This brings me to a popular fan theory that Captain Marvel is actually trapped in the Quantum Realm and is found by Ant-Man and Wasp, who then bring her to the present day MCU. How Carol Danvers ends up in the Quantum Realm is anyone's guess, but it would be one way to explain where she's been all this time if she first got her powers in the 90s. This isn't to say that she plays a big part in Ant-Man and the Wasp. I could see Scott and Hope somehow leaving the door open, so to speak, when they free Janet from the Quantum Realm, giving Carol her chance to escape. Then she pops up in Hank Pym's living room (or wherever) in a post-credits scene, which leads right into how she came into this predicament in Captain Marvel.