system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] At the start of A New Hope why doesn't Vader realise that Leia is force sensitive when they're face to face, yet later in the movie he can sense Obi-Wan from the other side of the Death Star?
gpt
Because she hasn't awakened to the Force like her brother has.

Likewise, Vader had over a decade of being close with Obi-Wan - He's recognize the way Obi-Wan feels through the Force over a long distance easily.