Your favourite superhero Superman can accomplish some pretty spectacular feats but he may be breaking a fundamental law of physics while doing so!
Superman would not be able to get all the energy he needs to fly from the sun alone, as suggested in the DC Comics, researchers have found.
University of Leicester physics students showed that Superman is able to use 6,560 times more energy than he would feasibly be able to absorb from the sun's rays.
The superhero gets his energy from the electromagnetic radiation contained in the light from our sun - giving him various super powers here on Earth, including superhuman strength and the power of flight.
The students therefore decided to test his solar cell efficiency - the measure of how much energy output solar cells give out for each unit of energy they absorb from the Sun.
This equation is used to calculate the efficiency of regular solar cells - such as photovoltaic panels on the roofs of buildings.
The most efficient solar cells on Earth have a 44.7 per cent efficiency, according to this equation.
Using a rough estimate of the area of Superman's body in contact with the sun's rays, the team was able to work out that he absorbs 1096 joules per second from the sun.
The team then needed to calculate the amount of energy Superman actually uses in flight to overcome drag forces. They found that - for an eight hour flight at an altitude of 30 km - he would use 207 billion joules of energy to overcome drag forces and stay in the air over the course of the journey.
Based on the two figures, the students calculated that Superman has a solar cell efficiency of 656,000 per cent - in other words, he used far more energy in flight than he can possibly absorb from the Sun.
According to the law of conservation of energy, energy cannot be created or destroyed within a closed system - it can only be converted. It would therefore be impossible for him to be getting all of his energy from the Sun.
The students note that he must be obtaining energy from alternate sources. Alternatively, they said it is possible that instead of immediately using all energy he obtains, he stores the energy for future use.
The findings were published in the Journal of Physics Special Topics, a peer-reviewed student journal run by the University's Department of Physics and Astronomy.