In spite of the risks, people are lining up to solve their weight problems in the operating room. And if the latest device -- an implantable stomach "pacer" -- works out, millions more will be taking the surgical way out. We follow two patients as they go through the life-transforming experience of gastric bypass surgery, causing dramatic weight loss. Both patients achieve major life goals, from the simple act of shopping in a regular - not plus-size - clothing store, to the substantial reduction of health risks like heart attack and diabetes. Alan Alda observes Amy's surgery at a Boston hospital, and visits Rodney as he recovers the day after his operation. Gastric bypass, in which a small, one-ounce, stomach "pouch" is created to replace the natural stomach, is the most common stomach surgery in the US, with 100,000 procedures performed a year - ten times the rate ten years ago. Nationally, 75% of those patients will achieve substantial permanent weight loss, although some will be able to "behaviorally" reverse their surgery. The "lap-band" procedure is an alternative weight-loss procedure to gastric bypass, involving the surgical placement of a restrictive plastic collar around the top of the stomach. "The bottom line is none of these surgeries are a cure for obesity in a vacuum. They all have to be part of a program that provides the behavior and the counseling." says Shikora. The obesity surgical group at the Tufts-New England Medical Center in Boston is now beginning large scale clinical trials of the latest surgical approach to weight loss. A "pacer" - similar to a heart pacemaker - is implanted just under the skin of the abdomen and connected to electrodes attached to the stomach. Regular, imperceptible electric pulses create a feeling of fullness. With the pacer in place, patients are able to control their constant "grazing" eating behavior.

The fully automatic car may be down the road a ways, but cars that do your thinking for you are just around the corner -- they watch out for hazards, they listen to you, they read your lips, they even know when you're distracted. Alan travels to Germany to find out what happened to the research program originally intended to develop cars that would drive themselves. He finds the goal changed; DaimlerChrysler engineers now working on technology that will help the human driver by alerting him or her to potentially dangerous situations. Equipped with stereo cameras, the research cars are now able to recognize hazards that the driver may have overlooked - like bouncing balls or wayward pedestrians. In a strikingly realistic driving simulator called VIRTTEX at Ford in Dearborn, Michigan, Alan finds out for himself the distraction caused by using a cell phone in a car traveling at high speed on a highway. The VIRTTEX simulator is also being used to study how tiredness affects a driver, and is helping to develop ways to alert the driver to his or her potentially deadly inattention. At IBM's Industry Solutions Lab in Hawthorne, New York, Alan goes for a drive with a virtual smart passenger named Sally. Sally listens in to the driver all the time, picks up on what he or she is saying, and responds appropriately. Sally also knows the driver's likes and dislikes, so if Alan says he's hungry she directs him to the nearest Italian restaurant, not a German one! Sally also checks to see if the driver is showing signs of sleepiness, and offers to play a game - such as "Name the Tune" - to keep him entertained and alert.

A look back at the decades of effort that culminated in the deep sub Alvin reaching the ocean floor, and a look forward to what's next now that Alvin's retiring. In the summer of 1964, the first tentative dives into the shallow waters of Cape Cod, Massachusetts, were made by the new deep diving submarine, Alvin. The sub, built for the US Navy and operated by the Woods Hole Oceanographic Institution (WHOI), was to become arguably the most successful research submarine ever. We go on a typical Alvin science dive, accompanying a biologist as the WHOI pilot takes the sub down 8,000 feet into the pitch darkness of the Galapagos Rift, to collect samples. It was here in 1977 that people first saw, from the Alvin, a kind of life that we had never known existed on the planet - colonies of giant clams, tube worms, fish and crabs living not on sunlight but on bacteria that consume the gases dissolved in water gushing from warm, undersea volcanic water vents. Back at WHOI on Cape Cod, Alvin's successor is now taking shape - in computer models, and wood and fiberglass mockups. The new sub will retain the same time-tested basic components as Alvin - the massive spherical forged titanium pressure hull, the tough, pressure-resistant glass foam flotation material. But working conditions for scientists will be greatly improved - more room, faster dive and ascent speeds, access to almost the entire global ocean floor, and the ability to actually see the same outside view as the pilot.

A visit with an engaging if unruly bunch of cousins that we formally broke up with about 6 or 7 million years ago - with whom we share almost all of our genes but not a lot of our lifestyle. Why the difference? Maybe it's in how we learn. Alan visits a troupe of seven chimpanzees at the Lincoln Park Zoo in Chicago and learns from them how to go fishing in an artificial termite mound - not for termites, but for ketchup. Just how the chimps themselves learn to deftly insert sticks into the mound is what fascinates primatologist Elizabeth Lonsdorf, who first watched chimps termite fishing in Africa. Alan sees for himself what Elizabeth discovered in her studies of wild chimps: that there are big differences between how boy and girl chimps learn. The young females in the Lincoln Park Zoo quickly picked up the skills of fashioning appropriate tools and fishing out the ketchup from holes in the mound. One young female, Chuckie, is so good at making fishing sticks that they are regularly stolen from her by the other chimps. By contrast, the troupe's alpha male appears bored by the whole idea, while the youngest male, Kipper, prefers to swipe his mother's ketchup off her stick with his hand. The chimps' ketchup fishing is a big hit with the public at the zoo, and Elizabeth hopes that the intriguing parallels and differences between how humans and chimps learn will motivate zoo visitors to support one of her main goals: furthering the conservation of endangered chimpanzee populations in the wild. How chimps learn about the world around them is also the subject of research with chimps raised in a sanctuary in Florida. These chimpanzees, by contrast with those at the Lincoln Park Zoo, were raised in close contact with humans. We see a nine-year-old male, Grub, very quickly learn from a human demonstrator that he can make a lot of noise with washboards and trowels. And Grub also shines in an experiment to see if he can tell when something very odd is going on - like a blackbird being used as a screwdriver, or a rock treated like a pet.

So you think global warming won't affect you? Wait until the great Atlantic Conveyor shuts down. And find out what's already happening in Alaska. In the last couple of decades, oceanographers have come to understand the central role the Gulf Stream plays in the enormous ocean currents that circle the globe. It brings a third of all the sun's heat that falls on the North Atlantic up to northern latitudes and, in the process, warms the northeast U.S., Europe and Scandinavia. Researchers at the Woods Hole Oceanographic Institution have found that in recent decades significant amounts of freshwater have been flowing into the Nordic Seas from the Arctic Ocean to the north that could potentially disrupt the operation of the Ocean Conveyor's recirculation pump, in turn reducing or even shutting down the flow of the Gulf Stream. Another group of researchers have found that the Russian Arctic rivers, which contribute two-thirds of all the freshwater that flows into the Ocean, have significantly increased their flow rates in recent decades -- the result of the higher precipitation that goes along with global warming. In Fairbanks, Alaska, the large glaciers in the mountain region that runs between southern Alaska and Canada have been melting and receding at an increasing pace, also in recent decades. Scientists have discovered several abrupt cooling events in the 12,000 years since the last Ice Age. One such event happened 8,200 years ago and may have been triggered when a huge lake of fresh water burst through the remains of ice sheets bordering Hudson Bay. The surge flooded down Hudson Strait and out into the path of the Gulf Stream. Ocean sediments show a cooling at the same time, all around the north Atlantic.

We've all heard of hydrogen as the fuel of the future, but what will it take to get there from here? How can we create hydrogen from renewable sources like the sun - and how do we store it safely once we've got it? Alan visits a multi-million dollar company, based on the wizardry with exotic metal alloys that soak up hydrogen like a sponge. The best-known of these metal hydrides is the nickel metal hydride rechargeable battery invented by Stan Ovshinsky and now used in millions of electronic devices - as well as the new generation of hybrid cars. Their company now produces flexible, durable solar panels literally by the mile, using a unique technology very different from that used to produce conventional silicon solar cells. Alan sees for himself how the Ovshinskys hope to use these solar panels to make hydrogen in unlimited quantities and without burning fossil fuels. Alan also visits Iceland, where he sees (and hears) for himself the astonishing power of Iceland's geothermal wells, which produce cheap and abundant electricity that can be converted to hydrogen. He visits the nation's first hydrogen fueling station, where electricity is turned into hydrogen. Then, he also visits the roof of MIT in Cambridge, Mass, where an extraordinary device made of large triangular glass tubes soaks up sunlight and uses it to grow algae - algae that can later be turned into hydrogen. But Isaac Berzin's invention not only converts sunshine (indirectly) to hydrogen; it also cleans up the smokestack gases from power plants.