It's not every day that scientific researchers need to defend themselves against charges of destroying humanity. And yet a group of several dozen physicists associated with the Large Hadron Collider may be getting pretty good at it--and, at the same time, actively engaging in public education and debate in ways that university scientists have traditionally shunned. Just eight months after fighting off accusations that their $10-billion particle-smashing project in Switzerland might create microscopic black holes that would devour the Earth, the scientists are now explaining why the world's largest Christian church can not easily be annihilated with antimatter. The occasion is the opening in mid-May of the new Tom Hanks movie "Angels & Demons," in which a secret society opposed to the Roman Catholic Church tries to destroy the Vatican. The attackers use a small amount of antimatter made at the hadron collider and stolen from its host institution, CERN, the European particle-physics laboratory where some of the film was shot. The movie might have meant more bad news for the Large Hadron Collider. But many of the scientists associated with the collider are seizing the opportunity "Angels & Demons" presents. The film is "a chance to tell their story." That story includes the numerous benefits already realized by humankind from quantum mechanics in general and particle-smashing colliders in particular. Devices such as the hadron collider are designed to help scientists discover the fundamental elements that form the universe. Practical applications have included critical technologies underlying medical-scanning equipment, more-durable automobile tires, food preservation, and the Internet. Antimatter is another of the accelerator's products. Most kinds of particles found in the matter of the universe have associated antiparticles that are equal in mass and in other properties like average lifetime and magnetic strength, but carry the opposite electrical charge and magnetic direction. And particles and antiparticles do give off energy when combined. But antimatter is not as easy to make and transport as "Angels & Demons" suggests, and can only be produced in extremely minute quantities by advanced particle accelerators like those at CERN. While scientists find themselves disagreeing on how much detail to provide, what risks and uncertainties to discuss, and how much potential danger is really present, they also need to do a better job of helping taxpayers understand what research they are financing and why, according to Karen Gibson, a postdoctoral researcher at the University of Pittsburgh now involved in experiments at Fermilab, the government-owned laboratory near Chicago. who is credited with conceiving the "Angels & Demons" lecture series.