Marinka Zitnik

Fusing bits and DNA

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ACM XRDS: The Brownian Wanderlust of Things

The Spring issue of ACM XRDS is here! This issue is centered around digital fabrication, which in many ways highlights the expanded role of computer in today's society. Digital fabrication is not merely about 3D printing knickknacks, rather it enables individuals to create their own systems and devices using new technologies.

My department contributed a column on the Brownian wanderlust of things. Consider a gambler who starts with an initial fortune and plays the following simple coin tossing game. At each turn, the dealer throws an unbiased coin. If the outcome is head, the gambler wins a unit; if the coin comes up tails, the gambler loses a unit. The gambler continues to play until he is either bankrupted or his current holdings reach some fixed desired amount.

Stochastic models of this kind can have much wider implications than just estimating the fortune of a gambler flipping a coin. For example, the way in which information flows within social media outlets can affect mobilization and strategic interactions between participants of mass social movements, such as protests. While traditionally social movements have spread through on-the-ground unions, the use of communication platforms—such as Twitter and Facebook—has offered alternative ways for organizing such events. As we see in the column, to truly capture propagation in such environments, we need to take into consideration the stochastic nature of information propagation.