A Field Guide to Great Structures

Throughout the ages, many of the world’s greatest works of architecture and civil infrastructure have been profoundly influenced by the principles of engineering mechanics that underlie their design. If we understand these principles, then we can appreciate our built environment in a deeper and more satisfying way. This lecture will provide you with the tools you’ll need to see, analyze, and understand the many fascinating structures we will encounter during our cruise. We’ll begin with some basic questions: what is an engineered structure, and what does it mean for a structure to carry load? Then we will examine five fundamental types of structural elements — beam, column, truss, arch, and cable — and learn how each functions within an engineered structural system. Finally, we will see how these elements are incorporated into the wide variety of structures we’re likely to encounter during our cruise — from the Progreso Bridge near Puerto Vallarta to the great León Cathedral in Nicaragua — a UNESCO World Heritage Site — to the Centennial Bridge spanning the Panama Canal.

Here are the slides (90mb file).

Thin-Shell Structures: Strength through Curvature

In this lecture, we will explore the exciting world of the thin-shell structure — a distinctly modern architectural form in which an improbably thin continuum of concrete, tile, or masonry attains its strength and stiffness primarily through curvature. By virtue of this defining characteristic, the thin-shell structure represents a perfect marriage of architectural beauty and structural efficiency. The quintessential example — Felix Candela’s Chapel Lomas de Cuernavaca in Mexico — is enclosed by a hyperbolic paraboloid roof that spans over 100 feet and is nearly 70 feet tall; yet the concrete shell itself is less than two inches thick. Our exploration will begin with an overview of the structural mechanics of thin shells, with emphasis on the geometric concept of curvature and its implications for structural load-carrying. We will examine the historical development of thin-shell structures through the late 19th and 20th centuries — with emphasis on the extraordinary work of Rafael Guastavino, Felix Candela, and Pier Luigi Nervi. We’ll conclude with a discussion of the economics of thin shells, as an explanation for why the most spectacular examples of these structures can be found in underdeveloped parts of the world.

Here are the slides (142mb file).

The Canal as an Engineered System

In this lecture, we will prepare for our trip through the Panama Canal by examining the canal generically, as an engineered system. We will consider the various types and purposes of canals and briefly review the long history of their development as technological systems. We will review the science of hydrostatics, as a means of explaining — at least in part — why canals have played such a vital role in the development of industrialized societies. From an engineering perspective, we will review the principal factors governing the design of canals, to include the all-important challenge of water supply and the vital functions performed by engineered structures — locks, dams, and bridges.

Here are the slides (56mb file).

Construction of the Panama Canal

In this lecture, we will examine the engineering and construction of the Panama Canal from 1881 to the present day. This endeavor has been characterized by:

• The initial French effort — an engineering failure that ended with bankruptcy and the loss of 22,000 lives by 1894
• U.S. military intervention in a revolution that fostered Panama’s independence from Columbia and the subsequent Hay-Bunau-Varilla Treaty, which established the Panama Canal Zone and granted the United States authorization to build the canal
• The U.S. construction effort from 1904 to 1914, conducted in three distinctly different phases under the leadership of chief engineers John Wallace, John Stevens, and George Goethals
• Continued technological improvements from 1914 to the present day

This story is both a fascinating human drama and an important chapter in the history of technology. In reviewing it, we will focus on the key engineering and construction issues, including:

• The fatally flawed French concept of building a sea-level canal
• The alternative U.S. design, involving the damming of the Chagres River, the creation of Gatun Lake, and the construction of three monumental flights of locks
• John Stevens’ recognition that the excavation challenge could be most effectively addressed as a problem in railroad design and management
• William Gorgas’ extraordinary efforts to preserve a viable workforce by eliminating the threats of malaria and yellow fever
• George Goethals’ genius in construction management and organizational leadership

We will conclude with an overview of the recently completed Panama Canal Expansion Project — its many technological innovations and its contributions to the capacity and long-term viability of the canal.

Here are the slides (195mb file).
 

Planets Everywhere

We now know that planets are common: Most stars have them and even the star closest to us (Proxima Centauri) has at least one. This is one of the most remarkable scientific developments of the past twenty years and it continues to astonish, with new planets being discovered every month. They come in many different masses and at many different orbital distances from their parent star. I will talk about their different natures and environments and explain why it is not contradictory to say that planets are common but planets that are very similar to Earth may be uncommon. I will argue that we should not obsess about planets that are Earthlike, just as we should not seek out McDonalds when visiting a foreign city. I will also talk about unbound planets (wandering the immense space between stars) and Planet Nine in our solar system.

Here are the slides (3mb file).

Albatrosses, Beetles, and Cetaceans

It is fun to apply physics to living organisms. I will mainly talk about three examples. The first is the physics of flight and why it is so energetically efficient. It makes sense for an arctic tern to fly between the Northern and Southern hemispheres of Earth twice a year. And an albatross can fly “forever” just feeding off the energy stored in the wind shear of the atmosphere. The second example is the physics of living small: the world of insects and the consequences of surface tension. I will explain how and why beetles are iridescent. My third example is how whales communicate over immense distances using the natural sound channel in Earth’s oceans. The common theme here is how biological evolution has “discovered” many physical principles that we have only been able to figure out in the past century and are in some cases still mysterious.

Here are the slides (2mb file).

Jupiter and Saturn Revisited

On July 4, 2016, the Juno spacecraft entered orbit around Jupiter. Data collection continues for over a year. And around April 2017 the Cassini spacecraft will change its orbit around Saturn to plunge inside the rings and get up close and personal with the planet for several months (before crashing into the planet). Although we have been to these planets before, these missions provide the first opportunity to get a deep understanding: What is at their centers? Why do they have magnetic fields? What powers their strong winds? My role in these missions is to interpret the gravity and magnetic fields and I will give a hot-off-the-press story that includes our current best understanding of how these planets formed, how this fits with our understanding of the solar system and how they affect us.

Here are the slides (6mb file).

In Defense of Crazy Ideas

After a lecture by the great physicist Wolfgang Pauli, Niels Bohr said: “We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct.” I will discuss the essential role of crazy ideas in science (not just physics) and what distinguishes bad crazy from good crazy. What does it mean to be “crazy enough”? Most published science is mundane and most funding mechanisms favor conventional directions and no consideration of others (cf. Robert Frost’s The Road not Taken). Even the best science can have a large amount of conventional scientific justification (LHC finding the Higgs boson, LIGO finding gravitational waves). Good speculation is hard. The proof of this claim lies in the evident rarity of examples. A well-formulated portfolio of science should include the good crazy. The trick lies in identifying it (even when it is wrong, as is often the case).

Here are the slides (4mb file).
 

Human Evolution: the Big Picture

An introduction to 7 million years of human evolution, from the time of our divergence from the African apes to the emergence of humans. In 1871, before there was any significant fossil evidence, Charles Darwin suggested that our evolution had begun in Africa. But it took another 50 years before that evidence started to emerge. The fact that we habitually walk bipedally — on two legs — distinguishes us from all our primate relatives, and Darwin attempted to explain this in evolutionary terms. Together we will look at how Darwin’s ideas have fared in the face of the latest discoveries, putting Darwin in context and perspective.

The First Humans

About 2 million years ago the first humans appeared in Africa. Through their larger brains, human body shape, tool-making and meat-eating, they were different from their more ancient African ancestors. Discover what drove their evolution and led to a spread from their evolutionary homeland to Asia and Europe. Could controversial finds from deep in a cave near Johannesburg and on the far-away island of Flores, in Indonesia, be a relic of these early stages of human evolution? Find out with Dr Stringer.

The Neanderthals: Another Kind of Human

Our close relatives, the Neanderthals, evolved in parallel with our own species. They are often depicted as bestial ape-men, but in reality they walked upright as well as we do, and their brains were as large as ours. So how much like us were they, and what was their fate? Track the evolution of the Neanderthals in the light of the latest discoveries, including reconstructions of the Neanderthal genome, learn about newly-discovered relatives of the Neanderthals — called Denisovans — and be open to surprise.

The Rise of Homo sapiens

Modern humans are characterized by large brains and creativity. How did our species arise and spread across the world, how did regional (“racial”) traits arise, and how did we interact with other human species? We will examine the different theories about modern human origins, including Recent African Origin (“Out of Africa”), Assimilation, and Multiregional Evolution. Delve into the origins of human behavioral traits such as complex technology, symbolism, art and burial of the dead for insights into essential humanness.
 

The Origin of Our Universe

With a cosmic flight simulator, we take a scenic journey through space and time. After exploring our local Galactic neighborhood, we travel back 13.8 billion years to explore our Big Bang and how state-of-the-art measurements are transforming our understanding of our cosmic origin and ultimate fate. Did cosmic inflation rapidly double the size of our baby Universe? How did galaxies form and usher in our cosmic dawn? We examine how cosmic microwave background measurements, radio telescope images of distant hydrogen, and gravitational waves from colliding monster black holes can give us crucial clues.

A Brief History of Biological and Artificial Intelligence

Our cosmic journey has now reached a point where Intelligence may go from minor perturbation to dominant force. How did our dead and boring early universe come alive, hosting intelligent and conscious beings able to marvel at its grandeur? What is intelligence? How does biological intelligence work? How does artificial intelligence work and how soon should be expect it to outsmart us at various tasks? How will ever-smarter AI impact society? What career advice should we give to kids to minimize the risk that their jobs will get automated away? What near-term impact will AI have on law, crime, and weapons? (For further reading: Life 3.0: Being Human in the Age of Artificial Intelligence

Mysteries of Our Universe

The last two lectures focused on what we’ve come to scientifically understand about out life and our universe. This lecture focuses on what we still don’t understand, and how experimental and theoretical progress is expanding the boundaries of science. We tackle the mysteries of both our external universe (dark matter, dark energy, our cosmic, the mathematical nature of nature) and our internal universe (intelligence and consciousness).

The Future of Life, the Universe, and Everything

In this lecture, we explore what will happen in the future. We discuss how Earth can be saved from asteroid collisions and solar scorching before facing potential “cosmochalypse” scenarios many billions of years from now. We also explore more urgent human-created threats, ranging from global warming to nuclear winter and problems with super-intelligent AI. On a more optimistic note, we explore ways in which advanced AI-powered technology may enable future life to flourish, and tackle the a remarkably challenging question: which future do you want us to steer toward?