Video · Light Is Waves: Crash Course Physics #39 TwitterShare on Facebook559 268 775 views Crash Course - January 26, 2017 Science Crash Course More Videos Myths About Diamonds: Crash Course Geology #8 Science · 3 days ago How Do Gems Form?: Crash Course Geology #7 Science · 1 week ago How Do Gems Form?: Crash Course Geology #7 Science · 1 week ago A Message From Hank Green Science · 2 weeks ago Where do rocks come from?: Crash Course Geology #6 Science · 3 weeks ago How Do Minerals Form?: Crash Course Geology #5 Science · May 14, 2026 How Do Minerals Form?: Crash Course Geology #5 Science · May 14, 2026 What’s at the center of the earth?: Crash Course Geology #4 Science · May 7, 2026