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Symmetry breaking of escaping ants is a phenomenon that happens when ants are constrained into a cell with two equivalent exits, and perturbed with an insect repellent. Contrary to intuition, ants tend to use one door more than the other in average (i.e., a there is a symmetry breaking in the escape behavior), so they crowd on one of the doors, which decreases the evacuation efficiency. ==Description== The symmetry breaking phenomenon arises in experiments described as follows. Worker ants freshly collected from the field are enclosed into a circular cell with a glass cover in such a way that they can only move in two dimensions (i.e., ants cannot pass over each other). The cell has two exits located symmetrically relative to its center. We will describe first a "reference" experiment, and then the one were the "escape symmetry" is broken. In the reference experiment, both doors are opened at the same time, and let the ants escape. If the experiment is realized many times, in average we see that approximately the same number of ants use the left and the right doors. In this experiment the escape symmetry is not broken. The second experiment involves a further step before opening the doors: an insect repellent fluid is poured into the cell at its center through a small hole in the glass cover. As a result, ants get very excited. So, we might say that they are "in panic". If the experiment is realized many times, we see that the number of ants escaping by one of the doors (which can be randomly either the left one or the right ones) is significantly higher that the number of ants escaping by the other one, i.e., the escape symmetry is broken. The crowding of ants at one of the doors while the other one may be eventually free results in an inefficient evacuation in terms of time. It is also interesting to see whether and how density of a group influence that symmetry breaking in escaping ants. Geng Li and coworkers from Beijing Normal University used Red imported fire ant (''Solenopsis invicta'') to repeat the experiment mentioned above with different total number of ants. The result shows that the symmetry breaking increases at low density but decreases after a peak.That is to say, when density is low, the ant group produces collective escaping behavior while at high density, ant group behaves more like random particles. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Symmetry breaking of escaping ants」の詳細全文を読む スポンサード リンク
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