Random Walk 2.2 – Gamer’s Guide to Ecology, Sonar-Busting Moth Wings, Cosmic Rays and Electronics


Hello, and welcome to Random Walk, a sciencey podcast where we take multiple steps of unit length, each with directions selected independently from the previous step. I’m your host Adam Fortais.

Your random walk for the week comes from economics. A level-one model for understanding the price fluctuations of a particular stock or whatever is the random walk. Here’s how it works, in very approximate terms. 

tl;dr: The random walk hypothesis is a financial theory stating that stock market prices evolve according to a random walk (so price changes are random) and thus cannot be predicted.

Random walk hypothesis test by increasing or decreasing the value of a fictitious stock based on the odd/even value of the decimals of pi. The chart resembles a stock chart. (wiki)

Ok! This week, we are talking about risk, reward, probability, and money:

  • If you were a moth, how would you protect yourself from predators? Researchers from Bristol have recently discovered a built-in strategy that keeps some moths safe from echolocation-based attacks. Wait, let me try that again. RESEARCHERS FIND NEW TECHNIQUE TO SURVIVE THE NIGHT. BATS HATE IT!
  • Video games can be hard, but maybe it’s not your fault you can’t make it past the water temple. ARE COSMIC RAYS MAKING YOU LOSE AT VIDEOGAMES? Actually, the story is about someone winning big. But it could work either way. You’ll see.
  • I’m out of clickbait ideas for this one. Ontario universities have moved to “performance-based” funding. Too-little-too-late for Laurentian, but… hold on, what the heck does that even mean? How do ontario universities get their funding anyhow?
  • And my favorite segment, Jessie brings you the gamer’s guide to ecology. 

But first: This podcast is brought to you by scientificanada.ca . The goal of scientificanada is to get real science to real people, which we do by producing entertaining and informative content about research, academia, and being a curious nerd. A big part of our thing is finding and promoting new projects and new voices with financial support and expertise. If you have an idea for a project, we’d love to hear from you. Head to scientificanada.ca to see some of the shows and articles we’ve helped with, and if you want to discuss details, you can find me on twitter at AdamFortais or email me at fortaisadam@gmail.com . Support for our projects comes from our generous and very very smart patreon subscribers. Find out more about how you can help us with our next projects over at patreon.com/scican . Thanks!

**Fade music out**

Block One (C): Gamer’s Guide to Ecology #3

— Commercial break —

Block Two (R): Some moths have wings equipped with bat-beating decoy systems

Wingtip folds and ripples on saturniid moths create decoy echoes against bat biosonar

Original article

The search for improved stealth technology has led scientists and engineers in some pretty strange directions. Maybe that’s a fundamental part of “stealth”; your hunting instincts develop in a way that lets you quickly identify your target so you can strike before it escapes. This is made easier when you know exactly what to look for. So, like the brilliant male model Derek Zoolander once said, “they’ll be looking for us, but they won’t be looking for… not us…”. One stealth strategy, then, is the art of disguise. 

If you are being tracked by a ruthless and indiscriminate killer, though, a disguise isn’t going to work. Maybe you try to hide and hope you go unnoticed. Or, if you want to take a more active and tricky, Home Alone-style approach, maybe you create a decoy or diversion. 

If hawkish birds of prey are built like fighter jets, moths are maybe more like a B2 stealth bomber or an F-117 attack plane. Some moths eschew what might be considered “traditional” aerodynamic designs for evasive function. Actually, some moths are loaded with technical features, kind of like an iPhone. Recently, Thomas R.Neil, Ella E.Kennedy, Brogan J.Harris, and Marc W.Holderied at the University of Bristol have discovered a wing-based feature that works as a decoy system. You wouldn’t know it to see it though. That’s because the goal is to create a //sonar// decoy.

If you are a bat, you might find your prey by screaming (or clicking) in the dark and chasing echoes. Sound waves will reflect off of different materials in different ways, and bats can use this feedback to map their surroundings. Because sound waves reflect differently off different materials, bats can figure out the size, shape, and some material properties of their surroundings, but most importantly, they can very accurately hear //where// things are. 

Quickly, I have two fun, now-refuted scientific theories to share with you. 1) early theories (400-500 BC, Plato, etc) of vision proposed that your eyes emit some sort of beam that interacted with matter, letting you see. Kind of like echolocation, but very, very wrong. 2) This one I’m not totally sure of, but I think it used to be considered a mystery how cave bats could swarm so densely and not smash into each other. How did their sonar and reflexes get so fast? Turns out, they do just smash into each other. 

Ok so where were we. Moths vs bats. So bats will scream at things to figure out where they are, and if they are a tasty moth, they dart after it. So how do these moths create audio decoys? First we need to know a bit more about the moths this team was studying. They’re huge. Like, top-2 biggest moths out there. The Atticus Atlas moth calls the forests of southeast Asia its home, where it flexes its big ass, 9.5 inch coppery-brown wingspan amongst the trees. At the tips of its wings, it has two interesting features. The first one actually begat its local Cantonese name, which translates as something like “snake-head moth”. The patterning and colors make it look like two snake heads facing outwards on the moth’s wings. The other feature is harder to see. It turns out they have very small and delicate ruffles. And it’s this ruffle that is critical to the moth’s evasive success. 

What the team from Bristol found was that this ruffle had some interesting audio-reflection properties. It actually bounced back more sound than the rest of its body, at almost any angle you shouted at it. (This sounds funny, but that’s basically what their experiment was. They held a moth still and fired sound waves of various frequencies at the moth, at various angles, and looked at how the waves were reflected and returned to the source). Other, less-evasive moths on the other hand, had “dimmer” wings and “brighter” bodies. So the trick is kind of two-fold. They protect their head and body by making the tips of their wings big, bright, and loud , and they keep those parts far away from their juicy bodies. If all goes well, this causes predators to swing for what they think is a tasty torso and end up with a mouth full of wingdust. Clever.

Block Three (C): You’re not bad at video games, cosmic rays just keep messing you up

A Rogue Space Particle Could Be Responsible For This Unsolved Super Mario 64 Speedrun Glitch

Cosmic Radiation: Why We Should not be Worried

The particle physics of you

**Outro music**

That’s it for this episode. If you have comments or questions, find me on Twitter at AdamFortais or email me at fortaisadam@gmail.com . Our music was provided by my friends from the band Boonie. Find them at boonie.rocks . If you liked the show, share it with a friend. We are on all streaming platforms and youtube, just look for scientificanada . If you want to learn more, or if you’d like to help us support more creators, head to scientificanada.ca . See ya later! 

Find more Jessie on Twitter and Twitch, and be sure to add the Gamer’s Guide to your favorite podcasting app!

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