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Halloween is right around the corner, so what better way to celebrate than a deep dive into the ‘scienceâ€� of ghost sightings? We touch on a bit of the psychology behind these experiences and then break down the equipment people use when searching for proof that spirits float among us, and how power lines and rats in walls muddy the specter detection waters. Then we switch to something a little more corporeal, but no less weird: cyborgs. Biohybrid robots hold a lot of potential, but their ethical use, especially when human tissues are involved, needs to be carefully considered.Ìý

Transcript of this Episode

Chris French: For my sins, I have taken part in some really, really dreadful TV programs over the years, and I was the skeptic on the team in a program over here on ITV called Haunted Homes.

Sam Jones: That’s Chris French, an emeritus professor of psychology at Goldsmiths University of London.

Chris French: My specialist area for want of a better term, I refer to as anomalistic psychology. It's essentially the psychology of weird experiences. So everything from alien abduction claims to people who claim to have psychic powers to people who see ghosts or think they've had a ghostly encounter. If it's weird, we're interested in it. And it's mainly from a skeptical point of view. We're seeing if we can explain these weird experiences that people definitely do have, but can we explain them in psychological terms without having to resort to any kind of paranormal explanation?

Sam: This episode comes out the day before Halloween, and we thought: what better topic than the science of ghost sightings? We’ll touch on a bit of the psychology behind them, but really our focus will be on the equipment that people use when searching for proof that spirits float among us. And then in the second half of the episode we’ll switch to something a little more corporeal, but no less weird: cyborgs.

Welcome to Tiny Matters. I’m Sam Jones. And today, I’m joined by Anne Hylden, a chemist, teacher, and science writer who has been working with us for a few months. Hey, Anne!

Anne Hylden: Hi, Sam! I’ve mostly been working behind the scenes here on Tiny Matters, but today I get to be a guest co-host! And I’m really glad to be here.

Sam and I spoke with Chris about his research, but also his experience on the show Haunted Homes.

Chris French: The star of the show, no doubt at all, was the medium. She would kind of go into these places and make contact with the spirit and find out why it hadn't moved on and so on and so forth. We also had a paranormal investigator, and he would typically have mountains and mountains of kit. He was really into his kit. So there'd be things like obviously night cameras, motion detectors, EVP recorders, are you familiar with that notion of the electronic voice phenomenon? The idea is that if you leave a recording device in a reputedly haunted location, you might actually record spirit voices.

Anne: Chris explained that sometimes these recorders inadvertently capture living human voices.

Chris French: I did a daytime TV show a few years back, and the paranormal investigator was proudly playing his EVP, and there's no doubt at all, it was someone singing Celine Dion songs, and it was pretty terrifying. I just don't think it was a ghost, that's all.

Anne: Or, sometimes the recorders pick up indistinct sounds that only seem like words once someone suggests them to us.

Chris French: People often like to use for EVP very old equipment. So the recordings are very hissy and really poor quality.

You typically find with those that you can't actually make out what the message is supposed to be until you either read it or someone tells you and then you listen again. Oh yeah, I can hear it now.

Sam: And once you hear it, you can’t unhear it.

Chris French: It's what we call top-down processing.

Sam: Top-down processing is when your expectations affect your perceptions. Sometimes your brain will make an assumption based on prior experience, like filling in the gaps when you look at a sign with missing letters. And this assumption can alter the sensory signals that you are receiving.

Anne: To demonstrate how easily top-down processing can skew our perceptions, here’s a recording of a very creaky door to the basement of my house [creaky door].

Just a door closing, nothing remarkableÌý â€� except how badly it needs some WD-40. But now we’re going to play it faster, and you can imagine the door is saying “Get out of here.â€� [creaky door, sped up 2x]

And now you could swear you hear those words, right? [creaky door, sped up 2x] Even if you didn’t before. Because now you expect to hear them.

So, EVP recorders are just one of many types of gadgets in the ghost hunter’s kit. Paranormal investigators also like to use thermal cameras, since they say that ghosts can leave hot or cold spots in the air. Thermal cameras measure the heat emanating from bodies or objects in the form of infrared radiation. They’re able to detect very small differences in heat, so they create high-contrast and colorful images even when pointed at an empty room.

Sam: That’s because different materials absorb and release heat at different rates. So even though we might assume that everything in a room should be the same temperature, it will look more like a mosaic of temperatures to the camera. This may cause shapes to appear on the screen where, to the naked eye, it looks like nothing is there.

EVP recorders and thermal cameras can produce very noisy results. In science, we use the word “noise� to talk about the random fluctuations in a readout that are not due to an actual thing happening. Typically we want the true signal to be large and distinct compared to the noise. So we asked Chris if these noisy results allow extra room for interpretation.

Chris French: The basic effect phenomenon is called pareidolia, where we think we hear some kind of clear and distinct stimulus in basically random noise as you're saying. I mean, it happens both in the auditory domain with things like EVP, but also in the visual domain. I mean, typically one of the things that we often see in visual noise is faces. You see faces in the clouds, you see faces in a stain on the floor or the pattern on the wallpaper and so on. I mean, they’re a hugely important stimulus for us for all kinds of reasons. Parts of the brain are dedicated to facial recognition, recognizing emotions and so on and so forth. But we sometimes think we see faces when they're not really there.

Anne: And there are good reasons why we might assume an unseen entity is there when it actually isn’t.ÌýÌý

Chris French: So we have a kind of bias towards always being on the alert for a possible threat in the environment. And if we're going to make a mistake, it's going to be making the mistake of thinking there is something there when there isn't, rather than there isn't something there when there is, because the first mistake isn't that costly where the second one is.

In terms of our evolutionary history, everybody always gives the same example. There's something rustling in the bushes. Is it a saber-tooth tiger? The caveman who just thought it's a saber-tooth tiger and got the hell out of there, would survive to pass on his gene to the next generation, whereas his more rational next cave neighbor who stood there scratching his beard waiting for more evidence could end up as lunch. So we've evolved to basically perceive threats, to perceive agents out there with intentions towards us. And it is still there as part of our cognitive system.

Anne: Throughout history and in every culture, people have believed in spirits, demons, and ethereal creatures. And people have been trying to capture them with technology for a long time.

Chris French: Back in the day when they first started using cameras there were spirit photographers who specialized. Now we can look at that stuff and see pretty obvious double exposures, but at the time, the whole technology was really mysterious to the general public.

Anne: Spirit photography may have begun as an honest mistake, since photographs at the time were taken on glass plates rather than film. If the plates were not scrubbed perfectly clean before reuse, shadowy images from previous photos could appear as the negatives were developed. That’s what Chris means by “double exposures.�

Sam: Spirit photography developed as soon as portrait photography became widely available. It also coincided with the Civil War, a time when many people in the U.S. wanted consoling images of their lost loved ones. Spirit photographs were usually portraits of a living person, with faint images of other figures appearing behind or next to them. Patrons would often recognize the figure as a deceased family member, even when the facial features were indistinct.

A famous spirit photographer named William Mumler was brought to trial for fraud in 1869 after some of his customers discovered ghostly images of themselves in the same poses and clothing in which they had sat for portraits, haunting the backgrounds of other people’s photos.

Chris French: These days, we've got a lot of paranormal investigators get very excited when they're using digital cameras about orbs, orbs are these kind of, you look at the pictures and it looks like it's a big spherical–well, big, small, it can be all sizes–white blob. Now they say, this is spirit energy that has not yet coalesced into a full form apparition, whereas the camera makers say, no, it's a speck of dust that's been caught out of focus in the flash and well, you pays your money, you takes your choice there really.

Anne: There’s a more recent technology that’s probably still mysterious to the modern public, so we want to talk more in depth about it, get into the ‘tiny stuff� if you will. And that tech is called an electromagnetic field meter, or EMF meter for short.

Bill Lee: Electric fields are the things that cause charged bodies, electrons or other things that are charged, even little pieces of paper that might have a lot of charge or socks that just came out of the laundry. It causes them to be repelled or attracted in a certain direction.

Anne: We spoke with Bill Lee, who is a physicist and the owner of AlphaLab Incorporated, a company that makes EMF meters.

Bill Lee: Magnetic field is produced when there's current flowing in a wire, and the wire doesn't necessarily have any positive or negative charge, it's just neutral. You can have a magnetic field without an electric field or an electric field without a magnetic field.

There's also the radio waves, which are a combination of magnetic and electric fields that are right angles to each other, usually.

Anne: So if the magnetic field in a radio wave is oscillating up and down, the electric field is oscillating from side to side. Together, they move forward through space in the form of traveling energy. This is known as electromagnetic radiation, which includes radio waves, visible light, X-rays, and everything in between.

Sam: AlphaLab makes a device called the TriField Meter, which can detect magnetic fields, electric fields, and radio waves.

Since electromagnetic fields cause charged particles to be attracted or repelled, the TriField Meter can measure how strongly electrons inside the device are being pulled or pushed away. The strength of this force is measured as a voltage. Electric fields affect the voltage of electrons in a metal plate inside the meter, and magnetic fields affect the voltage of electrons in a looped wire.Ìý

Bill Lee: Finally, there's a radio wave detector. What that does is it has an antenna. The antenna is detecting the electric field and it's connected to essentially a voltmeter that can measure very fast changes in voltage, typically a billion oscillations per second.

Anne: The TriField Meter is designed to measure /artificial/ sources of electric and magnetic fields.

Bill Lee: There are oscillating magnetic fields that come from power lines and appliances, things like that that's artificial.

Anne: But AlphaLab also makes devices that measure /natural/ EMF sources, like lightning and solar storms.

Bill Lee: There's one called the natural EM meter that we make that is intended to read the natural fields, and it's often used for things like paranormal research.

Anne: OK, so, let’s imagine you want to find some ghosts.

You’ve heard about a location that people whisper is haunted, so you go there, armed with your EMF meter. Imagine it’s nighttime, and a crescent moon peeks out from behind scattered clouds. You walk into the place, whether it’s a house or a cave or something else, and start pointing the EMF meter at the walls. You hold still so as not to startle any entities present, and you see the reading on the meter slowly go up and up and up, then suddenly down. You wonder, “What’s happening?� and start to feel uneasy. Then you hear a rustling noise behind you and quickly turn, catching a spike in electric field as you point the meter at the opposite wall. Was it definitely a ghost? Or could there be something else going on?

Bill Lee: Atmospheric electricity will do that. Simply clouds moving around and you start getting a little bit of any kind of atmospheric activity. You will see a lot of electric field going up and down and some magnetic field going up and down. And if there's distant lightning, you'll see pulses in magnetic field and pulses in the electric field.

Sam: Not to mention, the Earth’s magnetic field is constantly changing. The sun emits a flow of charged particles, called solar wind, which bombards the upper atmosphere on one side of the planet all the time. As the Earth rotates, different locations will experience increasing and decreasing magnetic fields. Solar flares, which are sudden bursts of electromagnetic radiation, can cause even more unpredictable changes in magnetic fields.

Alright, back to the haunted house [creaky door, sped up 2x]

Bill Lee: If anything is moving inside, if something falls inside, it might carry some static electric charge or something like that and cause a spike or it might be a piece of iron or something could move around and cause a magnetic field. Rats in your wall, they're usually charged a little bit. You can see if they're moving around in there. And that would be a little scary, I suppose. I bet they get a lot of signals in New York City.

Anne: That’s right. Static electricity sticking to animals or humans can be detected through walls. To be honest, I don’t know if I would choose rats or ghosts.

Sam: I would choose ghosts. Absolutely.Ìý

Anne: There are so many non-paranormal things that could cause an electromagnetic field reading, it’s extremely difficult to rule them all out. But Bill doesn’t mind that some people use his company’s equipment for ghost-hunting.

Bill Lee: I mean, it's always possible that various paranormal things could be happening and it's good to measure to see if there is a field associated with that. So, you know, have at it.

Anne: Although, when I ask him about scientific research associating paranormal activity with electromagnetic fields �

Bill Lee: It's all anecdotal stuff. There are a few shows, TV shows that do this and they're getting some results. It's interesting, but they're not publishing any papers, so it's really hard to say if there's specific research on there.

Anne: Here’s Chris again.

Chris French: I certainly self-identify as a skeptic, but for me an important part of skepticism is to always be open to the possibility that you might be wrong, new evidence might come along that makes you change your mind. And so in that spirit, we also do devote quite a lot of time to directly testing paranormal claims. Suffice it to say that I'm still a skeptic.

The thing about the paranormal investigation teams and the stuff you see on TV, these programs, they want it to look like they are doing science, and they're just really not. They don't have the kind of notion of, well, you obviously need a control condition and stuff like this. You need something to compare it with.

You’ll measure as many orbs in a non-haunted location as you can measure in a haunted location. So why is that taken as being evidence of spirits and so on?

Sam: Chris has observed that there are two factors that make people more likely to believe they are having a ghostly experience. The first is context.

Chris French: If you were being shown around an old building, old castle, or stately home, and if the person showing you around said, oh, and this room's supposed to be haunted, it immediately changes your mental set. You go in there, you notice every little creak and draft and change of temperature, things that you probably wouldn't even pay any attention to normally take on great significance.

Sam: And the second factor is prior belief. Chris describes a study that a friend of his did at Hampton Court Palace, a royal palace in London.

Chris French: I mean this is reputedly one of the most haunted locations in England and therefore the world. We do have the best ghosts. And as you might expect, it was the people who already believed in ghosts who reported more of those kind of sensations and were more likely to attribute them to some kind of ghostly encounter. So context and prior belief.

Sam: Although he’s a specter skeptic, Chris chooses to study anomalistic psychology because he thinks these paranormal experiences reveal important truths about humans.

Chris French: It goes all the way up to the most profound questions you could ask, you know, do we survive bodily death? What's the nature of consciousness? And at all points in between, why should we find some forms of evidence more compelling and convincing than others?

Sam: You can read more about Chris’s work in his new book, which is called:

Chris French: The Science of Weird Stuff, but it's not the word stuff. It's the other word you're expecting.

Anne: We’re gonna switch gears now, to talk about some research that’s rooted purely in the physical dimension. Our guest for this segment is Victoria Webster-Wood, an associate professor in mechanical engineering at Carnegie Mellon University.

Vickie Webster-Wood: My group is the Biohybrid and Organic Robotics Group at CMU, cleverly acronymed to B-O-R-G.

Anne: Borg. As in, cyborg. Vickie and other researchers like her make biohybrid robots: devices made of both living and nonliving parts.

Vickie Webster-Wood: There's examples of biohybrid robots from the early nineties that are primarily in this concept area of cyborgs.

So you would take the antennas off of a moth and interface that with electrodes, and then you could detect the chemical sensing signatures in the environment based on the electrical signatures in the antenna.

Anne: Wild, right? And it only gets cooler from there. Some biohybrids use living components as sensors, like with the moth antennae example. Some use neurons to control the robots. And some use muscle cells as actuators â€� the motors that make the robots move.Ìý

Vickie Webster-Wood: One of the kind of canonical examples of that, that jumps to my brain, was there was this medusoid paper that looked like a little baby jellyfish. And then from there, the field really starts seeing that no matter what you do in 2D, you're just not getting the hierarchy that you see in natural muscle. And so you start seeing this switch as the bioprinting techniques become more and more accessible to people moving into 3D tissue spaces.

Sam: Bioprinting is a type of 3D printing. But instead of building structures out of plastic, it can build them with cells, nutrients, and protein gels.

Vickie Webster-Wood: For example, in my own research, we've created organic robots using collagen to create scaffolds, and then we can grow muscle cells on top of these in order to create robots that crawl as the muscle contracts.

Sam: This type of work is known as tissue engineering. It’s how scientists can create totally new, functional organs or grow realistic meat in a lab. But Vickie has some different applications in mind.

Vickie Webster-Wood: Some of the things that we're working on in my lab in this space include being able to 3D print completely biodegradable actuators out of materials derived from algae. And so this is really cool. It gives us a farmable source of materials for our robots that completely degrade naturally in a marine environment.

Sam: While we totally agree that algae is cool, it did feel like a surprising choice, so we asked Vickie what inspired her to use algae in her work.

Vickie Webster-Wood: I did a lot of my academic training in Cleveland, Ohio, and we were right on the edge of Lake Erie. And in Lake Erie we get these toxic algae blooms and they develop out in the lake where you can't really see them, and they are pushed by the currents in towards the towns of Toledo and Maumee. If you don't detect it soon enough, it gets into the water intakes. Then you've got hundreds of thousands of people under boil advisories and you're not allowed in the lake and you're not allowed in the rivers. There's some real significant potential health and economic impacts.

Anne: If Vickie’s team could make her biodegradable robots emit a fluorescent signal in the presence of the toxic algae, they could literally light up the hazardous blooms and make them much easier to see from the air.

Vickie Webster-Wood: Could we create completely biodegradable robots out of materials native to Lake Erie that we can deploy and potentially monitor just by flying drones over the lake periodically, so that we can see these algae blooms indirectly through the robots far before we can actually see them just from airplane surveillance, which is what they currently do now?

Anne: And if all this talk of glowing microbots swarming around a huge lake is making you picture scenes that could be in a science fiction movie, you’re not alone.

Vickie Webster-Wood: I think a lot of research that we ultimately see come to fruition is really inspired by the fact that researchers were super into sci-fi when we were young. Cell phones are a great example of this.

Anne: In Star Trek, for example, characters would talk to each other on hand-held communicators that looked a lot like flip phones, way before mobile phones were invented. In Blade Runner, a movie that came out four decades before ChatGPT, artificially intelligent robots spoke and acted so convincingly that they could pass as human.

Vickie Webster-Wood: So you see these things in science fiction as a child, they inspire you to be a scientist, to be an engineer, and to try to move our technology towards those goals. And so I think that is the root for a lot of researchers in why they get into this.

Sam: But while some people out there are impatient for human cyborg technology, Vickie thinks human tissues should only be used for medical purposes. And she’s very aware of the ethical implications in her field.

Vickie Webster-Wood: I would never want to create a robot that could itself feel pain, and we don't really understand the human nervous system to the level that myself, as a researcher, I'm comfortable with working on it for a robot that is not inherently a medical device or something that is going to be put back into a patient.

Sam: Because she feels so strongly about this, Vickie makes a point of regularly collaborating with researchers who specialize in bioethics to help her think about where the boundaries of this very new field should be.

Vickie Webster-Wood: We don't want to do something, and then only after we've done it realize that the line should have been 20 feet behind us.

Sam: And on that haunting note, let’s switch gears again.

So today I want to talk with you about a new understanding of what the atmosphere of the moon is. So I somehow had never really thought about the moon's potential atmosphere, but essentially the moon has a blanket of gasses around it, and they're very thin, but still considered a version of an atmosphere called an exosphere. But researchers didn't really understand how it could have that exosphere because it really is, the moon is really super exposed to the vacuum of space.

So it appeared that the gasses making up the exosphere were constantly being diminished by solar activity but then replenished. And so then the question was by what? Where is it coming from? So now there seems to be an answer, which is that tiny micro-meteorites, and these are tiny, tiny, like size of dust tiny, are constantly smacking into the lunar surface. They're vaporizing lunar dust and then releasing atoms into the space around the moon, and that's what's really helping to replenish its atmosphere. So the team took a number of approaches to come to this conclusion. One of the things they did was they carefully studied data from a lunar orbiter called the Lunar Atmosphere and Dust Environment Explorer.

Anne: Does it have a cool acronym?

Sam: It's Ladee, L-A-D-E-E. So not great.

Anne: I bet they call it Ladee.

Sam: Yeah, Ladee, which operated for seven months between 2013 and 2014. What they were able to gather from that data was that during meteorite showers you could actually see more atoms in the atmosphere, which is like, oh, interesting. And then they went even further and actually looked at samples of the moon, moon dirt collected during the Apollo program. And so in particular, they were looking for two elements, potassium and rubidium. They're both known to occur on the moon. I guess both are easily vaporized. I don't know if there's another reason that they're looking for those in particular, but that's what they were looking at.

Anne: So you're telling me that the moon's atmosphere is made of gaseous atoms of metals, potassium and rubidium?

Sam: Yes. I think so.

Anne: Weird.

Sam: And so they're really interested in looking at other samples from, say, other moons to see if this is happening elsewhere in the solar system, and if tiny meteor impacts are actually helping shape the atmospheres of those moons or asteroids or whatever it may be.

Anne: This is cool to me for a couple reasons.

Sam: Okay.

Anne: First of all, those tiny meteorites wouldn't even get to the surface if there was a thicker atmosphere. It's like we wouldn't get that on the earth. They would burn up or whatever.

Sam: Right.

Anne: Also, it's just funny how much space science is about dust.

Sam: Yeah. There's a lot of dust in space.

Anne: Just keeps coming back to dust. So my tiny show and tell is also a little bit related to this episode, but more in the context of the electromagnetic fields, and it has to do with flowers and bees.

Sam: Oh.

Anne: Different substances, for whatever reason, tends to lose electrons, some tend to gain electrons. So some are often carrying around a negative electric charge, and some are carrying around a positive electric charge. And it turns out bees are usually positively charged, and flowers are usually negatively charged. And some scientists think that this electric field helps the bees sense where the flowers are, and it's actually kind of magical and a wonderful symbiosis because several things happen. So the electric fields can help the bee get attracted to the flower. Then the negative and positive charges will be attracted. And so then pollen from the flower will naturally jump onto the bee. And then when that happens, it temporarily neutralizes the charge of the flower.

Sam: Okay.

Anne: So then the bee will go buzz off, lose some electrons, and go onto the next flower. But the flower is temporarily neutral, and so then other bees will not be attracted to it because it was just harvested.

Sam: Interesting. So that kind of protects it from being depleted. Is that sort of the idea?

Anne: In what I saw and read, seemed the idea was that now other bees will know that that flower doesn't have nectar, or maybe they don't know it in those terms, but they won't seek out that.

Sam: They can sense it.

Anne: Yeah. They won't seek out that specific flower now that its nectar is gone.

Sam: Oh, so interesting. That's so cool. It is really a thing where I think we think about electromagnetic fields, and a lot of times it's in very specific contexts and more technology-based or space or something like that, and you don't think about it in nature or with bees and plants, and that's cool.

Anne: All living things can generate electric charges and they're so teensy weensy, but they serve purposes, really important ones apparently.

Thanks for tuning in to this week’s episode of Tiny Matters, a production of the American Chemical Öйú365betÖÐÎĹÙÍø. This week’s script was written by me, Anne Hylden, and was edited by Michael David and Sam Jones, who is also our executive producer. It was fact-checked by Michelle Boucher. The Tiny Matters theme and episode sound design is by Michael Simonelli and the Charts & Leisure team.

Sam: Thanks so much to Chris French, Bill Lee and Vickie Webster-Wood for joining us. To be featured in our bonus series, “Tiny Show and Tell Us,� write in to tinymatters@acs.org with science news you’re itching to share, a science factoid you love telling friends about, or maybe even a personal science story. And while you’re at it, subscribe to our newsletter! I’ve put links in the episode description. See ya next time!

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