# Why RED BUBBLES are impossible… or are they?! | Summary and Q&A

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September 25, 2020
by
Physics Girl
Why RED BUBBLES are impossible… or are they?!

## TL;DR

Bubbles appear to lack red color because of a phenomenon known as thin film interference, where specific colors are canceled out due to wave interference.

## Key Insights

• 😪 Bubbles lack red color because red light is canceled through thin film interference.
• 🤔 Thin film interference is the result of wave interference and occurs when light waves reflect off the surface and within a thin film.
• 🙂 The cancelation of specific colors is determined by the wavelength differences between colors of light.
• 🌊 Thin film interference is similar to wave interference in other mediums, such as water and sound waves.
• 🙂 White light, which contains all colors, interacts with the thin film of a bubble to create various colors through interference.
• 🤔 Different thicknesses and angles of the thin film result in different cancelation of colors.
• 👁️‍🗨️ Red bubbles can be observed by shining only red light onto a bubble, but they appear as striped colors due to the varying thickness of the bubble.

## Transcript

• Hey, I'm Diana and you're watching Physics Girl, go look at a picture of a bubble where I guess I could just show you one. If you don't trust me 'cause we've never met. Go search online for pictures of bubbles and look at what colors are on the surface. If you don't have colorblindness for me, it's magenta yellow Green, sometimes, sometimes a lit... Read More

### Q: Why don't bubbles have the color red?

Bubbles lack the color red because the thin film interference phenomenon cancels out specific colors based on their wavelength, and red light has a longer wavelength.

### Q: How do bubbles achieve their colors?

Bubbles obtain their colors through the process of thin film interference, where light waves that reflect off the surface and within the bubble interfere with each other, causing certain colors to cancel out.

### Q: Can red bubbles exist?

While it is theoretically possible to create red bubbles by manipulating the material and indices of refraction, in natural conditions, it is highly unlikely to achieve a red bubble because canceling out the necessary colors would require canceling out multiple colors across the visible spectrum.

### Q: What is the difference between thin film interference and rainbow formation?

In thin film interference, colors are canceled out based on their wavelengths, while in rainbows, colors are dispersed and separated from white light due to the refraction and reflection of light in water droplets.

## Summary & Key Takeaways

• Bubbles get their colors through thin film interference, a phenomenon opposite to rainbows, where colors are canceled out instead of combined.

• Light waves reflect off the surface and within the thin film of the bubble, causing interference and cancelation of certain colors.

• The cancelation of specific colors, such as red, is due to the wavelength differences in the various colors of light.