Princess Bride
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Credit: 20th Century Fox

Science Behind the Fiction: The very conceivable science of The Princess Bride

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Jun 7, 2018, 11:00 AM EDT

There’s something about the '80s that lifts it above other times in recent history. It’s like an entire decade met a demon at a crossroads and sold its collective soul. In exchange for the Cold War and New Coke, we got the single greatest concentration of pop culture the world has ever seen. Or maybe that’s the rose-colored glasses talking.

Nostalgia for times gone by seems to be at an all-time high with the popularity of properties like Ready Player One, Stranger Things, and the recent reboot of IT. There’s some dispute among experts as to the utility or danger of nostalgia obsession.

All that aside, it’s hard to dispute the cultural capital laid down in the years between the Mount St. Helens eruption (1980) and the launch of the Hubble Space Telescope (1990).

The world has changed a lot since 1987. Allow yourself, if you will, to fall down the well into time. The Bangles’ “Walk Like an Egyptian” and Starship’s “Nothing’s Gonna Stop Us Now” topped the Billboard charts. The United States and Russia were testing nuclear weapons. Pope John Paul II toured Dodger Stadium. And The Princess Bride was released to modest success, earning $30.8 million from its $16 million budget.

While “Walk Like an Egyptian” has been relegated to the wastebin of weird songs that have an unexplained obsession with other cultures (see “Kung Fu Fighting” by Carl Douglas) and “Nothing’s Gonna Stop Us Now” is considered by some to be the dying breath of the once-great Jefferson Airplane (no matter how many fond memories you have of eating root beer barrels and watching Mannequin with your dad), The Princess Bride has enjoyed a love affair with the public that has only increased with time.

Despite a middling theatrical release, The Princess Bride found a second wind on home video that’s never really abated. If you’re a child of the '80s or '90s, you likely don’t remember the first time you saw The Princess Bride, it was just a part of your cultural lexicon, the sort of referential material that spent like money on the courtyard at school.

The Princess Bride succeeds in its ability to balance romance (it is, after all, a kissing story) with swashbuckling adventure, interesting characters, and endlessly quotable dialogue. It lives on because the characters, situations, and stakes feel real. But how real is it, really?

The many varied adventures of Westley and Buttercup

The story starts ordinarily enough, as both Buttercup and Westley lead uneventful lives on a workaday farm. Their relationship is one of employee and employer. While a burgeoning love grows beneath the surface, the two interact through menial tasks laid on Westley, the farmboy, by Buttercup.

Westley famously responds to each of Buttercup’s demands by saying “As you wish,” and Buttercup soon learns that when Westley says this, what he really means is “I love you.”

As proclamations of love are wont to do, this sets their lives on end. Westley leaves the farm in search of his fortune in hopes of returning to provide Buttercup the life he imagines she deserves. In so doing, the two of them embark on a world no longer ordinary, a world populated by giants, evil princes, marauders, civil conflict, sea monsters, poison, biological anomalies, and much more.

When news returns that Westley’s ship was encountered by the Dread Pirate Roberts, Buttercup assumes Westley is dead and, after five years have elapsed, accepts a proposal of marriage from Prince Humperdinck.

Before the wedding can go off, Buttercup is kidnapped by a band of outlaws led by the Sicilian Vizzini. In his employ are a giant called Fezzik and a Spaniard called Inigo Montoya. While on the run, the outlaws are pursued by a mysterious man in black who finally catches up to them on the face of the Cliffs of Insanity. After winning a fencing duel against Inigo Montoya and besting the giant, Fezzik, the man in black pursues Vizzini in pursuit of the captured Buttercup.

A battle of wits… for the princess… to the death

The man in black finds Vizzini perched at a stone, holding a blade to the neck of a blindfolded Buttercup. They have, as the man in black states, reached an impasse. Vizzini knows he can’t compete physically, so the man in black challenges him to a battle of wits, one that involves a fictional poison, iocaine powder.

Iocaine powder can be sniffed but not touched. It is odorless, tasteless, dissolves instantly in liquid, and is among the more deadly poisons known to man, or so the man in black claims. After their two minds do battle, Vizzini and the man in black both drink. Vizzini dies instantly. It’s revealed that both glasses contained powder, though the man in black had spent a number of years building an immunity to iocaine powder. Which begs the questions, is there any such poison, and is it possible to build a tolerance?

Poison resistance

Iocaine powder is a fictional poison; however, there is at least one poison that has some of the characteristics the man in black attributes to iocaine: arsenic trioxide. It is odorless, tasteless, and dissolves instantly in liquid; however, it’s also toxic upon inhalation or contact with the skin. Using this compound, Vizzini would likely have died just about as soon as the man in black convinced him to sniff from the container.

While sniffing from the container might have inhibited Vizzini with a less than lethal dose, he still would have had to combat convulsions, cardiovascular problems, and coagulation of the blood, among other symptoms, leaving the man in black with plenty of time to slink off with Buttercup.

Let’s assume that Vizzini was not affected by the brief sniff of the container and was only in danger of actually ingesting the dissolved poison. Could the man in black have actually developed an immunity?

Not quite. Immunity to poisons isn’t something we seem to be biologically capable of. Instead, we are able to develop a sort of tolerance or resistance to certain compounds. In fact, it’s likely that you have some tolerance to a relatively common poison: alcohol.

That euphoria you feel after a few drinks, that’s the result of a moderate dose of poison. It’s the reason a few more drinks results in disorientation and vomiting and the origin of the term “alcohol poisoning.” Regular ingestion of alcohol can increase your tolerance, even to the point where what might be dangerous for some is non-dangerous for you. You might even be dependent on alcohol on a daily basis such that sudden abstinence can have deadly consequences.

Similarly, humans can develop a tolerance to other poisons.

The notion of building a tolerance to poisons goes back at least to Mithridates the Great, king of Pontus from 120 - 63 B.C. After the assassination of his father, Mithridates was wary of attempts on his life. As a result, he made efforts to make himself immune to poisoning attempts. This involved dosing himself with sub-lethal doses of poisons.

As a result, Mithridates ultimately attempted suicide by poison after failing to raise a new army. This attempt failed, due to his resistance to poisons, while killing his daughters, and Mithridates had to ask a subordinate to kill him rather than suffer the indignity of capture.

In practice, Mithridates’ method is not effective against all compounds. In fact, some toxins can build up over time such that micro-dosing will result in death. The important factor is the toxin in question. By convincing the liver or immune system to produce ways of combating particular compounds, it is possible to build a resistance to certain poisons or toxins. One such practice can be found in snake handlers of Burma who undergo weekly tattooing mixed with snake venom, which is believed to give them some resistance to bites.

In reality, you'd be better off tricking your opponent than attempting to make yourself resistant to an ingested toxin.

Flame spurts, lightning sand, and rodents of unusual size

After defeating Vizzini, the man in black is revealed to be both the Dread Pirate Roberts and Westley. Buttercup, having realized him to be her lost love, follows him into the Fire Swamp in an attempt to avoid capture by the pursuing company of Prince Humperdinck. Therein they discover the three dangers of the Fire Swamp: flame spurts, lightning sand, and rodents of unusual size.

Each of these has some foundation in reality. Flame spurts are, in the context of the tale, pockets of the swamp that burst forth in fiery gusts. In real life, swamp gas is the common name for biogas, which are the result of gases produced by the breakdown of organic matter in anaerobic environments.

It is possible, under the right circumstances, for these to burst into flame.

The closest real-world equivalent to lightning sand is quicksand, which occurs in similar environments as swamp gas with sand, silt, or clay being saturated by liquid such that it cannot support additional weight. Despite popular depictions, it is not likely that you would drown or be submerged by quicksand. Instead, you would sink until your center of gravity was submerged. So long as you could keep a cool head, it’s not unlikely that you would escape.

Rodents of unusual size, however, are entirely real. Rodents are a group of mammals characterized by upper and lower pairs of teeth that never stop growing; they are the largest class of mammals, constituting roughly half of all mammals.

The most well-known types of rodents are small -- mice, rats, and rabbits, though larger species exist and thrive. Capybaras are the largest known living rodent, standing two feet tall and living in groups, similar to the ROUSs found in the fire swamp.

That’s where the similarities end. ROUSs are violent, aggressive pack hunters. Capybaras, by contrast, are relatively docile. Which isn’t to say that there was never a rodent more terrifying than described in the film.

Paleontologists have uncovered an ancient rodent, Josephoartigasia monesi, discovered in Uruguay, that lived roughly 4 million years ago and was larger than a bull, estimated at more than a ton in weight. Westley might have doubted their existence, but this particular giant mouse was very real. "Imagine a mouse with the body weight of two racehorses — it's very impressive indeed," researcher Ernesto Blanco, a biomechanicist at the Uruguayan Institute of Physics in Montevideo, told LiveScience.

The Princess Bride might have cemented itself as one of the great fantasy stories of this, or any, generation, but it exists well within the realm of possibility. While many of its story elements might seem... inconceivable, it's the foundation in reality, both scientific and emotional, that make it so endearing.