Air is an invisible gas as are hydrogen and helium. How can you tell if a balloon contains hydrogen? Hydrogen has particular physical and chemical properties that can be tested. Dr. Cech enlists student volunteers to show how a chemical reaction can be used to identify a substance.
The floor of a rift valley is prone to periodic floods that carry in fine silt--the sedimentary matter responsible for fossil formation.
Fossils are extremely fragile. Scientists remove them in a protective layer of plaster and clean sand away one grain at a time.
Due to the delicate nature of fossils, a hardening chemical is dripped onto every fossil before it is removed from the soil.
Dr. John Shea demonstrates the two main principles in the study of rock layers: superposition and association.
What do humans, flies, and worms have in common? More than you might think. See how transgenic organisms are engineered, and how they enable researchers to study genetic diseases.
A new technique for making the brain transparent provides extremely detailed views of groups of neurons.
Dr. Charles Sawyers discusses how the identification of most cancer genes could transform cancer into a chronic disease.