In The Empire Strikes Back, Obi-Wan Kenobi tells Luke Skywalker he can’t help him if he chooses to fight Darth Vader, but it’s never quite been clear why. The Empire Strikes Back is widely considered one of Star Wars’ best movies, if not the single best, and there’s good reason for that. In addition to the now iconic Darth Vader twist, The Empire Strikes Back changed Hollywood in myriad ways.

That doesn’t mean that the movie was flawless, though. As is true of many of Star Wars’ movies and TV shows, there are moments that are only minimally explained or simply don’t make sense. One such confusing moment was Obi-Wan’s ᴀssertion that he couldn’t help Luke fight Darth Vader in The Empire Strikes Back, but I think I’ve finally figured out exactly why Obi-Wan had to sit out that fight.

45 Years Later, One Empire Strikes Back Scene Still Bugs Me

Obi-Wan “Can’t Interfere” … But Why?

In The Empire Strikes Back, Luke is eager to confront Darth Vader. However, Obi-Wan’s somewhat odd response is, “If you choose to face Vader, you will do it alone. I cannot interfere.” Obi-Wan doesn’t elaborate about why he is unable to ᴀssist Luke in this fight, and, although Luke says he understands, the audience is left in the dark (and has continued to be in the dark in the decades since) about what exactly is preventing Obi-Wan from helping Luke.

What makes this especially odd is that Obi-Wan had already proven his ability to help Luke as a Force ghost in A New Hope. After all, it is Obi-Wan’s voice that tells Luke to use the Force before he blows up the Death Star. Yet, in The Empire Strikes Back, not only does Obi-Wan not ᴀssist Luke in his final face-off against Vader, but he also doesn’t ᴀssist on Cloud City. Even in Return of the Jedi, when Luke must confront Palpatine and Vader together, Obi-Wan doesn’t appear. The question remains: why couldn’t Obi-Wan help Luke in these dire moments?

There’s Only One Possible Explanation, & It’s A Shocking One

The Jedi Had To Protect An Incredible Force Power

Given Obi-Wan is a Force ghost at the time, it seems only one explanation really makes sense: the Jedi didn’t want the Sith to discover that they knew how to become Force Ghosts. Becoming a Force Ghost is no easy feat, even as the number of Force Ghosts has grown considerably since The Empire Strikes Back. This is actually one of the Force powers in Star Wars, and it’s one of the most difficult to learn.

This was made clear in Star Wars: The Clone Wars when Yoda had to learn this ability from Qui-Gon Jinn. This was also the training Yoda was referring to in Star Wars: Episode III – Revenge of the Sith, which he told Obi-Wan he would be doing on Tatooine with his former Jedi master. As difficult as it was for the Jedi to learn how to become Force Ghosts, though, for the Sith, it was actually impossible.

The novelization of Revenge of the Sith, written by Matthew Stover, makes that quite clear. In that book, Qui-Gon describes immortality as “The ultimate goal of the Sith, yet they can never achieve it.” It makes sense that this would be the power the Sith sought most of all, as their desperation to obtain and maintain power was really what defined them.

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With immortality, they would be able to hold onto that power indefinitely (at least, in their minds). This would of course become especially dangerous in the hands of Palpatine, who was more obsessed than most with becoming immortal. As devastating as this power would have been in the hands of Palpatine, it would also have posed a major risk should Anakin Skywalker/Darth Vader have acquired it, given he was the Chosen One.

This explains why Obi-Wan Kenobi—and Yoda—could not appear as Force Ghosts alongside Luke in either The Empire Strikes Back or Return of the Jedi. The risk was simply too great that Vader and Palpatine would realize that this type of immortality was possible, and they would no doubt stop at nothing to achieve that ability themselves. Although it put Luke, and therefore the future of the Jedi, at risk, Yoda and Obi-Wan had to keep this secret from the Sith.

The Force Ghosts Would’ve Been Particularly Worried About Palpatine

Palpatine Was (Obviously) Desperate For Immortality

Becoming a Force ghost required selflessness, something that the Sith were never capable of because of their natures. Even so, the knowledge that such a power was possible would become too dangerous in the hands of the Sith. Palpatine’s narrative arc, particularly in the sequel trilogy, reveals precisely why the Jedi were so wary of the Sith discovering this secret.

While Palpatine’s resurrection in Star Wars: The Rise of Skywalker was incredibly controversial and continues to be one of the biggest complaints about the sequels, if not among the biggest complaints throughout Star Wars’ nearly 50 years, his return did drive home how desperate the Sith were for immortality, although Palpatine specifically. Star Wars is still working to reveal all the ins and outs of how Palpatine returned, but it’s clear he became obsessed with creating Force-sensitive clones of himself so he could return.

Had Palpatine known there was a path forward that didn’t require all this cloning science and extended trial and error period, he would of course have thrown everything he had behind trying to learn this power. Presumably, he would have been unsuccessful, given all we know about the process to become a Force Ghost, but that doesn’t mean he wouldn’t have done considerable damage had he known enough to try. Palpatine is also one of Star Wars’ most powerful Sith, and there’s still plenty not known about the dark side.

In that sense, who knows what Palpatine could have managed to do had he realized that Obi-Wan and Yoda lived on as Force Ghosts? Although Star Wars has never confirmed it, and perhaps a direct explanation may never come, this makes the most sense when it comes to why Luke was on his own in his fight against Darth Vader. In the end, Obi-Wan Kenobi appearing as a Force Ghost to help Luke Skywalker in The Empire Strikes Back was simply too risky.