Roland Barthes wrote that the centre of Tokyo is occupied by a void...it is a quiet forest that lies at Tokyo's heart.
...The centre of Tokyo is certainly a void, but one that is protected by a circular train line, the Yamanote, which forms a 40-km (25-mile) loop around it. It seems to me that this ring of steel emphasizes the importance of the void, and the depth of its significance.
This is the first site along the tour. In here we have a void. I remember the building that used to stand here, it was painted blue. Passing through it, you can imagine how us, as ghosts – should the building be standing here – would have to actually be invisible to pass through these walls and now it’s the reverse. The building is the ghost and we’re passing through these walls.
Japanese music is above all a music of reticence, of atmosphere. When recorded, or amplified by a loudspeaker, the greater part of its charm is lost. In conversation, too, we prefer the soft voice, the understatement. Most important of all are the pauses. Yet the phonograph and radio render these moments of silence utterly lifeless. And so we distort the arts themselves to curry favor for them with the machines.
Wang tiles (Hao Wang, 1961) are a class of formal systems. They are modelled visually by square tiles with a color on each side. A set of such tiles is selected, and copies of the tiles are arranged side by side with matching colors, without rotating or reflecting them.
The basic question about a set of Wang tiles is whether it can tile the plane or not, i.e., whether an entire infinite plane can be filled this way. The next question is whether this can be done in a periodic pattern.
In 1966, Wang's student Robert Berger solved the problem in the negative. He proved that no algorithm for the problem can exist, by showing how to translate any Turing machine into a set of Wang tiles that tiles the plane if and only if the Turing machine does not halt. The undecidability of the halting problem then implies the undecidability of Wang's tiling problem.