SIAM News Blog

Mathematical analysis reveals surprises of the Faraday cage

Errors in Feynman’s analysis of exponential shielding



Karthika Swamy Cohen
Managing Editor, SIAM News
Phone: 267-350-6363

Monday, August 15, 2016

Philadelphia, PA – “How can a big error in the most famous physics textbook ever published have gone unreported since 1964?” Nick Trefethen asks in his SIAM News article, Surprises of the Faraday Cage

In the article, Trefethen, a professor of numerical analysis at the University of Oxford, explores surprises that emerge from mathematical analysis of the Faraday Cage and inconsistencies in physicist Richard Feynman’s analysis of it. Trefethen got interested in the problem while investigating the mathematics of the trapezoidal rule, and determined that an analogy between the mathematics of the trapezoidal rule and that of the Faraday cage was in order.

This analysis led to an “interesting journey of surprises” as Trefethen says in the piece, leading to the conclusion that Feynman’s analysis of the Faraday cage, and his conclusion of exponential shielding, are incorrect.

Due to the wide interest the article has received, SIAM News is hosting a live chat with author Nick Trefethen.

The chat will take place on Thursday, August 18 from 12 noon - 1:00 p.m. U.S. Eastern time.

Join us to discuss this very intriguing subject with the author! To chat or ask him a question, simply visit the article page at, and post your question or comment under the “Comments” section during the aforementioned time. You can sign in to chat through Disqus, Facebook, Twitter or Google. Professor Trefethen will try to address as many questions as possible.

Trefethen received a bachelor’s degree in applied mathematics from Harvard University, and a master’s and Ph.D. in computer science/numerical analysis from Stanford University. He is a Fellow of the Royal Society (London) and a member of the National Academy of Engineering (USA). During 2011-2012, he served as President of SIAM (Society for Industrial and Applied Mathematics). 

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