Eugene Volokh links to an interesting example of the role computer evidence plays in modern murder trials, but that’s not what caught my attention. This did:
On the same date Jensen was planning a future with Kelly, his home computer revealed Internet searches for botulism, poisoning, pipe bombs and mercury fulminate. A website was visited that explained how to reverse the polarity of a swimming pool — the Jensens had a pool — by switching the wires around, likening the result to the 4th of July.
Okay, waitaminnit. This can’t be right. This has to be talking about reversing the polarity of the electrical current running through the pool’s electrically-powered filter or perhaps a robotic cleaner, not “the polarity of a swimming pool” itself. Pools, in my limited high-school-physics knowledge, don’t possess electrical polarity, nor will switching that polarity lead to some spectacularly murderous electrical result. And even reversing the polarity of a filter or cleaner wouldn’t electrocute the next person to hop in the pool, right? It’d just burn out the motor maybe.
Am I wrong here?
Ow ow ow, that made my brain hurt. Water is normally ionized, this is because of how the molecule is structured and is what causes surface tension. That said, I have never heard of switching the polarity of water. Like you I’m thinking they must be talking pump, and even then that would reverse the direction of the water flow or cook the pump.
If somehow you got a current flowing from one side of the pool to the other maybe it would use the body as a better conductor but I doubt it.
Just water itself is actually an amazing insulator, it’s the impurities in it that make it a conductor.
I would also suspect that creating a condition where the pool could be lethal would also create a large enough fault that your circuit breaker would most likely open, if you had any differential protection it would definitely open (GFCI).
Not to be morbid or anything, but if you’re going to kill someone there’s much less complicated ways to do it.
That is absurd, as a physicist this makes no sense. Someone clearly was clueless when speaking of this.
Water is not normally ionized, if a substance is ionized this means the electrons have been removed from the substance.
If water was normally ionized it would have a huge positive charge, water is typically neutral, as most things are. Think of this, if all the electrons from a human body were removed, the magnetic repulsion the human’s body would have would be strong enough to move the entire planet across the solar system almost instantly!!
I came across your blog while trying to search on this same thing. The best I’ve been able to come up with so far is that salt water pools use a chlorine generator that the water is pumped through, which performs some electrolysis to break down the salt, producing HOCl and NaClO — more or less the same chemicals used in traditional swimming pools. Instead of having to add chemicals to your pool to chlorinate it, you just add salt (besides dealing with any acidity issues I presume).
A by-product of this process is that the plates in the chlorine generator get calcified over time, reducing their effectiveness. As such, many such units with automatically reverse their polarity for short periods to decalcify the plates. From what I’ve been able to find, doing so has the side-effect of reducing the life of the generator.
(http://en.wikipedia.org/wiki/Salt_water_chlorination).
I fail to see where the 4th of July comes into play here however — it doesn’t look like this would produce any sort of catastrophic failure, merely the failure of an expensive to replace pool component. So my search for answers continues.
Yaztromo, happy as we are to be of service to the creatives in the homicidal community, bear in mind what happened to the last guy to search for this method…. [rolleyes] And I gotta tell ya, man, it’s way too complicated; save yourself the hassle. Ricin and DMSO, brother, ricin and DMSO…. ;p
Reversing the electrical polarity wouldn’t change the direction of the motor anyway unless it was a large commercial pool with a three phase pump. Residential pools are almost always single phase ant the pump mechanism is mechanically coupled to the drive motor and not electrically coupled. Yup much less complicated ways to do it.
Excuse me, I have to go reverse the polarity on the main deflector dish now… 🙂
You’re all wrong. Clearly the intent was to change the water to anti-water, thereby setting up a scenario where the intended victim would enter the pool and instantly have all the H2O in their body neutralized, leaving them a shriveled, dried out husk.
Kids these days. In my day we’d just drown ’em.
Lemme get this straight. As a former investigator, I assume that this chump was going to tamper with the physics/chemistry of the pool and/or it’s water, and do it in such a way as it was not going to be detectable by forensic analysis?
By the definition of the term “science”, if it can be done scientifically, it can be repeated.
Also, said chump assumed that 1. The rule that homicides are seldom stranger-crimes 2. The rule that if you can do it, someone has done it before you. 3. The rule that it’s HARD to be smarter than an entire Homicide Division, let alone the entire Nation’s homicide detectives. After failing to consider all these rules, It’s no wonder the chump got caught.
Wait, aren’t electric pool filters normally run on DC like most types of cathodic protection filters?
Hello! I just wanted to ask if you ever have any problems with hackers? My last blog (wordpress) was hacked and I ended up losing months of hard work due to no back up. Do you have any methods to stop hackers?