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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