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*puts on science communicator hat*
Have any of you read this ABC article, about how physicists have "debunked" the paranormal? The logic given struck me as incredibly flawed but being the good little ex-Phd student I am I looked up the orginal paper (which despite being quite easy to read was not linked from the ABC article, luckily there aren't many Efthimious on arXiv) and while some of it was just badly paraphrased the vampire example is bad maths pure and simple.
Their argument is as follows: every time a vampire feeds it kills one human and creates one vampire. Thus every time the vampire population as a whole feed their numbers will double, quickly leading to an absurd situation with a hundred gazillion vampires and no people.
They haven't disproven vampires, they've "disproven" predators. Since yes, like any predator, vampires reduce the prey population and "reproduce". But according to every vampire legend I'm aware of they can also die. So if the human population got too low, they'd start competing for food and killing each other, not to mention the ever prsent danger of angry mobs of peasants etc. This is your typical predator-prey situation as familiar to any student of basic differential equations (which is what I am, at least about predator prey models).
Admittedly, if the death rate of either species is lower than their "birth" rate then the only stable population size is fractional, ie zero. So to work the vampires can't reproduce as often as the paper assumes (once a month), which does debunk the vampire myths where vampires hunt all the time and any of their victims which aren't staked become vampires too, unless there's a whole barrage of Van Helsings/Buffys/those-cute-guys-from-Supernaturals chasing them over the countryside. But afaict most, or at least many myths only have a fairly small proportion of victims turning into vampires, so as long as that proportion is less than the number of vampires who die due to infighting/peasants/cute guys etc then we're in gravy.
This may seem like a lot of effort to go to for a silly theory, but
(a) This kind of bad science plays into the hands of the pro-supernatural, since they can justifiably point to it as proof that science is "out to get them"
(b) This guy (or girl) is trying to encourage university science lecturers to use this kind of discussion to teach physics (this paper looks interesting too), which I think is a great idea in principle but not if the science is wrong.
(c) I'm a big fat nerd. C'mon, maths + fantasy, how could I resist.
Also, today I got paid to play with hexaflexagons. Admittedly, I would rather have had the day off properly (I was home sick from my shift, but this activity stuff needs to be done asap) but it was still fun if draining. Clearly it got my brain ticking over, though :)
Have any of you read this ABC article, about how physicists have "debunked" the paranormal? The logic given struck me as incredibly flawed but being the good little ex-Phd student I am I looked up the orginal paper (which despite being quite easy to read was not linked from the ABC article, luckily there aren't many Efthimious on arXiv) and while some of it was just badly paraphrased the vampire example is bad maths pure and simple.
Their argument is as follows: every time a vampire feeds it kills one human and creates one vampire. Thus every time the vampire population as a whole feed their numbers will double, quickly leading to an absurd situation with a hundred gazillion vampires and no people.
They haven't disproven vampires, they've "disproven" predators. Since yes, like any predator, vampires reduce the prey population and "reproduce". But according to every vampire legend I'm aware of they can also die. So if the human population got too low, they'd start competing for food and killing each other, not to mention the ever prsent danger of angry mobs of peasants etc. This is your typical predator-prey situation as familiar to any student of basic differential equations (which is what I am, at least about predator prey models).
Admittedly, if the death rate of either species is lower than their "birth" rate then the only stable population size is fractional, ie zero. So to work the vampires can't reproduce as often as the paper assumes (once a month), which does debunk the vampire myths where vampires hunt all the time and any of their victims which aren't staked become vampires too, unless there's a whole barrage of Van Helsings/Buffys/those-cute-guys-from-Supernaturals chasing them over the countryside. But afaict most, or at least many myths only have a fairly small proportion of victims turning into vampires, so as long as that proportion is less than the number of vampires who die due to infighting/peasants/cute guys etc then we're in gravy.
This may seem like a lot of effort to go to for a silly theory, but
(a) This kind of bad science plays into the hands of the pro-supernatural, since they can justifiably point to it as proof that science is "out to get them"
(b) This guy (or girl) is trying to encourage university science lecturers to use this kind of discussion to teach physics (this paper looks interesting too), which I think is a great idea in principle but not if the science is wrong.
(c) I'm a big fat nerd. C'mon, maths + fantasy, how could I resist.
Also, today I got paid to play with hexaflexagons. Admittedly, I would rather have had the day off properly (I was home sick from my shift, but this activity stuff needs to be done asap) but it was still fun if draining. Clearly it got my brain ticking over, though :)
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