"Speedy Beet[hoven]" Speculations on his tempo markings

I saw a performance of Boston Philharmonic Orchestra play Beethoven's 9th Symphony very recently, and heard the fastest interpretation of the last movement most people have ever heard.  After the concert, I heard from performers that they were actually following Beethoven's tempo markings, which are almost never followed because they are impossibly fast.  Naturally, I stumble across NPR's Radiolab podcast about Beethoven's encounter with the metronome after writing eight symphonies the day after I see this performance.  He meets Johann Nepenuk Maelzel, who introduces him to the metronome.  Excited about the prospect eventually, he goes back and marks all his symphonies with tempos.  Alan Pierson, Artistic Director of the Brooklyn Philharmonic, got a group of string players to demonstrate how hard it was to play his works up to tempo.  The podcast shows an example of how slow his 5th Symphony is played at times compared to the tempo Beethoven marks.  The first speculation says his metronome was broken, but they tracked down his metronome and it worked fine.  The second claims it was a clerical error, which seems highly improbable to happen to all nine symphonies.  The third was because it was due to his deafness, and because the space in which he heard music in his head differed from acoustics in a real space.

The fourth is the speculation of interest, which mentions Vierordt's law.  Vierordt's law states that our perceived duration of time versus the actual duration of time is different.  He states that we tend to overestimate slow tempos, and underestimate fast tempos.  For example, for a slow tempo, we predict the next beat to be sooner than the actual beat, and the opposite for fast tempos.  They also talk about the indifference point, which is the tempo that we end up in sync with perceived and actual duration of time, which falls around quarter note to 94.  They matched up the tempo at which the Brooklyn Philharmonic string players felt comfortable playing the fifth symphony and it matched at around the same tempo.  The speculation states that Beethoven is trying to push this point of comfort, and to keep his music out of his time.  In the fifth symphony, the tempo he marks is 108.  The Brooklyn Philharmonic string players play the opening at 160.

This is an extremely interesting theory inside the workings of Beethoven's brain.  Of course, there is never a way of knowing what the inner mind of this genius is thinking.  Perhaps in his head it sounded normal,and his indifference point was higher.  It was definitely fun listening to the theme of the fifth symphony played at 160.  It really shows another aspect of how Beethoven pushed the boundaries of music, because we find ourselves constantly speeding tempos of other composers.