUX," "AND WITH AMPERE'S BRILLIANT IDEA" "THAT ALL MAGNETISM WAS ELECTRICAL IN ORIGIN." "OF COURSE, THOSE INSIGHTS" "HAD TO BE EXPRESSED MATHEMATICALLY." "#]THELINEINTEGRAL OFTHEMAGNETICFIELD" "AROUNDANYCLOSEDPATH" "EQUALSMU-0 TIMES THE ELECTRIC CURRENT" "THREADINGTHROUGHTHEPATH." "BUTFORELECTRICFIELDS," "THELINEINTEGRAL AROUND ANY PATH IS ALWAYS 0." "THEELECTRICFLUX THROUGHANYCLOSEDSURFACE" "EQUALS THE NET CHARGE INSIDE DIVIDEDBYEPSILON-0." "BUTTHEMAGNETICFLUX THROUGHANYCLOSEDSURFACE" "ISALWAYS0." "THESE ARE THE FUNDAMENTAL EQUATIONS" "OF CONSTANT ELECTRIC AND MAGNETIC FIELDS." "ALL YOU HAVE TO WORRY ABOUT" "IS HAVING YOUR AZIMUTH" "AND HAVING YOUR LINE AND ARROW LINED UP." "THAT'S IT." "WITH ALL THIS IN MIND," "I'M TELLING YOU" "AS I TOLD YOU BEFORE," "THERE WILL BE NO FLASHLIGHTS." "NOBODY HERE WANTS TO FAIL." "DOES EVERYBODY UNDERSTAND THE COMPASS?" "EVERYBODY WILL BE EXPERTS, RIGHT?" "NOW'S THE TIME FOR QUESTIONS." "THE ONLY STUPID QUESTION" "IS THE ONE THAT ISN'T ASKED." "ONCE AMPERE REALIZED THAT A LOOP OF CURRENT" "WOULD GIVE A MAGNETIC FIELD IN THE SAME SHAPE" "AS THE FIELD OF A BAR MAGNET, A PERMANENT MAGNET," "HE DECIDED THAT MAYBE ALL MAGNETIC FIELDS" "WERE DUE TO ELECTRIC CURRENTS," "THAT IS TO SAY, EVERY PERMANENT MAGNET" "PERMANENTLY HAD ELECTRIC CURRENTS" "RUNNING OUND INSIDE OF IT TO GENERATE THE FIELD." "WELL, THAT IDEA WAS IMMEDIATELY SHOT DOWN IN FLAMES" "BY A COLLEAGUE NAMED FRESNEL." "FRESNEL POINTED OUT" "THAT THE MATERIALS THAT CAN BE MADE INTO MAGNETS," "IRON AND STEEL," "ARE NOTORIOUSLY POOR ELECTRICAL CONDUCTORS" "AND THAT WHEN AN ELECTRIC CURRENT" "RUNS THROUGH A POOR CONDUCTOR, IT CAUSES HEATING." "IF AMPERE'S IDEA WERE RIGHT," "THEN ALL MAGNETS WOULD ALWAYS BE WARM." "THEY AREN'T, SO IT MUST BE WRONG." "BUT HE GAVE AMPERE A WAY OUT." "HE SAID, "WE KNOW NOTHING AT ALL" ""ABOUT WHAT GOES ON INSIDE OF ATOMS." ""MAYBE THE CURRENTS THAT CAUSE MAGNETISM" ""ACTUALLY OCCUR INSIDE OF THE ATOMS" "THAT MAKE UP THE MATERIAL."" "AMPERE EMBRACED THAT IDEA" "AND WORKED OUT A VERY CLEVER CONSTRUCTION." "AT THE TIME, IT WAS BELIEVED" "THAT THERE EXISTED THE LUMINIFEROUS ETHER." "WE'LL HEAR MUCH MORE ABOUT IT LATER ON," "BUT IT WAS, IN ANY CASE, THE MEDIUM" "THAT WAS SUPPOSED TO CARRY LIGHT THROUGH SPACE." ")A AMPERE SPECULATED THAT PERHAPS THE ETHER" "WAS MADE UP OF ENORMOUS AMOUNTS OF ELECTRIC CHARGE," "BOTH POSITIVE AND NEGATIVE," "BUT ORDINARILY IN PERFECT BALANCE," ")A SO THAT IT WAS COMPLETELY NEUTRAL," "EXCEPT, PERHAPS, INSIDE OF ATOMS." "THE IDEA HE HAD WAS THIS" "HERE IS AN ATOM," "AND HERE IS SOME ELECTRIC CHARGE" "RUNNING THROUGH THE ETHER," "POSITIVE CHARGE RUNNING )" "SO THE TWO OF THEM BALANCED AND HAD NO EFFECT." "BUT ONCE THEY GOT INSIDE OF THE ATOM," "THEY COULD SPLIT UP." "THE POSITIVE CHARGE COULD RUN AROUND ONE WAY" "AND THEN COME OUT AGAIN." "THE NEGATIVE CHARGE COULD RUN AROUND THE OTHER WAY" "AND THEN COME OUT AGAIN." "THE EFFECT OF THE POSITIVE CHARGE" "WOULD BE AN ELECTRIC CURRENT RUNNING AROUND" "WITH THE POSITIVE CHARGE LIKE THAT." "THE EFFECT OF THE NEGATIVE CHARGE" "WOULD BE AN ELECTRIC CURRENT" "RUNNING IN THE OPPOSITE DIRECTION." "THE NET EFFECT IS A COMPLETE LOOP OF CURRENT," "WHICH WOULD HAVE A MAGNETIC FIELD" "LOOKING JUST LIKE THIS." "THAT MEANT THAT IF THE ATOMS OF A PIECE OF MATERIAL" "ALL HAD THESE ELECTRIC CURRENT LOOPS IN THEM," "RUNNING AROUND IN THE SAME DIRECTION," "THE MATERIAL WOULD HAVE THE PROPERTIES" "OF A PERMANENT MAGNET." "THAT IS A VERY PECULIAR IDEA." "THERE ARE PARTS OF IT THAT WE STILL BELIEVE TODAY." "WE DO BELIEVE THAT THERE ARE ELECTRIC CURRENTS" "RUNNING AROUND INSIDE OF ATOMS" "AND THAT THOSE CURRENTS GIVE RISE" "TO THE MAGNETIC PROPERTIES OF MATTER." "WE NO LONGER BELIEVE IN CHARGES FILLING A LUMINIFEROUS ETHER" "AND THIS BUSINESS OF IT SPLITTING UP" "INSIDE OF THE ATOM AND RUNNING OUT AGAIN." "THIS PICTURE IS A SPLENDID ILLUSTRATION" "OF THE VERY STRANGE FACT THAT IT'S POSSIBLE IN SCIENCE" "TO HAVE AN IDEA THAT'S UTTERLY BRILLIANT" "AND COMPLETELY WRONG." "BUT IT'S PART OF THAT SCAFFOLDING" "THAT WE'RE ALWAYS BUILDING IN ORDER TO MAKE PROGRESS." "IN THE COURSE OF TIME," "OPINIONS ABOUT THE IMPORTANCE OF EVENTS" "TENDS TO CHANGE." ")A HEROES IN THE HISTORY OF SCIENCE COME AND GO," "BUT ONE THING IS CERTAIN," "AMPERE'S NAME WILL ALWAYS BE CURRENT." "[LAUGHTER]" "DON'T TAKE ANY WOODEN MAGNETS." "I'LL SEE YOU NEXT TIME." "CAPTIONING MADE POSSIBLE BY THE ANNENBERG/CPB PROJECT" "CAPTIONING PERFORMED BY THE NATIONAL CAPTIONING INSTITUTE, INC." "CAPTIONS COPYRIGHT 1986 CALIFORNIA INSTITUTE OF TECHNOLOGY," "THE CORPORATION FOR COMMUNITY COLLEGE TELEVISION, THE ANNENBERG/CPB PROJECT" "PUBLIC PERFORMANCE OF CAPTIONS PROHIBITED WITHOUT PERMISSION OF NATIONAL CAPTIONING INSTITUTE" "Annenberg Media" "¶" "For information about this and other Annenberg Media programs call 1-800-LEARNER and visit us at"