MacGyver Season 2 Episode 12 Science Notes: Jack + Mac

Before I get to this science for this episode (there’s some great MacGyver hacks here), let me say something else about the show. The storyline for this episode was great. It had a nice plot, and I really enjoyed the MacGyver and Jack flashbacks. Now for some science.

Photophone

The best Mac-hacks are real. This is real—very real. It is indeed true that this was an early idea for a phone. Here’s how it works.

  • You need a directed light. One way to do this is to get a mirror that reflects sunlight. A parabolic mirror works a little better, but still the mirror is a great idea.
  • Use your voice to shake this mirror. This changes the intensity of the reflected light to match the wave pattern of your voice.
  • Use some type of electrical photo device (solar panel, photo diode, photo resistor) to modulate an electric current to this same sound pattern from the light. Send this to a speaker.
  • That’s it.

For MacGyver’s build, he uses a microphone and connects it to a porch light. The idea is that the microphone will modulate the brightness of the bulb. For this to work, I think it has to be an LED bulb. An incandescent won’t work (I don’t think) since the hot bulb filament won’t change brightness quickly enough for sound frequencies.

There is also the problem of AC vs. DC. If MacGyver connects to the AC power line going to the bulb, this might not work. But still—it’s very plausible.

On the other end of the photophone, Riley uses a police car light as her transmitter. Again, if this is LED it should work (plus the car runs on DC, not AC). Finally, the only problem is aiming. In practice, you need your detector to pick up the changing brightness from that one light. Of course it’s daytime, so there are many “lights” outside. Putting a lens on the detector to aim it would help a bunch.

OK, now you want to build one of these yourself. You should. It’s actually not too terribly difficult. Let’s start with the simplest part—the receiver. The easiest way to get this to work is to connect a small solar panel to an amplified speaker.

Oh, do you know where I got that solar panel? Yes, it was from a garden light. You put these small lights outside and the solar panel charges a battery during the day and the light comes on at night. They were old and the battery was bad, so I took it apart.

Now for the transmitting side of the photophone. I tried to do this with a laser instead of a light (so that I could aim it). It mostly worked, but it’s a bit more tricky.

This is something I need to rebuild at some point in the future. Make it better. But still, this should be in my list of Top 10 MacGyver Hacks. I need to make that list.

Gum Wrapper and Battery to Start a Fire

Ok, actually this was to melt a wire. MacGyver takes a foil gum wrapper and connects it to two ends of a battery. The idea is that the foil will make a short circuit.

But there are two questions:

  • Is a gum wrapper an electrical conductor? I don’t think they are actually made from aluminum foil—but I suspect that many of these do in fact conduct.
  • Would it get hot? Even with a small battery, yes I think it would.

DIY Non-Contact Voltage Probe

MacGyver needs to find wires behind the wall. He puts together this awesome looking probe (or as Jack calls it—a doohicky)

Actually, this prop is great. Here’s why.

  • It looks cool and it’s clearly a combination of multiple items.
  • It’s not specific—it doesn’t show exactly what MacGyver uses. This is good because that way it could still be plausible.
  • Finally, it’s based on something real.

But how does it work? There are multiple ways to detect voltages without touching—I think the most common method measures a super tiny voltage that is created by nearby electric fields. The NCVP is essentially part of a capacitor. When in the presence of an electric field, there is a voltage across the capacitor and you detect this voltage. I need to build one of these—for fun. I’ve seen a very basic version somewhere.

Kitchen Chemistry to Detect Explosives

How do you detect explosives? MacGyver is correct that most explosives are based on nitrogen. If you measure the nitrogen, you can get an estimate of the type of explosive.

There are many things in the kitchen that can be used to detect chemicals. Here is one that you can do at home—it’s a chemical-based pH detector (to determine if something is acidic). The color of this cabbage juice will change color depending on the pH level of the material.

Here’s how to make it.

Laser-Based Wire Cutter

Here’s the problem. There are two bombs that need to be disarmed at the exact same time.

The idea is to use a laser that turns on two identical cutters at the same time. The first thing to use is a beam splitter. This takes a laser beam and breaks into two beams. I guess that’s fairly obvious from the name. Here is a video showing how that works.

For the cutter part, it uses a photocell as the “switch” to turn it on. Here is a rough diagram I created for this hack.

In the end, these two motors might not cut at the exact same speed. But it’s still a fairly fun MacGyver moment.

MacGyver Season 2 Episode 11 Science Notes: Bullet + Pen

MacGyvered Record Player

You only get a quick glimpse of this record player—and I’m not sure it’s the same as this super basic one. But you can build a record player with some pencils and a cup and a pin. Really, this is a fun one. If you have an old record laying around, you should try it. Here is a video.

I want to add something about records. Have you ever wondered why most songs on the radio are around 3 minutes long? The answer has to do with the record single. Here is my longer explanation. But more fun—here is a plot of the average song length as a function of year (the plotly version).

Check it out. So you can see that before the 80s, songs where around 3 minutes or less. After that, the song length got longer. What changed? The compact disc—that’s what. With the CD, there was a new way to share high quality songs with radio stations. This meant that you could easily make a longer song. The end.

Plastic lock pick

If you have a door like this, it’s not secure. MacGyver takes a piece of plastic and slides it between the door and the frame. The plastic pushes the door latch back. Boom. Door opened. Silly door.

Even if it’s easy to do, it’s still illegal to go past locked doors that you don’t own. Don’t do it.

Sodium Hydroxide Doesn’t Grow on Trees

That’s a funny line—because sodium hydroxide is a chemical in tree stump removers. Get it? OK, you aren’t going to find this stuff laying around with other ingredients like nail polisher remover and cold medicine. But you might find all of these things in a meth lab. Don’t do drugs kids.

Could you use this to make a bomb? Sure.

Exploding Dart

Classic MacGyver. He takes a pen and a bullet. With this, he mounts the primer and the gun powered to mount on the front of the pen. Add some paper fins and you have yourself an exploding dart.

Technically this would work—however, there would be a good chance it wouldn’t explode unless you hit it just right.

MacGyver Season 2 Episode 5 Science Notes: Skull + Electromagnet

Decoration with syringe hydraulics

As they decorate for Halloween, the crew builds this skeleton that is controlled by syringes. The basic idea is to use a tube to connect two syringes (the big kind). Fill it with water. When you push or pull on one syringe, it makes the opposite thing happen with the other syringe since water is incompressible.

Here is a nice video showing how to make something like this.

Directional Antenna

In order to track down a dude, MacGyver builds a directional radio antenna. Well, actually he just combines a yagi antenna and a dish antenna—I’m not sure it would work like that, but it looks cool.

I don’t think I should go into the physics of a yagi—it might take a while to explain. However, I can say this: that old style TV antenna you had on your roof? That’s a yagi. It does have a directional dependance on amplitude. That means that if you point it one way, you will get a better signal than pointing it another way.

DIY Thermal Camera

How do you find people in a dark abandoned military base? What about a thermal camera? A “thermal” camera is just like a normal camera except that it’s different. Instead of detecting electromagnetic waves in the visible region (we often call this visible light), a thermal camera works in the infrared range. That’s why they are also called infrared (IR) cameras.

Normally, that wouldn’t help you see in the dark—except for one important thing. All objects radiate light. The wavelength of this light depends on the temperature of the object. For most of the objects you see around you, the wavelength of radiated light is in the infrared range. So, with an IR camera these objects are like their own little light bulb. You don’t need an external light source—the objects are the light source.

Let me show you an example. This is an image using the FLIR One—it’s an IR camera attachment for your smart phone (pretty cool). Here you can see the family dog in IR. There’s a bunch of cool stuff you can see, but I will just leave this post for you if you want to know more.

The first devices to produce an IR image (mostly) came about in the 1950s. They used a single sensor that scanned over an area to produce an image. It wasn’t fast and the sensor had to be cooled. But still it worked.

So, how could MacGyver make an IR camera? Step one would be to find one of these sensors—maybe lead sulfide detector. This detector just gives a voltage though and not an image. To get an image, you need to scan over the scene and then run that into a television or something. Here is an early sketch.

Inline image 2

How far away could you detect a human? I tried this out using my kids and my FLIR One. Here’s what it looks like at a distance of 7 meters.

Inline image 4

Just for fun, here is the image from the episode.

In the end, IR camera’s are pretty complex. Honestly, it’s amazing that we have something that does this on a phone.

Escaping a hyperbaric chamber

Samantha Cage has been placed in a closed hyperbaric chamber that’s being filled with water. A hyperbaric chamber is essentially a person-sized scuba tank. You can put someone in there and then increase the pressure. This can be useful for a person suffering from decompression sickness (from scuba diving).

Anyway, she’s trapped and needs to escape. MacGyver builds a captive bolt gun to break the window. Oh, that’s cool and all—but I have a better option to escape.

What if you sealed up the chamber to get her out? It sounds crazy, but it would work. Here’s the problem. In order to add water to the chamber, you either need to increase the interior pressure by adding high pressure water. Or—you can add water while letting some of the air out. The second method is much easier to do (since it just uses normal water). But this means there is either a valve that is open to let the air out or maybe there are some old and bad seals that let air out.

Now, if you seal off the chamber the water can’t come in. And if the water does indeed enter, it will increase the interior pressure. Hopefully the pressure will get high enough on the inside that Cage can add a little extra and bust out.

It’s just an idea.

Electromagnet Lift

Could an electromagnet actually lift something large? Absolutely. Have you not seen those giant electromagnets at the junk yard that lift cars? But what about a human? The human body doesn’t really have enough ferromagnetic material in it for this to work (unless you are Magneto). However, it’s at least plausible if that person has a steel plate implanted. Yes. It’s true that many metal implants are titanium. Also, the steel implants are stainless steel and some versions of stainless steel aren’t magnetic. But still—it’s possible.

An electromagnet is really just a coil of wire with current running through it. It’s not hard to make, here you can do it yourself.

But what about a HUGE electromagnet? If you want a super strong magnetic field, you need a GIANT electric current. It’s possible to get perhaps 10 amps out of a truck engine (from the alternator or the battery)—but that might not be enough. My suggestion is to get a bunch of car batteries together so that you can get the highest current possible. Of course this high current is going to make the wires hot, so don’t run it for too long.

MacGyver Season 2 Episode 4 Science Notes: X-Ray + Penny

Hydraulic Hammer

OK, it’s not really a hammer. It’s more like a pressure gun. MacGyver hooks up a pressured line from a water heater to a tube with a rod in it. When the pressure is released, it shoots the rod and hits the door handle to knock it out. That’s great.

If you want it to “hammer” back and forth, you need to do something different. Here is a very basic design.

There is still a tube with a rod, but there are two differences. First, there is a hole on the side of the tube. As the rod moves forward (due to the pressure from the hose), it eventually gets to the part where the side hole is exposed. This would allow the pressure to escape and the rod would stop moving forward.

The other feature is a spring. One side of the spring is mounted to the outside tube and the other to the inside rod (yes, there needs to be a small slit in the tube). This spring will pull the rod back into place once the pressure escapes.

I really don’t know if this would work.

Finding Location with Sound.

This one was tough—but fun. How can MacGyver use evidence he collects to go back and figure out his location? In this case, he uses sound.

In air, sound travels at a finite speed. Technically, the speed of sound depends on the temperature of the air—but using a value of 340 meters per second is a reasonable value.

Since this sound speed is finite, it takes some finite amount of time for this sound to travel over a distance. But of course you already know this because you have seen lightning and heard the thunder. The light part of this lightning strike travels at the speed of light (which is really, really fast). However, the sound part of the strike travels much slower. This means that you see the lightning and then hear the thunder later. The farther away you are from the lightning strike, the bigger the time difference between these two signals.

For MacGyver’s case, he is going to use two sounds that start from different distances and at different times, but reach him (he hears them) at the same time. In this case the sounds are from church bells and a fire station. It’s sort of like the opposite of the lightning problem except that it’s totally different.

So, here is what he knows.

  • Church bells every half hour.
  • Fire station alarm went off at 1:29 and 58 seconds.

That means the sound from the church bells traveled for 2 more seconds than the fire station sound. How far away is MacGyver from the 2 sources? Yes, this is a more difficult problem—but it’s not impossible.

This is what MacGyver writes on the board to solve this.

Now for fun, here is my original solution.

Isn’t that fun? Well, it is for me. Oh, what about the two points? You can think of this problem as two expanding circles. Each circle represents a sound and the circle’s radius increases at a rate equal to the speed of sound. So, one circle is going to be bigger than the other one (because that sound was created first). We are looking for the places where the two circles intersect. Yes, there are two of these locations. MacGyver picks the location based on the direction of water flow in the sewer.

You know, I really should make a python animation for this problem. Maybe I will do that soon. Oh, one final note. For my solution above, I recreated the calculation so that it would have the correct values. At the time, I was at my son’s soccer practice. So this is a picture of my notes as they are sitting on the seat of the car. True.

X-Ray Fluorescence

It’s real. The basic idea is to use x-rays on the film. These x-rays excite some of the atoms in the film such that they fluoresce and produce infrared light. You can’t see the IR light, but a video camera can.

It’s something like this—a technique that is used to look at different layers in paintings.

https://www.livescience.com/13499-hidden-painting-features-xrays-110331.html

As a bonus, I made a short video explaining x-ray fluorescence.

MacGyver Season 2 Episode 3 Science Notes: Roulette Wheel + Wire

Is there a better MacGyver image than his radio build at the beginning of the episode? I think not. Here is an image.

Could you actually build a radio from a snow mobile? I think yes. Really, radios aren’t actually that complicated. The only difficult part would be building an amplifier so that the signal generated from a voice is powerful enough to be detected by someone’s radio. If the snow mobile had any kind of radio (like for listening), you would have all the parts you would need.

Stun gun on slot machine

They call these hand held zap things stun guns, but they don’t shoot. You just have to hold them up to someone to shock them.

MacGyver needs a distraction so he takes the stun gun and uses it on a slot machine. After that, the guy playing wins.

Is this even possible? Possible, yes. Likely, no. The stun gun has high voltage that creates sparks. These sparks can damage electronic equipment—especially the super tiny transistors in a computer chip. So, it’s possible that the stun gun does something to cause a win.

However, these slot machines are built with tampering in mind. They need to be able to resist humans messing around with them to win. So, I doubt this would work. Also, if MacGyver zaps that outside of the machine it’s probably grounded. This means that the electric current that gets into the case of the slot machine will just go around all the electrical components.

You probably have a better chance of winning on the slot machine than cheating on it.

Iris scanner hack

In order to get through an iris scanner on a door, Jack gets a close up picture of the target’s eye. Then Bozer prints out a fake lens to wear over the eye. Could this work? It’s possible.

In fact, check this out. Someone did the same thing with the Samsung Galaxy S8.

Handheld Cellphone Stingray

A cellphone stingray is a device that acts like a cell tower. Cell phones connect to it thinking that it’s just a tower—but blam, it’s actually another computer.

Of course the details are complicated (which means I don’t really understand them), but you would need some type of antenna. Jack has a tiny antenna in his cuff that has to get close enough to the target’s phone. I think this is plausible. At least it would give Riley a chance to get into the phone and steal some codes.

Magnetic Detector

Also known as a compass. MacGyver is trying to find a magnetic switch for a hidden door. He grabs a bit of metal (hopefully it’s ferromagnetic steel) along with a magnetic bottle opener.

The basic idea is that a metal like steel (most steel) has magnetic domains. When these domains are lined up, the material will act like a magnet. You can line up the domains by rubbing the steel with a magnet. Like this.

If the magnetized steel can float, it will rotate and point in the direction of an external magnetic field—either from the Earth or from that magnetic door switch.

OK, one small issue. In the episode it shows MacGyver rubbing the steel back and forth. You really just want to rub it one way. I think it would still work though. Oh, also many of those magnets like the one on the bottle opener have weird domains. They aren’t just like a plain north and south of a bar magnet, but it still might work.

Vacuum Cleaner Spider-Man

This is awesome (and mostly real).

Here’s how it works. The vacuum cleaner works by pulling air out of a region. If you put a vacuum cleaner over carpet, the air flow goes from the carpet to the vacuum cleaner (basically with just a super powerful fan). When the air moves in this manner, it often picks up other stuff—like dirt.

MacGyver has this vacuum hooked up to some metal tray covers. When the air is pulled from these covers, the air pressure inside the covers decreases. That means that the external pressure (due to the Earth’s atmosphere) will push the covers onto the glass wall.

Actually, this force from the atmospheric pressure can be quite large. The pressure is 10^5\text{ N/m}^2. So if the pressure inside the covers is just half an atmosphere with a radius of 10 cm, then the net force (for the two covers) would be:

F = PA=(0.5\text{ N/m}^2)(2)(\pi (.1\text{ m})^2) = 3141 \text{ N}

That’s some serious force. But wait! This is not the force that supports MacGyver. In fact, it is the frictional force between the cover and glass that keeps him from falling. The frictional force is an interaction between two surfaces that acts parallel to the surface. It depends on two things:

  • The types of materials interacting.
  • The magnitude of the force that pushes these two surfaces together.

If you push two surfaces together really hard, there will be a greater frictional force. So, this force from the vacuum cleaner exerts a force that increases the frictional force and this frictional force allows MacGyver to climb like Spider-Man.

Here is something similar with a guy that hangs from an overhang with a vacuum cleaner. Pretty cool.

Shrinking metal

This is real (based on something real). Yes, you can actually make metal things smaller. Here is a great video from Physics Girl (Dianna Cowern) that shows how this works.

The basic idea is to create a HUGE electric current very quickly. This large change in current can create a very high change in magnetic fields. When you put metal in this high changing magnetic field, it induces an electric current in the object. This induced current creates a magnetic field that interacts with the external magnetic field in such a way that the device gets squished. It’s awesome. Oh, when I say “a large change in magnetic field”, I am actually talking about the time derivative of the magnetic flux.

So, what do you need to make this coin shrink thing work? You just need super high current super fast. The best way to do this is to charge up some big capacitors and then discharge them through some wires. That’s essentially what MacGyver does.

The biggest problem is his capacitor. He builds one using two roulette wheels. Like this.

Yes. Any two metal devices can create a capacitor—but you want one with a large surface area and very close together. If you turned the two tables around so the flat side was close to the other one, it would be better—but it’s still a capacitor (but not really big enough for this job). Still, the idea is solid.

MacGyver Season 2 Episode 1 Science Notes: DIY or DIE

I’m kicking myself. I should have been writing these MacGyver notes for each episode as they aired on TV. But no. I had to make things more complicated. Well, here I am—starting the notes for season 2.

Let’s just jump in. Note: there’s some pretty good stuff in this one.

Blade from a button.

MacGyver takes a button from his shirt and breaks it in half. From this half button he sharpens the edge so that it can cut through a rope.

I wouldn’t normally include this one in the blog since there’s not much science to talk about—but I’m just excited.

Flare-based harpoon and winch.

MacGyver takes a metal rod and puts it in an empty dip stick tube from an engine. He adds the powder from a road flare to act as a propellant. This would then launch the improvised harpoon forward.

Once the harpoon is stuck into a fleeing car, Mac wraps the cable around the horizontal axle on the sidecar to a motorcycle. As the axle spins, the cable wraps around it and pulls the motorcycle closer to the car.

Mini gun as a starter motor.

They need a car. MacGyver finds one—but it’s missing a starter motor. Really, there is nothing super special about a starter motor. It’s just a DC motor that is strong enough to turn over the engine so that it can turn itself (using gasoline).

The mini gun also uses an electric motor. In this case, the motor spins a combination of gun barrels so that the fire rate can be higher than a normal machine gun.

Could you use one motor for another application? Theoretically, yes. The only tough part might be mounting the motor (which MacGyver does with some wire—wire is often better than duck tape). The other problem is making sure the gears on the motor match up with the gears on the car to turn over the motor—but it’s still possible.

Run up a wall with a pole

Sometimes, there are hacks that look too crazy to be true—but in fact would totally work. Here is an example of such a hack.

MacGyver and friends take a long pole. MacGyver gets on one end near a wall and the other two push the pole towards the wall. This allows MacGyver to walk up the wall.

But wait! Here is a video of this trick being used in real life by a Vietnamese SWAT team.

Here is my super short explanation.

  • If you push someone against a vertical wall, there will be a frictional force pushing UP.
  • If the push is great enough, this upward frictional force can be equal to the gravitational force.
  • Boom. That means a person can walk up a wall.

Here is a force diagram of that situation.

Spring 2017 Sketches key

Oh, I also made a video to show you how this works.

Finally, here is a more detailed explanation from my WIRED blog.

Cell phone in a soccer ball.

Ok, you can put a camera in a ball and kick it through a window. Not really much of a hack, but clever.

Improvised diver propulsion vehicle.

MacGyver needs to get through a submerged passage—it’s long enough that he can’t swim the whole way. This means he needs some scuba stuff. In particular, he needs the following:

  • Some type of air supply with a regulator.
  • A mask and some type of mouthpiece to breath.
  • A light.
  • A DPV—diver propulsion vehicle.

Please forgive me, but I’m going to go over more detail in this case that you would like. I can’t help it. MacGyver is basically cave diving—this is something that I used to do quite a bit.

Just to show you what that was like, here is an older picture of me. It’s not cave diving, but it’s using all of the same gear (it was practice).

Let’s start with the scuba gear. MacGyver doesn’t have a regular scuba tank, so he uses an oxygen tank used for welding. You don’t normally want to use oxygen for scuba—you want to use air (which is only 21% oxygen). You see, oxygen is actually toxic. If you breath oxygen at high pressure, it can do bad stuff to you. Fortunately, MacGyver is going to use this at very shallow depths—he should be fine. Also, he won’t need to much gas as you consume much more at greater depths (for open circuit systems like scuba).

What is a regulator? Suppose you have a pressurized tank at 1000 psi. You can’t really breath air (or any gas) at that pressure (although there are some tricks—ask me later and I can tell you about this). That’s where the regulator comes in. It takes pressure from the tank and reduces it to the ambient pressure. That’s really important. It has to deliver the pressure at the same pressure around the human. If it was too low, you wouldn’t be able to expand your lungs and breath.

Luckily, they have regulators for welding stuff too. You need a second regulator to let air out only when you breath—but it’s possible to build one of these (they are much simpler).

Now for the DPV. These things are very useful in cave diving. How are you supposed to get 5,000 feet back in a cave if you have to swim the whole way? The early DPV (or scooters as we called them) were essentially trolling motors from a bass fishing boat connected to a battery.

Just about any electric motor with a battery could work. Ideally, the motor should be sealed so it can run underwater—but it doesn’t have to be perfect. It only has to work for a short time.

I really like the scooter in the episode. It really looks like a home built scooter.

OK, you can’t see it too well in that image—just trust me. Or better yet, watch the episode.

I also like how MacGyver side mounts his tank. Even if you have done normal scuba diving, you might be surprised at how these tanks behave underwater. Just because they are heavy out of water doesn’t mean they will pull you down underwater. Very often we would bring extra tanks (stage bottles) in a cave and carry them on our side just like MacGyver did.

Parkour Wall Jump.

MacGyver gets to run up a wall twice in this episode. Just like the wall run with the pole, this case also uses friction. It’s your classic parkour wall run-jump.

If you run towards a wall and push yourself back, there is a force between you and the wall. The faster you run, the greater the force. If this force is great enough, there will be a large enough upward frictional force so that you can get an extra upward jump.

That’s exactly what MacGyver does to get out of the tunnel. Here is a more detailed WIRED post on this wall jump.

MacGyver Season 3 Episode 17 Science Notes: Seeds + Permafrost + Feather

The Seed Vault is real

It’s basically a giant insurance policy. Suppose something terrible happens and a bunch of crops are wiped out. What then? How do you start over? Yes, you go to the seed bank and withdraw your seeds.

https://www.croptrust.org/our-work/svalbard-global-seed-vault/

Feather to detect air currents

MacGyver pulls a feather out of his jacket and uses this to detect air currents. This should work since the feather will move due to super tiny air motion that would be too small for a human to feel.

This reminds me of a job I once had. The job was to go to people’s swimming pools and find leaks. I would take a small squeeze bottle with red dye and let out tiny amounts into the water to see what would happen. If the red dye got sucked into the wall—there’s your leak. Oh, this was done with scuba gear so that I could stay underwater for long periods of time. It was extremely boring.

Finding position from a smartphone accelerometer

Your phone has an accelerometer (probably). At the very least, this accelerometer is used to determine the orientation of the phone so that it knows if you are taking a normal video or a vertical video (don’t do vertical videos).

This accelerometer is essentially a tiny mass on a spring (but not an actual spring). When the phone accelerates, the spring gets compressed by an amount that is proportional to the acceleration. That’s how you get the acceleration. Once you have the acceleration, you can integrate twice to the get the change in position of the phone (assuming the phone started from rest). If you keep doing this every tenth of a second (or whatever time frame you want), you can track the location of the phone. True.

In fact, if you use the augmented reality (AR) on your phone then you have to use the accelerometer. Your phone figures looks at a surface from different viewpoints to figure out how far away it is. The different viewpoints are determined by the motion of the phone and the accelerometer.

Just because it’s cool—here is my short explanation of AR on the phone.

Toxic Pea

Can you actually make a toxin from a pea seed? Yup. That’s possible. In fact, there are a bunch of things out there in the real world that have some pretty deadly stuff in them. Here are some options.

Directional satellite dish

If you have a normal wifi antenna on your computer (and you probably do), it basically just transmits radio waves in all directions. It’s not a completely uniform signal strength in all directions, but let’s just assume it is.

Imagine these radio waves expanding out and forming a sphere. Since the area of the this radio wave sphere is proportional to the square of the radius, the signal power decreases with distance. That’s just how it works.

But wait! What if you redirect these waves into one direction? That would increase the radio power along that direction and give you a better signal. However, you now have to aim this thing.

There are several methods to make a directional antenna. The two common methods are to use a parabolic dish (like a satellite dish) or a wave guide. The wave guide uses a tube with an antenna located at a certain point. Waves go down the tube and then reflect to constructively interfere and make the signal stronger in that direction.

MacGyver Season 1 Episode 19 Science Notes: 19 Compass

What does “normal” mean?

Honestly, this a great physics joke. MacGyver and Jack are in a trash compactor—yes, there are some Star Wars jokes here too. In order to break the hydraulic pump, Mac wants to put a pole so that it pokes through a particular screw. Here’s the important part.

MacGyver: …if I hold the pipe perfectly normal.

Jack: Dude. Nothing about this is normal.

Jack messes up and hurts his arm. According to MacGyver: “I used a technical term that Jack didn’t understand.”

Ok, so what does “normal” mean? In short, it means perpendicular. That’s it. MacGyver needed the pipe to be perpendicular to the wall. That’s what normal means. That’s also why physicists call the force a surface pushes on an object “the normal force” —because it’s perpendicular to the surface.

Yes, we also use “normal” in geometry—but of course Jack wouldn’t get that.

What is a spectrometer?

Not a MacGyver hack, but I want to talk about spectrometers anyway.

My first idea of a spectrometer is a visible-light spectrometer. This is essentially a prism. Light goes into the prism and is then separated into different colors. By looking at the colors in the light you can identify the light source. Oh, but this kind of spectrometer wouldn’t be found in a chemistry lab—at least probably not.

There is also a mass spectrometer. This takes a gas of molecules and shoots them into an area. Using magnetic fields, the path of the molecules is bent. Based on the amount of particle deflection, you can get a value for the mass of the particles.

Also, it’s just fun to say “mass spectrometer”.

Origin of Hacking

Come on. We know that MIT didn’t really invent hacking. Humans have always been able to creatively figure out problems—which is the essence of hacking.

However, MIT might indeed have invented the word “hacking”. The history of this stuff is really interesting. Let me recommend the following book—Hackers: Heroes of the Computer Revolution (Steven Levy). I liked it.

Door Alarm

Another non-MacGyver hack. This is a hack from his friend. She creates a door alarm. You can’t really see it very well, but it would be a small battery with a buzzer. The circuit runs to a clothes pin with aluminum foil on the pinchers and a piece of paper between them. Since the paper is an insulator, there is not a closed circuit. The paper is then attached to the door (with tape) so that opening the door pulls the paper out.

It’s actually a pretty simple design. You can (and should) build one of these yourself. Here is a video showing how to do that.

Electric Whip

In order to make an improvised weapon, Mac takes an extension cord and cuts off one end. Then he strips the wires on that end and plugs it in to the wall outlet. Note: DON’T DO THIS.

When the two bare ends of the wires touch someone, they will get shocked. Oh, and it’s a whip.

So, would this work? I think it would mostly work. It wouldn’t make the lightning stuff, but that just makes it look cool. It does look cool, right?

DIY Centrifuge

This might be the best hack in MacGyver history. Basically, this is a real life MacGyver-hack. It’s a low cost and simple to build centrifuge.

What the heck is a centrifuge? It’s a super high speed spinning thingy. You can put liquids in there and the high rotation rate causes a centrifugal force (yes, I used that term correctly) to separate liquids of different densities. This can be used to process blood.

Here is a real centrifuge.

And here is the DIY version. It’s basically just string and cardboard. However, with this simple version people can process blood stuff in more rural areas. Awesome.

It’s real.

MacGyver Season 1 Episode 18 Science Notes: Flashlight

Hold on. There’s a metric butt ton of science in this episode. It’s going to be great.

Turning bullet

SPOILER ALERT. This episode has a bullet that can turn. It’s sort of the key plot element in this episode. These dudes are trying to steal the technology for these “smart bullets”. These bullets are essentially tiny guided missiles with fins so that they can turn in flight.

I’ll just leave this Wikipedia link on smart bullets and then move on (it’s not really a MacGyver hack anyway).

The physics of birthdays

Again, not a hack—but MacGyver thinks birthdays are dumb. Well, not dumb but arbitrary. I think he is right. In fact, I use the following phrase on people’s birthday’s:

Happy Solar Orbit Day.

Yes, that is the day the person completes another orbit around the Sun. I like thinking of it that way.

Fixing a generator inverter

There are lots of different types of generators. Most of them involve a gasoline engine that turns stuff. Some times this turning stuff involves a magnet to make an electric current. But what happens when the magnet get’s messed up? Yes, you have to fix it.

A permanent magnet is a ferromagnetic object (like iron) in which all the magnetic domains are aligned. If the domains are not aligned then it would just act like a dumb piece of metal. You can get the domains align by applying a strong magnetic field.

This is exactly what MacGyver does to the generator. He uses a defibrillator to generate the current and forms a loop of wire to create the strong external magnetic field. Seems like it could work.

DIY sand blaster

How do you get people out of a collapsed building? What if you could just cut through the wall? Yes, that’s the MacGyver plan.

In this case, he uses high pressure water mixed with sand—a type of sand blaster. If you have water at a high enough pressure, it can pretty much cut through anything. Of course MacGyver’s water by itself isn’t fast enough. That’s where the sand comes in. When the sand hits the concrete, the abrasive interaction is enough to eat away at the concrete.

Oh, this would take quite a while to work.

Seeing through walls with radar

Yes, this is a real thing. NASA made this device. Here is a description. Basically, this thing sends out microwaves and detects the reflected microwaves. But the magic is that it only looks for variations in reflections caused by small oscillations—these oscillations are from a human heart.

For MacGyver’s version, he starts with a radar gun (from a police car). These don’t use the same frequency as the microwave detector, but he can make a modification. With some software from Riley, that’s pretty much what he needs to get started. It’s at least plausible.

Screw jack

How do you lift super heavy stuff? You need a simple machine. All of the simple machines deal with force and distance. If you can increase the distance over which you apply a force, you can get a greater output force over a shorter distance.

In this case, MacGyver makes a screw jack. You can lift a large mass by turning the screw to get it to extend. In fact, you could do something like this yourself. Here’s how.

Ascender rig

The goal of an ascender rig is to allow some device to move UP a rope, but not down. This means you can climb up a rope one little bit at a time. Here is an example.

Oh, MacGyver made an ascender rig to climb an elevator cable and escape a collapsed building.

Modify laser

The smart bullet is aimed using a laser. Of course the bullet is only a little bit smart. It only aims towards the brightest laser. If you could make another laser that gets the attention of the bullet, you can get the bullet off course.

MacGyver takes the laser sight off a pistol. In order to increase the power output, he burns off a potentiometer. This could work on some lasers—like this.

Oh, DON’T DO THIS. You don’t want a powerful laser without knowing what it can do. These lasers can seriously damage your eyes in ways you wouldn’t be able to predict. Remember, you only have two eyes. Don’t mess them up.

So, they use this powerful laser to redirect a smart bullet. That part is plausible. It’s unlikely they could get a bullet to turn all the way around. They wouldn’t have time to move the laser dot and the bullet fins couldn’t make it turn that much.

Who cares. It was still a great episode.

MacGyver Season 3 Episode 16 Science Notes: LIDAR + Rouges + Duty

What is LIDAR?

Again, this is not a MacGyver-hack. Well, I guess it sort of is a Mac-hack since he designed the LIDAR. So, what is LIDAR? At the most basic level, LIDAR uses a laser to determine the distance to an object. By scanning this laser over some area, you can get a very detailed distance map. If you know the location of the LIDAR (in the aircraft), you get a very nice map of the terrain below.

But how do you get distance with a laser? The laser produces a beam of light (that’s what the “L” stands for in “laser”) and this light travels at a speed of about 3 \times 10^8\text{ m/s}. Yes, that is super fast. However, it’s not infinitely fast. So when this laser light travels and reflects off of something, it takes time to get back to the LIDAR. The longer it takes to return, the greater the distance. That’s the basic idea of LIDAR.

How do you start a jet engine?

I’m not an aeronautical engineer (in case you didn’t already figure that out). So here is my very simple explanation of a jet engine. The key to getting thrust is the same as a propeller driven aircraft: make the air coming in go faster as it leaves. This increase of air speed (into and out of the engine) means a change in momentum and thus a forward pushing force. For the jet engine, it increases the final speed of the outgoing air by also heating it by burning fuel.

So, how do you start a jet engine? It’s not the same as starting your car (but not completely different either). The main thing is that you need to get the jet turbines spinning first so that there is air moving through the engine. Then you can add the burning fuel to get the thing started. Here is a great video on how this works. Oh, this is why youtube is so nice—you can find a video on pretty much anything.

Pick lock with a paperclip

Oh, you missed this hack—didn’t you. When MacGyver gets into the old building, he has a paperclip in has hand. So, can you pick a lock with a paperclip? Maybe. You could use the paperclip to jiggle the lock pins, but you would need something to apply torque to the lock cylinder.

Here is a tutorial on lock picking—but don’t be a bad guy.

Break open door with a raft

MacGyver pushes open a locked door by filling a raft with water. Let’s start with the definition of pressure. Pressure is a force divided by an area.

Let’s start with the definition of pressure. Pressure is a force divided by an area.

P=\frac{F}{A}

You can solve this for the force.

F=PA

So, if you have a pressure (in the raft) it will produce a force equal to the product of the pressure and the contact area. The bigger the area, the greater the force. In fact, with just a small pressure you can get a pretty big force.

OK, this is from a previous episode but I still like it. Here is a demonstration in which I use the pressure from my lungs to lift myself. Yes, small pressure with a large area means a significant e force.

What about the water? Well, the water will give the raft more mass so that it doesn’t just push itself away from the door. If you want to open the door with air pressure, you would need to have something hold the raft agains the door.

Dart gun

I love this visual effect where MacGyver is looking around for stuff to build and it shows all the things he sees. In the end, he builds a dart gun that shoots morphine needles.

Really, I just want to talk about two parts of this build—the shooting and the injecting. MacGyver uses a propane tank to shoot the dart. This is the same as your basic potato gun. Compressed gas from the tank push the dart in the tube. The longer the distance of the tube, the greater the final speed of the dart.

For the injection, you can’t just shoot a needle into someone. You need to push that plunger on the back of the needle to get the drug into a body. That’s where the steel spacers come into play. When the front of the dart hits a person, it will stop. However, the mass on the back will want to keep going until a force slows it down. This force comes from the plunger—that means the plunger gets depressed and the bad guys get drugged.

Beam splitter

How do you make one laser look like many lasers? You need a beam splitter. This is exactly what MacGyver does to fool the baddies into thinking there are bunch of other good guys in the woods.

Basically, a beam splitter is a piece of glass. We like to think of glass as being transparent so that light goes right through it—and it does. That’s why we use glass for windows to see stuff outside. But light also reflects off glass. In fact, if the light (from the laser) hits the glass at an angle then you will get both transmission AND reflection.

It doesn’t even need to be glass. Here is a quick demonstration of a beam splitter with just a piece of clear plastic.