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Science Behind the Fiction: Making Thor's Infinity War hammer with a neutron star

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May 1, 2018, 12:54 PM EDT (Updated)

Can you believe it finally happened? After all this time, Thanos has arrived. Ten years ago tomorrow, Iron Man, hit theaters and set us on a path that led us to right here. After a decade and 19 movies, we've entered into a reckoning.

Avengers: Infinity War marks the culmination of the Marvel Cinematic Universe. Every thread laid down since the beginning has come together. We finally get to see The Guardians team up with the heroes of Earth. All the powers of science, gods, and magic come together to defend the universe. We even got Spider-Man. But at what cost?

**Spoiler alert: There are spoilers for Marvel's Avengers: Infinity War below**

The film opens where Thor: Ragnarok ended. The ship that was the last hope of Asgard is boarded by none other than Thanos and his Black Order. They do away with half the population, in accordance with Thanos' modus operandi then, after doing away with those closest to the God of Thunder, leave him for dead.

Thor was already in a bad way, having lost Mjolnir, his home, and an eye to the events of Ragnarok. His position is not much improved being marooned in the emptiness of space.

Enter the Guardians of the Galaxy, answering a distress call and finding Thor splayed out on their windshield like so many mosquitos. He knows what Thanos is up to. While the rest of the heroes of Earth and elsewhere are getting it together, Thor is doing everything he can do bring Thanos down in the only way he knows how: sheer muscle, chutzpah, and a chunk of metal to the face.

The Guardians splinter; Starlord, Gamora, and Drax chase Thanos across the cosmos while Rocket and Groot accompany Thor to Nidavellir, the home of the forge that created Mjolnir.

When they reach the forge, orbiting a neutron star, they find the place abandoned and cold. Everyone is missing, save for Eitri (Peter Dinklage) the only remaining dwarf with the knowledge to create new weaponry capable of defeating Thanos.

The mold for a new weapon, something capable of destroying the Mad Titan, is intact. But in order to complete the making, the forge must be fired. The star has gone cold and Thor must start it turning again.

Thor flings their ship, with Rocket and Groot inside, and uses the momentum to start the rings around the star turning, firing the star. When the iris around the neutron star closes, Thor holds it open, allowing the energy to flow and melt the metal that will become Stormbreaker, his new weapon. Thor takes a beating, bearing the brunt of the full force of a neutron star, but the ax is forged. Which brings us to the questions we're here for: what exactly is a neutron star, how much energy does it produce, could it be used as an energy source, and what would it do to a person caught in its midst?

Neutron Stars

In the cosmic scheme, stars are some of the longest-lived things there are. They accrete from cosmic dust in nebulae and form, before planets. Then, billions of years later, they die and take the planets with them. Depending on their makeup, they die in several different ways. For stars of a particular size, they explode. They scatter their guts through the void, offering up complex atoms for future systems.

Some of them collapse into black holes and some of them, after fusing all of their innards to iron, continue to collapse. Without the outward force of fusion to balance, they crumple, falling forever inward until their very positrons and electrons combine into neutrons.

When that happens, they reach a sort of equilibrium, a neutron star. Imagine the mass of our sun, compressed into the size of Manhattan Island. A body so dense that a teaspoon full would weigh a billion tons.

Then they spin incredibly fast. Due to the property of conservation of angular momentum, they spin faster and faster as they get smaller, in the same way a figure skater increases their spin as they pull their limbs in. Some neutron stars spin more than a hundred times per second. It's stupid fast.

Could they land?

In a word, no. The gravitational forces near a neutron star are staggering. They may be small but they retain a lot of the mass of their previously massive bodies. The gravitational forces of the average neutron star are so massive that, if you were sitting on the surface, you'd have to achieve between a third and half of light speed to escape its pull.

If Thor were to have landed on the rings of Nidavellir, he'd have been pulled into the center of the star and smashed into a finite Thor flavored two-dimensional paste... And that's not to mention the magnetosphere. That might sound like the powers of a certain other Marvel character we're not allowed to mention in the MCU but it's a very real phenomenon.

According to astrophysicist Paul Sutter, if you were to get within 600 miles of certain neutron stars the magnetic sphere would cause you to dissolve faster than Thanos could snap his fingers.

Energy output

Assuming Thor and his tag-alongs could survive the forces of being near so massive an object, could they actually use it as an energy source to fire a forge? I mean, yeah. Thor would have been ripped apart, torn down to his molecular parts, holding the iris open. But the energy output of a neutron star is more than enough to melt metal.

Neutron stars are capable, in some instances of producing gamma-ray bursts, the most violent form of energy known. These bursts are equivalent to more than the energy expended by our sun in its lifetime. You could melt metal pretty darned fast, no matter its composition. In truth, Thor wouldn't have had to hold the iris open so long, but he would have be long dead anyway.

Chalk it up to his Asgardian makeup that he survived and let's just hope the rest of our heroes are as lucky.