Warning! Spoilers ahead for Ms. Marvel.

Marvel Studios secretly broke the time travel rules set by Smart Hulk in Avengers: Infinity War's franchise's shaking ending, theories as to how the MCU could move forward after Thanos' (Josh Brolin) snap were born. Most of them resorted to the idea of time travel, which ultimately was the case, with all six original Avengers and their allies going on the risky time heist.

While time travel was the only clear path toward undoing Thanos' snap, how exactly it could be done was unknown until Avengers: Endgame. Earth's Mightiest Heroes needed both Ant-Man's (Paul Rudd) Quantum Realm technology and Iron Man's (Robert Downey Jr.) genius to make it possible. Amidst that, the specifics of the time heist were still confusing, even to some of the heroes involved in the mission. Smart Hulk provided an explanation as to how it worked. According to him: “If you travel to the past, that past becomes your future, and your former present becomes the past, which can't now be changed by your new future.”

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MCU's time travel rules in Avengers: Endgame are what hindered the Avengers from simply making it like Thanos' snap never happened. Phase 4, however, has squashed this idea in Ms. Marvel episode 5, "Time and Again." In the show's penultimate outing, Kamala Khan (Iman Vellani) is transported back to the night her great grandmother, Aisha (Mehwish Hayat) mysteriously disappeared during the Partition of India. With her dying breath, Aisha sends Kamala to help the lost young Sana (Zion Usman) reunite with her dad in the chaotic train station. The story had been recounted earlier in Ms. Marvel, but it was never clear how Sana was able to re her father; episode 5 of the series reveals that it's Kamala's involvement that made this possible.

How Ms. Marvel Breaks Hulk's Endgame Time Travel Rules

Iman Vellani as Kamala and Mehwish Hayat as Aisha in Ms. Marvel

As touching as this is, however,  it blatantly goes against Smart Hulk's Endgame time travel creed which states that no one can change the past by going back to the past. For a while now, Avengers: Endgame's rules for time travel have been a favorite topic of conversation. There have been various takes, and ittedly, there is still some confusion about it, especially since the film never really delved deep into the matter. Smart Hulk's explanation was done in the briefest way possible. The most important thing for the film, however, is that it worked for Avengers: Endgame's story in a way that didn't simply undo the events of Avengers: Infinity War, which would've cheapened the Infinity Saga's arc. For what it's worth, MCU's time travel explanation is rooted in real-world studies as the majority of research also points to this. It just so happened that pop culture contorted the idea in an effort to use the concept of time travel more dramatically in movies and TV shows like how Marvel Studios did with Ms. Marvel.

That said, perhaps Smart Hulk didn't really know how exactly time travel works. After all, the real world still doesn't have a definitive explanation as to how it works or if it's even possible at all. Bruce Banner himself said that time travel was outside his area of expertise. Perhaps there are different ways that time travel can be achieved in the MCU, which is why its rules are different for Avengers: Endgame and Ms. Marvel.

More: The Avengers 2012 Already Explained Thor's Biggest Avenger Problem

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