Why do bubbles pop, and why do bubbles have shadows? We’re in double bubble trouble with two listener questions. Luckily, Dr. Bubbles is here to save the day! We’ll find out how a normal, everyman physicist named Justin Burton became a superhero bubble scientist, on a quest to make a scientifically proven recipe for giant bubbles. Along the way, we’ll discover the answers to our listeners’ bubbling curiosity. Hear from the inventor of edible bubbles, Li Wei Tan, in a bonus interview episode available on our ad-free Patreon feed! It’s available for just $1/month when you pledge to support Tumble at patreon.com/tumblepodcast. We’ll have free resources about bubbles on the blog on our website, sciencepodcastforkids.com. This episode is sponsored by MEL Science. Check out their awesome science boxes at https://melscience.com/sBHH/ Make sure to use the offer code "TUMBLE" at checkout for 60% off your order.  Here is Dr. Bubble’s Giant Bubble Recipe, courtesy of Emory University: Ingredients 1 liter of water (about 2 pints) 50 milliliters of Dawn Professional Detergent, which is available online (a little over 3 tablespoons) 2-3 grams of guar powder (or guar gum), a food thickener sold in some grocery stores or available online (about 1/2 heaping teaspoon) 50 milliliters of rubbing alcohol (a little more than 3 tablespoons) 2 grams of baking powder (about 1/2 teaspoon) Directions Mix the guar powder with the alcohol and stir until there are no clumps. Combine the alcohol/guar slurry with the water and mix gently for 10 minutes. Let it sit for a bit so the guar hydrates. Then mix again. The water should thicken slightly, like thin soup or unset gelatin. Add the baking powder and stir. Add the Dawn Professional Detergent and stir gently, to avoid causing the mixture to foam. Dip a giant bubble wand with a fibrous string into the mixture until it is fully immersed and slowly pull the string out. Wave the wand slowly or blow on it and enjoy the physics of giant soap bubbles! Results may vary based on humidity.