Cosmos: A Spacetime Odyssey Recap - Episode 103

"When Knowledge Conquered Fear"

Episode 3 of Cosmos focused on the history of Physics
Cosmos: A Spactime Odyssey (episode 103). FOX

 (Note: This is a recap of Cosmos Episode 3. Click here for previous episode recaps.)

This week’s episode of Cosmos begins with a voice over from our fearless host Neil deGrasse Tyson. He tells us we were born into a mystery. An adorable baby in a basket said to have been abandoned is used as a metaphor for not knowing who we are and where we come from and that we had to figure it all out for ourselves.

We have a gift of pattern recognition that has been sharpened via evolution. It was an advantageous adaptation for humans and our survival. For instance, we look at the stars and see pictures drawn up there. Our forefathers and mothers would read the stars to know when to camp and when to move on. If the sky was a calendar, they thought someone left a message for humans. Comets were thought to be a message sent by the gods or a particular God and they brought bad news. All of the ancient groups of people thought comets brought doom. Tyson tells us that the word “disaster” comes from a word meaning “bad star.”


Each ancient group had its own disasters that it thought the comet would bring. They thought the comets told of impending war, death of a leader, disease, and even something as specific as small pox.  The Chinese, in 1400 BC, started to record the types of comets and the disasters they would bring.

 A three tailed comet told of disaster for the state, while a four tailed comet said an epidemic was coming.

Humans are almost too good at finding patterns and often see false patterns. We are too eager to see a divine figure in a grilled cheese sandwich, but we know today exactly what comets are made of.

 With that, we board the Ship of the Imagination and head to an area of space that holds ice and the remnants of the beginnings of the universe called the Oort Cloud. It’s named after Johann Oort who predicted its existence in the 1950s.

Comets are largely made of ice, so they lose mass every time they come near the Sun. After a comet loses enough of its ice, it turns into an asteroid and will often collide with planets or other heavenly bodies.  Oort figured that comets must come from a sphere that surrounds our solar system.  Even though we could never see it, science has yet to disprove it exists.

Oort also correctly determined the distance from the Sun to the center of our galaxy.  It is about 30,000 light years from the center that has titanic explosions where there might be a super massive black hole.  Tyson challenges that even though the majority of us can name mass murderers, most people probably do not know of Johann Oort, so what does that say about us?

The Oort Cloud is so big that it takes one of its comets almost a million years to complete a single trip around the Sun.  Even just a little gravity from planets or other pieces of space debris can pull a comet out of its path around the Sun.

Next, we follow a comet as it flies by various planets and watch as its path gets changed when it goes by Saturn and Jupiter. Heat from the Sun starts to bake it as it reaches the inner part of the solar system. It now has what Tyson describes as a glowing halo and a tail. These layers can tell how the comet was made nearly 4 billion years ago.  He estimates that over the 40,000 generations of humans that have existed, there must have been about 100,000 comets that could be seen from Earth.

The History of Physics

A friendship between Isaac Newton and Edmond Halley would help set us free from our “prison” on Earth. The comet of 1664 terrified the people of Europe, especially when the fires of London soon followed. It was thought to bring famine, disease, death, storms, and civil treasons all across Europe.

One child, Edmond Halley, was not afraid, but rather intrigued. His father nurtured his curiosity by buying him the most advanced scientific instruments and funding his voyages. Halley dropped out of Oxford when he was 20 in order to go St. Helena, an island off the west coast of Africa.  However, the weather was bad there.  It took an entire year for him to make a map of the stars. He saw new constellations there such as a toucan, a compass, and a bird of paradise.

When Halley returned home with the Southern Hemisphere map of the sky, he was able to put it together with his map of the Northern Hemisphere and sell it to sailors who could now travel all over the world. The Royal Society of London was the central clearinghouse of all new scientific discoveries and Halley’s map caught the eye of Robert Hooke, the head of the Society. There are no pictures of Hooke, but he was described as mean and ugly, but he was curious about everything. In fact, he was the first to discover a cell by looking at cork through his invention -- the compound microscope, which predated Charles Darwin’s Theory of Evolution by 200 years.  

Hooke also improved the telescope and drew very detailed depictions of the heavenly bodies he saw. He helped rebuild London after the great fire and also discovered the properties of elasticity that we know today as Hooke’s Law.  He perfected the air pump for experimentation on respiration and sound. He even experimented with cannabis and found it was completely safe because a sea captain friend of his used it regularly.

Coffee was the drug of choice in the 17th century London.  Coffeehouses popped up everywhere and people gathered to get news, launch ventures, and debate ideas. Everyone was an equal in the coffehouses. Halley and Hooke met Christopher Wren to figure out why planets move the way they do.  Johannes Kepler demonstrated 80 years earlier that the planets’ orbits were not circles, but rather ellipses and they moved faster the closer they got to the Sun.

Was there an invisible force that caused the change of motion and was there a mathematical law that explained it?  Christopher Wren could not figure it out and offered a reward for anyone who could. Hooke claimed he could and he’d already done the calculations.  However, he couldn’t do the math and Halley knew someone somewhere would be able to figure it out and he sought out to find him.

Halley found the man hiding out in Cambridge.  The young man had discovered other mathematical laws and invented the reflecting telescope when he was only 22 years old. After a disagreement with Hooke over reasearch about light and color, he got angry and went to Cambridge to hide out. The meeting between Halley and Sir Isaac Newton on an August day in 1684 would forever change the world.

Isaac Newton

After the commercial break, Tyson tells us about Isaac Newton’s birth on Christmas day in 1642. His father was already dead and then his mother left him when he was three.  She did not return to him until he was 11. She came home with a new husband and family that Newton despised.  He threw himself into learning how nature worked.

In 1661 he became a lousy student at Cambridge without friends or family. Instead, he holed up in his room and learned about philosophy, geometry, and languages while pondering deep questions about the nature of matter, space, time, and motion. He also believed in alchemy and hoped to rediscover how to turn metals into silver and gold. He also tried to mix up an elixir to give himself immortality while he combed all sorts of different translations of the Bible looking for hidden messages. He tried to calculate the date of the second coming of Christ. None of these pursuits went anywhere.

Newton had gone into hiding 13 years before that day he met with Halley. He had become a hermit when Hooke had accused him of stealing his work on light and color. However, it was Newton who had discovered the secret of light and color, not Hooke. He didn’t want to go through that humiliation ever again. Halley let Newton in on the debate on why planets travel in ellipses and move faster near the Sun. Newton informed him that he had calculated five years ago that gravity decreases with the square of the distance between the objects. Newton agreed to send Halley the calculations. Back in the present, Tyson sits at a desk and shows the actual pages that were sent to Halley that included calculations about gravity and the laws of motion.

Halley rushed back and begged Newton to create a book to be published by The Royal Society of London of all of his findings. Newton did produce the book, but then the funding was not there to publish it to the masses as it should have been. The Royal Society of London had blown its entire yearly budget printing multiple copies of the History of Fish.  Those books did not sell and even Halley’s yearly salary was paid via copies of the worst selling books. The entire future of science hung in the balance with this dilemma of not being able to publish Newton’s book.

When we return from commercial, Tyson picks up the story by telling us Halley was on a mission to bring Newton’s brilliant work to the world. Halley resolved to not only edit the book, but also pay for publishing out of his own pocket. Newton finished the first two volumes which set out the basic physics of motion. The third volume showed how his calculations could explain the motion of everything on Earth, and also the motion of the planets. Unfortunately, Hooke had been going around telling everyone who would listen that Newton had stolen the idea of gravity from him and he insisted on being acknowledged in the third volume. Newton, still upset at Hooke for taking credit for his work with light and color, refused and said he’d rather burn the copy of the third volume than to deface it with such lies.


Halley and Wren decided to confront Hooke about his false claims and demanded he show the proof that he had discovered the law of gravity. Of course, Hooke could not produce such proof. If it weren’t for Edmund Halley, Newton’s book never would have been written or printed. That would have had major consequences for all of society, even today.

Back in the time when Newton was born, everyone just believed that a God or gods created the universe as it was and there was no other explanations necessary.

Newton was a man who believed in God and was also a genius. His laws of nature made perfect sense and could be applied universally to everything. Newton’s laws of gravity and motion proved that there were laws of nature that could explain why the solar system is the way it is. He also happened to invent calculus and imagined space travel.

He imagined a cannon ball that moved with so much force that it could break free of gravity and leave the orbit of the Earth. This idea changed everything. We then see breathtaking footage of various satellites and rocket launches. Tyson says that Newton’s Principia Mathematica set us free by finding the natural laws of how comets moved, and it released us from our fears of the unknown in heavenly bodies.

Edmond Halley’s Work

The next segment starts with Tyson sitting back at the desk. He says that if Halley hadn’t pushed Newton to make his discoveries then perhaps he would be more well known for his own work.

The only thing that comes to mind for most people when Halley’s name is mentioned is the comet. While he did many great and important things, discovering that comet was only one of them.

After Newton’s book was published, Halley went on more voyages to solve navigational problems for the British Navy, as ordered by the King.

He used the opportunity to make the first map of Earth’s magnetic field. He also perfected the diving bell and used it to start a commercial salvage operation. He personally tested his own invention and stayed underwater for four hours. He also invented the weather map, which some symbols, like those for prevailing winds, are still used today.

Halley laid the groundwork for population statistics. He paced off the entire perimeter of Paris on foot to find its size so he could track births and deaths to compare to London. He calculated each couple had to have four children to maintain the population since many chose not to reproduce or had children die before reproducing. He also calculated the scale of the solar system. He figured out the distance from the Earth to the Sun that used the precise time it took for Venus to cross the Sun. 27 years after his death, Captain James Cook made his first voyage to Tahiti to see if Halley’s method was correct.  He wanted to time how long it took Venus to cross the Sun and then he calculated the Earth is 93 million miles from the Sun.  

Halley also was the first to claim that the stars were not fixed in space. He studied what the ancient Greeks had written about the brightest stars and compared them to what he had seen 1800 years later.

He figured out that unless enough time passed between observations, then no difference could be seen. He had let enough time pass and was able to prove the stars were moving.  All stars are cruising past each other around the center of our galaxy.

Halley wanted to solve the mystery of comets. He got every recorded astronomical observance of comets in Europe from 1472 to 1698 to study.  He did all of this without search engines or computers.  All he had was books and his mind. He had to take all observations and find the shape of the actual path through space.  Halley applied Newton’s laws to these observations and discovered that the comets traveled in long, elliptical paths around the Sun. He also figured out that the comets seen in 1531, 1607, and 1682 were a single comet that returned every 76 years.

Recognizing the pattern, he predicted it would be seen again in over 50 years in the future.

Mystics may have thought comets brought messages and prophecies, but Halley had proven it was much more scientific than that. He had discovered the regular pattern of these comets as they blazed their path around the Sun and returned in the future to be seen again at a regular interval. He stated flatly the comet would return in 1758 from a particular part of the sky and follow a specific path. No mystic ever tried to predict with such precision.

Tying It All Together

After a break, we are back on the Ship of the Imagination and getting a closer look at the comet that bears Halley’s name. At the edge of the solar system it looks like a big hunk of ice and rock. Beyond the orbit of Neptune, nearly 5 billion kilometers from the Sun, comets have a very calm life. As a comet reaches the far end of its orbit, it slows down until the Sun starts to pull it back down toward it. Everything is in free fall around the Sun as gravity pulls the planets toward it, but their velocities never propel them into the Sun.

Robert Hooke died from ruining his health with daily bad habits like using opium and mercury. Halley was elected to replace him as the head of The Royal Society of London.  He worked there until his death at age 85. His last minutes alive were spent drinking and enjoying some wine. Legend has it that at some time, Newton took his revenge on Robert Hooke by burning the only known portraits of his arch nemesis and that is why there are no portraits of Hooke today.

Halley’s prophecy was not forgotten after his death. Astronomers clamored to be the first to see Halley’s comet in 1758. They weren’t disappointed, and it has returned every 76 years since then. It was last seen from Earth in 1986 and iIt will return in 2061 next. Newton’s laws made it possible to predict the behavior of a single comet and scientists have used these laws ever since to do remarkable things like traveling to the moon and just knowing the cosmos.

Tyson tells us that using nothing more than Newton’s laws of gravitation, astronomers can comfortably predict that our home galaxy the Milky Way will merge with our neighboring galaxy Andromeda several billion years from now. The distances between the stars compared to their sizes means that few, if any, stars in either galaxy will collide. The merger will be safe for any future life forms and one of a brilliant light show that will last for a billion years. A beautiful computer rendition of this merger is accompanied by a lovely musical score to end the episode.