How hot is the Human Torch?

The Human Torch is a famous and well-known Marvel comicbook character. He first appeared as an android in Marvel Comics #1 in 1939. Later on Stan Lee and Jack Kirby reinvented the character in Fantastic Four #1 in 1961, as Johnny Storm. Johnny Storm is the brother of Sue Storm and a member of the Fantastic Four. After the incident of the unauthorised space mission with Reed Richards, Sue Storm and Ben Grimm, he gained the ability to set his body on fire. His main abilities consist of pyrokinesis and flying. In the following discussion I will mainly concentrate on Johnny Storm in his first appearances, but similar arguments can be made for the other appearances of the Human Torch. The main question of this post is how hot is the Human Torch? To give an estimate of his temperature I will use the theory of black body radiation.

The Human Torch has in his early appearances a deep red coloring. The specific color is hard to deduce and differs sometimes, but the inner flames of his body are red. Because we are only interested in estimating his body temperature, we will assume that he mostly emmit radiation in the red-color region of the electromagnetic spectrum. I first thought to get the specific wavelength from the RGB-color of a comicbook color, but it is actually not so trivial to convert RGB-colors to wavelengths. So for now we’re going to assume Johhny emits mostly radiation with a wavelength around the 720 nm . I will sometimes give a rough error estimate during my calculation. Just to see how the errors propagate trough the calculations and how precise our final answer is.

The theory of black body radiation was a very important milestone in the beginning of Quantum Mechanics. We will assume that the Human Torch is a black body, this assumption is also made by astronomers to study stars. There are corrections possible, because Johhny isn’t an ideal black body, but we’re not going to account for this deviation. So the distribution of radiation of a black body is given by the Planck-spectrum. To find out the temperature of our black body, we will be interested in the peak of this black body spectrum. We assumed that Johhny will mostly radiate red light, so the peak will be around our estimated wavelength. Now we can us Wien’s displacement law to estimate the temperatur of the Human Torch. Wien’s displacement law gives a connection between the temperature of the black body (T) and the peak of the radiation spectrum (lambda). It’s given by:

If we plug in our estimate for the peak wavelength, we will get an estimate for the temperature of the Human Torch.

For reference the Sun is 5,778 K, so the body temperature of Johnny is around 70% of the Sun’s temperature. We can go one step further and ask : How much energy does the Human Torch radiate per second? For this question we will need the Stefan-Boltzmann law. It states that the power radiated by a black body (B) is proportionate to the fourth power of the temperature (T) of that black body.

Plugging in our found estimate for the temperature, we get an estimate of :

To get the total power radiated by Johnny we need to have his body surface area. The mean body surface area of an adult man is around 1.9m^2. So now we multiply our previous answer with the surface area of Johnny to find the total power radiated.

This is a huge number! According to Wolfram Alpha one bar of milkchocolate weighs around 43g and contains 950kJ of energy. A quick calculation gives us that the Human Torch needs to eat 30 bars of chocolate give or take 8 per second! That’s a lot of chocolate and a very efficient way to literally burn calories.