I'm reading Feynman's QED, which is a nontechnical overview of quantum electrodynamics. In this book Feynman makes three claims that I am curious about. I have a math background but regrettably not much in physics.(adsbygoogle = window.adsbygoogle || []).push({});

1. Light is a particle, period. It's not true that light is "sometimes a particle and sometimes a wave."

Is this the consensus interpretation these days? In high school or college physics do we no longer teach people that light is a wavicle? Or is light a wavicle in high school but a particle in grad school?

2. Over short distances, photons can go slower or faster than the speed of light. The speed of light is constant only over sufficiently large distances. This one really surprised me. Is that true?

3. It's not known whether renormalization is mathematically consistent. Feynman's book is from 1983 I think. Is this still true? I know that renormalization was mathematically questionable originally, but is it true that it's still never been properly formalized?

Thanks for any insight.

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# Amateur question about QED and the modern understanding of light

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