It's the perfect chance to show the old folks up and prove that mutants and Avengers can actually work together and not kill each other!
Um...well, they're literally doors in a spooky house at the end of the road. They open up into other dimensions, could be anywhere, anytime? If Hank was here, he'd totally figure it out. But if you feel like you need to get into nitty gritty maybe ask one of the wizards. Or apparently there's an alien space lady who floats around in a telephone booth that's also an expert.