Rule 90
... that, in the Rule 90 cellular automaton, any finite pattern eventually fills the whole array of cells with copies of itself?
... that, in the <b id="mwCwQ"><a href="./Rule_90" id="mwCwU" rel="mw:WikiLink" title="Rule 90">Rule 90</a></b> <a href="./Cellular_automaton" id="mwCwY" rel="mw:WikiLink" title="Cellular automaton">cellular automaton</a>, any finite pattern eventually fills the whole array of cells with copies of itself?