Two Drunk Researchers

Two drunk researchers are located on an infinite line and they are looking for each other. In order to meet, they need to be at the exact same location at the exact same time.

Before they start searching, an adversary decides upon their orientations (what is `left' for one researcher may be `right' for the other). As they are searching, they are constrained to stay on the line and they have to follow the same algorithm. Moreover, the adversary controls the speed of each of them independently and in real time. However, he cannot stop a researcher forever. Finally, neither researcher is aware of the location, orientation and speed of the other researcher.

Can this problem be solved? What is the best known algorithm? What is the best known lower bound for this problem?

(Alcohol not included.)