When Robert Downey Jr., arguably Marvel Studios’ leading actor, tweeted an innocuous photo of him and a few friends hanging out and eating lunch on the set of Avengers: Infinity War, he probably didn’t expect it to lead to a new, big theory.
But this is the internet, and people like to theorize.
In the photo, seen below, Downey Jr. can be seen wearing a shirt with a round hole in the middle. It didn’t take long for people to notice it and put two and two together: It’s the exact shape of an arc reactor, the electromagnet Tony Stark surgically embedded in his chest to keep him alive. The vibrant blue piece of technology, which also sits at the heart of the Iron Man costume, defined the superhero’s look ... until the end of Iron Man 3, when Stark figured out a way to safely remove the shrapnel that had been embedded in his chest since an explosion in the first movie.
Stark went through Avengers: Age of Ultron and Captain America: Civil War without the arc reactor, making it all the more interesting to see that hole in his shirt. Since he can power the Iron Man suit without it, and considering the surgery has largely been regarded as a success, it doesn't make sense for Stark to return to his cyborg-like look.
What could it all mean? One of the more popular theories circulating is that it has something to do with the Time Stone. Since The Avengers, one of the Marvel Cinematic Universe’s core story arcs has been about hunting down the Infinity Stones before Thanos gets his hands on them. Guardians of the Galaxy, Doctor Strange and, of course, The Avengers all made a point to address the Infinity Stones, using post-credits scenes to tease the future. Each stone represents a different core facet of life and the universe: Mind, Soul, Space, Power, Time and Reality.
The Time Stone was first introduced in Doctor Strange, hidden inside the magical artifact known as the Eye of Agamotto. The Eye allowed Strange to wield the flow of time against the sorcerer Kaecilius and the mystical entity Dormammu as a way to restore the Hong Kong Sanctum and save life on Earth. The Time Stone is what allows the user of the Eye of Agamotto to turn back time.
Here's where the latest fan theory kicks in. If Thanos or any of his goons were able to get their hands on the Time Stone, they could reverse time and make it so that Stark would have to rely on the arc reactor again. When Iron Man 3 came out, writer Drew Pearce told SciFi Now that even though Stark would remove the arc reactor, he would still undeniably be Iron Man.
“We take his arc reactor out, but I think we also make a pretty definite statement that he is Iron Man,” Pearce said. “And although Joss [Whedon, director of the first two Avengers films] isn’t part of the process as such, he saw all the cuts of the movie, so I’ve got to assume he knows exactly what he wants to do with Tony in [in Age of Ultron], and how we’ve left [Stark] is going to help that, not hinder it.”
If Stark were to go back to using the arc reactor, it wouldn’t be a personal, aesthetic decision. The billionaire would need a life-saving reason to return to it and, based on everything we’ve seen so far, something to do with Thanos and the Time Stone makes the most sense.
That being said, Spider-Man: Homecoming isn’t out yet, and Iron Man does have a role in it. Something could happen there that leads to Stark needing the arc reactor again. Hopefully Homecoming will provide some more answers — or at least a couple more hints — when it’s released on July 7.
And, naturally, it could all be explained by something as simple as a flashback. There’s no shortage of flashback sequences in Marvel movies, and there’s no reason to think the simplest answer isn’t the correct one.
All will be explained when Avengers: Infinity War is released on May 4, 2018.