5 Ways to Detect the Invisible Stuff Hiding From Us

5 Seismometers Spot Quakes and Save Trains

Not a single person has died in an accident aboard Japan’s bullet trains. True, someone once got his finger stuck in a door and got dragged to his death when the train took off, but when we talk about train “accidents,” we mean collisions and derailments. The system hasn’t had even one fatal collision or derailment in its 60 years of operation. 

One reason that’s surprising is Japan has its share of earthquakes, and trains are vulnerable to them, since they usually travel over the earth. But the Shinkansen rail system has its own early earthquake detection system, which responds to the seismic waves that come ahead of the ground shaking. Within two seconds of these waves reaching the sensors, every train hits the emergency brakes.

Even in 2011, when that 9.0 earthquake hit Japan, collapsing a bunch of bullet train stations and ripping up the track, seismometers on the ocean floor detected the first tremors and shut down the trains in time. Only one bullet train derailed, and that was a test train, so no one cared about it. 

4 The Mountain Pool of Ultrapure Water

Japan is also home to Super-Kamiokande, an observatory for detecting neutrinos. It’s a tank a hundred feet tall and hundred feet wide, located in a mine a thousand feet under a mountain. Even looking at a photo of it is guaranteed to cause insanity unless you’re holding a protective talisman. 

Neutrinos travel at the speed of light and pass through the planet without affecting much of anything, but we still manage to detect them using Super-Kamiokande. Super-K contains ultrapure water, water so pure that if we spot an electron in it, it can only have appeared because a neutrino shot through the water from space and created the electron, using its neutrino powers. 

Thanks to Super-K, we discovered that there are non-electron neutrino components in solar neutrinos, and that the total flux of the active ⁸B-neutrinos was 5.44±0.99 × 10⁶cm⁻²s⁻¹. That last sentence obviously sounds like complete gibberish to all reasonable people, so let’s just add that if we spot the right neutrinos, that tells us a star is collapsing and about to turn into a black hole, and that’s something anyone should want to know.

3 ShotSpotter, the Gunshot Detector

Sometimes, you hear a gunshot outside, and you shrug your shoulders, saying, “Eh, what can you do?” If you call the police and report what you heard, they might not have enough information to respond properly, and going outside brandishing guns of your own might land you in trouble.

Starting in 1997, several cities in the U.S. set up a system of sensors that pick up the sounds of gunfire and relay the location of the source directly to police. In D.C., for example, the sensors picked up some 40,000 shots in a 20-square-mile area over the course of seven years. A person who calls the shot in might say, “I heard a shot somewhere north of me, I don’t know exactly where,” but ShotSpotter tells cops the exact location. They can sweep in and look for a victim, or at least look for evidence.

So, does ShotSpotter reduce crime, or at least help us solve crimes? We don’t have much evidence of that. It keeps alerting cops to false alarms, and a Houston investigation suggests that it actually diverts police from calls that matter more. This surveillance might not even be legal either. 

The company behind the system continues to market it hard, though. Last year, they changed their name to SoundThinking, to give off a better impression. That sounds like a joke about euphemistic language, but then you realize “sound” has a double meaning, and it’s an entirely different joke: a pun. 

2 The Detectors that Detect Radar Detector Detectors

Police also use a far more familiar sort of sensor in their everyday duties — radar guns, for clocking the speed of passing cars. If you want to be on the lookout for speed traps, you might want to invest in a radar detector, which spots the radio waves these guns use to measure your speed.

Naturally, such devices use waves of their own, which means they’re vulnerable to being spotted by radar detector detectors. Of course, that means you should equip your radar detector with a radar detector detector detector, which will shut your device down as soon as it realizes it’s being spotted. 

1 The Parkinson’s Sniffer

When Joy Milne was a girl in Scotland, her grandmother knew about her powers but told her she must hide them from the world. Joy, like her grandmother before her, was hyperosmic, which meant she was extremely good at distinguishing different scents. As a girl, this meant playing games where she could identify different varieties of rose by sniffing individual petals, but grandma said she shouldn’t tell people about her supersense. Odors are not the stuff of polite conversation, said grandma, probably speaking from experience.

Joy went on to become a nurse, and she discovered she was able to smell such diseases as leukemia and tuberculosis. Though impossible for most people, this wasn’t so crazy. Dogs are able to smell these diseases, as anything that changes your blood may change what sort of chemicals you emit. One day in 1982, she noticed her husband giving off a new smell, and she had no context at the time to know what that meant. A dozen years later, he was diagnosed with Parkinson’s. A dozen years after that, she noted the smell on someone else, and this guy had Parkinson’s as well. 

Smelling Parkinson’s is potentially more useful than smelling other diseases since it’s harder to diagnose. So, she now approached scientists with her power, and they tested her. They had Parkinson’s sufferers and control subjects wear T-shirts then cut the shirts up and had her smell the pieces. She correctly identified each piece as belonging to either a Parkinson’s patient or not — with one single false positive, which is still pretty impressive. Then, a year later, the scientists discovered that hadn’t been a false positive at all. The control subject behind that shirt was diagnosed with Parkinson’s. 

Normally, when scientists have people sniff dirty T-shirts (believe it or not, this is a common field of investigation), the smeller focuses on the armpits, since that’s the smelliest part. Joy instead noted the smell in each shirt’s neckline. From this, the scientists concluded that something special lay in the sebum of Parkinson’s sufferers, sebum being a skin secretion totally separate from the sweat squirted by those apocrine glands under your arms. 

They used this knowledge to create a new test for Parkinson’s, which requires just a swab of the patient’s back and returns a 95 percent accurate result in three minutes. If you’re concerned you might have Parkinson’s, just be sure not to scrub your back too hard before taking the test. However, be honest: When was the last time you really gave your back a thorough scrub?

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