All Things Great and Small (Deeper, Deeper, Deeper Still): Cosmos Episode 6 Recap
“There are more atoms in your eye than there are stars in all the galaxies of the known universe.” We’ve spent a lot of time thinking about galaxies and stars and planets and not so much time at the smaller scales of the universe. This quote, relating galaxies to atoms, is the perfect entry point into this episode about all things great and small.
It makes sense that water is mentioned a lot in a show such as Cosmos. But Tyson’s pronunciation of it—“warter”—really starts to become noticeable in this episode. He starts out by explaining the physics of what makes water a liquid in most places on earth. It’s because the molecules can slide past each other.
Sunlight shining on a dew drop causes the water molecules at the boundary to gain energy, breaking the weak hydrogen bonds between molecules, causing evaporation.
The reverse is condensation, which can form that dewdrop the “momentary triumph” of condensation over evaporation. “And while it lasts, it’s its own cosmos,” Tyson tells us.
Life inside a dewdrop is ruled by battles between single celled organisms like paramecium. And our cuddly friends the tardigrades are back! We learn more about their mastery of survival; for every human on earth, there are a billion tardigrades. Talk about being outnumbered. An alien could be forgiven, Tyson says, for thinking of earth as the “Planet of the Tardigrades.” I, for one, wouldn’t mind seeing a statue of liberty with a tardigrade face on it.
Have made our way through the dewdrop proper, it’s time to enter the plant on which it rests, through the opening in the leaf called the stomata. In case we missed 3rd grade science class, Tyson reminds us that plants are super important! They make food out of sunlight, something that we cant do. Even if we tried, we probably burn our tongues.
“If we could steal their trade secrets, it would trigger a new industrial revolution.” To do so, we’d have to break the secret of the chloroplasts.
Chlorophyll? More like bore-ophyll, amiright? Framing it as industrial espionage only goes so far in making it interesting. Chloroplasts use sunlight to split water into hydrogen and oxygen, which it combines with carbon dioxide from the air to form sugars, which provide energy. To see it all, we have to shrink our spaceship of the imagination even smaller, down to the molecular level.
Here, the inside of the cell looks like an industrial assembly line, with brass piping and conveyor belts. Sunlight triggers a series of chemical reactions that saw apart water molecules and frees electrons. There's a night shift too, using the energy of free electrons with carbon dioxide with hydrogen to create sugars for the plant to use as energy.
We can recreate photosynthesis in the lab, but we’re not as good as plants are. If we found a way to equal their efficiency, it would make coal and natural gas obsolete.
When we think of plants, we often think of ones with flowers. But for millions of years, there were no petunias, or crab apple blossoms; flower plants first evolved about 100 million years ago.
Orchids were among the first flowering plants and they’re among the most diverse. Darwin himself was interested in orchids, specifically by the comet orchid of Madagascar, which has pollen hidden at the bottom of a long thin spur. He speculated that there must be an animal, likely an insect, with a long thin tongue to get at the pollen and spread it around. It was a testable prediction of his theory of evolution, something all good theories must provide. Nobody had ever seen something that filled the niche afforded by that particular flower until 1903, when a huge moth with a foot long tongue was discovered slurping pollen from the bottom of that basket.
“Ahh, fragrance of lilacs.” Hearing Tyson say these words may be reason alone to watch this episode. It’s funny, because we can’t quite tell if he’s remembering his own memories of lilacs or trying to convey somebody else’s. Either way, it’s a cute interruption and a good example of how powerful molecules can be.
We identify flowers both by sight and by smell. Having already explained how we detect the color on a rose petal in the last episode, Druyan now goes for smell. Smell is mostly chemistry: every odor, from burnt toast to gasoline comes from a cloud of molecules. The particular shape of the fragrance molecule fits a receptor in a cell in the nasal pathway, a chemical signal that is translated into an electrical one to be interpreted by our brains.
Why is it that smell is so linked to memories? It has to do with the way our brains evolved. The olfactory center is close to the amygdala, which is integral to processing emotion and to the hippocampus, which is important to forming memories.
Smell evolved to alert us to danger — especially predators or fire. Ever burn a pot in your kitchen and smelled nothing but campfire smoke for weeks? It’s because humans can detect smoke at very low concentrations, on the order of TKTK parts per billion. The sooner we’re alerted to forest fires, the quicker we can get to safety.
It’s time to take a rest after our little romp that brought us through a dewdrop and into the human olfactory system. But even breathers aren’t a wasted opportunity on this show.
With every breath we take. Every breath we exhale is circulated through the air and mixed gradually across the continents. With each breath, we inhale “about 100 million molecules that once passed through the lungs of everyone who ever lived before us,” Tyson says. You may have heard that each one of us has breathed a molecule that came from Julius Ceasar as he uttered “et, tu, Brute?” Stick around for a little while and you’ll also get a molecule from Lance Stephenson’s breath that also passed across the face of LeBron James. “This kind of atomic reincarnation is another link to our distant ancestors, including those who first launched us on our exploration of unseen universes.”
Some of these ancestors lived in ancient Greece, about 2500 years ago. In some of those cities around the Mediterranean, “the most fundamental elements of the way we live now first appeared.” The first plays, dramas and comedies popped up here, as did government by the people. But according to Tyson, the most revolutionary idea was that the workings of nature could be explained without invoking the supernatural.
The concept of a universe governed by natural laws that we humble humans could figure out is first attributed to a Greek man named Thales, though none of his books have survived to the present day. After Thales, Democritus, who first thought up the atom, took up the mantle of investigating nature. In addition to being a thinker, he was also a partier, and we get an animated look in at one of his lectures/parties. “That’s all there is?” an upset party pooper asks, “just a bunch of atoms in a void?” Democritus’s answer is pretty much, “Yup!” If the universe weren’t made of atoms, nothing could grow or change, the world would be solid static, and dead. So don’t be sad, he says, trying to save his party’s vibe, “just think of the infinite possibilities that arise from different arrangements of those atoms!” He ends with a toast to atoms, those in his wine and those in his cup. We’re about to learn about both.
The some of the atoms in Democritus’s cup are arranged as minerals, trapped in a lattice framework that provides some stability but stuck in drearily repetitive architecture. Even the most complex minerals, Tyson says, feature the same patterns of atoms over and over again.
To get more interesting molecules, you need atoms that can bond with itself and other atoms. Carbon, which can string together into chains and rings, building molecules much more complex than crystals, fits the bill nicely.
Proteins, the molecules on which life is based, contain hundreds of thousands of molecules. Carbon is the backbone of the molecules that make every life form on earth. That’s the difference between the atoms in Democritus’s cup and the organic molecules in his wine.
Remember those flowers? We’re about to see that they serve a narrative purpose. We come in from the commercial break to see a young boy running with the flowers up to a house with a girl out front. He gives her the flowers and, like any awkward kid, gives her a poke on the cheek. Could have gone with a peck, but he looks like he’s 11 so we’ll give him a pass. The girl’s dad, of course, won’t stand for such a defilement of his daughter’s purity, so he shoots the kid a glare. Don’t worry, dad, Tyson says, he didn’t “actually” touch her.
On the scale of the atoms in the boy’s finger and the girl’s cheek, Tyson’s technically correct. The electromagnetic forces from the positively charged nuclei repel one another, so the atoms don’t come into contact with one another. But since most of the atom is empty space to begin with, it’s hard to say what contact would actually look like.
To illustrate how tiny the nucleus is, Tyson takes us to a cathedral. If the atom were the size of the entire building, the nucleus would, by comparison, be the size of a dust mote. The atom, for all its importance, is mostly empty space.
All atoms have a nucleus, which are made of protons and neutrons. The simplest nucleus is that in the Hydrogen atom, which is a solitary proton. To have a nucleus with two protons requires some additional particles. The protons, if left to their own devices, would repel each other, so neutrons have to be added to keep the nucleus stable. This makes a helium nucleus if it’s accompanied by a pair of electrons, or an alpha particle if it’s a free particle. Carbon has six protons, gold has 79. “every additional proton in the nucleus requires enough neutrons to bind it together,” Tyson says. But only up to a point.
“There’s an upper limit to the number of neutrons you can stuff into a nucleus before it becomes unstable,” he explains.
We then head to the Sun to check out some crazy atomic states. In the heart of the sun, the atoms are moving so fast that when hydrogen atoms collide, they fuse. It’s a nuclear fusion reactor where the energy formed by fusion balances the inward force of gravity. The sun’s core is 10 million degrees Celsius, which is hot for us, but lukewarm for a star. It can’t fuse helium at this temperature. Other bigger and hotter stars can even fuse helium into carbon and oxygen.
Even more massive stars can go supernova, which happens about once a century in the Milky Way. In this process, elements like iron get fused into all the higher ones. A supernova is so powerful, that when it happens, it can be as bright can be as bright as the entire rest of the galaxy.
When a dying star goes supernova, the core collapses first. Most of a supernova’s energy isn’t in the form of light, but in the form of neutrinos. The neutrinos produced race out at near the speed of light, while light waves get caught up in a shockwave that takes a little longer to spew them out into the universe. In some cases, astronomers have detected neutrinos from a supernova as much as three hours before they see the light.
The lengths scientists have had to go to hunt these fundamental particles is almost insane, certainly obsessive. Neutrino detectors have to be stuck far underground, like the Super-Kamioka Neutrino Detector in Japan. NDT is casually telling us all this while floating on a raft in the middle of this detector, which is filled with distilled water. The detector itself looks like something out of The Matrix, an inescapable cavern made of giant ball bearings. The detector can detect because most particles coming out of the sky, like photons and cosmic rays, are blocked by the rocky Earth, but not neutrinos. Neutrinos hardly interact with matter at all, passing right through it like the sounds of my neighbors 4 A.M. dance parties through my apartment’s walls. They have some mass, but only barely, weighing a million times less than an electron. So if you see any collisions within the detector you can be pretty sure that the only thing that can penetrate that many layers of rock is a neutrino.
Like Darwin’s long tongued moth from earlier in the episode, the neutrino was posited long before any were ever detected. The German theoretical physicist Wolfgang Pauli thought it up to satisfy the law of conservation of energy. To illustrate how immutable this law is, Tyson takes a heavy pendulum and lets it go from in front of his nose. When it returns, he doesn’t even flinch as it comes right up to his mug before retreating again. The pendulum converts gravitational potential energy into kinetic energy of motion, but it can never gain more energy without getting a push. If Tyson is willing to bet his handsome face on the fact that “the energy accounting books are always strictly balanced,” you better believe Pauli needed to respect it.
Here’s why Pauli needed to satisfy the law of concentration of energy: in the 20th century, scientists found out that the nucleus can spontaneously eject an electron. That’s right, an electron. But there aren’t any electrons in the nucleus! So what’s going on? When this happens, a proton into a neutron, transforming the atom into a different element. Physicists were bewildered. The combined energy of the escaped electron and the new atom was adding up to be less than the original atom, but they had no way to account for the difference. They correctly assumed they had missed something. In 1930, Pauli predicted there must be some particle that made off with the missing energy. He wasn’t optimistic that it would ever be discovered, “but that was a rare failure of his imagination.” We’ve been discovering neutrinos since we started making nuclear reactors and have been finding absurd ways to detect them ever since—one of them even involves a cave full of cleaning fluid.
Neutrinos sometimes make photons look clumsy by comparison. A neutrino formed at the center of the sun takes only a few minutes to reach Earth, while a photon could take millions of years to escape. Sure, light travels fast, but the inside of the sun is so dense, a random photon will rattle around inside for eons before finally reaching the surface.
Think about this the next time you go sunbathing: every photon burning your skin took a very long time to reach you.
Because neutrinos can travel unimpeded through dense, they’re an ideal candidate to learn more about the early universe. There’s essentially a wall of light, the afterglow from the big bang, which prevents us from seeing any further back in time using microwave astronomy. But even when all the matter and energy in the universe was packed into a volume the size of a golf ball, neutrinos could zip through. “The very thing that makes them almost impossible to detect is what allows neutrinos to sail through the curtain that conceals the beginning of time,” Tyson says. Today, all the neutrinos created in the big bang are all around us and everywhere else throughout the universe.
Did you get lost somewhere along the way? If you did, not to worry. This episode has been a free-wheeling scamper across time and space, perhaps the most disconnected of them yet. But there’s a certain beauty in the balance of scales presented here. This is an episode about the very small—molecules, atoms, and fundamental particles—but in order to explain these concepts Tyson and Druyan had to turn to the stars to do so. It’s part of the wonder of the cosmos that the smallest and largest scales are so strongly coupled. That in order to understand the stars and galaxies we also have to understand electrons and atoms.
The magnificence of modern physics is on full display here.
Photo credit: Dew Drop on Lily petal by Anita Ritenour via Flickr