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Science Journey: Defects in Crystals: The Tiniest Engineering Tool

Why can you bend a metal without breaking it, but not a ceramic plate? Why are rubies red and sapphires blue? What enables LEDs to work? The answer is defects! Usually we think about defects as undesirable flaws and things we need to engineer our way around, but this is not always the case. At the nano-scale, defects become one of the most powerful tools for engineering material behavior. Rebecca Gallivan will explore how these atomic-level defects give rise to macroscopic properties and why they are critical for pushing the boundaries of science and technology.

Some activities and questions to ponder before watching:

  1. Find 5+ different materials around you. Sort them into groups based on their properties. Think about why you categorized the materials in the way you did and why it would be helpful to group materials by their properties?
  2. How small can a defect be in a crystal?
  3. When something breaks in your house, what steps and tools you can take to investigate how it broke?
  4. What is one difference between science and engineering? What are some tools or knowledge that both scientists and engineers use?
  5. What is the smallest thing you have ever seen? What are some tools you can use to see really small materials? What are the smallest features in materials that scientists can look at (or take pictures of)?

About the Speaker

Rebecca Gallivan is a PhD student in material science at Caltech studying 3D printed nanomaterials and how processing affects their mechanical properties. Always incredibly inquisitive, Gallivan started her path to research with many "why" questions and fell in love with material science after hearing several talks by professors at MIT. A strong science advocate, Gallivan shares her love for materials and research through the Caltech Science Night program and mentorship of undergraduates and local high school students. She is involved as a peer leader in both the graduate living community and the applied physics and material science department, and an active member of the Society of Women Engineers.

Gallivan grew up on Bainbridge Island, Washington, with her two pet tortoises. She spent much of her childhood outdoor, reading books, and playing piano. In high school, Gallivan attended Holy Names Academy, an all-girl's school, and worked to promote science at the Seattle Aquarium. She went on to study material science and engineering at MIT and found a personal passion for archeological materials and heritage-inspired sustainable materials engineering.

Gallivan continues to enjoy the outdoors, reading, and playing piano while expanding her adventures to include scuba diving and exploring different and ancient cultures around the world!

About the Series

Science Journeys online programs are recommended for grades 8 and up, but everyone is welcome to attend.

These programs are made possible through the generosity of the Friends of Beckman Auditorium.

If you have questions, please email Mary Herrera at

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