Physicists from the University of Leicester have calculated exactly how long it will take for a vampire to drink human blood without putting his victim at risk of death. This is reported in the University Journal of Physics Special Topics, and briefly about the study tells Gizmodo.
It is known that after losing 15 percent of blood, the pulse changes and irreversible changes begin to occur in the human body. With this in mind, physics students calculated how long it would take for 15 percent of the blood to drain from two small holes in the neck.
To make things easier for themselves, the students made several assumptions. First, the vampire's goal is not to kill a person, but to get drunk and escape as soon as possible. Second, they do not take into account the force of gravity (and do not take into account the pressure of the circulatory system on the blood). Finally, they assume that all five arteries leaving the aorta are of the same size and smoothness.
Then, calculating the speed of blood flow through the arteries, young researchers found that a vampire, two bite marks of which are 0.5 millimeters in diameter, will drink 15 percent of a person's blood in 6 minutes 24 seconds. It is at this time that authors of novels and feature films about vampires should be guided.
The relationship between vampires and humans is a fairly popular topic among scientists. One of the most recent and complete mathematical studies was presented in 2013 in the journal Applied Mathematical Sciences. Scientists used, in particular, the Lotka-Volterra model, in which the population dynamics is given by a system of two linear ordinary differential equations with the corresponding initial conditions (determining the number of predators - in this case vampires - and their prey at the initial moment of time).