During the summer of 1982, I worked at the City of Houston Tax Office. Listening to homeowners grouse about their taxes 8 hours a day was not fun, but the job paid well, and it beat working at McDonald’s for the summer. Lunch hour was literally that – one hour long and it gave me a lot of time to explore downtown Houston. Across the street from City Hall was the central library. On the first floor was a nifty bound periodical section that included all the issues of Life Magazine from its run starting in 1936 and ending in 1972. The release of the movie Detroit this week concerning the 1967 riots brought me back to that summer.
Typically, to read old issues of a magazine such as Life, one had to head towards the microfilm room. It was a treat to spend my summer lunch hours reading the real deal. Historians will usually claim that history can’t truly be understood until 50 years afterwards. It often takes that long for classified documents to become public. However, I think there is certainly value in experiencing history as the people did during any given time period. And for most of its run, Life was the go to source for photojournalism. Being a World War II buff, I made it a point to examine every issue from 1939 to the end of the Nuremberg trials. And it was the Detroit riots that provided a first crack in the edifice for me of standard World War II history, where America was entirely united in wartime.
I was nineteen and by then, I had a pretty good background on the war, the politics, and the battles, but was still lacking in nuance. How did the Detroit riots of 1967 play into this? To understand what happened in 1967, you have to understand the 1943 Detroit riots. And those riots are not typically addressed in high school history or encyclopedia accounts of World War II. Life magazine gave me a first glimpse into that aspect of American history and later in the 1980’s, Studs Terkle and Paul Fussell, among others, provided a more comprehensive understanding of America during that period.
Google has partnered with Time-Life and has all the issues of Life online. Besides allowing me to relive the summer of ’82, we can take a look at how the Detroit riots were covered at the time. It started in 1942, when a white mob attempted to block African-Americans from occupying the Sojourner Truth Homes. As the war resulted in intense labor shortages, blacks were recruited from the South to work in the war plants. Life’s coverage of that event can be found here. Five months later, Life followed up with a series on the racial factions in Detroit and the ongoing tensions still existing. Tragically, Life’s reporting was prescient of things to come.
The 1943 riots lasted from June 20-22 and left 34 dead. The start of the riot, as is often the case, was generated by false rumors of both white attacks on blacks and vise versa. The root cause was ongoing racial discrimination from housing and the best jobs in the auto industry. Detroit’s population surged from 465,000 in 1910 to 1.6 million in 1940 resulting in a housing shortage that left blacks in sub-standard dwellings. The casualties of the 1943 riot were mostly black as both white mobs and police outnumbered black residents. The Life coverage of the riot notes that, “Detroit can either blow up Hitler or blow up the U.S.” In the end, Detroit blew up Hitler, but as Life noted, the riots were a huge propaganda tool for Nazi Germany. Life’s nine page coverage of the riot can be found here.
The 1967 riot was a link in a long chain of racial tensions in Detroit. The 1967 riot was more deadlier – 43 died and it came just after the Newark riot. Life begins its coverage by referring to the riot as “the Negro revolt” akin to the phrase rebellion used today. The economy was booming in 1967 with a national unemployment rate of 3.8%, even lower than it was in the late ’90’s boom. However, it was 11% for blacks in Detroit. Also, the decade saw the migration of whites and jobs out to the suburbs and out of reach for inner city blacks. Add in the additional stress caused by the Vietnam War and you got a toxic brew of racial tension. Life’s coverage of the 1967 riot can be found here.
Riots weren’t the only thing I read about in 1982. Here are some links to articles that stand out to me 35 years later.
These, of course, reflect my personal interests. To explore the Google Life archives you can go to its homepage. Also, the Google Life photo archive has millions of photos and you can take a gander at that here. The online search function makes it easy to locate issues of interest, but browsing through issues and randomly looking at articles and advertisements can provide some nuggets as well. The dichotomy between the articles on the war front and home front is particularly striking during World War II.
And what of the collection at the Houston library where I originally read these articles? Its been moved to the closed stacks and replaced by a computer lab. Like everything else, progress sometimes comes with a price.
Social media, like all things on the internet, can provide great benefits or be a total cesspool depending how it is managed. On the plus side, a teacher can funnel new discoveries directly to students. This is much preferable to waiting a few years for that to be published in textbooks. On the downside there are the usual trolls waiting for you. And obviously, we don’t want the classroom to resemble a website comments section. For this post, I’ll focus on Twitter and Facebook.
I was reluctant to sign up on Twitter with its 140 character limitations. However, I teach astronomy, and NASA is a Twitter machine. This is particularity true with ongoing missions. Once a mission has ended, but the data is still being processed, NASA seems to prefer Facebook to make those announcements. In Twitter culture, there is an emphasis on acquiring large amounts of followers. Unless you work in mass media, I would recommend looking for high quality of interaction over quantity. The Twitter landscape is populated by trolls and bot accounts. Target certain accounts that are subject related and be quick to use the block feature to prevent an interloper from ruining the experience. If Twitter is being used in a class, using a private account may be a good option.
Twitter is at its best when researchers are disseminating and reviewing results. At times, you may get to see the scientific process at work when scientists debate their results. In the class, this can be a demonstration of the dynamics of scientific discovery. Sometimes it’s messy! It can be used to display professionalism when researches volley back and forth over the meaning of their data. It can also be used to demonstrate that even professionals can stumble and personalize their arguments. In science, its the argument, not the person, that wins the day. Used wisely, Twitter can be a useful mechanism to bring current research results into the class.
Facebook is a different animal. With greater privacy settings, it is easier to contain the trolling element without going completely private. Once a mission has ended, NASA’s twitter accounts tend to go silent while further discoveries are announced on their Facebook accounts. For example, after the Messenger mission ended, the discovery that Mercury was shrinking was released on Facebook but not on Twitter. For astronomy, this makes Facebook a key supplement to Twitter. Unlike Twitter, Facebook does not have a character limit allowing for more descriptive posts. Also unlike Twitter, you are not likely to see scientific debates on Facebook. However, Facebook has a higher quality interface for images which is especially helpful for astronomy. To start off, below are some links.
For Twitter, you do not need an account to access a public Twitter feed. The blue check marks next to an account name verifies this is a legit feed.
Of course, as you explore various Twitter accounts you’ll find others that strike your fancy. Like Twitter, Facebook allows accounts to verify themselves as legit with a blue check mark. Facebook requires an account to view other feeds. Some good Facebook feeds to start with:
Over a thousand years ago, the Silk Road served to transport knowledge and ideas between Central Asia, China, India, and Western Europe. The internet serves the same purpose today and social media is a key component. With a little experience and time to manage it, social media can play a constructive role in the classroom.
In high school, students are typically introduced to the three basic particles that constitute atoms, that being, protons, neutrons, and electrons. Unless you decide to take physics in college, education of the atom typically stops there. That gives the impression that these particles are the smallest bits of matter to be found. Both protons and neutrons consist of even smaller sub-atomic particles. The electron cannot be broken down any further. However, unlike the simple models taught in high school, it is not a particle that orbits the nucleus like planets orbiting stars.
Quantum mechanics dictate the properties of sub-atomic particles which behave quite differently from the large objects we can see. As a result, their behavior can be counter-intuitive as our eyesight is not capable of resolving these particles. In the quantum world, particles can pop in and out of existence and consequently, tunnel through barriers in a manner large objects cannot. The Standard Model guides our understanding of this realm. This model predicts dozens of quantum particles and configurations – the subatomic jungle. This post will not be a comprehensive going over of that as that would require a Modern Physics course, but will serve to stretch the bounds of your knowledge beyond the simple atomic model.
Protons and neutrons make up the nucleus of an atom. Protons have a positive electrical charge and neutrons have no charge. Both protons and neutrons are made of quarks which have a charge that comes in thirds. Up quarks have a charge of 2/3 while down quarks have a charge of – 1/3. It takes three quarks to make a proton or neutron. In the case of a proton, there are two up quarks and one down quark (the charge is 2/3 + 2/3 – 1/3 = 1). The neutron is made of one up quark and two down quarks (the charge being 2/3 – 1/3 – 1/3 = 0). Besides the difference in charge, there is a slight difference in mass between protons and neutrons.
Neutrons are slightly more massive than protons. If the neutron resides in the nucleus, it is stable. If it is a free-floating particle, the neutron eventually decays into a proton. During this process, known as beta decay, an electron and an antineutrino is released. Beta decay often occurs in nuclear reactors. An antineutrino is the antimatter version of a neutrino. Neither an antineutrino or a neutrino have electrical charge and their mass is close to zero. Neutrinos are produced in the nuclear fusion of stars including the Sun. In fact, each second, tens of billions of neutrinos pass through your body. These particles interact very weakly with matter and it requires very complex instruments to detect them.
It can take many thousands, and according to some estimates, millions of years for a light photon created in the Sun’s core to reach the solar surface and begin its journey in space. As neutrino’s interact very weakly with matter, it only takes a few seconds to reach the solar surface. Thus, the study of solar neutrinos can provide clues pertaining to the current state of the solar core. Of course, this same property makes it very difficult to detect neutrinos and require specialized instruments. One such facility is the SNOLAB near Sudbury, Ontario. The detectors are located 2,000 meters below the surface to shield it from cosmic ray noise. This is similar to locating a telescope in a dark area to prevent noise from human made light. Neutrinos can also give an early detection method for supernovae. As a supernova will release neutrinos before light, detecting these neutrinos can alert astronomers to turn their telescopes to observe the moment light is released from these events.
Like neutrinos, electrons are a fundamental particle. Unlike neutrinos, electrons have a negative charge. In neutral atoms, the negative charge of electrons offsets the positive charge of an equal amount of protons. In high school, we are taught the model that electrons are point-like particles orbiting the nucleus. This is a simplified model to start students off in understanding the atom and has provided the misconception that electrons are similar to miniaturized planets orbiting the Sun. The reality is more complex. Electrons are smeared into a cloud encircling the nucleus. The cloud is a probability curve in which the electron exists in all its possible states. Bizarre? Welcome to the quantum world.
How would this translate to the large-scale world we can see? Think of a dice in a box. Shake the box, which number of the dice is facing up? In the quantum world, all six configurations exist simultaneously in the box. That is, until you open the box and the probability curve collapses to the configuration observed.
Helium atom with 2 protons and 2 neutrons in the core. The 2 electrons are smeared in the surrounding orbital cloud. The darker the area, the higher the probability the electron resides in the area. Heisenberg’s uncertainty principle states that more we know about the position of a quantum particle, the less we know about its momentum (and velocity). Also, the more we know about a quantum particle’s momentum, the more uncertainty there is about its position. Thus, the atom is not mostly empty space as we are taught in grade school. Credit: Wiki Commons
That’s how Niels Bohr saw it and it is referred to as the Copenhagen Interpretation. To some, this explanation was unsatisfactory and led to Schrödinger’s cat. Erwin Schrödinger proposed a thought experiment where a cat is placed in a box with a cyanide capsule that would be triggered when a Geiger counter detected a radioactive decay. The decay had a 50% probability of occurring. Thus, in the quantum world, the atom exists in both states-one where it had decayed and released radioactivity and the other where it had not. But what about the cat? Did it too exist in two states, one dead and one alive? Worry not, no one has tried this experiment. It was Schrödinger’s way of pointing out the inconsistencies between quantum mechanics of the atom and the law of relativity which governs how large objects behave. Others, such as Hugh Everett III, sought another explanation.
In his 1957 doctoral thesis, Everett argued that the universe splits with each possible action. Thus, in the dice example, once you shake the box, the universe splits into six different universes. Each universe has the dice with a different number facing up. This removes the need for an observer to collapse the probability wave. It’s a fascinating proposal, as this would mean there exists separate universes for each course of action you could have taken in your life. While many physicists are very enthusiastic about Everett’s work, they have not yet devised a way to test it experimentally as we are unable to observe other universes. Unless such a way is devised, for now, we have to treat it as a very interesting hypothesis. The same can not be said about the Higgs boson.
Unlike the particles above that make up matter, bosons transmit the basic forces of nature. There are four of these forces, electromagnetism, weak-nuclear, strong-nuclear, and gravity. Photons are particles of light that transmit electromagnetic force. W and Z bosons transmit the weak-nuclear force that causes radioactive decay. Gluons transmits the strong nuclear force that binds atomic nuclei together. It is this force that is released in nuclear weapons. Gravitons are a speculative boson that would transmit gravity. To date, we do not have a quantum theory that explains gravity on an atomic scale. And then there is the Higgs boson, the so-called God particle.
The God particle is a misnomer. Leon Lederman, who was awarded a Nobel in 1988, referred to the Higgs boson as the Goddamn particle as it was so difficult to detect. Lerderman’s popular book on nuclear physics published in the early 1990’s was to be titled after the original moniker, but the publisher shortened it to The God Particle. While the Higgs boson has no religious connection, it is crucial as it imparts the property of mass in atoms. Mass is often confused with weight. Mass is constant whereas weight can change. If you travel to the Moon, your weight will be 1/6th what it is on Earth but your mass will remain the same. Weight is a measure of the force of gravity on a body whereas mass measures the amount of “stuff” in a body.
Aerial outline of the CERN facilities. Credit: Maximilien Brice/CERN
In 2012, it was announced the Higgs boson was discovered at the CERN Large Hadron Collider (LHC). The Higgs boson was predicted by the Standard Model and the evidence matched the prediction. CERN is a consortium of 22 nations and operates by the Swiss-France border. The LHC was opened in 2008 and is a 27 km ring that accelerates sub-atomic particles close to the speed of light via supercooled magnets. Besides its many discoveries in particle physics, CERN invented the World Wide Web in 1989 to disseminate its work. CERN allowed the World Wide Web to enter the public domain in 1993, making the internet boom of the 1990’s possible, not to mention, this blog.
The LHC is the world’s most powerful supercollider. The Superconducting Super Collider (SSC) that was being built in Texas during the early 1990’s would have dwarfed the LHC. The SSC would have been a 87 km ring and three times as powerful as the LHC. Construction on the SSC was halted in 1993. Several factors conspired to do in the SSC, among them the economy, politics, and cost overruns. The US economy entered into a recession during the early 1990’s prompting the federal government to look into cost cutting. Then there was Texas senator Phil Graham, who brought the bacon back to Texas but delighted in nixing projects in other states. Cancelling SSC was a way of returning the favor. At the time of cancellation, over $2 billion had been spent and the project was running several billion dollars over its original estimate.
The SSC under construction. Credit: Physics Today
That the SSC had cost overruns is not a surprise. In any project where technology has to be invented to complete it, there is a large degree of uncertainty with costs. This is true of the space program as well. When entering the realm of the unknown, the economics of that kind of project are not really known until completion. The SSC site now lies abandoned, with over 20 km of tunnels dug. Had it been completed, it could have opened our knowledge of quantum physics in the same manner the Hubble did for astronomy. The largest American supercollider, the Tevatron at Fermilab in Illinois, was shut down in 2011 in the aftermath of the global financial crisis. The next generation of supercolliders is being built in China, set to begin construction in 2020, will be twice the size of the LHC. To date, there is no American proposal to match these efforts.
While the traces left behind in particle accelerators allow us to deduce the properties of sub-atomic particles, we are unable to see the particles themselves as they are much smaller than lightwaves. Using x-rays, which have shorter wavelengths, we can see atomic structure in crystallized lattices, but not the particles themselves. This gets even more problematic when it comes to string theory which posits sub-atomic particles consisting of strings with a length of 10–35 meters. Detecting this is beyond the capability of the LHC and while string theory is impressive in its mathematical formulation, it will remain a hypothesis until a means is found to experimentally verify their existence. For other properties of sub-atomic particles, we can look into the most extreme environments of the universe.
If a hydrogen atom were the size of Earth, the nucleus would only be a few hundred feet wide with the rest being electron orbitals. If that’s the case, why can’t we walk through walls? When atoms are compressed in a smaller volume, electrons are excited to higher energy states and create outward pressure. This pressure is what prevents you from walking through walls. It takes a lot of energy to compress atoms. In white dwarfs, gravity compresses matter to the point where all the available energy states are taken up by electrons. The intense gravity of a white dwarf, 100,000 times that of Earth, is offset by the outward pressure force created by the energized electrons. Neutron stars can compress matter even more than white dwarfs. Formed by the supernova explosion of high-mass stars, these objects crunch electrons and protons to form neutrons – hence neutron stars. A teaspoon of this material would weigh about a billion tons compared to 5.5 tons for a white dwarf.
The Sun, in about five billion years, will shed its outer layers and form a planetary nebula with a white dwarf at the core. In a few tens of thousands of years afterwards, the nebula will dissipate leaving the white dwarf. There is no longer any fusion process when a star becomes a white dwarf, its luminosity is caused by the initial core temperature of 100,000 C. It takes many billions of years for white dwarfs to cool down. In fact, more time than the current age of the universe of 13.8 billion years.
Understanding the nature of sub-atomic particles allows us to understand the ultimate fate of the Sun. It has also allowed us to make many technological advances. Transistors, lasers, semi-conductors all owe their existence to our understanding of the tiniest particles of the quantum world. The pure theoretical work of modern physicists in the first half of the 20th Century made possible the world we currently live in.
*Image on top is the remains of neutrino collision at CERN. The particle tracks represent electron-positron pairs recorded in the particle accelerator. Credit: CERN
