Journal of Physics Special Topics an Undergraduate Physics Journal
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Journal of Physics Special Topics An undergraduate physics journal P3 1 Forging Stormbreaker H. Conners, S. Lovett, P. Patel, C. Wilcox Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH October 24, 2018 Abstract This article investigates the scene in the film \Avengers: Infinity War" where Thor attempts to harness the energy of a neutron star to forge a new weapon, \Stormbreaker". We estimate that 8.4x1025 J is required to forge the axe and Thor himself would have to withstand 8.8x1024 J. Introduction output of the star we use Equation 1, the Stefan- In the 2018 film \Avengers: Infinity War", the Boltzmann Equation: superhero \Thor" attempts to forge a battleaxe, L = σA T 4 (1) \Stormbreaker" to defeat the Villain \Thanos", Star by harnessing the power of a fictional neutron Where L is luminosity (power), σ is the Stefan star, \Nidavellir" [1]. Thor uses a forge along Boltzmann Constant, AStar is the surface area of with a Dyson Sphere like structure to focus the the star and T is the surface temperature of the energy from the star through an \iris" to create star. We used Equation 2 to calculate the star's a beam of energy. This is concentrated on to surface area. a furnace where a pot of metal ingots is stood. During the scene Thor is pictured holding open A = 4πr2 (2) the iris and absorbing some of the energy inci- Star dent on the forge. By comparing the star in the Where r is the radius of a sphere. Using the ra- film to one in reality, the amount of energy re- dius of RX J1856.5-3754 in Equation 2 we get the quired to make Stormbreaker can be estimated surface area as 1.3x109 m2. Using this value we as well as how much energy Thor is able to ab- found the total radiative power of the star to be sorb. 4.6x1024 W. We assumed all energy is absorbed and focused through the iris as a side character Theory \Eitri" states \You are about the take the full We have made the following assumptions re- force of the star"[3]. From this we will calculate garding the neutron star: it is a perfectly spher- how much of that energy is absorbed by Thor ical blackbody and is identical in radius, mass and how much is used to forge Stormbreaker. and surface temperature to RX J1856.5-3754; a We assumed Thor absorbs all incident energy. typical neutron star nearby to Earth. The mass An approximation for the surface area of Thors of the neutron star is given as 1.8x1030 kg, the body exposed to the focused energy was made radius as 10,000 m and the surface temperature using the Mostellar Equation [4]. The Mostellar as 500,000 K [2]. To calculate the total power equation can be seen below in Equation 3: we find that the total energy absorbed by Thor, r 24 hm EThor is 8.8x10 J and the energy required to ABody = (3) 25 3600 forge Stormbreaker, EStorm is 8.4x10 J. Where ABody is the body surface area of per- Discussion son, h is the height of person in cm and m is As expected the amount of energy used to the mass of person. We assumed the height and forge Stormbreaker and that which Thor ab- mass of Thor to be 100 kg and 200 cm respec- sorbed is implausible. We have assumed all tively. Inputting into equation 3 gives ABody as energy from the star had been been perfectly 2 2.4 m , whilst this is the total surface area of absorbed by the Dyson Sphere and transferred Thors body, the incoming energy is only incident without heat dissipation into the beam focused upon the rear half of his body so the exposed through the iris. Realistically, heat dissipa- 2 surface area becomes ABody=1.2 m . To find ex- tion would significantly lower the energy focused actly how much energy is absorbed by Thor we through the iris. Also both the furnace and Thor also need the cross sectional area of the beam of have been treated as perfect absorbers. We also energy. We approximated the beam to have a ignored the immense gravitational forces near a diameter, D of 4 m, twice that of Thors height. neutron star, which would make the whole sce- Finally we assumed the beam to have a circular nario impossible. area. Conclusion 2 With our estimates of the neutron star we ABeam = πr (4) were able to calculate the amount of energy Where ABeam is the cross sectional area of the needed to forge Stormbreaker. This would re- beam and r is the radius of cross section. Using quire 8.4x1025 J. During this process Thor would the fact that r = D=2 we used equation 4 to give absorb 8.8x1024 J. However, many assumptions us the cross sectional area of the beam as Abeam= have been made regarding the neutron star, the 12.6m2. Taking the area of Thors' body exposed Dyson Sphere and the furnace. We also assumed to the beam as a ratio of the area of the beam that Thor has absorbed all energy incident upon and multiplying this by the power of the beam, him. For further study we suggest investigating we calculate how much power Thor receives and the absorption coefficient for a human, as well how much goes on to forging Stormbreaker. Us- as considering the efficiency of the process and ing the above values Thor approximately absorbs applying both to the calculation. 4.4x1023 W or about 10% of the total power out- References put of the star. This means that 4.2x1024 W [1] carries on in the beam to forge Stormbreaker. http://marvelcinematicuniverse.wikia. [Accessed 3 Octo- However we require the total energy absorbed com/wiki/Stormbreaker ber 2018] by Thor and the total energy required to forge Stormbreaker. Using Equation 5 we can cal- [2] https://en.wikipedia.org/wiki/RX_ culate the total energy from the values for the J1856.5-3754 [Accessed 3 October 2018] power. [3] http://transcripts.wikia.com/wiki/ E P = (5) Avengers:_Infinity_War [Accessed 3 t October 2018] Where P is power, E is energy and t is time interval. As seen above we need the time interval [4] https://en.wikipedia.org/wiki/Body_ in which Thor is in the path of the beam. Ap- surface_area [Accessed 3 October 2018] proximating t is 20 seconds. Using Equation 5.