National Geographic: The Invisible World Page #2

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a comfortable home

by burrowing directly into the skin

On the warm, moist regions

of our skin

there is life in enormous abundance

Bacteria the simplest form of

free living life-are constantly with us

A single bacterium can multiply to

more than a million in about

eight hours

and mo matter how much we wash

millions remain on our skin

Each of us is the keeper of a huge

invisible zoo

In fact, at any given time

there are as many creatures

on our bodies

as there are people on Earth

If our numerous companions do

not inspire our love

at least we have the consolation

of knowing

that we are never completely alone

At the Enrico Fermi Institute of

the University of Chicago

a new frontier of the microworld

has recently been bridged

Using a powerful electron microscope

which took 14 years to develop

Dr. Albert Crewe has captured

on film

what no one had ever seen

You are looking at atoms-uranium atoms

The smaller single specks are

individual atoms

each with a diameter of only a

few billionths of an inch

The larger masses are clusters

of several atoms

Colorized artificially to enhance

our view

atoms exhibit unpredicted movement

revealing that solid objects

when seen on an atomic scale

are actually a sea of moving particles

The level of magnification

of the movies

on the home TV screen is

about ten million,

maybe 20 million, depending on

the size of your TV set

That's about the equivalent to blowing

a basketball up

to the size of the Earth

The ability to see single atoms

to isolate them at that

could have considerable importance

Where it will lead is very

difficult to

except what we have is

a new technology

a new way of looking at

materials in the world

And every time you have a new way

of looking at things

you find out something new

We are exiled from other worlds

by time as well as by size

In a world of motion

there is infinite detail too fast

for the unaided eye

In the 1870s an ingenious photographer

Eadweard Muybridge

invented a way to record movements

normally too quick to be seen

A wager about the stride of

a running horse

brought Muybridge to the stock farm

of a wealthy Californian

With a battery of 24 cameras

that were activated by threads

stretched across a track

Muybridge captured aspects of motion

that had never been witnessed before

Muybridge's patron had bet that all

four legs of a running horse

were sometimes simultaneously

off the ground

Stop-action photography proved him

to be right

By projecting his photographs in

rapid succession

the first motion pictures were born

The movement of people as well

as animals became

for Muybridge a passionate

subject of study

Much more than just a

technical curiosity

Muybridge's pioneering work was the

first photographic analysis

of the dynamics of physical motion

Today, modern high-speed cameras

can record rapid motion

with a clarity that Eadweard Muybridge

could only have dreamed of

Slow-motion film is now

a commonplace tool

in analyzing athletic performance

For Dr. Gideon Ariel

a physical education expert

and a former discus thrower on the

Israeli Olympic team

slow-motion film is just the first

in the scientific coaching

of athletes

Dr. Ariel has turned to the computer

for aid in the analysis of movement

Slow-motion film of an athlete

is projected frame

by frame onto a recording screen

Each touch of a sonic pen transmits

into the computer memory

the dynamically changing positions

of the athlete's joints and limbs

Human movement is governed by

the same laws of motion

that apply to the entire

physical world

And from the visual information

contained in the film

the computer can rapidly calculate

the interrelationship of force

acceleration, and velocity in the

athlete's movements

Computer-created images combined

with a mass of numerical data

can pinpoint

where athletic technique

is hindering performance

So, what coaches in the past thought

they can see with eyes

we are finding out you can not do

You have to quantify.

With the advent of computers

we can provide the coaches

with much more objective

reliable information on how

the body moves

Dr. Ariel's computer analysis

of Olympic discus

thrower Mac Wilkins revealed

that useful energy which would

effect his throw

was being wasted on ground friction

Additional force was being spent

by not rigidly planting his forward

leg at the moment of the throw

Based on this analysis

Wilkins altered his

throwing technique

Several months later

in international competition

he threw the discus over 13 feet

farther than he ever had before

and set a new world record

In a remarkable laboratory at the

Massachusetts Institute of Technology

time and motion are

dramatically dissected

With the aid of a pulsating

strobe light

Dr. Harold Edgerton can freeze a flurry

of movement onto a single plate of film

Dr. Edgerton developed the strobe

light in 1931

Unable to see how electric

motors behaved

when they rotated at various speeds

he designed a light which

could flash so quickly

and brightly that motion seemed

to stop

Now we're going to do an experiment

here to take a picture of a

bullet-a very high-velocity bullet

as it cuts this playing card in two

The playing card will be attached

to this tape

The bullet will come out of the

gun at 2,800 feet per second

If we aim it correctly

it'll cut through the card

And we want to turn on a light

a very special strobe light

that lasts less

than a millionth of a second

in order to stop the bullet

effectively on film

and make a sharp, clear photograph

The sound of the bullet will trigger

the strobe light

which creates an image on film

A first shot will

test Dr. Edgerton's aim

Here we go

Now, the event as the strobe

light reveals it

Less than a millionth of a second

is permanently frozen in time

Another striking example of the

strobe's revealing power is

what Edgerton calls "making applesauce"

Perhaps the most dramatic of

Dr. Edgerton's visual techniques

combines the powerful strobe light

with a high-speed

motion-picture camera

There you go. All set?

Three, two, one, two

Stretching events thousands of times

reveals invisible detail

that can be seen and studied

in no other way

The explosion of a firecracker

now slowed down 1,200 times

Examine the "plop" of a milkdrop

and it becomes a magical vision of

hydrodynamic behavior

Unbounded by our human sense of time

specialized cameras can also record

events much too slow to see

For nature cinematographer

Ken Middleham

the technique of time-lapse

photography

provides a fascinating window

on an otherwise hidden realm

By taking single photographs at longer

than normal intervals

time and events are compressed

into a dramatic new scale

The two weeks it takes for

an orange to spoil

are telescoped into several seconds

A bunch of unripened bananas mature

before our eyes

The natural world is alive in ways

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