Elemental
Page 13
Color photography relies on silver as well but with additional chemicals that respond to different frequencies of light. When red light hits the layer of film containing the red-sensitive chemical, it causes silver powder to form. The same happens in the blue layer with blue light, and the green layer with green light.
You end up with a black-and-white image of where the reds should be, one for the blues, and one for the greens. By developing each layer with the correct dye in the right order, you can recreate the color image with which you started.
It’s hard to imagine a world where photographs or film didn’t exist because they are so ubiquitous. We rely on them to give us reliable information and silver is what made it possible. In recent years the invention of computer editing technology and digital cameras has changed things somewhat, but there was originally truth to the phrase “the camera doesn’t lie.”
DESTROYER OF WORLDS
For a long time, the science of nuclear bombs was highly classified. When Nobel Prize–winning chemist Linus Pauling gave a public talk on the subject, an FBI agent showed up at his office to interrogate him on how he knew the workings of a bomb so perfectly. Pauling responded, rather coolly, by saying, “Nobody told me, I figured it out.”19 Nowadays, the design of an atom bomb is well known and it’s all about uranium.
Uranium atoms have 92 protons in their nucleus and usually 146 neutrons, giving a total of 238 particles. But roughly 0.7 percent of uranium atoms have 143 neutrons instead, making uranium-235. This combination of protons and neutrons is volatile, and when the nucleus fractures it spits out neutrons. These neutrons go flying off and get absorbed by other uranium nuclei, making them unstable and causing another fission event.
If you’ve got 1 kg of uranium, most of your neutrons can escape through the surface of the metal, but once you get to around 47 kg, what’s called critical mass, the neutrons in the center don’t escape. The energy builds, fissions multiply, and the result is a nuclear blast.
It might be fair to say that gold dominated global politics up until 1945, but uranium certainly dominated it afterward. With 47 kg, you can end one war and start another.
On August 6, 1945, a uranium bomb was detonated over Hiroshima, causing the deaths of over eighty thousand people. Three days later, a plutonium bomb (made from uranium as a starting agent) was dropped on Nagasaki, killing forty thousand people and bringing the Second World War to a close.
With the ability to manipulate uranium, the United States became the most powerful nation on Earth. That kind of strength invites challenge. Four years after Hiroshima and Nagasaki, the USSR demonstrated its own nuclear capability and the Cold War began, shaping the technological, cultural, and economic landscape of the twentieth century.
Most nuclear weapons today are based on plutonium but uranium is still the starting ingredient. Getting hold of it isn’t difficult, mind you. Uranium was used for Fiesta dinnerware glazes (hilariously the US government confiscated the products during the Cold War). The tricky bit is extracting the 0.7 percent of atoms that are fissile.
At the time of writing, nine nations have the technology to do this, with the United States and Russia owning the largest stockpiles. The precise number of warheads is unknown but it’s estimated to be well over five thousand each.20 With that arsenal, you could eliminate all life on Earth many hundreds of times over.
The physicist who coordinated the invention of nuclear weapons was Robert Oppenheimer. He was once asked in an interview what it was like to witness the first nuclear-bomb test, codenamed Trinity. His response was chilling:
We knew the world would not be the same. A few people laughed, a few people cried. Most people were silent. I remembered the line from the Hindu scripture the Bhagavad Gita. Vishnu is trying to persuade the prince that he should do his duty and, to impress him, takes on his multi-armed form and says “Now I am become Death, the destroyer of worlds.” I suppose we all thought that. One way or another.21
WE WANT INFORMATION … INFORMATION … INFORMATION
Silicon sits right below carbon on the periodic table and has a similar electronic structure. The only difference is that it’s bigger, so its bonds are not as strong.
It can form crystals similar to diamond with comparable strength, and can also be strung into plastic chains, the most famous of which is the silicone gel responsible for some people’s career success in Hollywood. But silicon’s primary use is at the nerve center of every electrical device you own.
If the nineteenth century is remembered for the Industrial Revolution and the internal combustion engine, the twentieth century should be remembered for the silicon revolution and the transistor, an invention of which many have never heard.
Invented in 1947 by Walter Brattain, William Shockley, and John Bardeen (the only person to win two Nobel Prizes for physics), transistors are to computers what bricks are to houses. Your smartphone contains about three billion of them and your laptop contains seventy times that.
A transistor’s job is to let electrical current pass through it sometimes and block it at other times. On its own, this sounds mundane, but get enough transistors hooked up in an intricate pattern and you’ve got a microchip. By programming a series of instructions for these transistors as 1s and 0s, we can tell transistors to switch currents on and off, allowing us to control circuits and store information.
The problem with making a transistor out of metal is that metals always conduct. Similarly, non-metals are always insulators. In order to create something capable of switching on and off at different times you need an element that is halfway between a metal and a non-metal. Enter silicon.
Silicon atoms are large so they’re vaguely metallic in nature, but their shape has more in common with non-metals like carbon and boron. These hybrid properties make silicon a semi-conductor and its crystals form the backbone of transistors.
Not only that, silicon is also the key ingredient in glass, giving us the optical fibers for the internet. Not to mention making windows.
Most optical fibers are made by one company called 3M and their glass is so transparent that, if you were to make the ocean out of it instead of saltwater, you would be able to see to the bottom with perfect clarity.
During the 1950s, after inventing the transistor, William Shockley set up a business in California doing research with the computer science department of Stanford University.22
Prior to his invention, all computers were mechanically based and occupied whole rooms. Silicon offered the possibility of computers you could have on your desktop.
Once interest in silicon began to boom so did the local economy, and today Shockley’s neighborhood is the headquarters of Apple, eBay, Facebook, Google, Intel, Netflix, Yahoo, and Visa. It’s a region of southern San Francisco called the Santa Clara Valley, more commonly known by a name inspired by the element that built it: Silicon Valley.
Silicon enables us to perform calculations that previously took a library of people days to complete and runs everything from our digital watches to our mobile phones, although that technology comes with a moral dilemma tied to a different element—tantalum.
Tantalum vibrates when electrified, making its importance in mobile phones obvious. Seventy percent of the world’s tantalum deposits come from the Democratic Republic of Congo, a country whose economy is based on its mining and export. The civil war that raged there from 1994 to 2002, the bloodiest conflict since the Second World War, was funded through the sale of tantalum.23 Sometimes our relationship with the elements is ethically quite dark.
SAVIOR OF WORLDS
In the 1930s, hydrogen was set to be the element of the future. It’s easy to get ahold of, easy to transport, and when it burns the only by-product is water. It’s the cleanest, greenest fuel imaginable.
Not only that, its low density makes it perfect for generating lift. An airplane needs to build a lot of speed for its wings to bite the air, but a hydrogen dirigible will float without assistance or persuasion. Helium is less re
active, which makes it safer, but when the United States began stockpiling it in 1925 at the National Helium Reserve in Amarillo, European agencies turned to hydrogen as the obvious alternative.
The German government was particularly eager to harness hydrogen technology and in 1931 began constructing the world’s largest zeppelin, LZ-129 Hindenburg, a marvel of chemical and aeronautical engineering.
But on May 6, 1937, as it was being tied to the ground of Lakehurst Naval Air Station, the Hindenburg caught fire. Nobody knows how it started (spontaneous zeppelin combustion?) but in under thirty seconds all two hundred thousand cubic meters of hydrogen had combusted.24
The crash was caught on camera and the accompanying audio by Herbert Morrison shouting “Oh the humanity!” has become iconic. People saw what a hydrogen fire looked like and the age of the zeppelin was over before it began.
The world didn’t hear much from hydrogen for a few decades, until the USSR detonated the Tsar Bomba in 1961 (see Chapter 4). The Tsar wasn’t any old uranium bomb: it was a hydrogen bomb and the difference was obvious. With a mushroom cloud reaching 64 km into the sky, it made the bombs dropped at the end of the Second World War look like fire crackers.
The exact details of how a hydrogen bomb works are still classified and, bearing in mind what happened to Linus Pauling, I’m reluctant to do extensive research on it. While writing this book, I’ve investigated the price of plutonium and how much thallium is needed to kill someone. I should probably exercise caution before I start asking people how to build an H-bomb.
The basic premise, though, is fairly well understood. Einstein’s E = mc2 equation tells us that we can obtain energy from an atom by splitting it. What’s surprising is that reversing the process and fusing nuclei together releases even more energy (because quantum mechanics, that’s why).
The bomb works in two stages (I think). First, a conventional uranium bomb is triggered and the heat from that blast causes a capsule of hydrogen atoms to fuse, generating a miniature sun as they convert to helium. That’s the awesome power being demonstrated in images of the Tsar Bomba explosion.
Combined with the terrifying sight of the Hindenburg, hydrogen has been an element of terror in the public eye. But we shouldn’t give up on it. In fact, as the future creeps toward us, we may find ourselves becoming entirely reliant on it.
The energy released from fusing hydrogen doesn’t necessarily have to be done in one go. In the same way uranium rods can be brought near each other to generate heat rather than explosions, it should be possible to bring hydrogen nuclei together in controlled conditions.
Fusion-based nuclear plants would produce no toxic products, would end our dependency on fossil fuels, would end all conflicts fought over fossil fuels while providing limitless energy for the planet, as well as bringing an end to human-made climate change. Fusing hydrogen could really be the ticket humanity needs to solve all of its problems. There’s only one slight snag—we haven’t been able to do it.
In order to fuse hydrogen atoms, you have to heat them fast enough to collide. That takes energy, and all our current fusion reactors take more power to get going than we can usefully extract.
We have only achieved one positive fusion reaction so far, at the National Ignition Facility in California in 2013. There, a group of researchers led by a man whose name is genuinely Omar Hurricane, blasted samples of hydrogen with laser beams and excited them into fusing. Mr. Hurricane and his team are the first and, to date, only people to have successfully got more out of a fusion reaction than they put in.25 It’s not perfect and it’s not enough to power the world, but it’s a promising step.
And there’s something that may be even more important. Because hydrogen burns beautifully with oxygen, it’s a perfect rocket fuel. Those enormous tanks you see on the sides of ships being launched into space aren’t full of petrol, they’re full of chemicals that generate hydrogen and oxygen.
Hydrogen isn’t just the element which may save the world, it’s the element which may help us leave the world altogether. And sooner or later, we’re going to have to.
At the moment we’re living in a golden age of pulling elements out of the ground with abandon, but it can’t last. Assuming our planet doesn’t get obliterated by an asteroid (we’re overdue), we will eventually consume all the resources Earth has kindly given us.
If our species wants to survive, we’re going to have to do it somewhere else, which means we need to get out there and exploring. For that, we’re going to need hydrogen, our ticket to ride the universal express.
A FINAL THOUGHT
Each element on the periodic table has a story to tell but what that story is depends on us. It is our duty not to abuse such power. And I don’t think we will.
When I look at the periodic table, I see a monument to how far we have come and how much we have learned in such a short time. Through science we are capable of understanding the Universe and using its resources to do amazing things. I truly believe that science will save our species.
APPENDIX I
Sulfur with an “f”
Naming an element is usually an honor given to the person who isolates it. Unfortunately, it can cause disagreements when scientists give elements unpopular names.
In 1875 the French chemist Paul-Émile Lecoq named a new element gallium from the Latin gallia, meaning France. However, it was soon suspected he had been a bit sneaky. Gallus is also the Latin for the rooster, which translates into Lecoq, his own name. Perhaps he had immortalized the Lecoq name by subtly naming the element after himself.
To try and solve these problems, the International Union of Pure and Applied Chemistry, IUPAC, has stringent rules for the naming of a new element. Elements can be named after:
1. a character from mythology (e.g. thorium, after the Norse god Thor);
2. a place (e.g. rhenium, from Rhenus, the Latin name for the Rhine river);
3. a property of the element (e.g. bromine, from the Greek bromos, meaning foul stench);
4. the mineral from which it was extracted (e.g. samarium, after the mineral samarskite);
5. a scientist (e.g. roentgenium, after Wilhelm Röntgen the discoverer of X-rays).
IUPAC will deliberate a proposed name for up to five months before giving the thumbs up and then, once they have spoken, the name is internationally recognized and periodic tables are adjusted to incorporate it.
Many British chemists were horrified in 1990 when IUPAC endorsed the American spelling of sulfur with an “f” as opposed to the British spelling of sulphur with a “ph.” And throughout this book, I have gone along with their decision.
To be clear, IUPAC is well within its right to favor sulfur over sulphur. The etymology of the word is unknown and anyone who claims otherwise is misinformed. The first recorded usage is to be found in the writing of the second-century BCE poet Ennius, who called it sulpureus. That word itself (whose etymology has been lost), however, may come from the word swefel (whose etymology has also been lost).
As we don’t know where the word comes from, there is no reason to prefer one spelling over another. Spelling it with a “ph” isn’t just a matter of British pride: it’s refusing to accept the agreed international standard.
Personally, I find it infuriating I have to write the name of an element with a lower case and my own name with a capital, but I have to play ball (in this book, at least; on my website I capitalize whatever I feel like!).
I have heard some people suggest IUPAC accept a trade where sulfur is spelled with an “f” in exchange for aluminum being spelled with two “i”s (the British way, aluminium). It’s maybe worth pointing out that Humphry Davy, the English scientist who named it, did originally choose aluminum so the American spelling is more authentic after all.
APPENDIX II
Half a Proton?
The closer we look at particles the more substructure we find. Atoms are made of electrons and a nucleus. The nucleus is split into protons and neutrons. How do we know when we’
ve really got to the bottom of it?
During the 1960s, theoretical physicists decided it was time to take a bottom-up approach rather than a top-down one. Starting with the basic laws of nature, what fundamental particles should we see arising? The resulting framework, called quantum field theory, predicts a buffet of particles, all of which have been found, so the approach is definitely along the right track.
Electrons turn out to be fundamental, as do photons, the particles that make up light. There are lots of others with names like neutrinos, gluons, and Higgs bosons, but protons and neutrons are not on the list.
It turns out that protons and neutrons themselves are not fundamental but can be thought of as three particles that are. A proton can’t be split in half but it can be described as being made up of thirds. Murray Gell-Mann named these particles quarks (pronounced “kworks” not “kwarks”).
It still wouldn’t be right to say you can chop a proton into thirds, however, because they don’t actually let you do that. Quarks do not exist as individual things, but in little pairs and trios.
If you were to take a proton, made from three quarks, and break it apart you wouldn’t end up with the three individual quarks, you’d end up with six … that’s quantum field theory, folks.
So, while in one sense you can describe a third of a proton, you could never actually have it. The quarks never leave their proton so it’s fine to talk about protons as if they were fundamental particles. They might as well be!
APPENDIX III
Schrödinger’s Equation
Schrödinger’s equation is a full description of everything we can know about what a particle is doing. We might be interested in looking at how a particle is going to behave at a specific point in time or at a specific point in space. We might not be interested in either and only want to know what energies are involved or what rotations a particle can have.