Glass is based on the premise that while here, the top group of panes looks vertical and the bottom group looks horizontal, ...
![](https://freight.cargo.site/t/original/i/c6b734b2d35008913e3606937276a0d3bc67e958fd310b1d2cc68e78db07a800/Glass.001.jpeg)
... if we see only a small subset of these clusters, we cannot distinguish them.
![](https://freight.cargo.site/t/original/i/462b779735c53ff2eead74e453ab347e57742141ad3016b63223fe8fc237ee8e/Glass.002.jpeg)
So the two states exist in superposition, until we reach an edge, where typically one particular orientation is favoured. This represents a measurement in quantum mechanics: the collapse of the wave function.
* The Consistent Histories Interpretation, proposed by R.B. Griffiths (1984) and elucidated by the late Pierre Hohenberg in his Reviews of Modern Physics article (2009).
** This statement is shared by all interpretations of quantum mechanics.