In the garden behind the house, where fragrant roses bloomed and busy bees buzzed, little Eliza sat on the grass. In her hand, she held a small ring with a handle, which she dipped into a bowl of soapy water. She took a deep breath and blew gently.
Whoooosh!
A transparent sphere broke free from the ring, shimmered in the sun, and began to float towards the sky. This was Bubble, a brand-new soap bubble. As soon as she was born, she felt how light she was and how the breeze gently rocked her. But then she noticed something strange. When she turned, her entire surface lit up with colors. For a moment, she was greenish like young leaves, then purple and blue swirls appeared, intertwining with yellow and pink stripes.
“Wow!” she breathed quietly. “I’m colorful! But… why?”
She floated slowly higher, over the red geraniums in a flowerpot. She looked at them. They were all red. She looked at the grass. It was all green. Only she was like a constantly changing rainbow.
“Maybe I’m sick,” she thought and grew a little sad. “Maybe I should just be transparent, like the glass in the window.”
As she was pondering, she suddenly felt a pleasant warmth on her thin wall. It was a sunbeam, bending down to her from the sky. It was bright, golden, and looked very wise.
“Good day, little Bubble,” it greeted her in a warm voice. “Why are you so thoughtful? You are beautiful.”
“Beautiful?” Bubble wondered. “I feel strange. Everything around me has one color, but I have all of them. Look, now I’m blue, and now purple! Why do I keep changing?”
The Sunbeam smiled. “It’s not a sickness, nor a spell. It’s one of the most beautiful secrets of light. And I am light.”
“You’re light?” asked Bubble, gazing at it curiously. “But you just look sort of yellow-white.”
“It only seems that way,” the Sunbeam explained patiently. “In truth, I am made of all the colors of the rainbow. They are all together inside me, which is why I look white. It’s like when you mix all the watercolor paints together, you also get something dark and indistinct. It’s similar with light, only the result is bright and white.”
Bubble listened intently. This was more interesting than she had thought.
“And what does that have to do with me?” she asked.
“A great deal,” the Sunbeam continued. “Your coat, that soapy wall, is very, very thin. So thin we can’t even imagine it. When I, the sunbeam, travel to you, part of my light reflects right off your outer surface, like a ball bouncing off a wall.”
Bubble trembled. She could feel the Sunbeam gently reflecting off her.
“But the other part of my light,” it continued, “passes through your thin wall and reflects off the inner side. And then it travels back out, following the first part.”
“So your light splits into two parts?” Bubble guessed.
“Exactly! Now, imagine two little waves on a pond. When they meet, they can join together to create one bigger wave. Or they can cancel each other out, and the surface becomes calm for a moment. Do you remember?”
Bubble nodded. She had seen it when Eliza threw pebbles into a small watering can.
“My colorful waves of light do the same thing when they reflect off your two walls, the outer and the inner one,” the Sunbeam explained enthusiastically. “Some colors meet in a way that they reinforce each other and shine brightly. Others, on the contrary, completely cancel each other out and disappear. And because your wall isn’t the same thickness everywhere—here it’s a hair’s breadth thinner, there a fraction thicker—a different color is enhanced in each spot.”
Bubble spun around. And it was true! Where her surface was probably thinnest, the colors were fading. And where the soapy water had pooled a little, she glowed with rich, iridescent colors.
“Aha! So where I see green, the green color from your beam was reinforced, and the others perhaps weakened?” she asked.
“You’re very clever, Bubble! Exactly!” the Sunbeam praised her. “And since the breeze keeps you moving and your wall gently stretches and changes, the places where the colors shine also change. That’s why your rainbow patches flow and dance so beautifully. We call this phenomenon the interference of light. It’s a little dance of colors.”
Bubble spun around once more with joy. She was no longer sad. Quite the opposite! She felt special. She wasn’t sick; she was a stage for a magnificent performance of light.
“Thank you, wise Sunbeam!” she called out cheerfully. “Now I know why I’m so beautiful! I’m not just an ordinary bubble, I’m a rainbow dancer!”
The Sunbeam smiled at her and caressed her with its warmth. “I was happy to explain it to you. Now fly and show the world that beautiful dance of colors.”
Bubble floated happily through the garden. She no longer wondered about her colors but proudly showed them off. She twirled in front of a bee, which stopped buzzing for a moment in surprise. She showed her pink and yellow swirls to a butterfly, which flapped its wings as if applauding her.
Finally, she flew back to Eliza, who looked up and watched her colorful beauty with amazement. “Wow, that one is so beautiful!” she whispered.
Bubble smiled quietly. She knew her beauty wasn't an accident, but the result of a wonderful collaboration between herself and the sunlight. And with this sweet secret, she let the wind carry her, until she gently touched a blade of grass and, with a soft “pop,” disappeared. She left behind only a tiny drop of water and the memory of a dance of colors.
What do you think, children? The next time you and your parents are blowing bubbles, will you notice how their colors change as they spin? Try to look closely, and maybe you too will see that amazing dance of light.