Thor, love and thunder: what is the magic hammer Mjolnir made of?

armed with Mjolnir, his faithful magic hammer (or scientifically feasible?) that accompanies him everywhere, Thor is about to resume service in Thor: Love and Thunder, the next film in the saga which will be released on July 13, 2022. The opportunity to question the origin, and above all the nature of this mysterious hammer. He calls the thundercan destroy all existing materials, has a mass so big that only Thor can lift it, moreover the latter can recall it at will and the hammer returns to him, by any means. A detail added in the Marvel universe: the character of Captain America was also able to use it during a fight against Thanos. With all that, it seems like the hammer is approaching a lot more of a fantasy element than a sci-fi element. But it is possible to imagine elements that would explain its behavior. Or at least a part.

Origins close to Norse mythology

In marvel universeMjolnir is forged in a star dying by dwarfs, more precisely in a neutron stara star result of the death of a massive star. Two dwarves, the brothers Brokk and Eitri, take care of it, at the request of Odin, father of Thor. But in Norse mythology, the story differs slightly. It all starts when Loki, who is not supposed to be Thor’s brother but Odin’s half-brother, cuts off the golden hair of the goddess. sif, wife of Thor. Threatened by the latter, Loki goes to the dwarves to ask the Ivaldi brothers to forge a new hair, then takes the opportunity to bet with the Brokk brothers and Eitri, other less famous dwarves, that they could not create such valuable items.

As a result, after various adventures, the two dwarves come out, Mjolnir of the forge, in addition to two precious objects, which is then offered to Thor. No question ofneutron star in the forge however, which on the contrary seems to be a classic forge, although it handles a metal Asgardian the Uru. But mythology tells that the handle of Mjolnir would be short because of Loki who, in the form of a fly, would have titillated Brokk’s eyelids until he bled in order to prevent him from operating the bellows, and thus winning his bet. . His brother Eitri was finalizing the run, so it was shorter than expected.

Neutron stars, these monsters of density

Marvel’s choice to forge Thor’s hammer in a neutron star is not so crazy: these stars are so dense that the mass of all of humanity would be contained in a teaspoon of this star! Created during the death of massive stars, neutron stars result from the contraction of the star’s core. With a density of about 10¹⁷ kilograms per cubic meter, if we consider that the volume of the head of Thor’s hammer is 25 x 15 x 15 cm³then its total weight would be 5.6 x 10¹⁵ kilograms, or more than five million billion kilograms! This kind of material obviously cannot be found on Earth, and would find itself caught up in the core by gravitational attraction because much more compact than the crust where the coat.

Moreover, such a hammer would exert a gravitational pull very intense, which is proportional to the mass of the two interacting bodies, and inversely proportional to the square of the distance which separates them. Thus, at about 30 meters, the perceived acceleration would reach 400 m/s²i.e. being immobile at the start, the speed reached in one second would be 400 m/s, therefore greater than the speed of sound ! The tidal forces are also to be taken into account: the part of the body farthest from the hammer is less attracted to it than the part closest to the hammer. A person attracted by the hammer would then see his body deformed, even torn by these tidal forces. Although obviously not realistic, it gives an idea of ​​what a hammer as dense as a neutron star would look like. Except that an object taken from a neutron star, if it were possible, would take a spherical shape because the gravity would balance the distribution of particles.

An emission of gravitons by Mjolnir

But if we stick to a presentation card of the hammer published by Marvel, Mjolnir actually weighs only 20 kilos: no neutron star therefore. Its immense weight could then be explained by another element whose existence has not been proven to date: the graviton. This particle, according to standard modelis the force vector of gravitationin the same way as the photons for the electromagnetic force. If we consider that the people of Asgard, and especially the dwarves of the forge, have scientific knowledge unimaginable for us, then they would be able to fill the hammer with gravitons. This one, then, would “choose” or not emit gravitons according to the person who tries to catch it, by evaluating if this last is worthy or not.

It remains to be seen how Thor can summon him from a distance. Indeed, this one, as soon as it is called, changes the direction in which it was to move immediately towards its possessor. This means that a force is exerted between the hammer and Thor, or at least his hand, which surpasses all other forces that set Mjolnir in motion. This force is obviously invisible: it could then be a “modified” form of gravitation, with a gravitational constant which would be different from G. But be careful, such a force should only be exerted between the hammer and the holder. Hard to imagine, then.

Summon lightning: what if Mjolnir was a capacitor?

Finally, another important element: the summoning thunder. This is where the electromagnetic force comes in. Like gravity, it acts at a distance, but this time not through mass, but through electrical charge. As soon as a particle is charged, negatively or positively, it interacts in a electromagnetic field, which also influences all other charged particles. However, the soil of the Earth is globally negatively charged, while theatmosphere is globally neutral. Summon the thunder would mean summon a storm : thus creating an electric discharge between the upper atmosphere and the ground.

During stormsthe cloud ofthunderstormalso called cumulonimbus, accumulates positive charges at its top, and negative charges at its base. The ground then becomes gradually positively charged, by electromagnetic influence: the negative charges of the cloud repel those of the terrestrial ground and attract to them the positive charges. The lightning occurs during discharges: a current passes between the cloud and the ground, ionizes the particles on its way which then emit light. If elements are high, such as lightning rodsit is they who will be most affected by the lightning, because the current will flow more easily there. In Thor’s case, there’s no need for a cloud: he summons lightning simply by wielding Mjolnir. The only solution: the hammer is capable of becoming electrically charged, in order to induce a current between itself and the atmosphere. In the case of a storm cloud, it is much simpler. By emitting gravitons, but this time only towards the surface, then Mjolnir can become the only possible way out of lightning, the equivalent of a gigantic lightning rod.