not a variation of “the man in the arena,” but a term from the world of cryptography.  It’s the technique British magician Derren Brown used while playing 9 others in games of chess, to come out on top.  This is the video of the performance:

Not that’s impossible to do so without trickery - this is an old picture of the late Bobby Fischer:

the example I remember of the man-in-the-middle attack is that of the South African air force.  Each airplane has a transponder on it that’s used to identify-friend-or-foe - yet an enemy side can impersonate them by intercepting the signal, relaying it to another South African station, recording their response, and replaying it to the airplane.

Prof. Steve Squyres from Cornell delivered an awe-inspiring lecture a few months ago about his work on the NASA Mars rovers, and later signed his book for the audience.

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It was cool how he made a point of answering questions from children in the audience first - a true successor to Carl Sagan. I wanted to ask him how they navigate if there is no GPS system on Mars - it seems like this is the answer, which would have to be supplemented with visual calibration of some sort.  As Mars has days shorter than here on Earth, every team member had specially-designed watches made that would run on Mars time, bringing them into work half an hour earlier every day!

You can download and play around with the software that the engineers at NASA use to control the rovers, using real data.  You can fly around Mars as well, using digital elevation data with software like this or this.  Astronomy is becoming more accessible now thanks to Microsoft’s WorldWide Telescope and Google Sky.

Most of the deep-space probes actually only send data using a single radio sideband in order to save power, and are received through the Deep Space Network (I visited the Goldstone site in the Mojave desert outside L.A. a few years ago, which is actually situated on the live-fire Ft. Irwin military base).

Here are some of the pictures/videos from his slide deck:

sunset on Mars:

dusty solar panels:

purgatory dune (video of the wheels burning rubber here)

the landing site:

soil test:

parachute testing in the wind tunnel at Moffett Field (they have great tours)

Mars rover petals unfolding

wheels burning rubber

dust devils on Mars:

the Mars 2020 video referred to in the Q&A session is here.

at the Louvre in Paris:

Prof. Martin Hellman gave a talk recently about the rationale behind his decision to work on “foolish” problems.  The first of which resulted in the discovery of public-key cryptography with Diffie and Merkle, which is now used to secure all modern communications - from email (PGP) to credit card transactions (SSL) and phone calls (Skype).  The prevailing wisdom at the time was that there was no point doing the research because the the NSA had probably already done it (they’re the largest employer of mathematicians in the world), and even if one were to to find something out, the government would classify it.

This is the best analogy I’ve seen for how it works, in the form of a puzzle:

You’re living in the Soviet Union under Stalin’s rule.  You’ve been jailed and sent to the gulags, but you must tell your wife in St. Petersburg to arrange for your release.  You’re afraid, however, that your mail will be read by the secret police, so you think of using a lock (assume that it’s not going to be broken due to the time it would take to do so).  The problem is, your wife doesn’t have the key.  This is how you’d do it:

Put a lock on the package you send to your wife.  On the outside of the package, enclose a message that instructs her to put a second lock alongside your lock, and mail it back.  When the package is returned, remove your lock, then mail it once again to your wife.  When she receives it, she can then unlock it with her own key.

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The “version 2″ refers to his new project related to the elimination of nuclear weapons - he’s asking for help changing the “conventional wisdom” about nukes through online advocacy (he’s already got signatures from former heads/deputy heads of the NSA and CIA, respectively).