¶ ¶
NEIL DEGRASSE TYSON: We were born into a mystery,
one that has haunted us
since at least as long as we've been human.
We awakened on this tiny world
beneath a blanket of stars,
like an abandoned baby left on a doorstep
without a note to explain
where we came from, who we are,
how our universe came to be.
And with no idea how to end our cosmic isolation.
We've had to figure it all out for ourselves.
(fussing)
Best thing we had going for us
was our intelligence,
especially our gift for pattern recognition,
sharpened over eons of evolution.
The ones who were good at spotting prey and predator,
telling poisonous plants from the nourishing ones,
they had a better chance to live and reproduce.
They survived and passed on those genes
for pattern recognition
with its obvious advantages.
Cultures all over the planet
looked up at the same stars
and found different pictures there.
We used this gift for recognizing patterns in nature
to read the calendar in the sky.
The messages written in the stars
told our forefathers and mothers
when to camp and when to move on.
When the migratory herds
and when the rains and the cold would come.
And when they would cease for a time.
When they observed the direct connection
between the motions of the stars
and the seasonal cycles of life on Earth,
they concluded, naturally,
that what happens up there
must be directed at us down here.
It makes sense, right?
If the sky was a calendar
and somebody stuck a Post-it note on top of it,
what else could it be but a message?
And so, when the heavenly order was suddenly violated
by the apparition of a comet in the sky...
they took it personally.
Can we really blame them?
Back then, they had no other logical explanation
for what was happening.
This was long before
anyone had yet to imagine Earth
as a spinning planet with a tilted axis,
revolving around the Sun.
Every ancient human culture made the same mistake:
a comet must be a message,
sent by the gods... or one particular god.
And almost invariably, our ancestors concluded
the news was not good.
It didn't matter if you were an ancient Aztec,
Anglo-Saxon, Babylonian, Hindu.
Comets were portents of doom.
The only difference among them
was the precise nature of the coming disaster.
"Dis-aster," as in the Greek word for "bad star."
To the Masai of East Africa,
a comet meant famine.
To the Zulu in the south,
it meant war.
To the Eghap people of the west,
it meant disease.
To the Djaga of Zaire,
specifically "smallpox."
To their neighbors, the Luba,
a comet foretold the death of a leader.
The ancient Chinese were remarkably systematic.
Starting in roughly 1400 BC,
they began recording and cataloguing
the apparitions of comets.
A three-tailed comet
meant calamity for the state.
A four-tailed comet
signified an epidemic was coming.
The human talent for pattern recognition
is a two-edged sword.
We're especially good at finding patterns,
even when they aren't really there--
something known as "false pattern recognition."
We hunger for significance,
for signs that our personal existence
is of special meaning to the universe.
To that end, we're all too eager
to deceive ourselves and others,
to discern a sacred image in a grilled cheese sandwich
or find a divine warning in a comet.
Today, we know exactly where comets come from
and what they're made of.
Our Ship of the Imagination,
fueled by equal parts of science and wonder,
can take us anywhere in space and time.
It can travel faster than light
and render visible those things
that cannot be seen.
It's carrying us to a mysterious realm
that lies one light-year from the Sun.
What is this swarm of worlds?
Was it organized by alien beings?
No.
Just gravity.
These are the snows of yesteryear,
drifting mountains of ice and rock,
the preserved remnants of the birth of the solar system.
It's called the Oort Cloud,
after Jan Oort, the Dutch astronomer
who foretold its existence
back in 1950.
He was trying to solve a paradox.
There's so many ways for comets to die.
Because they cross the orbits of planets,
comets frequently collide with them.
Comets are largely made of ice,
so every time they come near the Sun,
they lose a part of themselves through evaporation.
And after several thousand trips,
their ice is all gone,
and what remains of the comet is now an asteroid.
Comets can be gravitationally ejected from the solar system
and exiled into space.
And yet, somehow,
the comets keep coming.
Oort and other astronomers wondered,
"Where do all the comets come from?"
Oort calculated the rate at which new comets appear
and concluded that there must be
a vast, spherical swarm of them,
a few light-years across,
surrounding the Sun.
Oort's logic still holds up,
even after all the discoveries we've made about comets
and the solar system in the many decades since.
And yet, the Oort Cloud is a sight
that no one has ever seen.
Nor could we.
It's dark out here.
And each comet is about as far from its closest neighbor
as the Earth is from Saturn.
But science gives us special powers of our own.
It gave Jan Oort
the gift of prophecy.
Oort was also the first to correctly estimate
the distance between the Sun
and the center of our galaxy.
That's a big deal--
finding out where we are in the Milky Way.
Our star is about
30,000 light-years from the center.
Oort was also
the first guy to use a radio telescope
to map the galaxy's spiral structure.
And he discovered that the center of our galaxy
was a place of titanic explosions,
the first indication
that there might have been
a supermassive black hole lurking there.
Does the fact that most of us know
the names of mass murderers,
but never heard of Jan Oort,
say anything about us?
The Oort Cloud is so enormous
that it takes one of its comets about a million years
to complete a single trip around the Sun.
Out here, at the far edge of the solar system,
even a little tug from the gravity of a passing star
can liberate some of these comets
from their gravitational bondage to the Sun.
Some comets are flung out of the solar system
to wander interstellar space.
But for others, there's a different fate.
This one is plunging towards the Sun,
gaining speed in an unbroken free fall
that lasts hundreds of thousands of years.
When Neptune's gravity gives it another tug,
there's a small change in course.
Mighty Jupiter, the most massive
object in our solar system--
other than the Sun-- attracts the comet
with its powerful gravitational pull,
bending its path.
When our comet reaches the inner solar system...
heat from the Sun bakes it.
A beautiful transformation has begun.
The barren, sooty iceberg
now sports a glowing halo...
and a tail.
These layers tell the story
of how the comet was made,
some four billion years ago.
During the 40,000 generations of humanity,
there must have been roughly 100,000 apparitions
of a bright comet.
For all that time,
the best we could do was look up in helpless wonder,
prisoners of Earth with nowhere to turn
for an explanation beyond our guilt and our fears.
But then a friendship began between two men that led
to a permanent revolution in human thought.
Isaac Newton and Edmond Halley could not know it,
but their collaboration would ultimately set us free
from our long confinement on this tiny world.
DEGRASSE TYSON: The Comet of 1664
sent shivers of dread throughout Europe,
and the terror seemed justified when the Plague
and the Great Fire of London followed soon after.
WOMAN: There, with long bloody hair,
a blazing star threatens the world
with famine, plague and war.
To princes, it spells death...
to kingdoms, many crosses...
to all estates, inevitable losses...
to herdsmen, rot,
to plowmen, hapless seasons,
to sailors, it brings storms,
to cities, civil treasons.
DEGRASSE TYSON: But for one child,
the comet was not the least bit frightening.
For him, it was a thing of wonder.
Like all of us, Edmond Halley was born curious.
Hell's bells!
He was lucky to have a father who encouraged
and nurtured his curiosity,
buying him the best scientific instruments
and even funding his expedition
to make the first accurate star map of the Southern Hemisphere.
Halley dropped out of Oxford when he was 20,
and sailed to St. Helena,
an island below the equator, off the west coast of Africa.
Hell's bells.
DEGRASSE TYSON: The problem was, nobody told Halley
that the weather on St. Helena
was generally lousy; it took him 12 frustrating months
to observe enough southern stars to make a complete map.
The gods and heroes of ancient Greece were now joined
by the mythic figures of a new world and age:
a toucan, a compass, a bird of paradise.
When Halley came home with the other half of the sky,
his map created a sensation.
Now merchants and explorers could navigate by the stars
visible anywhere on Earth.
At the time, the World Society of London
was the world's clearinghouse of scientific discovery.
Its motto, "Nullius in verba,"
sums up the heart of the scientific method.
It's Latin for "see for yourself."
In other words: "question authority."
Halley's star maps caught the attention
of the Society's Curator of Experiments.
I'd show him to you if I could,
but no portrait of Robert Hooke exists from his time,
only the verbal descriptions of his contemporaries.
They called him "lean, bent, ugly."
He was possibly the most inventive person who ever lived.
And despite his appearance,
he was the most sought-after party guest in all of London.
Why?
Hooke's insatiable curiosity
encompassed absolutely everything.
Hooke discovered a little cosmos,
and we still call it by the name he gave it: the cell.
Hooke discovered the cell by looking
at a piece of cork with one of his own inventions,
the compound microscope.
He anticipated aspects of Darwin's theory of evolution
by almost 200 years.
Hooke also improved the telescope.
The drawings he made of the astronomical bodies he observed
attest to his uncanny precision.
After the Great Fire destroyed central London in 1666,
Hooke partnered with the architect Christopher Wren
to redesign and rebuild the city.
Hooke was the foremost experimentalist of his age.
Using coiled springs,
he derived the "law of elasticity,"
known today as Hooke's Law.
He perfected the air pump,
the height of technology in its time,
and used it to experiment on respiration and sound.
And he experimented with cannabis.
He reported to a meeting of the Royal Society
that a sea captain friend of his
"had so often experimented with it,
"that there is no cause of fear,
though possibly there may be of laughter."
But coffee was the drug of choice for England
in the 17th century.
Coffeehouses sprang up all over London.
This is where people came to get news,
to launch new ventures, and to debate ideas.
The coffeehouse was an oasis of equality
in a class-obsessed society.
Here, a poor man needn't give up his seat
to a rich man, nor submit to his opinion.
It was a kind of laboratory of democracy.
In this highly caffeinated atmosphere,
Halley and Hooke met Christopher Wren to discuss a deep mystery:
Why do the planets move as they do?
The astronomer Johannes Kepler had demonstrated,
some 80 years before,
that the orbits of the planets around the Sun
were not perfect circles, but actually ellipses,
and that the closer a planet was to the Sun,
the faster it moved.
Why?
Could some invisible force from the Sun be responsible
for this change in motion?
If so, how did it work?
Could there be a simple mathematical law to describe it?
Maybe something like Hooke's Law of Elasticity?
Perhaps.
But try as he might,
Christopher Wren couldn't figure it out.
(Wren sighs)
Damned if I haven't tried.
It's beyond me.
I'll wager a book worth 40 shillings
to the man who can solve it!
That book is mine, Mr. Wren.
I've already done the calculation.
DEGRASSE TYSON: Halley was delighted.
Show us, Mr. Hooke.
But months passed, and Hooke failed to deliver.
He couldn't do the math.
None of them could.
Finally, Halley had enough of Hooke's excuses.
Halley knew there must be someone, somewhere,
up to the challenge.
What about that mathematician at Cambridge?
Clever fellow.
He had solved central questions about the nature of light
years before, when he was still only 22.
And he invented the reflecting telescope.
Odd bird.
Dropped out of sight a while back;
some squabble over Hooke and his discovery about light.
Went completely to pieces over it
and has been hiding out in Cambridge ever since.
Halley wondered if this strange, and by all accounts,
exceedingly difficult man, might succeed
where Hooke and others had failed.
What he couldn't know,
what no one could possibly imagine at the time,
were the countless ways
the world would be forever changed by this meeting
on an August day in 1684.
DEGRASSE TYSON: Isaac Newton was born in England
on Christmas Day in 1642.
(baby cries)
Before he even opened his eyes, his father was already dead.
His mother left him when he was only three
and did not return until he was 11.
When she did, it was with a new family and husband,
a stepfather who Isaac Newton despised.
Newton's refuge from his miserable family life
was his passion to understand how things worked,
especially nature itself.
In 1661, the talented young Isaac entered Trinity College
at Cambridge University
where he was a consistently lousy student,
one without friends or a loving family
to provide any warmth or encouragement.
Newton mostly kept to himself, sequestered in his room,
studying ancient Greek philosophers,
geometry and languages,
and pondering deep questions
on the nature of matter, space, time, and motion.
This budding scientist was also a passionate mystic.
Newton believed that a secret knowledge
called alchemy, known only to a small group
of ancient philosophers, was waiting to be rediscovered.
He hoped to learn how to change ordinary metals
into silver and gold,
and maybe even cook up the elixir of life,
the key to to immortality.
He was also obsessed
with finding hidden messages in the words of the Bible.
He combed through translations in several different languages,
hoping to decipher coded instructions from God.
He made elaborate calculations in an effort
to discover the date of the Second Coming.
His lifelong research in alchemy
and biblical chronology never led anywhere.
When Halley found Newton that fateful day,
he was living as a virtual recluse.
Newton had gone into hiding 13 years earlier,
after Robert Hooke had publicly accused Newton of stealing
his groundbreaking work on light and color.
In fact, it was Isaac Newton
who solved the mystery of the spectrum of light,
not Robert Hooke.
This wound was painful and deep,
and Newton resolved to never expose himself to that kind
of public humiliation ever again.
Sir, I don't suppose you recall
our meeting a few years ago?
Yes, Mr. Halley.
I'm sorry to bother you.
Never mind the formalities, get to your point.
I've been talking with our friends, Mr. Wren and Mr. Hooke.
That scoundrel Hooke's no friend of mine.
Yes, I understand, sir.
But the thing is we've been debating
the puzzling question of planetary motion.
We all agree that some force of attraction
from the Sun governs the motions of the planets.
We suspect there must be a mathematical law
to describe how this force
changes with distance.
And knowing of your skill...
Yes, yes, the attraction of gravity
weakens with the square of the distance.
That's why the planets move in ellipses.
But, sir, how can you know this?
Why, I have calculated it some five years ago.
I beg you, show it to me.
The calculation is here...
somewhere.
Well, no matter.
I shall redo it and be sure
to send it on to you.
This is stupendous!
Why have we not had word of it before?
DEGRASSE TYSON: Newton remembered all too well
what Hooke had done to him
the last time he put forth an idea.
Just when Halley may have begun to wonder
if Newton was bluffing as Hooke had done earlier,
a messenger arrived with an envelope from Newton.
Here are the opening pages of modern science
with its all-embracing vision of nature...
universal laws of motion, gravity...
not just for the Earth,
but for the cosmos.
Halley raced back to Cambridge.
Mr. Newton, I beseech you to work all of this
into a book as soon as possible.
I can assure you the Royal Society will publish it.
DEGRASSE TYSON: But there was one little problem.
We are in agreement
that Mr. Newton has produced a masterpiece.
However, I'm afraid the Royal Society has...
well, regrettably sales for the History of Fish...
have not lived up to expectations.
DEGRASSE TYSON: It's an impressive book.
Extremely comprehensive.
Really.
It's filled with lavish illustrations of...
well, fish.
The disappointing sales led to a bigger problem.
The Royal Society pretty much blew
its total annual budget on the History of Fish.
In fact, they were so strapped for cash,
they had to pay poor Halley's salary
with copies of their worst-selling book.
With no money to print Newton's Principia,
the scientific revolution hung in the balance.
Without Halley's heroic efforts,
the reclusive Newton's masterwork
might never have seen the light of day.
But Halley was a man on a mission,
absolutely determined to bring Newton's genius to the world.
That pre-scientific world,
the world ruled by fear,
was poised at the edge of a revolution.
Everything depended on whether or not Edmond Halley
could get Newton's book out to the wider world.
Halley resolved not only to edit Newton's book,
but to publish it at his own expense.
Newton completed the first two volumes,
laying the mathematical framework
for the physics of motion.
The third volume would settle once and for all
who won the coffeehouse wager.
Newton applied his principles to explain
all the known motions of the Earth,
the Moon and the planets.
Unfortunately, there was this problem.
Now Halley also took on the role
of Newton's psychotherapist.
Isaac, I'm afraid that Mr. Hooke requires
an acknowledgment in the preface of your third volume.
But I have done so.
Thanking him, Mr. Wren and yourself
for prodding me to think again on astronomical matters.
Mr. Hooke has been going about London saying
that you got the Law of Gravity from him.
Why, that litigious little...
Never!
I would sooner burn the third volume
than deface it with such a lie.
To hell with Hooke.
He will be long forgotten
when your ideas are still being celebrated.
More copies of that dreadful book?
Wherever shall we put them all?
We talked about this, Mary, dear.
This is my salary from the Society.
They have nothing else with which to pay me.
If only Mr. Hooke and Mr. Newton
were more like you.
DEGRASSE TYSON: Halley and Wren decided to confront Hooke
about his false claims.
That law is mine, I tell you!
I proved it first.
Then fetch your proof here at once.
Let us see it.
Surely we have waited on it long enough.
You'll simply have to take my word for it.
Empty claims may persuade elsewhere,
but not here.
Put up or shut up, Mr. Hooke.
Blasted Newton. I'll make him pay.
DEGRASSE TYSON: If it wasn't for Edmond Halley,
Newton's great book would've never been conceived,
nor written, nor printed.
Okay. So what?
What difference does that make to us?
What's the big deal?
When Isaac Newton was born in this house
in 1642, the world was very different.
Everyone looked at the perfection
of the clockwork motions of the planets in the sky
and could only understand it as the work
of a master clock maker.
How else to explain it?
There was only one way such a thing could come about
in their imagination;
only one answer for them--
God.
For reasons beyond our understanding,
God just created the solar system that way.
But this explanation is the closing of a door.
It doesn't lead to other questions.
Along came Newton,
a God-loving man who's also a genius.
He could write the laws of nature
in perfect mathematical sentences--
formulas that applied universally
to apples, moons, planets
and so much more.
With one foot still in the Middle Ages,
Isaac Newton imagined the whole solar system.
Newton's laws of gravity and motion
revealed how the Sun held distant worlds captive.
His laws swept away the need
for a master clock maker
to explain the precision and beauty of the solar system.
Gravity is the clock maker.
Matter obeyed commandments we could discover,
laws the Bible hadn't mentioned.
Newton's answer to why the solar system is the way it is
opened the way to an infinite number of questions.
Principia also happened to include
the invention of calculus,
and the first sound theoretical basis
for an end to our imprisonment on Earth--
space travel.
Newton envisioned the firing of a cannonball...
(cannon fires)
...with increasingly greater explosive thrust.
He reasoned that with enough velocity,
the bounds of gravity could be broken,
and the cannonball could escape
to orbit the Earth.
This changed everything.
¶ ¶
Newton's Principia Mathematica set us free in another way.
By finding the natural laws
governing the comings and goings of comets,
he decoupled the motions of the heavens
from their ancient connections to our fears.
If Halley hadn't been standing next
to Newton for all those years,
perhaps the world would remember him
for his own host of accomplishments and discoveries.
But the only thing that comes to mind
for most people is the comet.
The irony is that discovering a comet
is actually one of the few things
that Halley never did.
Mountain of ice to starboard!
Come about!
Aye, aye, Captain Halley!
DEGRASSE TYSON: After the publication of the Principia,
Halley was commanded by his king
to lead three ocean voyages.
Scientific expeditions to solve navigational problems
for the British Navy.
Halley used this opportunity
to make the first map of the Earth's magnetic field.
And he was also a businessman.
Halley perfected the diving bell...
...and used his invention to start
a flourishing commercial salvage operation.
Mmm, ah, Dr. Halley's gone and done it this time.
I reckon he's been down there at least three hours.
DEGRASSE TYSON: Not one to risk the lives of others,
Halley personally tested his own invention.
I make it exactly four hours since our descent.
Not at all bad for ten fathoms.
DEGRASSE TYSON: He invented the weather map.
And the symbols he devised for indicating prevailing winds
are still in use today.
Halley laid the groundwork
for the science of population statistics.
How?
He compared the birth, marriage, death,
and population densities of London and Paris.
He actually had to pace off
the entire perimeter of Paris, on foot,
to learn its true dimensions.
He came to the conclusion
that since roughly half of all adults fail
to reproduce children,
who themselves survive to reproduce,
every married couple must have four children
in order to maintain the population.
And it was Edmond Halley who gave us
the actual scale of the solar system.
He figured out a clever way to find the distance
from Earth to the Sun.
It involved precisely measuring the time it took
for the planet Venus to cross the Sun's disc.
27 years after Halley's death,
Captain James Cook made his first voyage to Tahiti
for the express purpose of testing Halley's method
during a transit of Venus across the Sun.
Using a special filter to protect his vision
from being destroyed by looking directly at the Sun,
Cook and his men made it possible for us to know
that the Sun is 93 million miles from Earth.
And Halley was the first to realize
that the so-called "fixed" stars were not fixed at all.
How'd he do it?
He pored over the observations made
by the ancient Greek astronomers of the brightest stars.
And he compared their observations with the ones
he himself made of the same stars 1,800 years later.
Why hadn't anyone noticed this before?
Halley figured out that it would only become apparent
if you waited long enough between observations.
It's hard to perceive the motions of things
that are far away.
And the stars are so very far away,
that you would need to track them for many centuries
before you could detect that they moved at all.
Halley discovered the first clue to a magnificent reality:
all the stars are in motion, streaming past each other,
rising and falling like merry-go-round horses
in their Newtonian dance around the center of our galaxy.
And, oh, yes, there was that thing about the comet.
What were those strange and beautiful celestial visitors
that appeared without warning from time to time?
Halley set out to solve this mystery as a detective would,
by gathering all credible eyewitness testimony.
The earliest precise observations of a comet
that Halley could find were made in Constantinople
by Nikephoros Gregoras, a Byzantine astronomer and monk
in June 1337.
Halley hunted down every astronomical observation
of a comet recorded in Europe between 1472 and 1698.
And remember, there was no such thing
as a search engine or a computer.
All Halley had were his books and his mind.
Now here comes the hard part:
Halley had to take the observations made for each comet
and find the shape of its actual path through space.
No one else but Newton had yet attempted
to apply his new set of laws to an astronomical question.
In an arduous tour de force of mathematical brilliance,
Halley discovered that comets were bound to the Sun
in long elliptical orbits.
And he was the first to know that the comets seen in 1531,
1607, and 1682...
were one and the same--
a single comet that returned every 76 years.
In a stunning example of true pattern recognition,
he predicted it would be seen again
more than 50 years in the future.
For millennia, comets had been props for mystics,
who considered them to be merely omens of human events.
Halley shattered their monopoly,
beating them at their own game,
a game that no scientist had ever played before:
prophecy.
And he did not hedge his bet.
Like Babe Ruth predicting
where his next home run would land in the stands,
Halley stated flatly that the comet would return
at the end of 1758, from a particular part of the sky,
following a specific path.
There is hardly a prophecy attempted by the mystics
that ever even strives for comparable precision.
That's Halley's Comet.
Out here at the edge of the solar system,
it doesn't look like much.
Just a big hunk of ice and rock in space.
That's because beyond the orbit of Neptune,
nearly five billion kilometers from the Sun,
comets lead very quiet lives.
As it reaches the far end of its orbit,
it'll slow down till the Sun allows it to go no farther.
Then it will begin its long fall back to the inner solar system.
Halley's comet is in free fall around the Sun.
Everything in our solar system-- the Earth, the Moon,
the other planets, comets, asteroids,
all of them are falling around the Sun.
Gravity pulls the planets towards the Sun,
but because of their orbital momentum,
they keep moving around the Sun, never falling into it.
Robert Hooke had died years before,
having ruined his health with some bad habits:
daily doses of wormwood, opium, mercury.
A few months later, Newton was elected to replace him
as president of the Royal Society.
It is said that a portrait of Hooke
once hung on these walls.
Halley lived on to accomplish many more astonishing feats.
He worked right up to his death at age 85.
His final act was to call for a glass of wine.
He downed it with pleasure...
and breathed his last breath.
(glass breaks)
Some believe that it was on a night like this
that Isaac Newton finally took his revenge
against Robert Hooke.
But Halley's prophecy was not forgotten.
50 years later,
as the time of the predicted return approached,
the world's astronomers vied
to be the first to catch sight of his comet.
They weren't disappointed.
It's been welcomed back every 76 years since.
When Halley's Comet returns to our skies,
sunlight will warm up the ice on its surface,
once again setting loose
the dust and gases trapped within.
Halley's Comet most recently visited our neighborhood
back in 1986.
And if you're seeing this in 2061,
then you'll know it's back.
May you feel the wonder of all those
who came before you...
and none of the fear.
Newton's laws made it possible for Edmond Halley
to see some 50 years into the future
and predict the behavior of a single comet.
Scientists have been using these laws ever since,
opening the way to the Moon
and even beyond our solar system.
The baby in the basket is learning to walk...
...and to know the cosmos.
Which brings me
to one last prophecy.
Using nothing more than Newton's laws of gravitation,
we astronomers can confidently predict
that several billion years from now,
our home galaxy, the Milky Way,
will merge with our neighboring galaxy Andromeda.
Because the distances between the stars
are so great compared to their sizes,
few if any stars in either galaxy will actually collide.
Any life on the worlds of that far-off future
should be safe, but they would be treated to an amazing,
billion-year-long light show...
a dance of a half a trillion stars...
to music first heard on one little world
by a man who had but one true friend.
Captioned by Media Access Group at WGBH access.wghb.org