Listener Grab Bag

an executive producer here at hell Stuff Works. I love all things tech, and typically I would cover a specific topic at this point, but instead I'm going to look at a bunch of different topics have been sent to me over the past several months that perhaps don't merit a full episode, but I could group them together and actually address them instead of just leaving them to hang

in the air or in the ether. So I'm gonna take a several handful of requests from various listeners to chat about very different topics and kind of give you a quick overview of each one some of them. One of them in particular, I will do a full episode on later, but we'll mention that when we get there. First listener Marcus wrote in and asked if I could cover fido net. So, for those of you who have been around for a while, you may be familiar with this term, and so Marcus said, this is for you,

what the heck is fido net? Well, from the name, you might think it's a computer network for dogs, and in fact the logo is an as key art image of a dog, but that's not what the network actually is. First, fido net is closely related to bulletin board systems or bbs is. I've talked about these in the past, but let me give a quick summary of what those are, and then we'll get back to phido net. Bolton board Systems developed not long after the home computer market got established.

If you've listened to my episodes about the early computer days, the home computer days, you know that hobbyists made up a large chunk of the computer owning population. Many of those hobbyists weren't just interested in getting a new toy or a fancy calculating machine. They wanted to experiment with what they could do with these machines, and they wanted their computer to be able to communicate with other computers.

In places like California, there were hobby clubs like the Homebrew Computer Club, but in other places it could be hard to find someone who shared your interests. It was just difficult to track anyone else down. So what was needed was a means of communication between different machines, even if they were separated by hundreds of miles from each other. These days, we use the Internet to send and retrieve information all across the world through millions of interconnected machines.

But back in the late seventies and early eighties, the Internet was still kind of taking shape. It was really young, and it was not accessible to most people. It's pretty much a network connecting some government and academic institutions, and slowly a few other machines were growing and joining the network, and that was about it. The average person didn't have Internet access. Heck, at that time, the average person had no idea that the Internet was even a thing at all.

In nine, a couple of members of the Chicago area Computer Hobbyists Exchange also known as CASH, began to experiment with their newsletter archives. Then this crazy idea, why not use a microcomputer, you know, a personal computer or home computer to host the newsletter. The computer would have a modem, a dial up modem that hooks into the telephone line, and members could use their own computers that had dial up modems to call into the host machine and read

the newsletter archives. If this sounds a bit like a rudimentary Internet, You're not far off. The Internet uses a similar structure, with machines acting as servers serving data to other machines that are acting as clients. With a BBS, the host computer is a server and the users computer is the client, except this was a one to one

connection in most cases, not a persistent Internet. A cash club called their hosted system Ward and Randy's Computerized bulletin Board System, which was frequently shortened to c b b S that would later become BBS. This was named Afterward Christensen and Randy Seuss. Those were the two who created this software. They wrote up a report about their idea and how they did it, and a magazine called byte b y t E ran the story. More hobbyists began

to create similar systems on their home machines. Now over time, these systems became more sophisticated. Programmers began to make hosting software that would allow for more complicated features and operations. By the mid nineteen eighties, typical bbs could host messages, including a simple version of email. You could log into the host machine, You could look for other members who also used that service, and you can leave them messages.

But it was all limited to that host machine. You couldn't leave messages for someone on a front BBS because there was no connection at that point between the two. So a BBS was limited by the host computer, and the users were often limited by which bbs is were within their dialing network. So if you wanted to log into a local BBS, it wasn't a big deal. You could do that. You could look at the user list

and you'd say, Oh, that's my buddy Bill. I'm gonna leave Bill a message and use the hosting service to leave a message for your buddy Bill. Bill. When Bill logs in can see that he's got a message, he sees into Oh, Sally sent me a message, and sends a message back to Sally, and so on and so forth.

If you want to log into a different BBS, you had to call a totally different number, the number for that particular machine, and then you would connect into it and you could navigate and leave messages to those users.

Some of these bbs is might be in other area codes, as in telephone area codes, and back in those days, you had to pay for a long distance and the rates were depending and upon lots of different things, but it boiled down to the fact that most people weren't willing to spend lots of money to connect to other bbs is, so you were kind of limited in your options.

This created an opportunity for programmers and BBS operators. Users loved getting access to files, systems, and games that were on other machines, but they didn't necessarily have the money to dial up for a long distance call to connect their computer to another one that was across the country. Kristensen and Seuss had proposed a way to network bbs is to allow for information exchange, but it was another

enthusiast named Tom Jennings who actually made it happen. In four Jennings created a BBS hosting program he called fidoh. This was for computers running on MS DOSS. As MS DOSS was establishing itself as a power player in the home computer space, more BBS operators began to adopt Fido, and so Jennings added in a little feature in his BBS hosting program m. It would let to Phido bbs is call each other, so as long as they were

both running the phyto software, they could communicate. The call would be automatic, and upon making a connection, the two separate bbs is could exchange data, meaning messages in this case, so messages from one user to another. This would effectively allow users from one BBS to send mail to people connecting to the other bbs. So if you, Sally wanted to send a message to Bill, but Bill was using a different BBS, and your BBS and Bills BBS, we're

able to talk to each other. Suddenly you could do that, when as before, you could only leave messages for the people who logged into your specific BBS. This was revolutionary. You were no longer restricted to chatting with people that were only in your own community. It was kind of like opening up a highway between two previously isolated cities. People could come and go and make new connections. And by adding more bbs is to the system, you could

increase this even greater. Right, you could suddenly leave messages for people at all sorts of different places. Administrators had to figure out a few ways to make the system efficient and reduce costs as much as they could. That included coming up with ways to compress data so it could be sent quickly across dial up modems, and since exchanges frequently happened between systems that had to call one

another over long distance. Time was money, so you wanted to cut that time down as much as possible, thus the need for compression strategies, because the smaller the file, the less time it takes to transmit it across the

telephone lines. Phone companies also would charge different rates for a long distance at different times of the day, which would lead administrators to try and tweak their systems to connect to one another at the low points of the day, typically in the middle of the night, although the middle of the night in one place is not the middle of the night in other places, so even that required

some tricky work. This meant that you could have technically received a new message, but you weren't able to see it yet. So let's say you've got a friend named Julie. Julie lives across the country, and she writes you a really nice letter on her BBS. You log into your local BBS, but because your system and julie system have not yet called each other that day to exchange information,

you don't yet see Julie's message. It lives on her native BBS but has not yet made the transition over to yours, so it would look as if Julie hadn't written you yet, when in fact she had. It's just that the two systems have not sinked up yet at that point. Once they did sink you would see her letter once you checked your mail. So it wasn't quite as seamless as web mail would be later on, but it was still far faster than using something like snail mail.

By the early ninety nineties, fido net had twenty thousand bbs s or nodes connected to it. By this time, phido net could support many different inter networked features. Websites could end up adopting some of the popular features later on,

such as message forums. Jeff Brush cre aided a system called Echo Mail in nineteen six that was essentially a message board where people could post a message and anyone connected to one of the bbs is on that network could respond to that message, so it could become all sorts of discussions, just like you see on forums and

message boards today on the web. Fido neet kept going strong as online service providers like a O L Online showed up later, but once internet access became more common and broadband access became a thing, the BBSs saw a steady drop in activity many node administrators chose to take their machines offline or they didn't bother to fix them once a machine broke down. Phido neet still exists to this day, however, with computers still sending information back and

forth to each other. It interconnects with the Internet, meaning it's not entirely separate from the network of networks. And that's the general skinny on fido NEETs. So we're gonna now move on to the next topic, and this one is about agile work environments in general and Scrum in particular,

and it's a request from listener Lucien. So if you're a software developer, if you're in that business, you're you've likely at least heard about agile methodology and agile processes, or maybe you've gone through the actual process of adopting agile methodology. But for the rest of us the term might sound a little mystical. So what is agile methodology? Basically, it's just a framework for getting work done. It's a process, if you will, to follow when you're working on developing software.

There have been many proposed methods of streamlining the development process so that a development team is making the best use of its time and talent. Scrum technically predates the current versions of Agile, but many of the concepts from scrum have been adopted by the Agile framework. Ikuhiro No Naka and hiro Taka Takuchi proposed the process in an article in Harvard Business Review back in nineteen six. They elaborated on the idea over time, likening software development to

a game of rugby. Now, in rugby, players try to move a ball down a field into an opponent's end zone, and they can pass the ball back and forth to one another. Not not in a forward line, but they can pass it back and forth to one another in an effort to try and get the ball to that

end zone. That basic concept plays over to software development, in which part of a team, or a small team within a team, might have control of the project the ball, in other words, for one part of the process before passing it over to another mini team to keep the development moving forward. By the ninet nineties, this method had taken on the name scrum, which is also the word for a massive rugby players trying to gain possession of

a ball during a rugby game. If you've ever seen anything that looks like a big huddle in rugby, and it involves both teams and they're all kind of pushing against each other's shoulder to shoulder. That's a scrum. The development moves forward in phases called sprints, and each sprint can take anywhere between a week to a month or more. There are three big roles within the scrum methodology, and everyone falls into one of those categories. First, you have

the product owner. Now, this is the person who defines what the software is supposed to be, what it can do, what it looks like once it's all finished. The product owner is supposed to think of the software in terms of how the final customer is going to experience that software. Now that customer might be an average person, or it might be another company, but whatever it is, the product owner is the one who defines what the software is supposed to be able to do. So let's just say

that it's a spreadsheet program. The product owner would be the one who has to say, all right, this program has to be able to record and tally long lists of figures and run various operations on those figures. But the product owner probably and say also it should play

music and display headlines of breaking news. The product owner sets the expectations for the rest of the team as to what the software should ultimately do at the end of the day, and a good product owner won't make lots of changes to that expectation as the project moves forward, Otherwise the team will have to deal with the dreaded feature creep. If you listen to the Apple episodes, you

heard me talk a lot about feature creep. That's when typically well meaning but perhaps naive stakeholders add more requirements to an increasingly bloated and complicated project. It also makes it harder to actually make the project work. The more stuff you add to it, the more opportunities there are for stuff to go wrong. Next, you've got your scrum master. Now, this should be a totally different person from the product owner.

The scrum master's job is to run interference for the rest of the team to smooth out potential obstacles, to make sure the team has the assets they need to get their work done on. They're kind of a facilitator. They're also in charge of making sure the team is able to follow the scrum philosophy, which relies very heavily on self organization. Now, if you've ever been a work environment in which self organization played a big part and you were new to it, you might have experienced some

difficulty in adjusting at first. It is something that some people find really challenging. The scrum master is supposed to help team members who are feeling a bit lost. The final role is what the majority of the people on any given project fall into, which is the development team. These are the people responsible for creating the product according to the expectations of the product owner. Typically, the team

works on incremental segments of the development process. Each increment represents a sprint, and they might be implementing a new feature or developing something totally different that's supposed to integrate with the rest of the software later on. It can really depend upon whatever the software development project is. Most projects require several sprints, and each sprint has a predetermined deadline.

So when I say sprints take maybe a week to more than a month, that deadline is set ahead of time based upon the assessments of the product owner and the scrum master. They take a look and they say, well, based upon what we need and based upon what our team is able to do, we expect that this part of the project is going to take two weeks, so

we're gonna set that sprint time for two weeks. Ideally, each sprint ends with a fully developed increment in the product that would be ready to go if it were fully realized piece of software. So, in other words, if you are developing a specific feature for a software program, at the end of that sprint, that feature should be completely done, and if everything else were ready to go,

you would say, let's ship today. You're not supposed to have something that's partly finished or it's dependent upon something else. Ideally it's all self contained. Each sprint begins with a meeting to define requirements and expectations, and it ends with

another meeting to review how the process worked. In addition to those bookend meetings, the development team has a daily scrum, which is a short fifteen minute meeting that's meant to review what work has been done already, what work still needs to be done, and what could possibly cause problems

in getting work done for that day. So if you say, hey, I need to do X, Y and Z by the end of today, but I can't or it's gonna be hard because of this other thing, the scrum master can try and take care of that other thing and remove that obstacle from your path. Then you rinse and repeat until the full project is finished and ready to go.

And that's scrum in a nutshell. There's a lot more that has been said and written about it extensively, and it's not a one size fits all solution to software development. For example, if you've got a team that has a lot of ultra specialized workers, people who really focus in on a narrow but deep set of software development skills, scrum probably won't work so well because it's really meant

for people who are more general purpose programmers. Uh. They have to be really flexible and be able to move from one thing to another. If you've got someone who's got a kind of a razor sharp focus on a very deep subject, they probably can't be as flexible as other people. And it's not to say that one type of developer is better than another. They both have their

uses dependent upon what it is you need to create. Uh. So this particular methodology, while it might be ideal for certain organizations and the types of software they develop, may not work at all for others. And I can tell you having observed it at firsthand. Anytime you implement a new methodology, a new process. There are so many growing pains and so much a smith It has to happen, and typically the people who are going through it hate it when it first starts because change is scary and

no one likes to have to do it. Uh So it's it's one of those things where is it an effective tool. It's completely dependent upon your circumstance. Also, I should add that while there's anecdotal reports about scrum and agile methodologies improving workflow, there's no empirical evidence necessarily that actually states that these approaches to work are inherently better

than others. It may just be that it is a way for you to write down how projects get done so that you have a better way of keeping track of it, which has its own value, But it doesn't necessarily mean that this particular approach is going to get things done in a more efficient and uh cost effective manner. I've got a lot more to say in this listener grab bag episode, some more subjects to cover, but before I do that, let's take a quick break to thank

our sponsor. One of the other requests I received recently was in response to the show I did about the history of clocks. The request was to talk about atmospheric clocks, a particular type of clock that harnesses physics to keep the clock wound and keeping time properly. And it's pretty cool stuff. So here's to you, climber z z z whomever you may be. First, a quick review. For a mechanical clock. To keep time, you need a few elements

in place. You need some sort of way to generate the force necessary to turn the hands on the clock's dial. This force should be steady, but it also cannot be constant if we want it to be easy to read the time on the clock. If the hands are constantly in motion, even if they're moving slowly, it's harder to read the time. So there needs to be a method of regulating the movement of the clock pieces to make it simpler and more regular to tell time, and to

make sure you're you're telling time accurately. Enter the escapement. Now it sounds like a trap door or something, but an escapement is actually a device that helps regulate the motion of a clock's innards. And there are a lot of different types of escapements, but they all basically do the same thing. They act as a break for the other parts of a clock, and they released that break at regular intervals to allow the parts to move and

for the hands to progress around the clock dial. So let me explain with an example, and this is when I talked about in that previous episode about the history of clocks. I mentioned that there was a famous water clock tower built in China around the year ten ninety four, which was eight years after they had started building the thing. It took eight years to build it. The inventor of this tower was a genius named Sue Song. He used a water wheel to transmit force from flowing water to

the clock's mechanisms. Now, imagine that you've got a vertically aligned water wheel, and around the rim of the water wheel are buckets. As water falls from above, it fills the bucket on the furthest edge of the water wheel, and the weight of the filled bucket causes the wheel to rotate. Now, if you didn't have a break, the wheel would rotate rather haphazardly. Su Song knew this, so he built in a simple but effective system on the opposite side where the water was flowing. He created a

weighted lever. On one end of this lever, you would have a little bit of a weight, and on the other end, it would actually rest against the backside of the bucket opposite the one being filled. If you're having trouble imagining this, draw a circle. Then draw some simple buckets, all facing along the same direction. So let's say we're making the buckets face counter clockwise. So the bucket on the rightmost side of your wheel should be facing upwards,

open style. The bucket on the leftmost side of the wheel should be faced down, so it's the bottom of the bucket that's toward the top of the circle. The lever would rest against that downward facing buckets bottom. It would stop the water wheel from rotating freely. The lever was weighted so that would only hold back the wheel until the bucket on the other side had a sufficient

amount of water in it. At that point, the bucket with water would weigh enough to turn the wheel, lifting the lever up, and the wheel would rotate one position.

And as the bucket cleared that lever, after it's lifted it up, because it's on a little pivot, the lever would fall back down and stop the next downward facing bucket, And meanwhile, some of the water would slash out of the bucket that just moved downward the filled bucket, and there'd be a new bucket in the place of the old one that would be filling up with water, and the whole system would start again. Now, that was the escapement that lever because it controlled the rotation of the

water wheel. As clockmakers created more sophisticated clocks, the escapement took on other forms, but its purpose remained the same, to create a means to keep the rotation of a clock's inner works regular according to the divisions of time we humans have arbitrarily set as being meaningful. One other thing that did change was how clockmakers would provide the force necessary to operate the clock. Sue Song was using falling water and a water wheel, but most clocks use

some other methods, such as a wound spring. Winding such a time piece means you are curling metal ribbon, creating stored energy. So take a piece of metal, cut it into a ribbon, usually use steel, and then you curl that into a coil, and you keep curling the coil tighter and tighter and tighter. The metal ribbon quote unquote wants to return to its natural state of being a straight piece of metal the spring under tension creates the

force that drives the rest of the clock's gears. As it starts to unwind, it provides the energy needed to turn the other gears of the clock. But eventually this spring, often called a main spring, well unwind to a point where it no longer can provide the force needed to keep accurate time, which is when you have to wind the clock back up again. If you've ever had a

watch that did this, you know what I mean. Like, once a day, you'd wind your watch, which would actually coil this spring tighter so that it would continue to unwind and provide the energy necessary to make everything else move. But what if you came up with a way that didn't require you to wind the clock on a regular basis. What if the clock was somehow able to wind itself using physics. Enter the atmosphere clock, also known as the utmost.

There was a man named Jean Leon Reuter, who was a Swiss engineer who was living in Paris at the time, who invented the device in nineteen twenty eight. He wanted to create a clock that was self winding, and to do so he looked to the weather. Specifically, he figured if he could create a device that depended upon variations in air pressure due to changes in temperature, he could provide the winding motion necessary to keep a clock in

good working order. The heart of the ATMOS clock is a sealed chamber filled with an expandable fluid or gas. The original patent suggests mercury, but more recent ATMOS clocks use gases like ethel chloride, which boils at fifty four degrees fahrenheit or a little more than twelve degrees celsius. It's this gas that provides the force needed to wind the clock. The gas will expand or contract with changes

in temperature. Higher temperatures make the gas expand, and lower ones will make it contract to the point where it will condense. If you get the gas cold enough, it'll condense into a liquid. The gas will respond to small variations in temperature, which is good because these clocks were meant to be stored indoors, where temperature variations are less extreme than they are outside, so little changes in temperature can provide enough energy to keep the clock wound for

a couple of days. In some cases, expanding gas can do a lot of work, like pushing against stuff, so if you either put something in that sealed chamber to push against, or you make the chamber itself part of a mechanism. So it's kind of like bellows that expand and contract. You can leverage that to do useful work. In the case of an atmos clock, that work involves providing the force necessary to wind the clock's mainspring. So the big trick there is translating this expanding and contracting

motion into a winding motion. Now, a typical approach is using a chain attached to a bellows that contains the gas. The other end of the chain is wrapped around a ratcheted opponent that can wind the spring. If you replace the chain with a knob, you could physically turn the knob and wind the spring that way. Turning one way winds the spring. Turning the opposite way would allow the ratcheted component to keep the existing tension on the spring,

but allow the free rotation of the knobs. So, in other words, you can't unwind the spring by turning the knob because the ratchet allows you to turn it freely without actually losing any of that tension. Turning it the other way would allow you to actually wind the spring. So you can only turn it one way to affect the spring. So this chain is under tension. On this ratcheted component, you might use a spring attached to the chain that keeps it under this tension, so it's always

pulled tight. No matter if the bellows is fully expanded or completely contracted. This pushes. So let's say that the temperature increases. When the temperature increases, the gas inside the bellows will expand end, so the bellows moves outward. That would mean that the bellows is quote unquote pushing the chain. Now, you can't really push chain or rope, right. If you have a length of rope in front of you and you try and push it, it doesn't really do anything.

But if the rope is under tension as then if there's a weight on the other end of the rope and then you quote unquote push it, what you're really doing is letting out the rope a little bit, right, same thing works with this particular approach. The chain gets pulled a bit from this tension, and the bellows expanding allows the chain to move in that way. This would end up turning the ratcheted portion in a way where it was freely rotating so it's not it's not winding

the spring, it's just rotating so it doesn't unwind. Then when it gets colder, the bellows contract and pull the chain inward. This ends up turning the ratcheted component so that you are winding the main spring. So every time the temperature goes down, the main spring gets wound a little bit more, and as it unwinds, it's winding back

whenever the temperature drops. It does this over and over and over again, so it keeps that mainspring pretty much under tension consistently, so you don't ever have to wind it by hand. As being wound by actual physical changes in the environment, it's being wound by changes in air pressure, which in turn is being affected by changes in temperature.

It's pretty awesome. The interesting thing to me is that the in the end result, it looks like the whole thing is winding itself, and at a very casual glance, it almost sounds like it's a perpetual motion device. But that's not the case. Let me explain why, because there's a lot of confusion about the concept of perpetual motion machines. A true perpetual motion device if such a thing were possible,

and spoiler alert, it's not. Would continue to work once you set it in motion, with no need for any external power source. So imagine a pendulum and you started swinging, and it continues to swing indefinitely. It will swing until the heat death of the universe or the surfaces on is destroyed, but it will continue swinging until something forces it to stop. That would be a perpetual motion machine, but it's also impossible in our world. It would counteract

all limitations on the system. So the laws of physics as we understand them, states such a thing is impossible. If it is in fact possible to create a true perpetual motion machine, it would mean that our laws of physics are wrong, that we are incorrect in the way we have formed the laws of physics. But that would also mean that all the observations we have made based

upon those laws would need to be readjusted. And we've made a lot of technology that depends upon those laws being true and the technology works, which seems to be pretty strong evidence to support that those laws, while they may not be comprehensive, are on the right track, Because if science didn't work, we wouldn't have stuff like computers, technology is essentially science made physical. So why is perpetual motion impossible? Like, what was about our laws of physics

that state that this is an impossibility. Well, let's look at thermodynamics. The first law of thermodynamics is about the conservation of energy. Energy cannot be created or destroyed, but it can be converted from one type of energy into another. So, for example, potential energy stored in a wound spring can convert into kinetic energy as it unwinds, but no energy was actually created in that system and just changed from potential to kinetic, So you didn't create energy, you just

kind of translated it. A mechanical object is always going to have to deal with friction. It's always going to have parts that rub against other parts, and friction is this resistance that matter encounters when it moves against other matter. A mechanical system with enough power can overcome friction, but it loses some energy in the form of heat. Now, again,

it's not having energy destroyed. Instead, is that some of the energy that would be used to do mechanical work gets converted over into heat, which can dissipate into the environment. That means that the overall system has lost energy. We just lost it, and that means we can no longer use that energy to continue to do work. So any mechanical system, however well engineered, will eventually lose enough energy from heat so it will stop working without external energy

being poured back into it. That is, so that's the only way you can counteract that is to add more energy into the system. And that's what our modern technology does. It draws power from various sources. Some of those sources are physical, like water wheels or windmills. Some of them rely upon electrical sources like batteries, but all of them require a source of energy to keep things moving because they cannot go perpetually. They have to have that extra

boost of juice. There are a lot of free energy machines out there. Such a thing is completely impossible based upon our understanding of the laws of physics. Most of these free energy machines, on closer inspection, either don't work

at all. Actually, when I say most, I should say all the other don't work at all, or it turns out that they were using some other external power source in order to keep going, and either the person who created it did not understand what was actually happening, or their purposefully trying to cover it up in an effort to market something that simply cannot exist. In an Atmos clock, while it might seem like the spring is magically wound over time, the added energy is actually coming from the

external environment. Changes in temperature and then air pressure are the key because they create the work necessary to wind the clock. That's your external source of energy. So while it might look like it's all doing this on its own, it's actually reacting to its environment. The environment is the thing that's providing the extra oomph needed to wind the clock.

It's pretty awesome. By the way. These Atmos clocks are sought after by clock enthusiasts around the world, and you can get new ones if you've got about six or seven grand on you. You can find them on eBay for a few hundred dollars, depending on the make and model, and it's uh and what shape it's in. They're incredibly delicate, these clocks. They need to be on level surfaces. You're

not supposed to handle them too much. You're not supposed to move them around while they're actually working because it can disrupt the workings of the clock. So they're beautiful. They'll keep accurate time for ages because you don't have to wind them, but they are incredibly persnickety. So if you are a clock enthusiast and you want to find

something truly special, start looking around for atmos clocks. If you got you know, a few hundred, a few Hondo says that, or if you're like really rolling in at a few thousand, if you want a new one. Um also if you are rolling in it and you want to spend a few thousand on o'clock. Uh hey, my birthdays in June. I'm just saying alright. One more listener requests to go before we take another break. This one comes from Sam, who wanted to learn more about tests iracts.

So I just talked about physics. Let's talk about super duper crazy physics. Now. You may have heard of the term tests iract if you're a fan of the Marvel films that have come out over the last few years, or if you read The Wrinkle in Time or A Wrinkle in Time, because the characters travel through time and space using tests iracts, although the ones in that book

are different from your typical tests iact. One of the Infinity Stones in the Marvel universe, which will play a pretty important part in the next couple of Avengers movies, is in a form that they called the tests Are Act. So what the heck is it? Well, first, it's not

what Marvel depicts. A tests Are Act is technically a four dimensional object, or at least the three dimensional representation of a four dimensional object, and really is a three dimensional representation on the two dimensional medium of a four dimensional object. But let's explain that in a second. Let's just wrap our heads around this whole idea and review our concept of what a dimension is. So a point, as an a DoPT a single point in space is

a zero dimensional object. There's no dimension to It has no height, and has no length, and has no depth. Now, if you take two points and you draw a line between the two points, you now have a one dimensional object. A line has width or length, depending upon your perspective and frame of reference, but it cannot have both. It has one or the other. It's just got the one dimension, which you can express in units that measure length, such as centimeters or inches or miles or yards or meters

or whatever. But that's the measurement we use for length. That is one dimension. It has no area, It has no volume. Next we get our two dimensional up images. These are your basic geometric figures like squares and circles and triangles. They have height, they have width, but they do not have depth. We can measure these objects not only by how long their individual sides are or single side, as is the case of a circle, but also how

much area they cover. If we take a square and we extend the corners back a bit and draw a second square, and we connect things up, we we now have a cube. This is a three dimensional object or representation of a three dimensional objects. It has height, width, and depth, which means it not just has the width and length and depth. The depth creates the concept of volume. A three dimensional object can hold stuff in the real

world and it's it's got volume to it. This is the world in which we live, or at least the world that we can perceive. Our senses allow us to understand three dimensions. Pretty much everything we encounter, with the possible exception of some politicians and celebrities are happens to be three dimensional. And that was just a snarky joke, because even politicians and celebrities have three dimensions, unless they

are traditional cartoon characters. In which case two dimensions. A test erect is the three dimensional representation of a four dimensional object on a two dimensional medium. We sometimes call these hypercubes. You can actually draw a representation of this. Obviously, it has to obey the rules of our three dimensional perception, so it's a little tricky. The accepted octacorn figure is made up of eight cubes joined together, which isn't that

crazy when you first think about it. After all, regular cube is bound by six squares. So you take with six squares, you bind them together, you've got a cube. Take eight cubes, you bind them together. You get a tessaract. There are three cubes to each edge, which means in total you have thirty two edges and twenty four squares in one tests or act A rotating tests. I act defies easy explanation. Let's just say it doesn't move the way you think it would based off our understanding of

three dimensional objects. You can actually rotate it along two planes simultaneously. There are animations that simulate this. They show testaracts rotating along these two planes at the same time, and I suggest you look them up to see them, because there is no way I can describe what it looks like in words, you kind of have to view it. If you go to even a Wikipedia article on the tessaract,

you can see these things in this kind of animation. Also, these animations of rotation aren't a real representation of four dimensional rotation because we cannot do that in this particular medium. This isn't that big a deal either when you think about it, because you can draw a cube on a two dimensional sheet of paper, and the cube you draw isn't really three dimensional. It's a series of lines on the two dimensional sheet of paper, so it's impossible to

be three dimensional, but it represents a three dimensional object. Now, Einstein got all relative on us and proposed that the fourth dimension in our universe is time. There are various mathematical models of the universe that follow things like string theory that suggests there may be eleven or twenty six dimensions out there, or maybe more. But because of the way we've evolved, we can only directly perceive and understand three spatial dimensions, and we can recognize the passing of time.

So I hope that that is an interesting discussion on the tests or act. It is a fascinating, uh hypercube of a subject, but again, really tricky to describe in an audio podcast, So I do wreck when you go and look at those animations, because they'll break your brain a little bit. All right, let's take another quick break to thank our sponsor. MICHAELA wrote me and asked if I might do an episode on speakers and headphones, and

I might. In fact, I will. I'm gonna do a full episode on speakers and headphones and talk about the evolution and development of the technology. It will warrant a full episode, but for now, I'd like to give a brief explanation of how speakers work, and then when I get to the full episode about speakers and headphones, you can listen to me do it again, or at least

give a summary. I probably won't go into full detail right here, but I want to give you kind of an overview because it is interesting and it will be a nice lead into the episode they'll be coming up in the near future. So it helps if we look at the process of recording sound first, since playing soundback is essentially the same process, but reversed sound is a physical phenomenon. Sound waves pass through physical media like the air.

The air is a is a physical medium. It's got molecules in there, so when you make a sound, molecules in the air vibrate, and this vibration gets passed from some air molecules to the next, to the next, to the next, and it propagates outward. And we often draw a sound as moving out in a wave. It kind of moves out, almost more like a bubble, but it's in a wave in all directions that it can move through until it loses enough energy where it's no longer

really moving anymore. Molecules will vibrate through the medium and pass that vibration along, and if you're close enough to the source of the vibration of the source of the vibration was strong enough, your ears will pick it up. That's because the air is moving in and out of your ear canals, changing the air pressure slightly due to those vibrations, which in turn essentially pushes and pulls against

your tim panic membrane. It's more fair to say it pushes the tim tympanic membrane in, and then when the pressure is lower than inside the inner ear, the tympanic membrane pushes back out again, rather than to say push and pull. But that that's getting kind of into semantics at that point, I think anyway, the timpanic membrane is better known as your ear drum. Now, that causes some fluid in your inner ear to slash around a bit. I'm skipping over some stuff like the tiny little bones

connected to ear drum. But ultimately it makes some fluid slash around, and it activates some nerve cells that pick up this slashing of fluid. It sends electrical impulses to your brain, and the gray matter in your skull interprets these electrical impulses as sound. Higher frequency sounds cause the air pressure to fluctuate faster, and we perceive these sounds as having a higher pitch. The air pressure level is a sound waves amplitude, which we register as volumes. So

the greater the amplitude, the louder the sound. When we record sound, we use a microphone incited to tpical microphone is a diaphragm. It's a thin layer that's made out of a very flexible material, like very thin plastic. The diaphragm responds to sound waves in a way that's similar to our own tympanic membranes. High pressure pushes the diaphragm in lower pressure allows the diaphragm to extend outward. Components in the microphone detect this vibration and convert the physical

vibrations into electrical signals. This is a transducer. A transducer takes uh these kind of energies from one form and turns into an energy of another form, in this case physical vibration to electric signals. I'll go into more detail about that in the full episode. And then this electrical signal would go on to amplifiers and other components to ultimately head towards either a speaker so you're broadcasting live straight out, or a recording device, or some combination of

the two. So a speaker takes this process and effectively reverses it. Basically, it takes an incoming electrical signal and translates that into physical vibrations, using a flexible cone called a diaphragm to do it. The diaphragm is attached to a suspension inside the speaker. The suspension, in turn is connected to a frame inside the speaker. The whole apparatus of this one part of a component is called a driver, and a speaker can actually have multiple drivers in it.

It doesn't have to have just the one. A lot of them do have one or two. And these are the big circular things you're looking at when you're looking at speakers, So the speaker is kind of like the overall structure. The drivers are the individual noise making devices inside of them, and the vibrations that these these uh diaphragms make these cones, these drivers inside the speakers, that's what's making all the sound. It's just those components vibrating.

I have a lot more to say about that process, including the actual mechanisms that cause the drivers to move within a speaker, and spoiler alert that has to do with magnets in an upcoming episode, but I wanted at least to give the basics now to kind of be a teaser for it, and also because I wanted to thank MICHAELA for writing in and and suggesting it. I

didn't want a chance to forget it. Our last request comes from Nathan, who wanted to know more about the site I Fix It I F I X I T. This site helps both repair professionals and d I Y hobbyists understand the components of various pieces of hardware on the market, including stuff like smartphones and game consoles and

all sorts of electronics. Typically, it can be really hard to find information on those devices unless you happen to be a licensed professional who essentially gets permission from the respective companies to work and repair their products. I fix It helps reverse this trend of technology becoming progressively more like a black box. A black box piece of technology is one where the hardware is locked away so that you can't really observe how it works. A lot of

companies make hardware hard to act access. Apple is infamous for this, so that it's very difficult for you to get under the hood and make it do what you wanted to do. When you might want to hack it so it's doing something it wasn't intended to do. You might just want to repair it, but a lot of companies make it very difficult to do and they guard the secrets about how these devices work, and I fix It is philosophically opposed to that. It's a crowdsourced approach

to tear downs and repairs. The community of users can contribute guides, photo albums, and more to help others work on their gear or someone else's gear if they need to. The site got its start back in two thousand three, there were a couple of college students who were attending California Polytechnic University and the two roommates started off by

trying to fix an Eyebook device. There was no reference guide available for the actual computer they were working on, so they rolled up their sleeves, they unscrewed the case, and they started poking around. Eventually they identified what the problem was and they were will to fix it. And then they thought, huh, I bet other people are having

a similar problem with their devices. What if there were a centralized database of repair information that people could use that they don't have to either rely on an expensive licensed repair man, or even worse, that they might just throw away a salvageable piece of technology in order to go out and buy a new one. Eventually, their help

site evolved into a user powered community. Again. The people are the ones who submit repair guides and photo albums, and they explain step by step what every piece inside various technologies is, what it does, how to fix or replace it, and more. On a personal note, I have found I fix its site to be incredibly helpful whenever I needed to research a particular device to learn about the components inside it. I did it all the time

for how Stuff Works articles. If you read some of my old How Stuff Works articles, you'll often see I fix It as one of the sites I source as one of the ones that I used while I was researching the material. Some companies, it turns out, are not

very forthcoming about the tech that's inside their products. They might not tell you what kind of graphics processing unit is in their computer, or the type of processor that you might find inside a hand set, and so the only way to really know for sure if you don't have access to internal company documents is to break one

of them open and take a look yourself. Fortunately, that's what the people and I fix It do for you, so you don't have to do it yourself unless you need to in order to fix it, in which case you go to I fix It and you'll learn how

I fix it. Teardowns have a ton of different popular gadgets that remove all this mystery, and it also removes the need for me to do it myself, which I greatly appreciate, although I did once do it for the Nintendo three D S. We had it for about three days and then I took it apart and I took it apart in away where I can guarantee it will never work again. It was in a bucket on my desk for a long time though. Anyway. The philosophy of the founders is that anyone with a desire to learn

should be able to maintain his or her technology. It should not be kept apart from us as an almost mystical object that we never fully understand. They want to put the power back in the hands of the users and to help consumers avoid what could become predatory policies. After all, if a company is using proprietary hardware, even down to the types of screws it uses to hold everything together, it is locking the users into an ecosystem, whether that's best for the consumer or not. And news flash,

it is rarely best for the consumer. It is almost always best for the company. From a business standpoint, you can't really blame companies for doing this, But from that practical standpoint as a consumer, it kind of bites if you've not checked out, I fix it. You should fix that. It gets pretty technical, but it also will help you understand your technology better, and who knows, you might see the opportunity to write a guide all of your own. Well, that does it for this grab bag. I want to

thank all of you for sending in requests. I've got tons of requests for full length episodes that I've started to schedule out try and I looked at the schedule earlier today and it looks like listen, I'm pretty much set until mid June. I'm recording this at the beginning of April and now I've got through mid June. Of course, one of those episodes is the upcoming tenth anniversary of

tech Stuff. If you guys have suggestions for topics I should cover on any episode, but in particular, if you have requests for the tenth anniversary, please send them my way. You can send them to my email address that is tech Stuff at how stuff works dot com. You can send them to me on Facebook or Twitter. The handle of both of those is text stuff hs W. I would love to hear from you. Don't ask how tech Stuff Works. I have done that episode at least three times now, so I'm not going to do it for

the tand anniversary. But if you have a suggestion for what should be the tenth anniversary episode of tech Stuff, I want to hear it. Also, remember we have an Instagram account. You can follow that and see all sorts of interesting pictures and behind the scenes photos and stuff like that. Also, on Wednesdays and Fridays, I record this show and if you ever want to watch me record it live, you can go to twitch dot tv slash tech stuff and you'll be able to watch me mess

things up right in front of your face. You can also chat with me and point out when I mess things up and hopefully do it in a way that doesn't make me want to cry because Tari is getting tired of having to hug me after every show. It's exhausting. I'm a very high maintenance podcaster. You guys, thank you so much for listening. I really look forward to chatting with you again really soon. For more on this and thousands of other topics. Because it has to works, dot com one