The stars of The Big Bang Theory are two fictional Caltech physicists, but the physics problems they study are real. Bill Prady, the program's co-creator and executive producer, talks about including real-world science in the script, from dark matter to magnetic monopoles.

In Smallpox: The Death of a Disease, Dr. D.A. Henderson recounts the history of the deadly virus, from the development of the first vaccine in the late 18th century to his involvement in the successful global eradication campaign in the 1960s and 70s.

New guidelines from the U.S. Preventive Services Task Force recommend women start getting routine mammograms at age 50, not 40. Ira Flatow and guests take a closer look at the guidelines and what they mean for women's health.

The holiday season is here and for many that can mean a surge in stress. But what is stress exactly? Science Friday hit the streets of New York City to gauge stress levels and consulted with experts on the effects of stress and strategies for how to cope.

Researchers are hoping to improve solar energy installations by coupling a solar panel to an efficient hydrolysis unit that splits water into oxygen and hydrogen. Daniel Nocera of MIT says the approach could lead to personal solar power units that could get many houses off the grid.

With NASA reporting a "significant amount" of water on the lunar surface, is it time to re-examine our priorities regarding living and working in space? Mark Sykes, director of the Planetary Science Institute, talks about why and how people should venture beyond Earth.

Dengue fever, malaria and other tropical diseases took center stage at the American Society of Tropical Medicine and Hygiene conference. Nathan Seppa of Science News offers details, including a strange story of palm trees, fruit bats and human infection.

Actress Anna Deavere Smith traveled across the country interviewing people about their thoughts on health care. From an injured bull rider to a medical school dean, she recounts what she heard through monologues in her latest documentary-style theater production, Let Me Down Easy.

Moving beyond traditional superheroes, two new graphic novels recount the epic tales of scientists and the research that made them famous. Ira Flatow talks with authors Michael Keller and Apostolos Doxiadis about their graphic novels on natural selection and logic.

Researchers have figured out how to track the facial expressions of one person and map those movements onto a digital image of another person's face in real time. The result is something like a digital video puppet, which psychologists say may reveal something about human nature.

Can people develop different personalities in response to abuse? Some therapists say up to one percent of the population suffer from dissociative identity disorder. Others say the disease doesn't exist, or is very rare. Two therapists discuss the controversial diagnosis.

In the vacuum of space, photons — not wind — may someday fill the sails of lightweight spacecraft, propelling them without need for engines or fuel. Louis Friedman, executive director of The Planetary Society, discusses the society's plans for a sailing spaceship prototype.

A NASA rocket slammed into a lunar crater in October. A second spacecraft followed minutes later, taking inventory of kicked-up debris and sending data to Earth. Scientists have now analyzed those data, which may reveal whether the moon harbors significant quantities of water ice.

As health care legislation moves through Congress, bioethicist Thomas H. Murray asks if enough attention is being paid to concepts such as justice, fairness and liberty. Murray and health care economist Len Nichols discuss the role of values in the health care debate.

Football players take a lot of hits, but when does hard-headed play go too far? New research suggests that head trauma can do lasting damage. Two brain researchers talk about what happens in the brain when a player gets hit, and how athletes can better protect themselves.

At the 2009 International Genetically Engineered Machine competition, undergraduates from all over the world unveiled the living machines they'd created with snippets of DNA, from bacteria that change color when they detect pollutants to ones that secrete non-toxic superglue.

Faced with declining fish stocks, many nations are looking for sustainable ways to have their fish — and eat it too. But how much fishing is too much? Oceanographer Sylvia Earle discusses this and other topics in her book The World is Blue: How Our Fate and the Ocean's Are One.

The U.S. Department of Energy is offering $10 million to the first individual or company to develop an energy-efficient LED replacement for the standard 60-watt incandescent bulb. DOE lighting program manager James Brodrick discusses the L Prize, and what makes a better bulb.

Psychiatrist Steven Schlozman recently expanded his practice from humans to the inhuman. Poring over his library of classic zombie films, he came up with neurobiological explanations for the behavior of the undead, such as lack of a frontal lobe and an overactive amygdala.

For gadget lovers, Halloween is more geeky than spooky. Mark Frauenfelder, editor-in-chief of Make Magazine, talks about the geekiest do-it-yourself Halloween costumes and decorations, from spray foam guts and singing pumpkins to a fortune-teller costume built on a Segway.