In “Avengers: Infinity War,” the latest superhero smash-em-up, Captain America, Iron Man and company face off against villain Thanos. Thanos is the baddest of the bad guys to swagger on-screen in 10 years of Marvel blockbusters. Joe Russo, who co-directed the movie with his brother, Anthony, told The Washington Post earlier in May that Thanos is “the Genghis Khan of this universe” with a philosophical bent.
Because superhero blockbusters demand that philosophers must also pulverize, Thanos matches his big brain with bigger purple muscles. He doesn't just look the brutish part. Based on a recent “whimsical by design” analysis, Northeastern University engineering assistant professor Steven Cranford calculated that Thanos is powerful enough to dead-lift the RMS Titanic.
To get to that calculation, Cranford made real molecular models of a fictional cube called the Tesseract. The peer-reviewed journal Extreme Mechanics Letters published his models earlier this month.
The Tesseract, as seen in this “Avengers” movie trailer, is a glowing blue box that Thanos crushes to dust. It's an undignified end for an object included in no fewer than nine Marvel films. (Iron Man's dad sketched it in his notebook.) For our purposes, picture the Tesseract as a very strong, and four-dimensional, crystalline cube.
Cranford, a Marvel movie buff and a materials scientist, has two reactions to such science-fiction inventions as the Tesseract. Frequently he rolls his eyes. Other times, though, he has a thought: Well, that's interesting.
When Thanos demolished the cube, Cranford had one of those thoughts. In his Boston office, the day after the trailer hit the Internet, Cranford fired up a molecular dynamics program to figure out what a four-dimensional box could look like. If he cracked the cube's geometry, he could calculate its material strength. And if he knew the cube's strength, he could calculate how powerful Thanos needed to be to crush it.
Luckily for Cranford, tesseracts are not just gobbledygook churned out of the Marvel Studios machine. They also exist in the pages of geometry textbooks. “It was probably just called that in the movie because it sounded technical or something,” Cranford said. As a square becomes a cube by adding the third dimension, a cube becomes a hypercube — a tesseract — by adding a fourth. Picture a smaller cube suspended perfectly within the center of a larger cube, and you have approximated a tesseract.
Using the modeling software, Cranford began to construct molecular tesseracts, linking carbon atom to carbon atom.
Carbon appeals to theoretical tinkerers like Cranford because the element's atoms bind to one another in multiple ways. With multiple forms come vastly different properties. Consider diamond and graphite. Both substances contain only carbon atoms. Compactly bound atoms lend diamonds their incredible strength. In soft graphite, the carbon atoms are strung looser and farther apart, like sheets of chicken wire.
When a form of carbon gets really weird, materials scientists describe the arrangement of its atoms as an “exotic geometry.” One such form, fullerene, is a spherical cage of carbon atoms. Fullerene cages have been synthesized in laboratories and detected in space. Cranford's computer program, a tool used by many materials scientists, is stocked with similarly exotic geometries. These include graphene, a flat sheet of carbon arranged like a honeycomb's hexagonal chambers, and carbyne, a one-dimensional daisy chain of carbon atoms.
Liberated by sci-fi but constrained within the realistic bounds of the software, Cranford cooked up carbon formations that no laboratory on Earth can synthesize.
Leaning on the program's “reactive force fields” allowed him to create “crazy molecules,” said materials scientist Julia Greer, who studies nanomaterials at the California Institute of Technology and was not a part of this research. “In these kind of simulations you can construct anything you want.”
Still, plenty of the would-be tesseracts fell apart. Too-tight angles broke the carbon bonds. In some cases, the carbon atoms just wouldn't stick, rejected like mismatched puzzle pieces.
But Cranford was successful twice. He designed two new types of stable carbon arrangements and published their theoretical structures earlier this month. Greer, who applauded Cranford's comic-book inspiration, said his playful approach generated “toy molecules.”
One carbon form, connected loops of carbon atoms, Cranford named pentatope. The other form, carbon cubes-within-cubes, he called hypercubyne. This was his carbon tesseract. He tested the strength of his simulated creations, digitally compressing the molecules to see what force buckled their bonds. Ten-billionths of a newton bent the hypercubyne bonds, which, alone, is not very impressive. (By way of comparison, professional boxers punch with forces of up to 5,000 newtons.)
Yet, if hypercubyne molecules were linked together like billions and billions of Lego bricks, its strength rocketed into science fictional digits. A hypercubyne with 6-inch-long edges, resembling the Tesseract in Marvel films, would weigh less than a cube of pencil graphite. But Cranford concluded that squeezing the cube to dust required a force equal to 42,000 tons, or the combined grip strength of 750,000 average U.S. men. (That's about the number of men living in Philadelphia.) Assuming a proportional relationship between grip strength and what the average male American can lift, back-of-the-envelope math suggests Thanos could heft 120 million pounds, 10 million pounds more than the weight of the Titanic.
“Thanos was extremely strong, not just, you know, marginally stronger than a human,” he said.
Greer was not enthusiastic about the way Cranford scaled the strength of the six-inch cube. “The link from the buckling of an individual bond to the strength of the material is a little dubious,” Greer said. If you plucked a few molecules from a chimney brick and compressed those, vs. compressing a brick itself, you would get disproportionate forces, she said. “There's nothing wrong with the toy molecules,” she said, but building the cube makes “a gross leap into the material properties.”
The study's author admitted that assembling individual hypercubyne molecules into a large cube was far-fetched. “To carry the strength from nano to macro, you're basically saying you can put these things together in an idealized way. And the technology is not there,” Cranford said. But he disagrees that it is theoretically impossible. “You would just have to place billions of atoms in the right spot.”
Both Greer and Cranford agreed that science fiction is a useful tool in materials science classrooms. Greer said she could envision using a similar example while teaching her undergraduate students.
Many materials scientists have looked to nature for a creative spark. The sticky pads of gecko feet, after all, inspired the creation of new adhesives. Cranford argues that wall-crawling Spider-Man could be just as inspirational as a lizard. Cranford is eager to poach more ideas from screenwriters and comic book authors, he said. “You don't have to be an engineer to come up with an idea about a material or materials science.”