Slime time: Goo draws crowds in Anaheim

For the second year, Squishy Science Sunday was buzzing with energy. Amidst thrums of sound from dozens of interactive science experiments, demonstrations, and conversations, one would occasionally hear a loud pop. No big deal — just the electromagnetic can crusher, a crowd favorite.

Held on the first day of the APS Global Physics Summit in Anaheim, California, Squishy Science Sunday attracted hundreds of visitors, including children of all ages, who came out to play with fog, bubbles, and sand; make slime and oobleck; talk to scientists; and, yes, eat freshly spun cotton candy.

“The kids loved the cotton candy, but they also really loved the Weissenberg effect thing,” said Hannah, an attendee, recalling a demonstration of a gooey, elastic liquid spinning up a rod like spaghetti twirling on a fork. “My daughter just loves slime, so I knew this would be right up her alley.”

A year after its inaugural event at the APS March Meeting in 2024, Squishy Science has returned to the largest physics conference in the world to show kids and adults alike why soft materials like sands, fogs, foams, biological matter, and polymers (including slime) behave the way that they do. With more than 15,000 scientists convening in the area to present the latest physics research — much of it about everyday materials like these — why not invite local communities to join the fun?

“The intent of something like this is to spark questions. ‘That’s really odd — why does it behave that way?’” said Shubha Tewari, a faculty member at the University of Massachusetts Amherst who helped plan the event. “It's about getting your hands dirty and asking those questions, trying to get to the bottom of things and not being satisfied with facile explanations.”

Organized by six APS units and staffed by nearly 150 volunteers, mostly APS members, the event drew more than 600 people — local families, teachers, APS members with and without their families, and other visitors. Young onlookers from a nearby dance competition, decked out in satin bomber jackets and sparkly headbands, crowded around Yale graduate student Zachary Sun as he taught them how to make slime with common household ingredients.

At another station, University of Michigan postdoc Philipp Schönhöfer showed a four-year-old how to operate a particle jamming gripper: a balloon full of tiny particles that “jam” when air is pumped out, making it a deformable, water-balloon-like ball. The gripper could grasp small objects — in this case, a chain of plastic seashells.

The child’s grandfather, Joseph Benko, a physics and chemistry teacher at Servite High School in Anaheim, watched his granddaughter pedal the vacuum pump on and use the gripper to pick up the chain and toss it from the sand pit. “She has such an inquisitive mind,” he said. He held up a cup of pink goo. “She made her own slime right here.”

The slime was fun for kids, but Tewari says the activities also gave people a glimpse into the kinds of questions researchers ask — no science jargon allowed. “You have to meet the person where they are and try to explain it to them,” she said.

And that’s what the volunteers did. Activities like “Ask a Physicist” and lightning talks — including one about the mathematics of knotting worms that tangle together by the hundreds, drifting around in a “nightmarish blob fashion” — ran throughout the event. Scientists at all career levels staffed more than 50 tables at the event, ready to explain their research down to the most basic concepts.

At the plasma physics booth, a new addition this year, Shannon Greco, a science educator at the Princeton Plasma Physics Laboratory, put a marshmallow in a pressure chamber and asked two children what they thought would happen when the air pressure changed. A rollercoaster of squeals and gasps followed as the marshmallow expanded and then crumpled. At a nearby table, Zachary Howe, a doctoral candidate at Auburn University, enticed spectators by levitating a ping pong ball in the air with a hair dryer — set to “cool,” of course — to demonstrate air pressure differences. Then, to introduce plasmas, he asked them to guess what’s hotter: lightning or the surface of the sun? What about its corona? (Answer: Lightning is hotter than the sun’s surface, but not its corona.)

It's great to get kids excited, Tewari says, but she also loves seeing volunteers find joy in sharing their work. “When I look at the feedback from the volunteers and how much excitement they felt, that makes me very happy,” she said. With plans to continue Squishy Science year after year, she hopes to get local universities and companies involved so they can bring their own flavor to the next event. “They keep it fresh,” she added — while keeping the slime and sweets, of course.