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Enchanting and otherworldly in their beauty, the polar regions are some of the most isolated and least understood places on Earth. Until relatively recently, few non-indigenous people had experienced their immense majesty. And yet, while remote, these extreme environments are endlessly fascinating, and eminently worthy of witnessing firsthand, especially if you are prepared to understand what you are seeing.
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What draws people to the poles again and again? What significance do these regions hold for the planet? Begin to answer these questions with Fen Montaigne, a journalist who has traveled extensively in the polar regions, as you delve into the awe-inspiring story of Ernest Shackleton's struggles in Antarctica, as well as Montaigne's own experiences.
In the latitudes where most of us live, it's easy to take the sun and its relationship with the Earth for granted. For us, the sun comes up and goes down reliably every day, yet the poles experience six months each of continuous night and constant day. What causes the seemingly strange behavior of the sun at the poles? What causes seasons? Find out in this lecture presented by astronomy professor Edward Murphy.
The North and South Poles share a history that is unique and unlike any other place on Earth. Join Professor Michael Wysession as he lays the groundwork for understanding the polar regions with a discussion of their geology, dominated by ice, ocean, climate, and even nearby outer space, as well as their similarities and differences.
Over the centuries, hundreds of people have perished trying to find their way through the Northwest Passage and to the North Pole, while hundreds more have spent months or years trapped on ships in Arctic sea ice. Discover how explorers such as Henry Hudson, Sir John Franklin, and Roald Amundsen opened up this polar region to the world.
Virtually every living thing in polar waters, from single-celled phytoplankton to whales, has evolved in a world dominated by sea ice. Study how Arctic and Antarctic marine ecosystems work, and consider what happens to a sea ice-dependent marine ecosystem when the sea ice begins to disappear.
Zoom in for a closer look at the unique geologic characteristics of the North Pole and surrounding Arctic Circle. First, take a brief geologic tour of the Arctic regions, then examine how the ocean, atmosphere, and surface geology all interact, and how this region has changed geologically over time.
Constellations were vital to the early Inuits' survival, as they used the daily, monthly, and annual motions of the stars for timekeeping, navigation, and tracking the seasons. Explore this tradition and how it differs from Western astronomy, then investigate what causes the breathtaking aurora borealis.
Although fewer than a half-million in number, Arctic dwellers are comprised of approximately 40 different ethnic groups. Learn how the Nenets of Russia, the Inuit of North America, and other communities survive, and how industrialization and other factors are altering traditional ways of life.
Delve into the past, present, and future of three of the most notable islands in the Arctic and sub-Arctic: Iceland, one of the world's most geologically active areas; Greenland, which dwarfs all other Arctic islands in size; and the Svalbard archipelago, home to The Global Seed Vault.
Now that Arctic sea ice is retreating, what will become of the polar bear? Will it survive and, if so, in what numbers? Learn how changes to the ecosystem are affecting the polar bears and the other remarkable animals that call the Arctic home, from the lemming to the Arctic fox.
Discover the astonishing array of avian life, primarily consisting of seabirds, that live in, breed in, and migrate to the planet's polar regions, including the albatross, the skua, the giant petrel, and the extraordinary Arctic tern, which carries out the longest annual migration of any living thing.
The waters of the Arctic and Antarctica teem with a remarkable number of marine mammals. Get an overview of the mammalian wildlife that inhabits or migrates to polar waters, including white beluga whales, leopard seals, crabeater seals, and walruses. Examine the sophisticated social structure of orcas, also known as killer whales, and why it makes them such effective predators.
Meet some of the towering figures of Antarctica's heroic era," explorers and scientists in the early 20th century who vastly expanded our knowledge of the southernmost continent. Learn what drove these adventurers despite extreme hardship, and witness the treacherous race to the South Pole between Norwegian Roald Amundsen and Brit Robert Falcon Scott."
The ice in Antarctica may be more than a mile thick and millions of years old, but at times in its history the continent has been covered with jungles. Investigate the unusual geologic processes occurring in Antarctica and discover what features may be buried under all that ice.
Above Antarctica is a cap of stars and constellations hidden from view in the Northern Hemisphere and containing some of the most beautiful sights in the night sky. Survey the region's astronomical highlights and learn why, at the South Pole itself, astronomers and other scientists enjoy research conditions unrivaled anywhere else on Earth.
How do humans get beneath the surface of Arctic ice or the Antarctic Ocean? Join marine conservationist Sylvia Earle, a National Geographic Explorer-in-Residence, as she explains the technologies scientists use to dive safely beneath the sea ice in an effort to expand our knowledge of marine ecosystems at both poles.
Humans are extracting krill and other marine life at unprecedented levels. Burning fossil fuels is causing ocean acidification. What will happen if we change the temperature or chemistry of the ocean? Consider such questions in this lecture on the delicate ecosystems of Earth's oceans and the consequences of treating oceanic wildlife as commodities.
Among the least inhabited places on Earth, the sub-Antarctic islands feature a spectacular array of wildlife despite a history of wanton exploitation beginning in the 18th century. Learn how seal, whale, and penguin populations were devastated on and around two of the sub-Antarctic's most significant islands, South Georgia and Macquarie, and how each population has largely recovered.
Legendary Antarctic adventurer Apsley Cherry-Garrard said all the world loves a penguin" and in this lecture, you'll understand why. Get acquainted with Adelie, emperor, and chinstrap penguins by exploring how each evolved into the fat, flightless swimmer it is today. Explore the history of their interaction with humans and their remarkable cycles of reproduction and survival. "
Survey the discoveries made and hardships suffered during centuries of scientific exploration in Antarctica, including a research expedition that sought viable emperor penguin eggs in an attempt to unlock an evolutionary mystery. See how Antarctic research helped create the modern sciences of oceanography, climatology, and glaciology, and is still driving scientific progress.
Picture being in the Arctic when a polar bear approaches your ship. What kind of camera should you use to capture the moment? What settings should you choose? Here, National Geographic photographer Ralph Lee Hopkins explains how to navigate the unique challenges of polar photography, from dealing with a white world" to shooting atop a moving platform."
Photography is a blend of the creative and the technical and, in this lecture, you'll focus on the creative side of the equation. Learn how to use lighting, composition, and moment to your advantage in the Arctic and Antarctica through techniques such as changing perspective, incorporating people into your shots, and using negative space.
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An invisible world of astonishing complexity is all around you. A world so small you can’t see it with the naked eye. A world so crowded that its population staggers the mind. A world in which you participate every day—often without even knowing it.
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Step into the hidden world of microbes and learn the challenges and advantages of being small—very small. Microbes live in a realm where water seems as thick as molasses and the smoothest surface conceals a canyon of hiding places. Also see how the geometry of a sphere explains how bacteria survive.
Turn back the clock to a time when our early ancestors escaped most epidemic diseases. But once we started gathering into villages, raising crops, and domesticating animals, we changed our niche and altered our habitat. Deadly microbes thrived in these new conditions.
Follow the trail of one of the most infamous microbes of all time, Yersinia pestis, the cause of the Black Death. Like typhus, malaria, and dengue fever, the Black Death is a vector-borne disease—one transmitted from human to human via a host intermediary; in this case, fleas.
In the days before the invention of the microscope and the rise of modern medicine, how did people explain a killer plague? Retrace the steps that led pioneers such as Louis Pasteur, Robert Koch, and Ignaz Semmelweis to the startling conclusion that organisms invisible to the naked eye cause disease.
In the first of three lectures on the coevolution that shapes our relationship with the microbial world, explore the discovery of antibiotics and the subsequent upsurge in antibiotic-resistant strains of bacteria, driven by our overuse of drugs that were once a magic bullet against infection.
Probe the different mechanisms that humans have evolved to defeat microbial invaders, and the strategies evolved by microbes to thwart those defenses. For example, our immune system is primed to produce fever and other infection-fighting responses, but many microbes have developed frighteningly potent countermeasures.
Virulence is a measure of the effectiveness of a microorganism at killing its victims. Discover that many diseases, such as syphilis, scarlet fever, and diphtheria, have grown less virulent due to competition and coevolution. On the other hand, vector-borne pathogens often succeed by growing more virulent.
Chart the human-created niches where microbes flourish. Trade, travel, and technological innovations provide new opportunities for the evolution or dispersal of pathogens, including Legionnaires’ disease in air conditioning systems, toxoplasmosis in kitty litter, and Oropouche fever in fields cleared for the cultivation of cacao, used in making chocolate.
Consider more examples of how ecological disturbances, both natural and human-made, can benefit harmful microbes. Thanks to land-clearing and the subsequent explosion in the deer population, Lyme disease now occurs throughout much of the United States. More frightening and deadly, if less widespread, are hantavirus, Lassa fever, and Ebola.
The hookworm influenced an early 20th-century stereotype of Southerners as indolent and undernourished, and it may have contributed to the outcome of the Civil War. Chart the war waged against this debilitating parasite by zoologist Charles Wardell Stiles, whose public health crusade helped transform the South.
In the first of three lectures on the deadliest epidemic of all time, meet the virus that caused the 1918 flu, investigating its structure, method of infection, and strategy for evading the human immune system. Also learn where it first appeared and how it mutated into a far more virulent strain.
Track the mutated form of the 1918 flu as it reached American shores and killed an estimated 675,000 people out of a population of 105 million. Philadelphia is a horrifying example of the medieval-like conditions that affected a bustling city trying to deal with mass infection and death.
Follow one of the most gripping detective stories of modern times—the search to recover an intact virus from the 1918 flu. Also learn what made the 1918 flu a more powerful killer than the similar strain that attacked in 1976 and 2009.
Given the proliferation of microbes in our midst, why aren’t we sick all the time? In the first of six lectures on the inner mysteries of the immune system, see how different cells have evolved to distinguish self from non-self, providing the first line of defense against infection.
Delve deeper into the mechanics of adaptive immunity to learn how a few hundred genes can easily make more than 100 million different antigen receptors, specific to any foreign invader that enters the body. Also discover the crucial difference between resistance and immunity.
In our age-old struggle with microbes, have we finally met our match with AIDS? The HIV virus that causes AIDS takes aim at the very heart of the human immune system. Probe this elegant strategy and learn where and when HIV first appeared, and why it is so lethal.
Explore the frightening scenarios that may yet unfold with the AIDS pandemic. Then follow the slow progress in developing an AIDS vaccine, and consider the policy of deferring questions of sexual morality to focus on preventing spread of the virus at all costs.
Consider what happens when the immune system turns on us, attacking our own cells and tissues as if we were the enemy. Such autoimmune diseases include multiple sclerosis, rheumatoid arthritis, Type 1 diabetes, and lupus. Examine the mysterious causes of this self-destructive reaction.
In the closing lecture on the human immune system, follow the microscopic chain of events that lead to allergies and asthma. Peanuts, pollen, bee stings, cat hair—all can cause an overreaction in the immune system, but for different reasons and with results that range from discomfort to death.
Investigate the history of microbes as weapons, which dates to the practice of catapulting disease-infected corpses into enemy strongholds. Germ warfare was even used during the American Revolutionary War, but it didn’t reach maturity until World War II with Unit 731, the notorious project run by the Japanese.
As if from Pandora’s box, the technology of germ warfare advanced during the cold war to a lethality rivaled only by atomic weapons. Draw back the curtain on the secret American and Soviet projects that perfected this weapon, and learn why biological warfare is the strategy of choice for terrorists.
When European explorers arrived in the New World, they unwittingly brought weapons far more lethal than firearms: namely, microbes, such as smallpox, that the Indians had never encountered. Learn why diseases bred through contact with domesticated animals in the Old World swept through the Americas like the angel of death.
Is there life beyond Earth? Space is filled with the chemicals essential for life, but so far only indirect evidence for possible microbial life has been found. Also, look at the microbes that thrive in extreme environments on Earth that may resemble conditions on other worlds.
In this last lecture, consider how the vast majority of microbes are harmless or even beneficial to humans. Microorganisms are responsible for everything from the oxygen in air to yogurt and many medicines. They may even help us clean up our planet, proving that the microscopic world is not always the stuff of nightmares!
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All Watched Over by Machines of Loving Grace is a BBC television documentary series by filmmaker Adam Curtis. In the series, Curtis argues that computers have failed to liberate humanity, and instead have “distorted and simplified our view of the world around us.”
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A critical look at the Ayn Rand's influence on American entrepreneurship and inspiration for the new economy led by computerization of systems.
The use of vegetational concepts role in the rise of the machines, our belief in the balance of nature, and how the idea of the ecosystem was invented.
Humankind's progressive belief in being machines, and how no one believes anymore that the world can be changed for the better.
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In My Favorite Universe, the astrophysicist who directs the nation’s most famous planetarium takes you on a spirited and intellectually engaging journey through the cosmos and all its history, from before the Big Bang to the most likely ways in which Earth, and perhaps the entire universe, might end.
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What forces tend to make objects round? And why is a sphere the most efficient shape an object can take? The answers will lead us across the cosmos.
Just how "thin"—low in density—is the "thin air" out of which a magician produces a rabbit? And if the universe contains components that are even thinner, exactly what does that mean to us?
This is a discussion of different levels of density and the inherent mysteries of this property, along with the ways in which an understanding of density helps us think creatively about the world.
Take a look at black holes, one of the most fascinating topics in the universe—including the ways in which they would kill a human being, how they wreak havoc in the universe, and some provocative new research.
Here is a detailed look at three scenarios for the destruction of our planet: the death of the Sun, the collision of the Milky Way and Andromeda galaxies, and the heat death of the cosmos.
We now know that a deposit of energy sufficient to kill off 50 to 90 percent of all species strikes Earth every 100 million years. This lecture looks at our risks of getting hit by an asteroid and what we can do to avoid it.
Take a break from the death and destruction of asteroids and the end of the universe and wonder, instead, at the enormity of the cosmos and what our place in it might be.
We now know without doubt how the universe began, how it evolved, and how it will end. This lecture explains and defends a "theory" far too often misunderstood.
A synthesis of the greatest discoveries of physics, astrophysics, chemistry, and biology creates a coherent story of the birth and evolution of the cosmos.
The origin of the elements that make up life is one of the most important discoveries in any field in the 20th century, yet underappreciated by the public because it happened over many decades. This lecture presents a step-by-step explanation of the long path to a Nobel Prize-winning idea.
Before 1995, the planets of our own solar system were the only ones we knew about; the total has now passed 100. This lecture discusses the tools and methods being used to find other planets that might be hospitable to human life.
This lecture examines the very real possibility that life exists elsewhere, and speculates about its origins and chemical makeup.
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Famed physicist Richard Feynman once said, “Anyone who has been in a thunderstorm has enjoyed it, or has been frightened by it, or at least has had some emotion. And in those places in nature where we get an emotion, we find there is generally a corresponding complexity and mystery about it.”
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From thunderstorms to typhoons to driving winds, the world's weather is often tumultuous, destructive, and surprising. And yet, all these phenomena represent Nature's attempt to mitigate extreme conditions. In this introduction, begin to explore some of these extremes as you examine the great complexity of the world weather system.
Why do cold and warm fronts exist? Can you dig a well so deep you cannot pump water from it? Find the answer to these and other questions as you explore three key concepts of weather—temperature, pressure, and density—and the equation that sums up their relationship: the ideal gas law.
What is air made of? Is it always true that hot air rises and cold air sinks? Learn more about the air that surrounds us and cushions us from the outer reaches of space, and examine the various layers that make up the earth's atmosphere.
Energy radiates all around us, streaming in from sunbeams and emanating from every object on Earth. Investigate the various kinds of radiation represented on the electromagnetic spectrum, and see how these forms of energy—assisted by the greenhouse effect—make life possible on our planet.
If all the Earth receives energy from the sun, why are there such wide temperature differences across the planet? Why do we have seasons? Answer these questions while learning about how heat moves through the atmosphere via two basic processes: conduction and convection.
Gain an understanding of how wind works as you explore the way temperature and pressure drive sea breezes during the day and land breezes at night. Then apply these findings to a dramatic wind condition, the famous Santa Ana winds of California.
Add a new element to your understanding of the atmosphere—water—and learn some basic facts about air's capacity to hold water vapor, including the impact of temperature on atmospheric moisture and the implications for weather.
Why does dew form on some mornings? Why does it take longer to cook food at higher elevations? Discover the answer to these questions as you learn about saturation: the point where air holds the highest amount of water vapor that it can contain.
One of the most familiar and beautiful features of weather is the cloud. In this lecture, examine different kinds of clouds, learn how clouds are born, why and how they take their distinctive shapes, and what kinds of conditions are likely to produce clouds.
Continue your discussion of clouds as you take a closer look at the climates and precipitation relating to this weather phenomenon. Discover why some clouds produce rain while others do not and see why deserts are often found on the lee side of mountains.
Move from clouds to wind as you begin to explore how and why air is transported around the globe. Examine how conditions, including differences in air pressure and temperature as well as the rotation of the Earth, determine where winds arise and the direction in which they blow.
In addition to pressure differences and the Earth's rotational movement, two other forces help to determine the winds' strength and direction: friction and centripetal force. Learn about these two forces and examine how they shape the winds the world over.
After mastering the four forces that affect wind, step back to view their patterns of flow across the Earth's hemispheres. Examine the two models of air circulation that help account for large-scale air-circulation patterns and variations in temperature from the poles to the equator.
In this lecture, you encounter some of the most dramatic air-flow patterns found in nature, the swift, turning winds of the cyclone. Trace the lifecycle of the extratropical cyclone, which draws its power from the huge energy generated when different air masses meet.
Shift your eyes to the sky and examine what happens in a higher level of the atmosphere called the middle troposphere. With this examination, you discover two new features in large weather systems—troughs and ridges that occur in areas of very low and very high pressure—and see how these features affect the weather.
Expand your understanding of how air moves by taking a three-dimensional view of atmospheric circulation. Discover what happens when winds change direction and what conditions cause these changes in wind shear.
In this lecture, investigate how mountains can disturb the atmosphere into which they intrude from below. Also, learn how these disturbances can be felt far and wide.
That familiar crash of thunder and the torrential rains that often accompany it are common weather during the warm season. Learn how these noisy storms can form near cold fronts associated with extratropical cyclones and see how scientists use radar to study these storms.
Delve deeper into tumultuous weather as you learn about the formation of towering supercell storms. You also take a detailed look at how the conditions that produce these storms can lead to deadly tornadoes.
With their massive volume and constantly moving currents, oceans provide a vast reservoir of energy. Explore how the winds help generate movement in the ocean and, in turn, how the oceans affect weather all over the world, creating a huge feedback loop that helps create our climate.
Building on your understanding of how the ocean affects weather, turn your attention to the tropical cyclone, generally known as the hurricane or typhoon. Examine the typical structures of the tropical cyclone, and investigate the conditions needed to unleash these dangerous storms.
Here, you bring together all you've learned in earlier lectures about the composition of air, the electromagnetic spectrum, the condensation of liquid, and the role of oceans in our climate, and use that information to explore two dazzling phenomena: light and lightning.
Scientists have learned a lot about how weather works and have developed sophisticated tools to predict what may happen in our weather. You learn about the sophisticated numerical models these experts use, as well as the inevitable limitations of those models.
Despite all their knowledge and tools, scientists cannot make perfect predictions. Find out why, using the example of Hurricane Rita in 2005, and explore the deep complexity of weather and climate that makes the subject of meteorology one that continues to fascinate.
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Kids, for all their youth and vigor, aren’t indestructible. They’re always growing, which makes their health needs different from those of the average adult. Enter pediatricians: trained medical experts whose sole mission is to help children reach their maximum potential.
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How do pediatricians treat the unique needs of children? This introductory lecture examines early pediatrics (using Helen Keller as an example), walks you through a 21st-century pediatric exam, notes the challenges pediatricians face, and presents a fever action plan" you can refer to when a child has a fever."
Assume the mantle of medical student and join Dr. Benaroch in his pediatric office, where you'll meet Jenna, a 14-year-old girl suffering from abdominal pain. As you follow the steps pediatricians follow to narrow down a diagnosis, you'll also learn about different types of abdominal pain and their root causes.
Focus on one of the most common medical problems diagnosed by anyone who provides medical care for kids: ear infections. While it may seem like a simple problem, it turns out there are a lot of ways ear infections present themselves-and a lot of ways doctors treat them.
Welcome to the complex world of childhood allergies. How do pediatricians know when to diagnose a specific allergy? How do allergies cause different problems at different ages? What are the best ways to avoid specific allergens? Follow one patient on the allergic march" as his symptoms evolve, beginning with eczema."
All healthy children should grow well, but sometimes they don't grow as expected. Consider the catalysts of growth in the human body and the places where growth can go wrong, including hormonal imbalances and rare genetic conditions. Then examine one young patient's growth dilemma and see if you can figure out the cause.
Meet Chaz, a 16-year-old whose complaint of a headache" sparks an in-depth discussion on childhood obesity. You'll cover the orthopedic complications, the psychological problems teens can suffer, the genetic influences of obesity, and ways to support healthy change in obese children."
Children are mostly healthy and strong, but they're nevertheless constantly vulnerable to infectious organisms. Learn some of the specific critical thinking and detective skills great pediatricians use to tell genuinely sick children from those who are going to be OK. Plus, discover why pediatricians should never trust a newborn.""
In this lecture, learn the inner workings of routine pediatric checkups. Dr. Benaroch reviews standard childhood growth and development; discusses how screening tests, chart reviews, standard examinations, and anticipatory guidance" work; and offers insights to help parents get the most out of their child's next scheduled checkup."
Get a window into how pediatricians uncover potentially serious symptoms that they sometimes can't see or hear. Topics include the differential" (a list of possible diagnoses), the importance of describing symptoms as accurately as possible, and why listening and building good communicative rapport are the most important tools in a pediatrician's toolbox."
What role can (and should) pediatricians play when a child isn't doing well in school? Discover how doctors ferret out clues from kids unwilling (or embarrassed) to talk, and see how they work with parents and teachers to accommodate and alleviate scholastic stresses.
Visit a neonatal intensive care unit (NICU) that provides specialized care to sick newborns. You'll learn about Apgar scores (which judge a newborn's health), the dangers of neonatal pneumonia and congenital heart disease, and how pediatricians take care of premature infants.
Some pain is fleeting. Some pain should make parents worry. Discover how different specialists (including orthopedists, rheumatologists, oncologists, and psychiatrists) think about and approach pain in children. Then, find out how doctors break the news of a life-changing diagnosis to a child and his or her family.
Focus on helping children of any age (and their parents) get a good night's sleep. You'll learn how to establish healthy sleep associations with children, go inside sleep issues like narcolepsy and sleep apnea, and learn how to help reset" a child's body clock to get better sleep."
Getting to know children as they grow lets pediatricians see how problems manifest at different ages. Here, meet Casey, whose development over time is a window into the world of delays in growth stages-and discover how doctors and families adapt to these circumstances.
In this powerful lecture, a patient case study offers a look at what Dr. Benaroch calls the grey zones of normal." Witness how a pediatrician's ongoing relationship with his or her patient establishes the trust necessary to discuss issues of patient privacy, bullying, gender issues, and drug use. Find out how these confidences lead to an accurate diagnosis."
Discover what health challenges children adopted from other countries are likely to face when arriving in the United States. How do pediatricians handle language barriers? What screening methods are appropriate to get a good picture of a child's health? The secret, you'll learn, is doing the best you can with the clues you've got.
Meet several children trying to overcome behavioral challenges, including a compulsive liar, a six-year-old who won't sleep in his own bed, and an 18-month-old girl with temper tantrums. Along the way, you'll learn when to contact a specialist, the keys to effective discipline, and more.
From headaches to irritable bowel syndrome, many symptoms are affected by the connection between the mind and body, which makes understanding psychology essential to pediatric care. Here, Dr. Benaroch illustrates how pediatricians navigate the waters of behavioral and psychosomatic symptoms that have a significant impact on the lives of children and their families.
Kyle, a homeless teen, arrives in your office complaining of a lump" in his neck. The path to Kyle's diagnosis leads you through topics ranging from toxic stress to prevalent diseases facing homeless youth (including mononucleosis and sexually transmitted diseases)."
Test your creativity with cases where common symptoms mask uncommon causes. There's Mabel, whose cold" has another cause; Peter, whose vomiting is not a typical tummy bug; Crystal, whose legs are covered in mysterious sores; and Vipul, whose nosebleed illustrates the unusual ways that children can get themselves into trouble."
Sometimes, tragedies happen. Learn how pediatricians examine their patients, investigating every potential factor that might cause medical distress. Discover what pediatricians do in painful situations, and get an intimate view into how pediatricians work with families facing a loss.
Hailey arrives in your office with a urinary tract infection (UTI). But what happens when the treatment leads to something that's even more potentially dangerous? Gain insights into the two types of UTIs and the advantages-and disadvantages-of antibiotic usage.
Follow Dr. Benaroch as he drills down through potential problems to the underlying cause of one patient's stomach pain and vomiting. Along the way, you'll learn how doctors determine the source of abdominal pain by dividing the abdomen into four quadrants, which contain different organs.
Examine several cases that illustrate just how far pediatrics has come-and where the field might be able to go next. You'll get up close and personal with the future of medicine, including gene therapy, fetal surgery, cochlear implants, and pharmacogenomics (which can tailor medications to an individual's genetic makeup).
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When you’re sick, you go to a doctor to figure out what’s wrong. But how doctors work isn’t some impenetrable mystery. Rather, there’s an art and science that goes into how they diagnose and treat patients.
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Start your rounds with a trip to a general clinic, where you meet a patient whose chief complaint is, “I never feel good.” Along the way, you’ll learn how doctors solve mysteries like this with the aid of several tools—the most important being the patient’s medical history.
Go back to an outpatient clinic in 1981, where a young man’s fever, cough, and ulcers led to a surprising diagnosis. This powerful lecture is an opportunity to learn more of the basic tools of medical diagnoses and to discover how doctors began to fight back against this modern epidemic.
Learn how critical a complete medical history, a thorough physical exam, and collaboration between doctors can be to make a tricky diagnosis. Your patient: “Louisa,” a woman who has suffered from abdominal pain for years. Does she have irritable bowel syndrome? Is it all just psychological? Or is it something else entirely?
This lecture’s case involves an illness that’s been around for millennia but which many of today’s physicians have never seen. It involves a 10-year-old boy suffering from a rash that doesn’t bother him, red-appearing eyes, and a cough. And the true culprit is one that could easily have been prevented.
Your patient is back in the emergency room with another “sinus headache,” but the nurses think he’s just after drugs. What’s the real story? In finding out, you’ll learn how physicians diagnose headaches; the differences between primary and secondary headaches; red flags doctors look for when determining their severity; and more.
Discover how doctors diagnose a common disease that can kill a healthy 36-year-old woman in months but, in a 90-year-old, may not need to be treated at all. Through the case of a woman with increasing hip pain, you’ll learn more about the genetics of this disease, ways to test for it, and more.
You’re at the grocery and the person next to you suddenly collapses. What do you do? Here, learn how doctors (and laypeople) can use basic lifesaving steps to deal with a sudden catastrophe. Also, explore the methods physicians use to prevent health emergencies before they happen.
Meet a surly young man who could just be your typical teenager—or who could be suffering from an illness that’s a severe threat to young adults. His story is a fascinating window into how doctors sort through myriad symptoms to diagnose and alleviate a highly prevalent—and all too serious—medical problem.
Tina suffers from attacks of dizziness and is certain she has hypoglycemia, but doctors should never fall into the mental trap of starting a diagnosis with a false assumption. In this intriguing lecture, Dr. Benaroch shows you how physicians make expert diagnoses when one specific test isn’t available.
Charlene has come into your office for a checkup and it is clear that she’s lost a significant amount of weight. Follow along as Dr. Benaroch uses his medical savvy to make a diagnosis, reveal insights into what the real problem is, and establish a course of treatment that goes far beyond just taking pills.
Discover how a young man’s painful calves lead to a surprising diagnosis. As you’ll learn, sometimes even the most uncommon of complaints can signify the presence of a fairly common illness. You’ll also discover why you should never underestimate the seriousness of this particular diagnosis.
Sometimes doctors make mistakes. As Dr. Benaroch guides you through the diagnosis of a patient with a case of recurrent hives, he reveals several powerful lessons for both doctors and patients. These include insisting on clear instructions and remembering that treating the disease is not the same as treating the patient.
The case here - a weak and listless baby - offers an illuminating window into how doctors treat sick infants diagnosed with this mystery condition (which has powerful roots in our genetic code). You’ll learn how genes encode for proteins; the psychopathology of diseases caused by genetic structural changes; and more.
How does a doctor get from the common complaint of constipation to a diagnosis of something much more dangerous? In solving this medical riddle, you’ll learn about a particular medical epidemic so powerful and prevalent that, in one county in Kentucky, it’s deprived many children of their parents.
At 55 years of age and quite overweight, Joe falls asleep all the time. Is it narcolepsy? Is it kidney disease? The real culprit, you’ll discover, is a condition originally described by author Charles Dickens; one whose effects are more wide-ranging (and life-threatening) on the human body than you can imagine.
Meet Sammi, an infant girl who’s brought to the emergency room and suddenly starts shaking right on the examining table. How do doctors act to both help her and diagnose her as the attack happens? And what are the mysterious connections between the underlying diagnosis and a critical deficiency?
Sometimes, a single patient can have more than one disease (a medical “philosophy” called Hickam’s Dictum). This idea is illustrated by a middle-aged woman who can’t stop vomiting. The road to determining her interconnected diagnoses is a harrowing story that illustrates why doctors always need to stay on their toes.
Explore from two perspectives the case of a patient with a mysterious illness. First, see how doctors diagnose his condition and work with the patient to prevent a medical emergency so old it’s mentioned in the Bible. Then, find out what happens in the worst-case scenario, where time is of the essence in saving a life.
Step inside a university’s student health center, where your patient, Elena, makes repeated visits complaining of nausea, then vision troubles, then a urinary tract infection. What’s going on here? Investigate how seasoned doctors act like Sherlock Holmes to arrive at a diagnosis of a disease that predominantly affects young adults.
This lecture’s diagnosis is surrounded by controversy about what causes this specific illness, how it should be treated, and even how common it is. In exploring how doctors approach it, you’ll learn insights into childhood development; specifically, how to know when something may be wrong and what tests can help narrow down a cause.
You’re on an expedition in Antarctica. You’re diagnosed with a problem that requires immediate emergency surgery, and there’s only one person who can perform it: you. Use this real-life scenario from the Soviet Union’s Sixth Antarctic Expedition in 1961 as an intriguing window into how doctors diagnose and treat this problem in less extreme, 21st-century circumstances.
This Grand Rounds starts with you as an eyewitness to a serious motorbike accident, where the diagnosis is obvious and the story lies in what happens to the body when it’s pushed to the edge of survival. Follow this patient from treatment at the site to lifesaving strategies in the emergency room.
Margo, a 49-year-old woman, goes to the doctor with a persistent cough. What are the common (and not-so-common) causes of persistent coughing? How do trained doctors analyze cough for clues about an underlying diagnosis? And when this particular diagnosis is reached—how is it treated in an outpatient clinic?
Dr. Benaroch concludes this lecture series with an elderly patient who has frequent confusion and forgetfulness. Is the most obvious diagnosis the correct one? Then, he sums up the many lessons you’ve learned throughout the course, both about being a good doctor and a good patient.
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A documentary about how Romania struggled to obtain a better life for their citizens. Going from getting rid of their dictator, to getting trapped in endless corruption scandals. In the end, what is this “democracy” all about? And is it better than what it was before it?
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How and when did life on Earth get to be the way it is today?
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Professor Anthony Martin introduces the nearly 4-billion-year history of life by reviewing the basic concepts of macroevolution—the appearance of new forms of life from older forms of life. Learn how macroevolution leads to the major transitions covered in the course, such as the development of multicelled animals, flowering plants, and primates.
Plunge into “deep time” by examining the two major types of evidence used in paleontology, which is the study of ancient life: namely, body fossils (shells, bones, molds, casts, eggs) and trace fossils (tracks, burrows, nests). Also, see how fossils are used together with radiometric dating to construct the geologic time scale.
Complex life traces back to the Proterozoic eon, when simple one-celled organisms called prokaryotes evolved specialized structures and became new types of cells called eukaryotes. Investigate how this major transition took place, paving the way for the profusion of life forms explored in the rest of the course.
Make the leap from individual eukaryotic cells to organized groups of cells, called metazoans, which represent the first animals. Learn what distinguishes animals from plants, and how strange forms of animals flourished about 600 million years ago in shallow-marine environments devoid of predators.
Fossil beds such as the famous Burgess Shale in Canada show that life diversified quickly in the Cambrian period, about 500 million years ago. Discover that the reason relates to an “arms race” between predator and prey, which saw the development of skeletons and other mineralized parts.
Delve into a long-running paleontological mystery: conodonts survive only as tooth-like fossils, but paleontologists now know these were parts of eel-like creatures with primitive backbones. Such early vertebrates later diversified into fish, amphibians, reptiles, and mammals.
Venture out of the water and onto land to learn how life adapted to terrestrial environments in the early part of the Paleozoic era, 500 to 400 million years ago. Algae, fungi, plants, and animals all had to evolve to survive and thrive in what were originally forbidding, barren landscapes.
Travel to the Devonian period, roughly 400 million years ago, and look at the early evolution of insects and insect flight. This major transition gave rise to what are today the most diverse and evolutionarily successful group of animals.
Landscapes without large trees were typical before the early Carboniferous period, about 400 million years ago. Survey the fossil record for clues to the evolution of the first seed plants, called pteridosperms (“seed ferns”). These and other plants formed early forests, now preserved in much of the world’s coal deposits.
The canopies provided by early forests gave vertebrates new opportunities to get out of the water and start moving around on land. Learn how all four-limbed vertebrates (tetrapods) owe their evolutionary origins to lobe-finned fish that started this transition about 380 million years ago.
The chicken versus egg question has a thought-provoking answer from evolution. Explore the factors that led to the enclosed, amniotic egg, an adaptation that allowed primitive reptiles to spread into new environments on land, some 150 million years before reptiles branched into birds—and only much later into chickens.
Jump ahead to the Triassic period, about 250 to 200 million years ago, to investigate how small diapsid reptiles, whose living descendants include crocodiles and lizards, evolved into the most popular and iconic of all animals from the fossil record: the dinosaurs.
Dinosaurs dominated the land from the Triassic to Cretaceous periods, about 230 to 65 million years ago, but evolution favored other reptiles to rule the seas and sky. Inspect these many “-saurs,” including ichthyosaurs, plesiosaurs, mosasaurs, and pterosaurs.
“Dinosaur” has become a synonym for a failure to adapt to changing circumstances. But the dinosaur lineage survives today through birds. Starting with the remarkable transitional fossil Archaeopteryx, examine the evolutionary transition of theropod dinosaurs into graceful creatures of the air, which still retain some dinosaur-like characteristics.
Flowers are so widespread that it’s hard to imagine a world without them. Return to just such a setting in the early Cretaceous period, and follow the selection pressures that led to primitive flowering plants, which developed in concert with the evolution of bees and other pollinating creatures.
Discover how mammals evolved from reptiles around 230 million years ago and later underwent an evolutionary leap from egg-laying to giving live birth. Surviving the mass extinction at the end of the Cretaceous period 65 million years ago, they took off in an astounding burst of adaptive radiation.
Among the transitions that took place about 50 million years ago was the move of some land-dwelling mammals to marine environments, leading to modern whales. Considering that some whales became the most massive animals in the history of Earth, explore the question, “Why so big?”
Professor John Hawks takes over from Professor Martin in the first of his six lectures on the evolutionary steps from early primates to modern humans. Learn how the first primates were uniquely adapted to navigate the complex canopies of ancient forests about 60 million years ago.
Trace the evolution of some primates into monkeys and apes, culminating in “the age of apes” beginning around 25 million years ago. Within their great diversity of size, diet, social structure, and ways of moving, one ape lineage appeared in Africa different from the others, sharing many features with modern humans.
Examine fossil clues to the first major transition of human evolution: the development of upright walking. Being a biped has many advantages but also some major drawbacks. What body changes allowed early hominins like Australopithecus (including the famous Lucy) to walk efficiently on two legs?
The first stone tools, 2.6 million years old, mark a change to a human-like social and cognitive system. Probe the nature of such early implements, and the hunting and gathering culture they represent—a way of life that placed many demands on human brains.
Follow modern humans from their African homeland, about 100,000 years ago, as they dispersed into the ancient populations of Europe and Asia, challenging the territory of earlier humans. These rivals include the Neandertals, who are now much better understood through the decoding of their genome.
Human evolution did not stop with the advent of modern people. Consider how humans today are the descendants of incredible survivors, with a legacy of new genes that continue to affect diet, disease, physical appearance, and features such as skull and brain size, which has actually decreased in the past 10,000 years.
Conclude the course by experiencing a fascinating discussion between Professors Martin and Hawks as they compare perspectives, probe common themes in the major evolutionary transitions over the past
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For thousands of centuries, humans lived near the ocean, wandered right up to its edge, and turned back to the relative safety of the known land. Even when we invented ships and the very bravest among us sailed out, our fears and imaginations took over. What creatures could be living in the unknowable darkness, the bottomless depths? Giant worms, microorganisms that eat metal, faceless fish, giant sea spiders? Marine life is even more otherworldly and fantastical than we ever imagined, and Life in the World’s Oceans brings you face to face with these exciting creatures. From the phytoplankton that can only float at the whim of wind and currents to the gray whale that migrates 16,000 kilometers each year, you will be amazed at the variety of life in the seas and what we have only recently learned about its biology, evolution, life cycles, and adaptations.
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So much of what we take for granted about our world—from our body’s access to and use of nutrients, to our planet’s liquid oceans, to the ice floating in your glass of soda—is a direct cause of the structure and polarity of H2O. Learn how those specific properties make water the essential ingredient for life as we know it.
No matter where you live, your climate, weather, and even available foods are determined to a great extent by ocean circulation. The uneven heating of the Earth by the Sun and the Coriolis effect result in vast circulation cells of air above the Earth, the movement of huge water masses in the oceans, and resultant “hot spots” of marine life.
How and where did life begin on Earth? The existence of both photosynthetic and chemosynthetic food chains—along with experiments confirming the mechanisms of abiogenesis—points to the possibility that life could have originated through two different paths. While many questions remain unanswered, two things seem certain: Life began in the oceans, and bacteria are the most successful organisms on the planet.
Beach organisms exist with the constantly changing winds, waves, and tides—sometimes underwater, sometimes fully exposed to the air. Life in estuaries, where rivers meet the oceans, face constant fluctuations in environmental salinity. And hard corals are continually pummeled by wave action. Yet each of these physically challenging environments can be diverse and fecund ecosystems.
Tropical oceans are relative deserts when compared to the potential productivity of higher latitudes—and it’s all due to spring and fall blooms of phytoplankton. These microscopic photosynthetic organisms form the base of almost all marine food chains, including that of the blue whale, the largest animal known to have ever existed. But far below the penetration of sunlight a very different and only recently discovered food web relies solely on the chemosynthetic ability of bacteria.
When we think of healthy marine ecosystems, we should be thinking about phytoplankton. In many ways, we owe our existence to these diatoms, dinoflagellates, green algae, cyanobacteria, and others. Not only do scientists believe they are the ancestors of terrestrial plants, but phytoplankton continues to produce about half of all the oxygen available in our atmosphere today.
The vast majority of animals on our planet are the gloriously diverse invertebrates. From microscopic organisms to the crab with a three-meter leg span, marine invertebrates exhibit enormous variety in form and function. They include sessile and mobile organisms, free-living and parasitic. They live at the surface and within the ocean floor sediments, protected by hydrostatic endo- and exoskeletons.
Only certain classes of vertebrates have a marine presence, while others are strictly terrestrial. Mammals are certainly represented in ocean life, but which species should be identified as “marine” when considering ocean productivity? The extremely complex marine food webs maintain long-term stability, even as they undergo natural perturbations over time. But when Homo sapiens enters as an apex predator, productivity can deteriorate, and systems can even collapse.
Through 550 million years of evolution, fish have developed a wide variety of adaptations to the unique demands of living in a watery and mostly dark world. Learn how gills, swim bladders, bioluminescence, chemosensory glands, echolocation, and electrolocation have allowed fish to succeed in almost every type of ocean environment. Which fish are our ancestors? You might be surprised.
While humans have been fishing for hundreds of centuries, we have only recently had a significant impact on marine food webs. Industrialization has led to problems with by-catch and overexploitation of resources. Today—since the megavertebrates we love to eat are often the apex predators of their natural food webs—we are creating trophic cascades with long-term impacts we do not yet understand.
Are you afraid of sharks? Fish certainly have good reason to fear these top-of-their-game predators with their multiple rows of teeth, extraordinary sensitivity to smell, taste, and vibration, and ability to detect electrical current better than any other animal. But while four species have been known to assault humans with no provocation, almost 99 percent of the many hundred shark species would rather swim away from us than attack.
While the reptilian evolution of the amniotic egg allowed animals to move completely from the sea onto land, some reptiles retained strong marine ties. These include sea turtles and sea birds whose wide variety of adaptations allow for drinking saltwater, remaining underwater for long periods, and flying great distances using very little energy. But wait . . . did we just classify sea birds as reptiles?
Marine mammals did not evolve from marine species. Rather, they evolved from land mammals who found a plethora of “suddenly” open ecological niches when the dinosaurs became extinct about 65 million years ago. Today’s marine mammals might resemble each other because convergent evolution has led to similar adaptation. But best as scientists can tell, they have five separate lineages and no single common ancestor.
Through tens of millions of years, evolution has resulted in a fascinating array of marine mammal adaptations. With the ability to process thousands of gallons of water each day or dive to a depth of almost three kilometers, and with numerous methods of locomotion or extraordinary social behaviors, these whales, porpoises, phocids, and more can thrive in varied environments around the globe.
If you’ve ever jumped into frigid water, you quickly realize humans are definitely not adapted to life in the sea. What are we missing? In a word, it’s blubber—the thick layer of fat just beneath the skin of almost every marine mammal. In fact, blubber is such a successful insulator that marine mammals have evolved internal and external means for getting rid of all that heat, possibly even including planetary migrations.
For all practical purposes, terrestrial mammals live on a plane. Marine mammals, on the other hand, navigate a more viscous, three-dimensional environment with all its opportunities and challenges. We understand their propulsion mechanisms fairly well. But how do they control their buoyancy to position themselves in the water column? We don't yet have the answers.
Not surprisingly, deep-diving marine mammals have evolved a physiology very different than our own. Adaptations including those related to blood chemistry, the location of stored oxygen, a variable heart rate, and articulated rib cages support the ability to go deep and stay long. But what about rising back up to the surface? How do they avoid getting “the bends”—or do they?
Sound travels much better in water than in air. In fact, low-frequency waves, such as those produced by certain whales, can travel through water uninterrupted for hundreds or even thousands of kilometers, allowing the animals to be “in touch” with their group over vast distances. Other marine mammals produce and hear sounds at high frequencies perfect for echolocation. But what happens when human-generated sound gets in the way?
Trophic patterns are complex cycling webs, often difficult to completely decipher. But two things are clear: Almost all marine food webs are based on microscopic photosynthesizers, and only a small fraction of the energy available at any trophic level becomes available to the next level. Adaptations such as baleen, ventral pleats, and unique tooth morphology allows these large animals to meet their energy needs.
With plastic and nylon lines and nets becoming common in the last century, by-catch became an even greater problem for the marine mammals. When the media picked up the story in the mid-1960s, the public became engaged, and the Marine Mammal Protection Act was passed in 1972. But whale entanglement remains a problem, and some argue that even whaling was far less cruel.
Semi-aquatic marine mammals exhibit behaviors quite different than those who live fully in the water. In the former, an entire female community in one geographic area can come into estrus simultaneously and needs relatively few males—the strongest and “sneakiest”—to reproduce. In the latter, reproduction appears to be one of the driving forces of whale songs that can be heard over thousands of kilometers.
From individual whales that corral their confused prey to highly coordinated bubble-net feeding and aunts who “babysit,” marine mammals have developed an extraordinary variety of social and hunting behaviors—each with its own “cost/benefit analysis” developed over millions of years. If the energy expenditure does not support the goal of passing on genetic material, natural selection will eventually drop the adaptation.
With sixty million years of evolution on their side, marine mammals have adapted to the widest possible variety of marine ecological niches. Some live only in rivers or lakes, others only in waters over the continental shelves, and some in the open ocean. A few—like the Weddell seal with exceptional blubber, diving skills, oxygen capacity, and ice-sawing teeth—are even adapted to live at the poles.
Within their own species, marine mammals have developed sophisticated communication. In captivity, we know they can be trained to learn rules, which indicates higher cognitive function. And even in the wild, we have documented some extraordinary instances of learning and cultural transmission of information. But is their intelligence comparable to our own? Maybe the question itself is meaningless.
Are marine mammals to be exploited as a resource? Or are they intelligent creatures to be revered with an almost religious admiration? Your answer might depend to some extent on your country and culture of origin—and the truth is probably somewhere in between. Our relationship with these impressive animals continues to evolve as we increase our understanding of their biology, cognition, and sociality.
Over and over, humans have behaved as if a given resource were inexhaustible. That was certainly the case with worldwide industrial whaling of the early 20th century when six species of whales were hunted to dangerously low numbers. In the near future, as their populations continue to recover, some countries are expected to promote a resumption of the commercial whale hunt.
Although the irony is unmistakable, our understanding of marine mammals increased tremendously by having access to carcasses during the years of industrial whaling. Today, we focus on species protection while learning as much as we can via SCUBA, SONAR, tagging, biopsy darts, photo-identification, studying animals in captivity, and examining stranded individuals when available.
Most of us seem to have a natural instinct to want to help a stranded marine mammal, but it requires very specific skills to render aid without causing further stress and harm. Even with the best intentions and professional assistance, not all animals can be saved. What can we learn from these strandings—no matter how they end—and where are they most likely to occur?
Our high-tech use of the ocean for food, transportation, and energy has far-reaching effects, particularly on certain species. Focusing on issues from noise pollution to microplastics, we can mitigate our impact to provide better futures for ourselves as well as for marine life. The work begins with understanding the extent of our true impacts.
Although there was a time when we treated the oceans as if they were too vast to feel our impact, we now know the truth: we have contributed to global climate change, ocean acidification, and overfishing. The results are potentially catastrophic—both to marine life and to our own health. But there is a bit of light at the end of this tunnel, and it depends in part on our own daily actions.
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Considering how many hours we spend with computers—phones, laptops, even “smart” screens on our home appliances—it’s easy to feel like they control us. But, in fact, we control them. Or, we do if we know how to use them.That’s what computer programming gets to the heart of: taking command of the most powerful, versatile, and productive machines ever invented. And among the array of programming languages designed to get computers doing exactly what we want, C++ ranks as one of the most efficient, powerful, and popular.
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Uncover the power and appeal of C++ for a wide range of uses. Then learn that by processing only 0’s and 1’s, a computer obeys the varied commands of a complex language such as C++. Write a traditional, “Hello, World!” program and discover the importance of adding comments to your code. Finally, follow the instructions in the Quick Start video at the end of this lecture to get C++ working on your own computer or device—by going to an online programming editor or by downloading a C++ integrated development environment (IDE), tailored to your operating system.
C++ QUICK START: With Browser or Download
Try out a program that calculates calories in different foods, demonstrating the essential elements of a program: input, variables, computations, and output. Learn to specify a variable’s type and value, and get advice on shortcuts for keeping your instructions clean. Also discover the origin of the name C++, which signals that the language is designed to do whatever C can do—and then some.
Probe the power of conditionals, which let you construct programs that can choose between true and false alternatives. Learn to use the keyword bool, which stands for Boolean variable—a value that can be either true (1) or false (0). Study the three basic Boolean operations—and, or, not—and see how they can be combined to make truly complex logical operations.
There’s more to making a program than writing code. Begin by focusing on the importance of the header and special commands. Then consider how to use comments as “pseudocode” to design the structure that a particular program should follow. Finally, explore the crucial strategy of testing as you go, rather than when the program is complete and errors made near the start are harder to track down.
Harness the power of loops, which are sections of code that repeat until a specified computation is complete. Focus on two main types of loops: while loops and for loops, with the latter being a compact way to make the loop occur a set number of times. Learn how to prevent infinite loops, and see how scope allows you to have separate variables inside and outside loops.
The secret for building an enormous program such as Windows, with millions of lines of code, is that it draws on ready-made code libraries. Investigate the options that libraries offer, from choosing random numbers to performing complex mathematical operations. Learn how to access a code library, and get tips for finding additional resources beyond the C++ standard libraries.
In the first of two lectures on storing large amounts of data, learn the utility of arrays. An array is a collection of variables of the same type. Find out how to declare an array of variables and how to provide an index, which permits access to a specific value within the array. Finally, probe the “out-of-bounds” error that can arise with arrays and see how it led to a notorious security breach.
Continue your study of data storage strategies by looking at vectors, which handle variables in much the same way as arrays but with distinct advantages, including the ability to change the size of a data structure dynamically. Learn how and when to use vectors, and discover that vectors offer a convenient fix for the out-of-bounds error introduced in the previous lecture.
Go beyond numbers to see how letters and punctuation are used in data strings, which are ordered sequences of characters. Examine string literals, which are specific fixed sequences of text; and string variables, which are the main way to process and control text data, such as names and addresses. Learn how to search, alphabetize, and concatenate string variables in C++.
Data files are collections of information that are accessed and manipulated through a program. See how data streaming techniques you've already used apply to reading and writing files with the library fstream. Discover that you've already been using an entity that will become increasingly important in the course: objects, which are entities combining variables and functions.
Get to know the vital task of debugging—finding and fixing errors in your code. First, consider the advantages of top-down design, where a complex task is divided into manageable sub-tasks, as opposed to the bottom-up approach that lets complexity emerge more organically, if less predictably. See how incremental development helps in debugging through tools such as the breakpoint and step-over commands.
Functions serve as ready-made, self-contained units of code that perform a particular task, such as solving an equation, enumerating a list, or even something as simple as closing a file. Prepare for the intensive use of functions in the rest of the course by learning the basic commands that allow you to create your own functions. Get your feet wet with several examples.
A parameter is a piece of data used as input into a function. Discover how to create two functions, each with the same name, but with different numbers of parameters—an approach called overloading. Also look at different ways to “pass” parameters to produce an output, either preserving the parameter’s value (pass by value) or changing it (pass by reference).
Dig deeper into debugging, learning to employ a tool called exception handling. An exception is a special note that something has gone wrong in a program. Know how to follow up these crucial clues. Also zero in on the six major steps of debugging: isolate the error, narrow down the failure point, identify the problem, fix the problem, re-test, and look for similar cases.
Revisit top-down versus bottom-up approaches to coding, this time using functions as the building blocks of your program. First, create a game with the top-down strategy, identifying the individual functions that you need in a flowchart. Then design a tool for word processing by using the bottom-up tactic, in which you take available functions and create something completely new.
So far, you’ve focused on procedurally oriented programming, which characterizes the original C computer language that led to C++. Now turn to one of the major strengths and innovations of C++: object-oriented programming. Learn that objects are variables and functions encapsulated within classes. Investigate the great utility of this technique for organizing and manipulating data.
The ability to design appropriate classes may be the single most important skill in object-oriented programming. Survey two key tools for using classes effectively. First, constructors let you create classes that fit the requirements of the objects within them. Second, operator overloading allows you to tailor operators to a specific function, providing a handy shortcut that streamlines coding.
C++ provides different ways to control data storage in memory. Investigate dynamic memory allocation, which allows memory to grow and shrink with the demands of a program as it is running—as opposed to static memory, which is fixed at runtime. Practice managing memory in a 20-questions-type game and compare the advantages of allocating dynamic memory with pointers versus vectors.
Explore the power of inheritance, which is a technique for creating classes that inherit properties from another class, called the base class. Using this tool, you can define a variable or function just once and then use it in multiple classes. Walk through several examples of inheritance, seeing how it greatly reduces complexity by eliminating redundant code.
Study a key object-oriented feature called polymorphism, which means “many shapes” and refers to the ability of a class to be used in multiple ways. Start with a superclass that is specialized into multiple subclasses, each of which has a different implementation. Learn to define virtual functions for the superclass, leading to diverse properties in the subclasses.
Use your knowledge of object-oriented programming to design a “game engine” that can be used for building multiple games. Take a top-down approach, drawing on encapsulation, hierarchical inheritance, and polymorphism to create the two-person game Othello, also known as Reversi. Discover the ease with which you can create other subclasses for additional games, such as checkers and chess.
Whenever you have an idea that’s so general that it’s not tied down by any specific data type, you’ll want to turn to generic programming, which substitutes a template for a data type. The Standard Template Library (STL) is a menu of generic container structures that address these types of problems. Learn the advantages of various containers, including queues, lists, stacks, and vectors.
Probe deeper into generic programming and the STL, focusing on associative containers and algorithms. The former is a set of templates that lets you group different elements into ordered sets, while algorithms are rules that handle data or accomplish some other task, allowing advanced operations to be performed very quickly. Learn that algorithms are a powerful tool in programming.
Finish the course by drawing on all you have learned to design a game-playing algorithm for artificial intelligence—that is, a program that makes “intelligent” game moves as if it were human. Finally, look ahead to your options for continuing study in computer programming. With elementary C++ under your belt, there are many directions you can go in mastering this valuable skill.
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Everyone loves to observe the beauty of the star-studded night sky, to say nothing of the dazzling images from the Hubble Space Telescope. But how many of us truly understand how stars shine, where Saturn’s rings come from, or why galaxies have their distinctive shapes? Observational astronomy excels at imaging and cataloging celestial objects, but it takes a more rigorous discipline to come up with physical explanations for them. That field is astrophysics.
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Why are the rings around Saturn and the much fainter rings around Jupiter, Uranus, and Neptune at roughly the same relative distances from the planet? Why are large moons spherical? And why are large moons only found in wide orbits (i.e., not close to the planets they orbit)? These problems lead to an analysis of tidal forces and the Roche limit. Close by calculating the density of the Sun based on Earth's ocean tides.
Use your analytical skill and knowledge of gravity to probe the strange properties of black holes. Learn to calculate the Schwarzschild radius (also known as the event horizon), which is the boundary beyond which no light can escape. Determine the size of the giant black hole at the center of our galaxy and learn about an effort to image its event horizon with a network of radio telescopes.
Investigate our prime source of information about the universe: electromagnetic waves, which consist of photons from gamma ray to radio wavelengths. Discover that a dense collection of photons is comparable to a gas obeying the ideal gas law. This law, together with the Stefan-Boltzmann law, Wien's law, and Kepler's third law, help you make sense of the cosmos as the course proceeds.
Survey representative planets in our solar system with an astrophysicist's eyes, asking what makes Mercury, Venus, Earth, and Jupiter so different. Why doesn't Mercury have an atmosphere? Why is Venus so much hotter than Earth? Why is Jupiter so huge? Analyze these and other riddles with the help of physical principles such as the Stefan-Boltzmann law.
Consider the problem of gleaning information from the severely limited number of optical photons originating from astronomical sources. Our eyes can only do it so well, and telescopes have several major advantages: increased light-gathering power, greater sensitivity of telescopic cameras and sensors such as charge-coupled devices (CCDs), and enhanced angular and spectral resolution.
Non-visible wavelengths compose by far the largest part of the electromagnetic spectrum. Even so, many astronomers assumed there was nothing to see in these bands. The invention of radio and X-ray telescopes proved them spectacularly wrong. Examine the challenges of detecting and focusing radio and X-ray light, and the dazzling astronomical phenomena that radiate in these wavelengths.
Starting with the spectrum of sunlight, notice that thin dark lines are present at certain wavelengths. These absorption lines reveal the composition and temperature of the Sun's outer atmosphere, and similar lines characterize other stars. More diffuse phenomena such as nebulae produce bright emission lines against a dark spectrum. Probe the quantum and thermodynamic events implied by these clues.
Take stock of the wide range of stellar luminosities, temperatures, masses, and radii using spectra and other data. In the process, construct the celebrated Hertzsprung–Russell diagram, with its main sequence of stars in the prime of life, including the Sun. Note that two out of three stars have companions. Investigate the orbital dynamics of these binary systems.
Embark on Professor Winn's specialty: extrasolar planets, also known as exoplanets. Calculate the extreme difficulty of observing an Earth-like planet orbiting a Sun-like star in our stellar neighborhood. Then look at the clever techniques that can now overcome this obstacle. Review the surprising characteristics of many exoplanets and focus on five that are especially noteworthy.
Get a crash course in nuclear physics as you explore what makes stars shine. Zero in on the Sun, working out the mass it has consumed through nuclear fusion during its 4.5-billion-year history. While it's natural to picture the Sun as a giant furnace of nuclear bombs going off non-stop, calculations show it's more like a collection of toasters; the Sun is luminous simply because it's so big.
Learn how stars work by delving into stellar structure, using the Sun as a model. Relying on several physical principles and sticking to order-of-magnitude calculations, determine the pressure and temperature at the center of the Sun, and the time it takes for energy generated in the interior to reach the surface, which amounts to thousands of years. Apply your conclusions to other stars.
Discover the fate of solar mass stars after they exhaust their nuclear fuel. The galaxies are teeming with these dim “white dwarfs” that pack the mass of the Sun into a sphere roughly the size of Earth. Venture into quantum theory to understand what keeps these exotic stars from collapsing into black holes, and learn about the Chandrasekhar limit, which determines a white dwarf’s maximum mass.
Trace stellar evolution from two points of view. First, dive into a protostar and witness events unfold as the star begins to contract and fuse hydrogen. Exhausting that, it fuses heavier elements and eventually collapses into a white dwarf—or something even denser. Next, view this story from the outside, seeing how stellar evolution looks to observers studying stars with telescopes.
Look inside a star that weighs several solar masses to chart its demise after fusing all possible nuclear fuel. Such stars end in a gigantic explosion called a supernova, blowing off outer material and producing a super-compact neutron star, a billion times denser than a white dwarf. Study the rapid spin of neutron stars and the energy they send beaming across the cosmos.
Investigate the physics of gravitational waves, a phenomenon predicted by Einstein and long thought to be undetectable. It took one of the most violent events in the universe—colliding black holes—to generate gravitational waves that could be picked up by an experiment called LIGO on Earth, a billion light years away. This remarkable achievement won LIGO scientists the 2017 Nobel Prize in Physics.
Take in our entire galaxy, called the Milky Way. Locate Earth’s position; then survey other galaxies, classifying their structure. Use the virial theorem to analyze a typical galaxy, which can be thought of as a “collisionless gas” of stars. Note that galaxies themselves often collide with each other, as the nearby Andromeda Galaxy is destined to do with the Milky Way billions of years from now.
Begin with active galaxies that have supermassive black holes gobbling up nearby stars. Then consider clusters of galaxies and the clues they give for missing mass—dubbed “dark matter.” Chart the distribution of dark matter around galaxies and speculate what it might be. Close with the Big Bang, deduced from evidence that most galaxies are speeding away from us; the farther away, the faster.
The Big Bang theory is one pillar of modern cosmology. Another is the cosmic microwave background radiation, which is the faint “echo” of the Big Bang, permeating all of space and discovered in 1965. The third pillar is the cosmic abundances of the lightest elements, which tell the story of the earliest moment of nucleosynthesis taking place in the first few minutes of the Big Bang.
In this last lecture, follow the trail of the greatest unsolved problem in astrophysics. Along the way, get a grip on the past, present, and future of the universe. Discovered in the 1990s, the problem is “dark energy,” which is causing the expansion of the universe to accelerate. Trace this mysterious force to the lambda term in the celebrated Friedmann equation, proposed in the 1920s.