Election polls often tighten up remarkably as the election date draws near. "Leave" (the European Union) won the UK election of May 2016 with a majority of 51.9%, but earlier the polls weren't nearly as tight—in January 2011 "Remain" was up by about 20 percentage points. In the 2020 presidential election in Poland, Andrzej Duda won with 51.0% of the votes, whereas he was up by about 5 percentage points just eight weeks earlier.

With a choice between only two candidates, the opinion of democracies often splits into quite evenly divided polarized groups.

"We can ask ourselves how, not why, a large collection of interconnected voters can consistently reach such a remarkably organized state," said Olivier Devauchelle of the Institut de Physique du Globe de Paris in France. His work, done with two European colleagues, has been published in Physical Review E.

Is there something that pulls the electorate to such an equal polarization? Naively one might expect that voters simply flip a coin, resulting in a 50-50 election. However, in Poland in 2020, eastern voters overwhelmingly preferred Duda, except in a few major cities, and voters in Poland west of the 1815 to 1914 Prussian border mostly voted for his opponent, Rafał Trzaskowski, except for bare majorities near the border.

This result suggests voters do not in fact "flip a coin," but make decisions that depend on those near them and closely related to them. They can be modeled as "interacting agents," adopting the dominant opinion of their neighbors.

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