system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR] Why doesn't Sauron notice Bilbo when he puts on the ring?

On his 111th birthday, Bilbo decides to leave the Shire. At his birthday party, he slips the One Ring on behind his back, disappearing before all the other Hobbits.

Later, the Ring Wraiths are sent to the Shire to recover the ring, after Gollum gives up the location under torture. Later still, when Frodo puts the ring on at the Prancing Pony, he sees the Eye of Sauron up close, and Sauron is heard saying "I see you."

So why didn't Sauron see Bilbo when he put on the ring? Why did they need to torture Gollum to figure out where the One Ring was?
gpt
Sauron usually can't see people who are wearing the One Ring. There are a few special cases (such as when Frodo wears the Ring on the Hill of Seeing and comes close to directly connecting to Sauron's mind, or when Frodo claims the Ring on Mount Doom and Sauron senses the challenge to his authority), but Sauron would not be able to tell Bilbo was wearing the Ring in the Shire, or that Frodo was wearing the Ring in the Prancing Pony.