Hurrah! The animals could have floated two by two according to physicists

University of Leicester students show Noah’s ark would have been strong enough to carry pairs of each animal species

This month, the classic biblical tale of Noah’s Ark will receive a Hollywood makeover with the release of the movie Noah - and Physics students at the University of Leicester have found that the ark would have indeed been able to float with all of the animals on board.

A group of fourth year master’s students from the Department of Physics and Astronomy have calculated that Noah’s ark, built to accommodate at least two of every animal species, would have floated using the dimensions ordained in the Bible.

In the book of Genesis, chapter 6:13-22, Noah is commanded to build an ark to survive a flood. Noah is provided exact dimensions for the boat which should be: 300 cubits long, 50 cubits wide and 30 cubits high and should hold Noah, his family, and at least two of every species of animal for the duration of the flood.

Using these dimensions, Archimedes’ principle and suitable approximations, University of Leicester Physics students Oliver Youle, Katie Raymer, Benjamin Jordan and Thomas Morris tested the instructions and were surprised with their results.

Research lead, Oliver Youle, 22, from Nottingham, explained: “Every object when immersed in a liquid has an upwards force acting against it – a buoyancy force; it also has a weight acting downwards – a downwards force, and in order for it to float, these two forces need to be equal.”

Student Benjamin Jordan, 21, from Bury St Edmonds, said: “Using the dimensions of the ark and the density of the water, we were able to calculate its buoyancy force, which, according to Archimedes’ principle, is equal to the weight of the volume of fluid the object displaces. This meant we were then able to estimate the total mass the ark could support before the gravitational weight would overcome the buoyancy force, causing the ark to sink, which we calculated as 50.54x106kg.”

The students faced a number of challenges when trying to calculate the buoyancy force of the ark:

  • The dimensions were provided in cubits, an archaic measure based on the distance between the elbow and the tip of the middle finger. Historical records provide different readings for one cubit and so the students settled on an average of the ancient Hebrew value (44.5cm) and the ancient Egyptian value (52.3cm), using 48.2cm for their calculations.
  • Noah was commanded to make the boat out of ‘gopher wood’ and in order to calculate the weight of the empty ark, they needed to know the density of the material the boat was constructed out of, however, there is no modern-day gopher wood. English translations of the Bible refer to cypress wood instead, and so this was the material that the students used.
  • In order to calculate the overall downward force of the ark, the students needed to know the mass of the animals on board. Previous research has suggested that the average mass of an animal is approximately equal to that of one sheep, 23.47kg, which was the figure used.

Oliver added: “Our conclusions were that the ark would support the weight of 2.15 million sheep without sinking and that should be enough to support all of the species that were around at the time.”

Student Thomas Morris, 22, from Chelmsford, said: “You don’t think of the Bible necessarily as a scientifically accurate source of information, so I guess we were quite surprised when we discovered it would work. We’re not proving that it’s true, but the concept would definitely work.”

Previous research has suggested that there were approximately 35,000 species of animals which would have needed to be saved by Noah, enabling the students to conclude that the dimensions given in the Bible would have allowed Noah to build an ark that would float with all of the animals on board.

It is a separate matter whether all of the animals would fit inside an ark of these dimensions  – the physics students were simply calculating the buoyancy of the ark.

The students presented their findings in a paper for the Journal of Physics Special Topics, a peer-reviewed student journal run by the University’s Department of Physics and Astronomy. The student-run journal is designed to give students practical experience of writing, editing, publishing and reviewing scientific papers.

Course tutor, Dr Mervyn Roy, a lecturer in the University of Leicester’s Department of Physics and Astronomy, said: “The aim of the module is for the students to learn about peer review and scientific publishing. The students are encouraged to be imaginative with their topics, and find ways to apply basic physics to the weird, the wonderful and the everyday.”

Student, Katie Raymer, 22, from Whitstable added: “Every other module that we do is a lot more serious and so the Physics Special Topics module was nice to do something different – allowing us to apply basic physics to something a bit more fun.” 

Full bibliographic information

Journal of Physics Special Topics, The animals float two by two, hurrah! O. Youle, K. Raymer, B Jordan, T. Morris, Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH. November 11, 2013

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