Now, when you look closely, there're actually a whole lot of mysteries floating around in the Marvel Cinematic Universe - not least a couple of very serious questions surrounding how the hell the Hulk ended up looking like Edward Norton, while everyone else stayed the same - but one in particular stands out as an especially peculiar scientific anomaly: Just how did S.H.I.E.L.D. manage to thaw out Captain America?
After all, the man was frozen in ice for 60-odd years, and then somehow woke up in the present day, alive, well, and ready to battle evil-doers all over again.
Which is where one intrepid Tumblr-er, BadScienceShenanigans, comes in - with an absolutely awesome scientific explanation for just how that could have happened.
First off, though:
We Start With One Frozen Super Soldier
Who, though he's been buried beneath Arctic ice for nearly 70 years, is still very much imbued with incredible abilities beyond the possibilities of normal humans - meaning, in other words, it's safe to assume that he was, in fact, still alive, and capable of surviving pretty rough treatment compared to the rest of us. Surely, then, you could just shove him in a giant microwave, and then let radiation do its thing?
So, What's the Problem, Then?
Well, that isn't really how things work in, y'know, science. Y'see, scientists in the real world have become fairly expert at thawing out giant frozen things - such as a 1.5 ton colossal squid - that've been stored in blocks of ice to keep them from rotting on their way back to a lab, and they don't seem to risk cooking them by using anything along the lines of microwave radiation.
Instead, as it turns out, you can just shove the body in question into a giant vat of brine that's kept just above 0°C, or 32°F, which allows the ice surrounding the body to melt, while keeping its core temperature as low as possible. This avoids parts of the creature thawing out completely long before others, and then rotting horribly.
The only snag? Those creatures are already dead - whereas Cap, despite being trapped in a block of ice, was very much alive.
So, How Did They Do It?
Well, as BadScienceShenanigans points out, Cap would, much like the squid, have had to have been kept at a consistent temperature throughout the process - if his extremities had thawed before his heart and lungs, they'd essentially die, leaving him limbless; and were his brain to do the same, he'd have likely suffered permanent brain damage.
So - the theory goes - they would have had to shove Cap into some sort of brine (or, if it was busy being used to store pickles, an anti-freeze solution would do it), and then hook him up to a heart-lung machine to keep keep his blood moving and oxygenated. On the basis that decompression (from the pressure change) was a risk, they'd likely have put him into a hyperbaric chamber, too - and then, in case he regained consciousness early, doped him up with sedatives.
And Then It Gets Really Interesting...
See, at this point, Cap should have been brought to a regular temperature, and be more-or-less safe from the horrifying after-effects of his stay in the world's finest no-star Ice Hotel, but that doesn't mean he'd have been able to just wake up and start punching villainy in the throat.
He would, after all, have still been chilling at something close to freezing-point - so his brine/anti-freeze bath would have been gradually brought up to normal body temperature, with his vital signs being carefully monitored throughout.
And then, the final touch?
Aim a whole bunch of hairdryers at him, and hope all of his organs are still working.
And, as BadScienceShenanigans puts it, most important of all:
"At this point it becomes necessary to dry and style Captain America and put him in period-appropriate jammies to sleep it off in a vintage hospital room. If you think hearing the wrong baseball game tipped him off fast, you should see him wake up with bad hair."
After all, otherwise he could end up running around Manhattan, completely freaking out...while not looking awesome.
And nobody wants that.
What do you think, though?