I don't know why light slows down in water. (part 2)

TL;DR

A physicist attempts to understand why light slows down in water through experiments, simulations, and theoretical analysis.

Transcript

I was convinced that light doesn't actually slow  down in water, and I thought I'd mathematically   proved it too, but then I did the experiment  and reality decided to completely contradict me.  So, I really am wrong. Since then, I've spent  a lot of time trying to figure out why light   actually slows down in water. And the thing is,  it's compli... Read More

Key Insights

• 🐎 Phase velocity of light decreases in water, but the information speed (the speed at which a message can be transmitted) also slows down significantly.
• ✈️ Plane waves and pulses of light have different characteristics and require separate analysis to understand light slowing down in water.
• 🤽 The behavior of electrons in water plays a crucial role in shaping the resulting light and determining its speed.
• 🙂 Understanding the speed of light in water involves considering the interplay between the original light, electron light, and their interactions in different layers.
• 😩 The simulation showcased that the front of the original pulse can be gradually worn down by the electrons as it travels through water.
• 🙂 The mystery of why light slows down in water remains unsolved, inviting further exploration and experimentation.

Questions & Answers

Q: Why did the physicist initially believe that light does not slow down in water?

The physicist had read Feynman's explanation of phase velocity in water, which showed a decrease, but misunderstood its implications on the information speed of light.

Q: How did the physicist's experiment with LiDAR on their phone contribute to their understanding of light slowing down in water?

The experiment showed that the information speed of light significantly decreases in water, providing evidence contrary to the physicist's initial beliefs.

Q: What is the role of the Fourier transform in understanding light slowing down in water?

The Fourier transform allows the representation of a pulse of light as a sum of plane waves, which simplifies the analysis and helps generalize Feynman's proof to pulses of light.

Q: Why did the physicist have difficulty interpreting the results of their simulations?

The simulations based on the Fourier transform lacked direct insight into the behavior of actual pulses of light, making it challenging to understand the exact reasons behind light slowing down in water.

Summary & Key Takeaways

• The physicist initially believed that light does not slow down in water, but experiments and simulations showed otherwise.

• The concept of phase velocity and information speed of light in different scenarios.

• Feynman's analysis of plane waves and how it relates to the speed of light in water.