I didn't believe that light slows down in water (part 1)

The video script introduces an experiment about the speed of light in water, which the author has been curious about for years. It discusses the common misconception that light slows down in water, contrary to Einstein's theory of relativity where light is constant across the universe. The author explains their skepticism and the process of using LiDAR technology in smartphones to measure the speed of light, which led to an unexpected result that took a long time to understand. The script also debunks common explanations for light slowing down and suggests that light might not actually slow down in water.

The script delves into the nature of light, challenging the particle view and instead focusing on light as a wave. It explains the concept of light as a messenger of electrical forces between charged particles and how light's role is to affect charged particles. The author clarifies misconceptions about the speed of light and introduces the idea that the speed of light, denoted by C, is the maximum speed of causality in the universe. The script also discusses the secondary wave explanation for light slowing in water, which involves the interaction of light with water's electrons, and how this explanation was partially misleading.

The video script addresses the flawed animations and explanations that claim light slows down when passing through water. The author attempts to replicate these animations and finds inconsistencies, leading to the conclusion that adding two light waves traveling at the speed of light (C) does not result in a slower light wave. The script points out mathematical errors and misplaced reliance on phase velocity and group velocity concepts. The author then corrects the mistake, suggesting a simple oversight with brackets in the mathematical representation of light waves.

The script explores the possibility that light does not slow down in water at all, referencing Feynman's lectures and other textbooks. It describes an experiment using a laser and a phone's LiDAR technology to measure the speed of light in water. The author hypothesizes that if the measured distance remains the same with and without water, it would imply that light's speed remains constant. However, the experiment's initial results are confusing and do not align with expectations, leading to further investigation.

The script details the author's repeated attempts to measure the speed of light in water using their phone, facing challenges and failures each time. Despite theoretical understanding that light should travel at the same speed (C) in any medium, practical measurements with the phone's LiDAR technology are not providing consistent results. The author discusses the importance of timing and the immediate reaction of electrons to light, which produces secondary light that adds to the original light without a time lag, maintaining the speed of C.

The video script discusses the paradox of light appearing to slow down in water despite calculations suggesting it maintains the speed of C. It explains that the light from oscillating electrons in water radiates in multiple directions, with the most significant radiation happening forwards and backwards. The author argues that while the original light continues at speed C, the cumulative effect of all the light, including that from the oscillating electrons, creates an illusion of a reduced speed. The script also mentions the Feynman lectures and a video by 3Blue1Brown that provide a deeper explanation of this phenomenon.

The script concludes with the author's decision to conduct a definitive experiment to measure the speed of light in water using a proper laser meter from a hardware store. The aim is to compare the meter's readings with and without water to confirm whether light's speed changes when it passes through water. The author expresses doubt and panic after an AI suggests that light does slow down in water, contrary to their calculations. Despite this, they remain determined to find the truth through experimentation.