# The cr.yp.to microblog: 2018.03.22 18:16:31

2018.03.22 18:16:31 (976870250187718656) from Daniel J. Bernstein, replying to "Jonathan Oppenheim (@postquantum)" (976868884509876225):

Do you understand the mathematical difference between a static field (a vector at each point in space) and a dynamic field (a vector at each point in space and each moment in time)? Motion of an electron inside the cage sends out an EM wave visible outside the cage.

### Context

2018.03.22 12:30:50 (976783257126744065) from "Jonathan Oppenheim (@postquantum)", replying to "Jonathan Oppenheim (@postquantum)" (976783149530218496):

...that measuring the EM field on a shell is sufficient to determine the EM field everywhere inside or outside that shell? 3) Do you believe that the holographic conjecture means that it is impossible to localise information?

2018.03.22 17:39:03 (976860819798544386) from Daniel J. Bernstein, replying to "Jonathan Oppenheim (@postquantum)" (976783257126744065):

Why do you keep trying to weasel out of finishing the Faraday-cage analysis? Is it because you're starting to realize how stupid your "cancel EM waves" claim was, and you don't want to admit it? Actually _understanding_ the Faraday example would help you with other examples too.

2018.03.22 18:04:28 (976867218410614785) from "Jonathan Oppenheim (@postquantum)":

I'm trying to return the discussion to the central thesis of your paper and my original tweet because life is short and this example is both tangential and far more complicated than the potential well I suggested (a point you ignore). Cancelling is what happens in the first...

2018.03.22 18:11:06 (976868884509876225) from "Jonathan Oppenheim (@postquantum)", replying to "Jonathan Oppenheim (@postquantum)" (976867218410614785):

...example I gave -- the charges in the cage create a field which when added to the field of the charges inside the cage sum to a constant (thus cancel). Your claim that Faraday cages "merely scramble information" is what I took issue with.