The MCU works as a whole, interconnected universe because of the countless ways in which the lives of individual Marvel superheroes intersect and connect with each other. Even the origins of each hero have been found to have been occasionally connected with other characters.
Following this train of thought, a new fan theory posted on Reddit by user TheLazerShell suggests that the super soldier serum used to transform Steve Rogers into Captain America may have a connection to Thor’s enchanted hammer Mjolnir. According to them, the enchantment that drives Mjolnir to only be wielded by someone deemed worthy is very similar in concept to what Dr. Erskine was describing to Steve as the requirement for being a successful candidate for the Super Soldier program.
If you’ll recall, Erskine said he was looking for qualities beyond the physical in his candidate, where the individual had to prove he was worthy, mentally and morally, to wield the power of the serum for it to properly work. The theory then goes a step forward and posits that Erskine somehow discovered the secret process behind Odin’s enchantment of Mjolnir, and used the same process to create the serum so that its power would not fall into the wrong hands.
Of course, this hasn’t been confirmed by Marvel just yet, but it would follow logically from the movie, where Erskine made several references to Norse mythology, and the fact that the Red Skull had also taken the serum and been deformed by it, presumably as a consequence of not being worthy.
Taken in conjunction with a remark made by Thor once to the effect that all magic is basically just really advanced science, and Erskine’s serum transforms into a piece of Asgardian magic. This would also explain why Captain America was the only Avenger in the MCU besides Thor to be able to wield the hammer, not counting Vision. It’s because Steve’s worthiness had already been determined by the serum.
