This is a joint science program you set with another friendly civilization.
To unlock this option, first you need to research Education, and then become friends with another player. You (or they) can then offer to enter a Research agreement. To start it, both parties must invest a set amount of gold based on the highest age both players are in. After some time, the research is completed and each player receives a bonus to their Science output, consisting of an immediate Science points boost. The bonus is calculated as 50% of the median Science value for all of the technologies the player can currently research. This bonus can be increased by acquiring the Rationalism Social Policy, or by building the Porcelain tower Wonder.
- Note: If you and your research partner declare war on each other, or if your research partner is wiped out, the Research agreement is cancelled, and the Gold you paid is lost.