JOAN CARTAN-HANSEN, HOST:
MEASURING IS A WAY OF FINDING
SIZES OR AMOUNTS.
IT ALLOWS US TO MAKE
COMPARISONS.
BUT WHY, WHAT AND HOW WE
MEASURE IS QUITE A STORY.
(MUSIC)
SOME SCIENTISTS THINK THAT THE
VERY FIRST SIGNS OF HUMANS
MEASURING SOMETHING CAN BE
FOUND IN THE PAINTINGS IN
CAVES IN FRANCE.
THE IMAGES ON THE WALLS IN THE
CAVES DATE BACK TO PREHISTORIC
TIMES.
SOME SCIENTISTS SUGGEST THE
BLACK DOTS ALONG WITH THE
OTHER IMAGES WERE A WAY TO
MEASURE TIME THROUGH THE LUNAR
CYCLE.
ONE OF THE OLDEST KNOWN
STANDARDS OF MEASUREMENT COMES
FROM ANCIENT EGYPT.
IT WAS CALLED A CUBIT.
IT WAS MEASURED FROM THE TIP
OF THE FINGER TO THE ELBOW.
BUT THERE WAS A PROBLEM WITH
THAT.
CAN YOU SEE IT?
TO AVOID CONFUSION, AN
EGYPTIAN KING SET THE OFFICIAL
LENGTH OF A CUBIT AND ALL
CUBITS IN THE LAND HAD TO BE
THE SAME.
CUBIT MEASURING STICKS WERE
HANDED OUT AND IF YOU DIDN'T
USE IT PROPERLY, THE PENALTY
COULD BE DEATH.
SO, WITH A UNIT OF MEASUREMENT
THAT WAS ALWAYS THE SAME, THE
EGYPTIANS WENT ON TO BUILD
SOME OF THE WORLD'S MOST
AMAZING STRUCTURES.
ANCIENT CHINESE KINGS BASED
MEASUREMENTS OF LENGTH ON BODY
PARTS TOO,
AS DID ENGLISH KINGS.
AN INCH BECAME THE WIDTH OF A
THUMB,
A FOOT WAS THE LENGTH OF A
FOOT.
A YARD WAS THE LENGTH OF A
MAN'S STRIDE.
AND, AS PEOPLE MOVED AROUND
THE WORLD AND TRADED GOODS,
STANDARDS OF MEASUREMENT WENT
WITH THEM.
BUT THERE WAS STILL A PROBLEM.
THE STANDARD OF MEASUREMENT
DIFFERED FROM COUNTRY TO
COUNTRY, EVEN CITY TO CITY.
WE NEEDED TO BE ABLE TO MAKE
COMPARISONS AND WE NEEDED TO
BRING ORDER TO OUR WORLD.
AND YOU CAN'T DO GOOD
SCIENTIFIC RESEARCH OR
PROPERLY BUILD THINGS OR EVEN
KNOW IF YOU'RE PAYING THE
RIGHT AMOUNT FOR SOMETHING IF
YOU DON'T HAVE AN ACCURATE AND
STANDARDIZED SYSTEMS OF
MEASUREMENT.
AND WITHOUT ACCURATE SYSTEMS
OF MEASUREMENT, YOU CAN'T
PREDICT OR ESTIMATE SUPPLIES
OR FIGURE OUT WHAT WILL
HAPPEN.
SO, STARTING ABOUT 1799, THE
FRENCH DEVELOPED THE METRIC
SYSTEM.
AND IN 1875, ESTABLISHED AN
INTERNATIONAL ORGANIZATION TO
MAKE SURE WEIGHTS AND
MEASUREMENTS WERE ACCURATE AND
THE SAME ACROSS THE WORLD.
THE ENGLISH STANDARDIZED THEIR
IMPERIAL SYSTEM A FEW YEARS
EARLIER
BUT AMERICA DIDN'T START
STANDARDIZING ITS OWN U.S.
CUSTOMARY MEASUREMENT SYSTEMS
UNTIL THE EARLY 19 HUNDREDS.
SO, WHAT DO WE MEASURE?
ALMOST EVERYTHING.
AND HOW WE DO IT, IS WITH
UNITS OF NUMBERS BASED ON SOME
PROPERTY LIKE HOW BIG OR HOW
MANY.
SO, LET'S LEARN ABOUT SOME
FUNDAMENTAL UNITS.
ROLL 'EM.
(NEWSREEL MUSIC)
MALE VOICE: TIME
CARTAN-HANSEN: TIME STARTED
OUT BEING MEASURED BY THE
MOVEMENT OF THE EARTH.
A YEAR IS HOW LONG IT TAKES
THE EARTH TO MAKE ONE COMPLETE
ROTATION AROUND THE SUN.
A MONTH IS ROUGHLY HOW LONG IT
TAKES THE MOON TO COMPLETE ONE
ORBIT OF THE EARTH.
A DAY IS HOW LONG IT TAKES THE
EARTH TO COMPLETE ONE TURN ON
ITS AXIS.
ANCIENT EGYPTIANS DIVIDED THE
DAY INTO APPROXIMATELY 24
HOURS USING SUNDIALS.
AN HOUR HAS 60 MINUTES,
AND A MINUTE HAS 60 SECONDS.
BUT HOW LONG IS A SECOND?
TO BE PRECISE, A SECOND IS NOW
NOT BASED ON THE MOVEMENT OF
THE EARTH BUT ON ATOMIC TIME.
SO WHAT DOES THAT MEAN?
WELL UNLESS YOU ARE A
SCIENTIST WHO NEEDS THAT KIND
OF PRECISION, DON'T WORRY
ABOUT.
JUST REMEMBER THAT SECONDS
TURN INTO MINUTES, MINUTES
TURN INTO HOURS, HOURS TURN
INTO DAYS, DAYS TURN INTO
WEEKS, WEEKS TURN INTO MONTHS,
MONTHS TURN INTO YEARS.
(NEWSREEL MUSIC)
MALE VOICE: LENGTH OR DISTANCE
CARTAN-HANSEN: IN THE U.S.
CUSTOMARY SYSTEM OF
MEASUREMENT, DON'T WORRY ABOUT
THE METRIC SYSTEM- I'LL GET TO
THAT IN A MINUTE-
LENGTH IS MEASURED IN INCHES,
FEET, YARDS, AND MILES.
SPEED LIMITS FOR CARS, FOR
EXAMPLE, ARE MEASURED IN MILES
PER HOUR.
THAT'S BECAUSE SPEED IS
MEASURED IN DISTANCE TRAVELED
OVER TIME.
SOME DISTANCES ARE SO VAST
THAT MEASURING IN MILES IS
CONFUSING.
SO, IN SPACE, WE MEASURE IN
ASTRONOMICAL UNITS AND LIGHT
YEARS.
THE EARTH IS 93 MILLION MILES
FROM THE SUN.
THAT'S ONE ASTRONOMICAL UNIT.
SO, MARS, FOR EXAMPLE IS 1
POINT 5-2 ASTRONOMICAL UNITS
FROM THE SUN.
A LIGHT YEAR IS HOW FAR LIGHT
TRAVELS IN ONE YEAR.
A LIGHT YEAR IS 60 THOUSAND
ASTRONOMICAL UNITS.
THE SUN'S CLOSEST STAR IS
ALPHA CENTAURI AND IT IS 4
POINT 4 LIGHT YEARS AWAY.
ONCE YOU KNOW HOW TO MEASURE
LENGTH, YOU CAN MEASURE
HEIGHT, HOW TALL, AND WIDTH,
HOW WIDE.
AND ONCE YOU KNOW LENGTH,
HEIGHT, AND WIDTH, YOU CAN
FIGURE OUT VOLUME.
(NEWSREEL MUSIC)
MALE VOICE: VOLUME.
CARTAN-HANSEN: VOLUME IS A
MEASURE OF SPACE, WHETHER IT
BE A SOLID, LIQUID OR GAS.
YOU CAN MEASURE THE SPACE TO
FIGURE OUT THE VOLUME.
LIQUID VOLUME IS OFTEN
MEASURED IN OUNCES, CUPS,
PINTS, QUARTS, AND GALLONS.
(NEWSREEL MUSIC)
MALE VOICE: WEIGHT.
CARTAN-HANSEN: IN THE UNITED
STATES, MASS, OR MORE COMMONLY
WHAT WE CALL WEIGHT, IS
GENERALLY MEASURED IN OUNCES,
POUNDS, OR TONS.
AND UNDER THE ENGLISH SYSTEM,
WEIGHTS ARE ALSO MEASURED IN
STONES.
(NEWSREEL MUSIC)
MALE VOICE: TEMPERATURE.
CARTAN-HANSEN: IN THE UNITED
STATES, TEMPERATURE IS
MEASURED ON THE FAHRENHEIT
SCALE WHERE 32 DEGREES IS THE
POINT WHERE WATER FREEZES AND
212 DEGREES IS WHEN WATER
BOILS.
AND THAT'S JUST PART OF THE
STORY OF MEASUREMENT.
WE MEASURE LOTS OF DIFFERENT
THINGS IN LOTS OF DIFFERENT
WAYS.
WE USE COMPARISONS AND WE TRY
TO BRING ORDER TO OUR WORLD.
AND WHEN WE MEASURE WE USE
UNITS OR STANDARDS OF
MEASUREMENT.
WE TRY TO MAKE THOSE STANDARDS
AS ACCURATE AND AS CONSISTENT
AS POSSIBLE.
IF YOU WANT TO LEARN MORE
ABOUT MEASUREMENT, CHECK OUT
THE SCIENCE TREK WEBSITE.
OH WAIT A MINUTE, I WAS
SUPPOSED TO TELL YOU ABOUT THE
METRIC SYSTEM.
TO LEARN ABOUT THAT, YOU'LL
JUST HAVE TO WATCH THE NEXT
SCIENCE TREK VIDEO.
YOU'LL FIND IT AT
SCIENCETREK.ORG
(MUSIC)
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