Strings, branes and two-time physics

We generalize the ideas and formalism of two-time physics from particle dynamics to some specific examples of string and p-brane (p≥1) dynamics. The two-time string or p-brane action can be gauge fixed to produce various one-time string or p-brane actions that are dual to each other under gauge transformations. We discuss the particular gauges that correspond to tensionless strings and p-branes in flat (d−1)+1 spacetime, rigid strings and p-branes in flat (d−1)+1 spacetime, and tensionless strings and p-branes propagating in the AdSd−n×Sn backgrounds.