"It's simple," said Finn Lewis plainly. "In the future, you will propose many theories, some correct and some not, but mostly correct. You are a great physicist; it can be said that you laid the foundations of future electromagnetism in physics. Without you, the world's scientific progress would likely be delayed by countless years. However, your later years were not very comfortable, and the research environment was poor. Therefore, I want to take you to another timeline to let you personally complete some of the research you proposed later."
Finn did not hide his purpose. In fact, hiding his purpose would have been impossible to keep from the other party anyway. With that being the case, it was better to just plainly state his intentions.