I hold that the sun cannot be run by nuclear fusion. For the sake of ClockTower, here is the maths to
prove this.
I'll do it by comparing a human's energy output to the sun.
To compare the per-kilogram energy outputs of the human body and the Sun, we need to know the mass and total power output of both.
Mass of the Sun. This is very close to 2 x 10^30 kg from science data books RE World).
Total power output of Sun. The Sun loses all of its energy by radiation. Above the Earth's atmosphere, 1.5 × 10^11 metres from the Sun, the intensity of radiation is 1370 W m-2. A spherical surface at this distance from the Sun would have an area of 2.84 × 10^23 m2. Assuming that the Sun radiates energy equally strongly in all directions, the total power passing through this surface would be 1370 × 2.84 × 10^23 = 3.87 × 10^26 W. Ignoring any losses from absorption on the way, this gives us an estimate for the total power output of the Sun.
(You can check this result by noting that the surface temperature of the Sun is 5800K, and using the Stefan-Boltzmann law. You get very good agreement).
Mass of a person. People vary a lot in mass, but a typical adult might weigh 65 kg.
Power output of a person. For a person whose weight is steady, their energy output must equal their energy input. People vary a lot in how much they eat, but 2000 kcal, or about 8.6 × 10^6 J, is a reasonable estimate for daily energy input. Divided by the number of seconds in the day, this gives an average power of of about 97 W.
Power outputs per kilogram of the Sun and a human being. We divide the total power output by the mass in each case to get 1.9 × 10-4 W kg-1 for the Sun and 1.5 W kg-1 as the overall power per kilogram of a human being. The human being's power output per kilogram is nearly 8000 times that of the Sun.
So that being the case, if the sun was really nuclear, surely the American's wouldn't have bothered inventing the A-bomb in WW2. They would have just thrown a squaddie out of an aircraft over Hiroshima.
*Edited as it sucked out my superscripts
