The night is dark and full of spoilers. No, really. Big spoilers. If you haven’t watched Sunday’s episode of Game of Thrones, stop reading now.

Ever since his untimely death in season five, GOT fans around the world have been scouring the web, combing through smokescreens and half-truths from the Game of Thrones cast and crew in the hopes of uncovering the fate of everyone’s favorite Crow. Most of us thought Jon Snow would come back, resurrected by magic like Beric Dondarrion in season 3. Others expected Snow would stay down, a satisfying middle finger to obvious plot twists from the show’s writers. Everyone had their theory, but it wasn’t until last week’s episode that the 10-month saga finally came to an end.

After five tense minutes, Jon Snow’s once-lifeless corpse took several gasping breaths. The bastard Stark lives. At least, for now. (Kit Harington says he’s sorry, you guys. It’s been a tough go.)

All it took was a bit of magical hoojeebaba – a Valyrian resurrection prayer, to be exact – from Melisandre to bring Snow back to life, but that got us thinking, could it have happened without magic? What are the limits to human resuscitation? And what would the extreme conditions at The Wall mean for Jon Snow’s body?

What is dead, may never die?

From Frankenstein’s monster to the death of Superman, nerd kind has been drowning in pop culture resurrections for decades. But is it actually possible to come back from the dead? The short answers is…yes and no.

The concept of resurrection is fuzzy because it all hinges on how you define death in the first place. If clinical death is defined by the stop of blood circulation, a patient can be revived anywhere from seconds to hours after “death.” If the brain, however, is the limiting system, a shut-down is met with minimal chance of recovery. Under the current definition, a clinically dead patient must display:

• An isolelectric — flat — EEG in two recordings 24 hours apart
• No reflexes
• Fixed and dilated pupils
• No spontaneous respirations
• Zero trace of sedating drugs in the blood for 96 hours
• Hypothermia ruled out as a cause of any of the above criteria

When all of these factors are taken into consideration, no human patients have been “brought back from the dead.” But as you can see, our ringlet-topped wilding-avenger has one thing going for him: it’s mother cussin’ cold at The Wall.

You are frozen, Jon Snow

There’s a reason corpses are cold-stored at the morgue: chilling slows the decomposition process, and prevents wounds from festering. In most cases, bodies are kept between two and four degrees Celsius (36-39°F). This “positive storage”  is used for keeping bodies up to several weeks, but it merely slows decomposition. When a body hasn’t been identified, or is the subject of a forensic investigation, it’s moved into “negative storage,” which, you guessed it, drops below freezing. At negative 50 degrees Celsius (-58°F), decomposition is slowed to a near-halt.

It’s tough to extrapolate the average temperature at The Wall, a place “so cold that a man’s laughter freezes in his throat,” but some of the northernmost human-inhabited regions on Earth regularly hit temperatures below minus 50. Oymyakon, Russia, for example sits at a 63.4608° N, 142.7858° E latitude, just a few hundred miles from the Arctic Circle. One February in 1933, when Oymyakon earned its title as the coldest place on Earth, the mercury dropped to an impressive -90° F.  So, it is plausible that Jon Snow’s wounds would remain clean during the time between his death and return. This much at least, checks out.

In the human body, cold also shuts down metabolism, which can be a saving grace for hypothermic patients. When cells are deprived of oxygen and nutrients, say, after the heart stops beating, they quickly begin to self-destruct. Brain cells are the most sensitive to deprivation, and within five to 10 minutes of cardiac arrest, neuronal membranes will begin to rupture, spilling their contents into the surrounding tissue. Once that happens, even a mad scientist can’t put Humpty Dumpty back together again – but as as Outside’s Peter Stark explains, “the chilled brain needs far less oxygen-rich blood and can, under the right circumstances, survive intact.”

Real-life cases

A bloody end

Even if the cold kept Snow alive (or at least neurologically functional) longer than would have been possible had he been stabbed to death in King’s Landing, there’s another important factor to consider when determining the feasibility of his resurrection: blood loss. If there’s anything Mad Max’s blood bag antics taught us, it’s that regardless of antihero status, here on Earth, you simply can’t survive without the blue gold pulsing through your veins.

Snow was stabbed at night, and not moved until the following morning when his brothers in the Night’s Watch discovered his lifeless corpse. Some have speculated that during this time, the cold would have slowed blood flow to his wounds. While that may be true, we can clearly see that at least in the moments after death, this was not the case.

In dire cases where massive blood loss caused cardiac arrest, doctors have replaced patients’ blood with ice-cold saline solution in hopes of buying time to repair the wounds before cells and organs begin to break down. But even with the greatest medical advances at our fingertips, outside of hospital settings, the resuscitation rate for patients who’ve experienced cardiac arrest due to blood loss is less than 10 percent. The reality is that Jon Snow likely lost too much blood for a successful revival.

All in all, we’re declaring Snow’s return a “no-go” in our realm, but it’s amazing to think that had Jon not been stabbed, his body may have been preserved enough to be revived after the few hours Melisandre and Ser Davos were deliberating.

Night gathers, and now my revenge begins. 

Will Snow stay alive? Is this all an attempt to get our hearts fluttering, only to crush them once again? Let us know your thoughts in the comments below.

Images: HBO, Smithsonian