If vampires—corpses that rise up to suck the blood of the living—sound biologically implausible to you, you’re not alone. They exist purely in legend, as virtually all scientists agree.

But for any vampire believers un­dissuaded by biological facts, a professor has come up with a sec­ond proof of their unreality, using math.

If vampires ever existed in the forms in which movies and books portray them, they would have quickly wiped out humanity long ago, ac­cording to physics professor Cos­tas Efthimiou of the University of Central Florida in Orlando, Fla.
Popular lore passed down through centuries holds that vampire vic­tims become vampires them selves, and launch their own blood-hunts on hapless humans.

To rule out vampires, Efthimiou re­lied on a basic principle known as geometric progression.
“If vampires truly feed with even a tiny fraction of the frequency that they are depicted to in the movies and folklore, then the human race would have been wiped out quite quickly after the first vampire ap­peared,” Efthimiou and a graduate student colleague wrote in a paper posted on line.
Efthimiou supposed that the first vampire arose Jan. 1, 1600, around the beginning of a century during which some of the first important modern writings on vampires appeared. There searchers estimated the global population at that time, based on historical records, as 537 million.

Assuming that the vampire fed once a month and the victim turned in­to a vampire, there would be two vampires on Feb.1, four the next month, and eight the month after that. All humans would be vampires with in 2½ years. “Humans can not survive under these conditions, even if our population were doubling each month,” which is well bey­ond human capacities, Efthimiou said.

But why would one vampire make every month a new vampire, when he can easily drink his hole blood,
and human would die?