Speaker 1: Welcome to tech Stuff, a production from I Heart Radio.
Speaker 1: Hey there, and welcome to tech Stuff. I'm your host
Speaker 1: Jonathan Strickland. I'm an executive producer with iHeart Radio and
Speaker 1: How the tech are you Now. In a recent tech
Speaker 1: News episode, I talked about how a Microsoft engineer named
Speaker 1: Raymond Chen revealed that the music video for Janet Jackson's
Speaker 1: hit Rhythm Nation was at one time the crasher of laptops,
Speaker 1: or at least of certain laptops. Some folks discovered that
Speaker 1: if they played this video on their laptop computer, or
Speaker 1: if their laptop computer was close to something else that
Speaker 1: was playing this music video, the computer would spontaneously crash. Now,
Speaker 1: to be clear, these computers were not nasty, as miss
Speaker 1: Jackson might say. They were not music critics. It turns
Speaker 1: out that a sound played in that music video matched
Speaker 1: the resonant frequency of the hard disk drives in these laptops,
Speaker 1: though it took some time to suss that out. Chen
Speaker 1: said that these were hard drives that we're spending at
Speaker 1: five thousand four rpm. That's revolutions per minute, so going
Speaker 1: around five thousand, four hundred times every minute. That's actually
Speaker 1: on the lower end of what we typically see with
Speaker 1: hard disk drives, they can top out at more than
Speaker 1: twice as fast as that. But it's not bad. I mean,
Speaker 1: you can still go out and buy a hard disk
Speaker 1: drive today that's at five thousand PM. People typically like
Speaker 1: faster ones. It means that you can read and write
Speaker 1: information to such a hard drive faster. Anyway, the sound
Speaker 1: from the music video was causing the hard drives to vibrate.
Speaker 1: The platters inside would vibrate, and ultimately this would prompt
Speaker 1: the computers to crash. So today I thought i'd talk
Speaker 1: a little bit about hard drives, a bit of out
Speaker 1: resonant frequencies, how a sound could cause a hard drive
Speaker 1: to actually crash, and maybe talk about some myths surrounding resonance,
Speaker 1: including one that I kind of perpetuated last week. So
Speaker 1: I gotta hold myself up to a correction here anyway.
Speaker 1: First up, if you were to take a hard drive apart,
Speaker 1: don't do that, by the way, You're more than likely
Speaker 1: going to destroy it. But you would see that inside
Speaker 1: the hard disk drive you have a spindle, and on
Speaker 1: the spindle would be at least one disc or platter.
Speaker 1: More likely it would actually be more than one, perhaps
Speaker 1: a stack of them, and each platter would be separated
Speaker 1: from its neighbors by a small gap, and the platters
Speaker 1: are kind of similar to a compact disk in some ways,
Speaker 1: but compact discs store information that's read and written through
Speaker 1: an optical drive. So with light laser specifically, hard disks
Speaker 1: store information magneticle, not through optics. Now, this platter or
Speaker 1: these platters are what spin inside a hard disk drive coding.
Speaker 1: The platter is a thin layer of magnetic grains, so
Speaker 1: using an electro magnetic head, the computer can write data
Speaker 1: to the platter by realigning these magnetic grains so that
Speaker 1: they point in a specific direction, essentially pointing magnetic north
Speaker 1: or pointing magnetic south, and thus they can represent zeros
Speaker 1: and ones. When the platter spins beneath the head or
Speaker 1: above the head, depending on how this goes, and the
Speaker 1: head is in passive mode, there's a little detector essentially
Speaker 1: on the head that can pick up the magnetic fluctuations
Speaker 1: from these aligned regions that are passing near it as
Speaker 1: the disc is spinning, so it's being read now. The
Speaker 1: head in this case can look a bit like tweezers
Speaker 1: in a sense. There's typically a pair of arms, one
Speaker 1: that goes over the top of the platter one that's beneath.
Speaker 1: They are not making contact with the platter. In fact,
Speaker 1: if they were to touch the platter, that would damage
Speaker 1: the hard drive. You gotta keep in mind, these platters
Speaker 1: are spinning super fast, so these electro magnets are separated
Speaker 1: from the platters. They're not actually touching, they're they're hovering
Speaker 1: above and below um. So really like every head is
Speaker 1: usually a pair of red Wright heads. There's one on top,
Speaker 1: one beneath each platter that allows the computer to store
Speaker 1: information on either side of platters. And as I said,
Speaker 1: your typical hard drive often has several of these platters
Speaker 1: arranged in a stack, separated from each of them by
Speaker 1: a small gap, and each platter has its own read
Speaker 1: right head. But that is the super basic way that
Speaker 1: hard drives work. I'm not even getting into things like
Speaker 1: actually how you store a file on these platters, because
Speaker 1: it's not as simple as like the roove on a
Speaker 1: on a vinyl album representing a song. It's not like that.
Speaker 1: But the reason for this rapid rotational speed is that
Speaker 1: you do want to be able to read and write
Speaker 1: information from this hard disk drive quickly. And you know,
Speaker 1: if it didn't spin at these fast rates, it would
Speaker 1: take forever, which is hyperbolie. It would take a really
Speaker 1: long time for your computer to retrieve stored information from
Speaker 1: the hard disk drive. And it blows my mind that
Speaker 1: you can have platters spending times per minute or faster
Speaker 1: and read or write information to those platters, storing gigabytes
Speaker 1: of data in the process. Technology is really kind of
Speaker 1: like magic, except you know it works. Now. If you
Speaker 1: have a mechanical device like this, clearly everything needs to
Speaker 1: be improper alignment or else you're going to have problems.
Speaker 1: Jostling a hard disk drive can potentially knock a disc
Speaker 1: off kilter, which would mean that once the spin doll
Speaker 1: that the disks start on starts to spin, you're gonna
Speaker 1: have some damage, possibly catastrophic damage. The platters need to
Speaker 1: maintain both horizontal and vertical alignment, and honestly, knowing how
Speaker 1: delicate a hard disk drive can be, I'm actually amazed
Speaker 1: that my first ever MP three players survived for so
Speaker 1: many years. I had a creative Zen device which had
Speaker 1: a spinning hard disk drive inside of it, which is
Speaker 1: a very tiny little hard drive, and I say I'm
Speaker 1: amazed that survived because I know that thing took a
Speaker 1: tumble more than once, and the impact could have been
Speaker 1: enough to damage the hard drive, but I guess I
Speaker 1: had more luck than brains anyway. According to a data
Speaker 1: recovery firm called drive Savers, of hard disk drive failures
Speaker 1: are the result of damage recording surfaces, typically created as
Speaker 1: the result of a physical shock. Other potential causes for
Speaker 1: failure include things like circuit board problems uh stiction, which
Speaker 1: is the combination of friction and sticking, where if you
Speaker 1: haven't used a hard des drive for a long time,
Speaker 1: sometimes there can be this kind of friction sticking issue
Speaker 1: that impedes the disks from spinning. And also drive motor failure,
Speaker 1: which makes up like less than a percent of all
Speaker 1: the hard disk drive failures. So usually the motor doesn't
Speaker 1: isn't the problem. By the time the motor has given out,
Speaker 1: something else has already failed in that hard disk. Now,
Speaker 1: if something were to cause the hard drive to stop
Speaker 1: spinning while it's in operation, you get a hard disk
Speaker 1: drive failure in that prompts a full crash of the computer.
Speaker 1: And this brings us to Janet or miss Jackson. If
Speaker 1: I'm nasty, and it turns out that the song Rhythm
Speaker 1: Nation has within it a frequency that resonates with a
Speaker 1: certain popular model of hard disk drives from many years ago.
Speaker 1: So this isn't really about current tech. We're actually talking
Speaker 1: about machines that were sold around the year two thousand five.
Speaker 1: So really kind of amazing that this even became a problem,
Speaker 1: right because Rhythm Nation came out in nine, this particular
Speaker 1: uh laptop that was prone to this kind of stuff,
Speaker 1: or these laptops, I should say, because they all had
Speaker 1: this hard drive in common. It wasn't the laptops fault.
Speaker 1: Those were sold around two thousand five, and specifically, the
Speaker 1: the sound frequency from the music video would resonate with
Speaker 1: the natural resonant frequency produced by the hard drive when
Speaker 1: the platter is spinning. So let's talk about frequency and
Speaker 1: sound and resonance for a bit. With waves. Frequency refers
Speaker 1: to the number of waves that pass a fixed point
Speaker 1: within a given amount of time, and we use the
Speaker 1: metric hurts to measure frequencies. So one hurts is equal
Speaker 1: to one wave passing a fixed point in one second.
Speaker 1: Two hurts would mean two waves would pass that point
Speaker 1: in one second. Now, notice I didn't say sound waves
Speaker 1: here because Hurts can refer to any kind of wave
Speaker 1: or oscillation, so we can use frequency to talk about
Speaker 1: stuff like light or sound or all sorts of other things.
Speaker 1: But in this episode we're mostly concerned with sound. So
Speaker 1: if you were to play the middle C on a piano,
Speaker 1: and assuming that piano had been tuned according to VERD tuning,
Speaker 1: which is not standard uh, the note would produce a
Speaker 1: frequency of two hundred fifty six hurts. So that means
Speaker 1: the sound wave travels at two hundred fifty six waves
Speaker 1: past a given fixed point per second. Now, sound waves
Speaker 1: are really vibrations, right. Physical vibrations is a physical phenomenon.
Speaker 1: It is why there's no sound in space, because you
Speaker 1: don't have stuff close enough to transmit vibration from one
Speaker 1: thing to another, and you have to have stuff close
Speaker 1: enough to vibrate and affect other things in order for
Speaker 1: that to propagate for it to travel. Most of the
Speaker 1: stuff we hear is traveling through the air, So in
Speaker 1: this case, the vibrations we're talking about are typically these
Speaker 1: little fluctuations in air pressure. You can kind of imagine
Speaker 1: that these changes in air pressure are effectively pushing against
Speaker 1: and pulling on your ear drum. Just slightly, which then
Speaker 1: transmits those vibrations to our inner ear. Our brains ultimately
Speaker 1: interpret this signal as sound, and the frequency at which
Speaker 1: the air fluctuations affect our ear drums determines what pitch
Speaker 1: we hear. So slower frequencies produce lower pitches. Faster frequencies
Speaker 1: produce faster pitches. Two fifty six fluctuations like full fluctuations
Speaker 1: per second produces middle C. Now, let's talk about resonant frequencies.
Speaker 1: Systems have a frequency that they tend to oscillate at.
Speaker 1: The reason middle C sounds like middle C is that
Speaker 1: there is a string in that piano that's at the
Speaker 1: right length and it's at the right tension to produce
Speaker 1: that frequency. When that string is struck by a hammer,
Speaker 1: when you push down on the key, a hammer strikes
Speaker 1: the string and it vibrates at this frequency, and thus
Speaker 1: we hear that middle C. Similarly, if you take a
Speaker 1: wine glass and you tap the wine glass, you will
Speaker 1: hear it ring out a tone. That tone is the
Speaker 1: resonant frequency, the natural frequency for that glass. It's the
Speaker 1: frequency at which it tends to oscillate naturally when struck. Now,
Speaker 1: if you were to produce that same tone near the glass,
Speaker 1: you would cause the glass to vibrate. You would induce
Speaker 1: vibration in the glass. If you produce the tone with
Speaker 1: enough volume or amplitude, if we're talking about waves, that
Speaker 1: vibration can start to deform the glass enough to cause
Speaker 1: the wine glass to shatter. And you've probably seen examples
Speaker 1: of this, you know. The classic one is you have
Speaker 1: an opera singer singing a clear note and holding a
Speaker 1: wine glass and the glass inevitably breaks apart. That is
Speaker 1: possible if you have someone with the lung power and
Speaker 1: the singing ability to produce a strong enough sound at
Speaker 1: the right frequency, but it ain't easy. In demonstrations and
Speaker 1: physics classes, folks typically use a tone producer and an
Speaker 1: amplifier and a speaker, which simplifies things, and it's also
Speaker 1: safer than holding a glass close to your face while
Speaker 1: trying to make it explode. You can also really dial
Speaker 1: into the proper frequency, and you can kind of think
Speaker 1: of this as being similar to pushing someone who is
Speaker 1: swinging on a swing set. If you push at just
Speaker 1: the right moment in their arc, you can really get
Speaker 1: them to go higher without putting in too much effort
Speaker 1: in your push but it does have to be at
Speaker 1: just the right moment within the arc of the swing
Speaker 1: to give a boost rather than interfere with the arc
Speaker 1: of the swing. The sound waves are kind of giving
Speaker 1: the glass of it just the right frequency for it
Speaker 1: to oscillate and to keep oscillating. When we come back,
Speaker 1: we'll talk about what this has to do with hard drives,
Speaker 1: and we'll talk a bit more about some misconceptions about resonants,
Speaker 1: including one that that I kind of talked about. Okay,
Speaker 1: So Rhythm Nations music video had within the music video
Speaker 1: a sound that was at a frequency that matched the
Speaker 1: hard disk drives resonant frequency when it was spinning. So
Speaker 1: if you were to play the Rhythm Nation music video
Speaker 1: on one of these laptops, that sound would start to
Speaker 1: push the platters on the hard disk drive at the
Speaker 1: frequency that they were naturally going to vibrate at, so
Speaker 1: they would start vibrating more and more, and that would
Speaker 1: cause the hard disk drive to ash and the subsequent
Speaker 1: computer crash. So how do you solve this problem? If
Speaker 1: if hard disk drives are delicate, you know, that's why
Speaker 1: they're in these very sturdy cases typically because they need
Speaker 1: to be protected from everything else. Well, if they're so delicate,
Speaker 1: how do you protect against this issue? Well, the hard
Speaker 1: disk drive is a mechanical device, and everything has already
Speaker 1: been engineered to work a specific way, so it's not
Speaker 1: super easy to change the hard disk drive. You've already
Speaker 1: sold all these laptops that have it in there. So
Speaker 1: the solution was really to create a sound filter that
Speaker 1: would mask the frequency, the resonant frequency. So essentially, this
Speaker 1: filter would block laptops from playing that specific frequency. All
Speaker 1: the other frequencies could play because they weren't going to
Speaker 1: resonate with the hard disk, but this one wouldn't, and
Speaker 1: chances are it was tough for human listeners to even
Speaker 1: tell the difference, because being able to pick out a
Speaker 1: specific frequency from a whole bunch of them in a
Speaker 1: song is and something your average person can do. So
Speaker 1: the thought was, yeah, this is technically going to have
Speaker 1: an impact on certain media that contains this frequency, but
Speaker 1: chances are no one's going to be able to tell
Speaker 1: the difference anyway, and it won't matter if it's crashing computer,
Speaker 1: So let's just block that from being able to play
Speaker 1: on these kinds of laptops. So that filter saved the day.
Speaker 1: But you could theoretically be working on your computer, and
Speaker 1: the video for him Nation might play on some other device,
Speaker 1: like say your home entertainment system. Presumably your home entertainment
Speaker 1: system would not have this sound filter on it, so
Speaker 1: your laptop might still crash because that frequency would be
Speaker 1: present in that version of the music video. So one
Speaker 1: reason I think Chen brought this up was that if
Speaker 1: we forget about these things, if we forget about these
Speaker 1: kinds of odd cases that require these patched solutions, then
Speaker 1: we end up with stuff that's no longer really necessary. So,
Speaker 1: like I said earlier, this regular problem was affecting machines
Speaker 1: sold around two thousand five. The hard drives today are different,
Speaker 1: and a lot of laptops don't even use hard disk
Speaker 1: drives anymore. They use solid state drives, which don't have
Speaker 1: any moving parts in them, And that means that filter
Speaker 1: may not actually be necessary anymore. It might not be needed,
Speaker 1: but it might still be in place on machines because
Speaker 1: it was in earlier machines, and it ends up being
Speaker 1: a carryover. So, in other words, something that was originally
Speaker 1: put in place in order to fix a problem stays
Speaker 1: in place because people haven't bothered to remove it. And
Speaker 1: if we don't remember why we put something there to
Speaker 1: begin with, we could just be living with stuff that
Speaker 1: doesn't really do anything anymore, or that can can, at
Speaker 1: least at some level impact our experience when we want
Speaker 1: to jam out to Rhythm Nation. But let's talk about
Speaker 1: some other residant frequency stories and myths, and let's start
Speaker 1: with one I kind of whiffed on last week. So
Speaker 1: I mentioned when first covering the story that subjecting something
Speaker 1: to its resonant frequency can be quite destructive, as illustrated
Speaker 1: by the wineglass demonstration that clearly shows that a resident
Speaker 1: frequency can break something well. I also mentioned suspension bridges
Speaker 1: in that particular news item, which I really should have
Speaker 1: stopped to think about, because I already knew this was
Speaker 1: not really relevant or correct, but for some reason to
Speaker 1: just skip my mind. But I was referencing a real
Speaker 1: world disaster that frequently is mentioned uh in concert with resonans,
Speaker 1: but the actual cause of the destruction wasn't resonants. The
Speaker 1: disaster in question was the collapse of the Tacoma Narrows
Speaker 1: Bridge in the state of Washington in the United States.
Speaker 1: So construction on this suspension bridge began in the nineteen thirties.
Speaker 1: The finished project opened for traffic on July first night,
Speaker 1: ten forty, and on November seven of that year we
Speaker 1: got the collapse. So first, let's talk about what a
Speaker 1: suspension bridge is. So it has advantages over your traditional
Speaker 1: solid bridges that had, you know, multiple arcs of solid
Speaker 1: material spanning whatever it is you're building the bridge across,
Speaker 1: whether it's a chasm or river or a bay or
Speaker 1: whatever it might be. One of the big advantages of
Speaker 1: a suspension bridges that you need way less material to
Speaker 1: make a suspension bridge than one of these traditional bridges were.
Speaker 1: Really the only thing you have to worry about is
Speaker 1: that the bridge is able to, you know, withstand the
Speaker 1: gravitational force of it being pulled down, right. That's it.
Speaker 1: Like otherwise they're pretty sturdy. Suspension bridges have other concerns.
Speaker 1: Suspension bridges can be lighter, that can be less expensive
Speaker 1: to build because you're using less material, and since the
Speaker 1: public typically foots the bill for a construction of bridges,
Speaker 1: making construction less spensive is a pretty high priority in
Speaker 1: most projects. So a suspension bridge consists of two towers,
Speaker 1: kind of like Tolkien, and these two towers are connected
Speaker 1: to each other by cables. Those cables also extend further
Speaker 1: to attached to either end of the bridged area. You
Speaker 1: have rods that connect these cables to the bridges surface,
Speaker 1: which is also known as the deck uh And so
Speaker 1: the deck is suspended above whatever it is. The bridge
Speaker 1: is crossing the chasm, the bay, the river, whatever it
Speaker 1: might be. Thus we get suspension bridge. Now, the Tacoma
Speaker 1: Narrows Bridge was the third longest suspension bridge at the
Speaker 1: time of its construction, and in an effort to maximize
Speaker 1: cost efficiency, the bridge was using plate girders along the
Speaker 1: sides of the bridge to provide rigidity to the deck. Now,
Speaker 1: typically instead of girders, you would use trusses, but trusses
Speaker 1: would require more material and thus would have been more expensive,
Speaker 1: So this was one of the considerations. One of the
Speaker 1: the compromises made to have the bridge be less expensive
Speaker 1: was to go with this model where you kind of
Speaker 1: had this this ribbon like effect across the bridge as
Speaker 1: opposed to trusses to make it more rigid. So this
Speaker 1: compromise meant the bridge was more flexible than other suspension bridges.
Speaker 1: Too flexible, you would say. Construction workers who were working
Speaker 1: on building the darn thing referred to it as the
Speaker 1: galloping Gurdie because of the girders and because well even
Speaker 1: before the bridge opened, it was clear that the bridge
Speaker 1: moved more than it necessarily should, at least under certain conditions.
Speaker 1: So on November seven in Washington, the winds were in
Speaker 1: high force, and as these high sustained winds were hitting
Speaker 1: the suspension bridge, vorteses were forming. So when a fluid
Speaker 1: hits a blunt object, vortices form as the fluid moves
Speaker 1: around and then beyond the object. So if you could
Speaker 1: see the wind, you would see it was creating this
Speaker 1: sort of wiggly vortices behind the components that was hitting
Speaker 1: on the bridge. And we were talking about some issues
Speaker 1: with residents here. If those vibrations were at the right frequency,
Speaker 1: then it starts to impart vibrations into the bridge itself
Speaker 1: and the bridge begins to move up and down. And that,
Speaker 1: in fact did happen, So there was at least some
Speaker 1: movement of the bridge on November seven that related to residents. However,
Speaker 1: that was not what caused the bridge to ultimately break
Speaker 1: apart and collapse. So the bridge began to twist, not
Speaker 1: just move up and down, but starting to twist along
Speaker 1: its length, and that was really the problem, and that
Speaker 1: twisting didn't come from residents. Instead, the wind was hitting
Speaker 1: these girders along the side, and the vote disease that
Speaker 1: we're forming, we're causing the bridge to move in a
Speaker 1: specific way, like one side would move down, the other
Speaker 1: side would move up. But then the bridge would try
Speaker 1: to return back to its neutral position, you know, being level,
Speaker 1: instead of being tilted to the left or to the right.
Speaker 1: But when it would return, it would go beyond its
Speaker 1: normal rest spot due to momentum, kind of like how
Speaker 1: if you pluck a string, it actually moves beyond its
Speaker 1: rest position when it when it uh when you let
Speaker 1: it go. So the wind would then push on the
Speaker 1: girders again as they had reached their other side, kind
Speaker 1: of like you know, pushing someone on a swing. And
Speaker 1: this introduced what engineers referred to as aero elastic flutter.
Speaker 1: If you hold up a sheet of paper to the
Speaker 1: wind and you see it like fluttering back and forth,
Speaker 1: vibrating kind of in your hand, you can see an
Speaker 1: example of aero elastic flutter. This is not resonance, it's
Speaker 1: a separate phenomenon. So it ends up shaking up the bridge.
Speaker 1: But it's not because it's at a resonant frequency. It's
Speaker 1: because the wind is creating these war disease that are
Speaker 1: putting additional pressures on the bridge and making it twist
Speaker 1: back and forth. And you know, when you physically move
Speaker 1: stuff like that, like if you're wiggling something over and
Speaker 1: over and over again, you weaken it. And at around
Speaker 1: eleven am, some concrete from the bridge structure broke loose
Speaker 1: from the deck and fell down. Then a cable broke
Speaker 1: and that drastically impacted stabilization, and it began to twist
Speaker 1: even more violently, and eventually the bridge buckled and collapsed.
Speaker 1: Reports say that at the peak of the twisting motion,
Speaker 1: the sidewalk on one side, like the left side of
Speaker 1: the bridge, would be nearly thirty feet higher than the
Speaker 1: sidewalk on the opposite side of the bridge, like on
Speaker 1: the right side. Um, as you were going down the bridge,
Speaker 1: and that is terrifying to think of. Also, there's film
Speaker 1: of the is happening. You can watch videos on YouTube
Speaker 1: showing the twisting of the Tacoma Narrows Bridge and it
Speaker 1: is dramatic to say the least. But as I said,
Speaker 1: resonance ultimately did not play the major part of destruction
Speaker 1: on that bridge. It did have an impact, but the
Speaker 1: actual destruction came from these vortices and the arrow elastic flutter. Now,
Speaker 1: when we come back, we'll talk about another mythical story
Speaker 1: about residents and our good friend Nicola Tesla. But first
Speaker 1: let's take a quick break Ah Tesla. Depending on what
Speaker 1: circles you run in on the Internet, Tesla can either
Speaker 1: be looked at as a very eccentric, tortured person who
Speaker 1: had to struggle with mental health both issues for much
Speaker 1: of his life and who got the raw end of
Speaker 1: the deal on more than one occasion, but also was
Speaker 1: a heck of a self promoter. Or you might see
Speaker 1: him as an unimpeachable source of genius and innovation who
Speaker 1: had come up with almost magical technologies that never manifested
Speaker 1: but he totally had them in his head, like death
Speaker 1: rays and stuff. Um. I tend to go on the
Speaker 1: more modest side, uh and and I would never say
Speaker 1: that Tesla was not a genius. He clearly was a genius,
Speaker 1: but again he was a born self promoter. In fact,
Speaker 1: I would say he was pretty darn similar to Thomas Edison,
Speaker 1: in that regard, and a lot of folks kind of
Speaker 1: referred to Thomas Edison as being lex luthor to Nick
Speaker 1: Nicola Tesla's superman. Uh that there were two sides of
Speaker 1: the same coin. Uh. I think that's being more than
Speaker 1: a little melodramatic personally. But one thing Nikola Tesla experimented
Speaker 1: with was an oscillating or reciprocating electric generator, and in
Speaker 1: fact he got it to work. The principle was very
Speaker 1: much sound. It's just that he found a better way
Speaker 1: of accomplishing what his goal was, which was to create
Speaker 1: a a sustained, consistent alternating current. So let's break this down. Now.
Speaker 1: Imagine that you've got kind of like it looks kind
Speaker 1: of like a metal post that's several inches long, maybe
Speaker 1: you know, maybe up to a foot or maybe even bigger, uh,
Speaker 1: and cylindrical in nature. Inside of that, you had a
Speaker 1: chamber where there was a piston that could go up
Speaker 1: and down the chamber cylinder. This piston would drive a
Speaker 1: post like an iron core that had copper wire wrapped
Speaker 1: around it, and this wire would connect to a circuit
Speaker 1: of some sort and that would freely move up and
Speaker 1: down the length of this one chamber based upon the
Speaker 1: movements of this piston inside a cylinder. Now surrounding this
Speaker 1: rod with copper coil on it was an electro magnet
Speaker 1: connected to a battery. So a battery generates direct current.
Speaker 1: That means the electricity always flows in the same direction
Speaker 1: from uh, I mean, if you're talking about you're talking
Speaker 1: about the way Benjamin Franklin thought of it. It goes
Speaker 1: from positive to negative. The actual electrons go from negative
Speaker 1: to positive. But you know, you you get what I'm saying,
Speaker 1: So it always flows in that direction that cannot reverse
Speaker 1: with direct current. So the electro magnet inside this piston
Speaker 1: generator thing was acting just like a stationary permanent magnet was.
Speaker 1: In fact, Tesla could have just put a very powerful
Speaker 1: permanent magnet in this thing. It would have worked the
Speaker 1: same way when you move a conductor through a stationary
Speaker 1: magnetic field. So like you have a conductive material and
Speaker 1: you pass it through a magnetic field that induces electricity
Speaker 1: to flow within the conductor. You induce electric current by
Speaker 1: moving the conductor up and down past this electric magnetic field.
Speaker 1: Rather then you know, having this oscillating or reciprocating action
Speaker 1: as the the coil moves up and down through this
Speaker 1: this magnetic field. You actually have a similar effect as
Speaker 1: if the magnetic field was fluctuating, was reversing its current
Speaker 1: back and forth. So it's it's almost the same as
Speaker 1: if the the coil were stationary, but the electro magnet
Speaker 1: around it was powered by alternating current. Now, the reason
Speaker 1: why this is important is that that would actually reverse
Speaker 1: the flow of electricity through that coil. You generate alternating
Speaker 1: current by moving this this coil up and down through
Speaker 1: this magnetic field. So you take a direct current source
Speaker 1: from the battery into this reciprocating electric generator, and by
Speaker 1: moving this piston up and down, you can output alternating current. UH.
Speaker 1: To provide the up and down power to move the coil,
Speaker 1: we have to go to the piston. Now, in this
Speaker 1: early invention, the piston was driven by steam power. Now,
Speaker 1: I wish I could adequately describe Tesla's design here because
Speaker 1: it really was genius. I mean, it was a beautiful
Speaker 1: approach to creating a piston that can move up and
Speaker 1: down be driven by steam, and it was beautifully simple
Speaker 1: uh in design. However, to describe it is really hard
Speaker 1: to do without visual aids. There are videos that You
Speaker 1: can watch that show how this worked, and I recommend
Speaker 1: you check it out if you want. But what you
Speaker 1: need to know is that Tesla's piston served also as
Speaker 1: a valve, and that valve controlled where steam could enter
Speaker 1: an exit the cylinder that the piston was moving in.
Speaker 1: So Tesla was using steam for both directions of the
Speaker 1: stroke of the piston. So the upward and the downward
Speaker 1: movements of the piston were driven by steam. Steam would
Speaker 1: push the piston down, steam would push the piston back up,
Speaker 1: and this would drive that coil to move up and
Speaker 1: down the magnetic field further up inside the electric generator,
Speaker 1: and thus the piston was providing the reciprocating motion. Now
Speaker 1: let's get to resonance. So the story Tesla told is
Speaker 1: that he was working in the lab late one night
Speaker 1: when his eyes beheld an eerie sight because his reciprocating
Speaker 1: electric generator or some oscillator that was similar to it
Speaker 1: because it changes from story to story, was moving at
Speaker 1: the same frequency as his buildings natural frequency. Some versions
Speaker 1: of the story say that he had attached the piston
Speaker 1: to a girder to provide stability, because obviously, if you
Speaker 1: have something that's moving up and down rapidly. It's going
Speaker 1: to be clattering all over the place unless you has
Speaker 1: strap it down somewhere. So he was saying that he
Speaker 1: was tuning in the resonance or the frequency rather of
Speaker 1: this oscillator, so it resonated with the girder that it
Speaker 1: was connected to within his building, and thus he began
Speaker 1: to introduce increasingly violent vibrations into the building, and those
Speaker 1: vibrations continue to build an intensity, and it led to
Speaker 1: a small man made earthquake, leading a lot of people
Speaker 1: to call this Tesla's earthquake machine. Then the story goes
Speaker 1: that police and ambulances responded to the scene and they
Speaker 1: got there justice Tesla was either taking a sledgehammer to
Speaker 1: his generator to stop it from tearing the joint apart,
Speaker 1: or that he had already stopped it and that he
Speaker 1: was just playing coy and saying, oh, I didn't even
Speaker 1: notice an earthquake. Now, could such a thing be possible?
Speaker 1: Maybe you could theoretically create a reciprocating device and tune
Speaker 1: it to a frequency that induces vibrations in a structure,
Speaker 1: And theoretically you could maybe do one powerful enough that
Speaker 1: ultimately it would start to cause damage. But We need
Speaker 1: to keep several things in mind here. One is that
Speaker 1: Tesla mostly told this story in his declining years. Uh.
Speaker 1: The account I see most frequently cited comes from an
Speaker 1: article that was published in nineteen on Tesla's seventy ninth birthday,
Speaker 1: and that the actual shaking of the building was said
Speaker 1: to have happened either in eighty seven or eight eight eight,
Speaker 1: according to that article. So even that article doesn't get
Speaker 1: specific on when this supposedly happened, and a different source
Speaker 1: targets the the event to eight, so we don't even
Speaker 1: have agreement of when this supposed earthquake happened. Tesla also
Speaker 1: told other stories at that same party that are referenced
Speaker 1: in the article I was mentioning, like the fact that
Speaker 1: he had discovered cosmic radiation before anyone else did, he
Speaker 1: just didn't think to tell anyone about it, and that
Speaker 1: he found there are particles that traveled perhaps as much
Speaker 1: as five times faster than the speed of light, which
Speaker 1: just isn't true. So my point is that Tesla is
Speaker 1: at best and unreliable source when it comes to stories
Speaker 1: about his own work. In many ways, his life depended
Speaker 1: upon his fame at this stage in his life he
Speaker 1: was drifting from hotel to hotel in an effort to
Speaker 1: avoid homelessness, and hotels would be happy to receive the
Speaker 1: famous Tesla at least initially, but eventually his welcome would
Speaker 1: wear out and he'd take the show on the road again.
Speaker 1: So I have my doubts about Tesla's stories. At least
Speaker 1: I doubt he was producing enough vibration to simulate an earthquake.
Speaker 1: And I definitely doubt the versions that suggests that not
Speaker 1: only was this building shaking, but that glass was bursting
Speaker 1: from nearby buildings and that the road outside was quaking.
Speaker 1: I don't believe that for a second. And one reason
Speaker 1: I doubt this is that you've got a lot of
Speaker 1: material and buildings that can have a dampening effect on vibrations. Right.
Speaker 1: Not everything is contributing to this resonant frequency, this resonant oscillation.
Speaker 1: Some stuff ends up resisting that and inhibiting that. And typically,
Speaker 1: or usually, like the larger the thing you're trying to
Speaker 1: to to vibrate, the larger the thing you're trying to
Speaker 1: shake apart, the more force you need to really get
Speaker 1: things going. In other words, if you walk up to
Speaker 1: a building and you happen to know exactly how frequently
Speaker 1: you need to tap on a girder to match the
Speaker 1: frequency of that girder, and you do it. Uh yeah,
Speaker 1: you're tapping at it, and you could probably feel those
Speaker 1: vibrations along the length of the girder, but you're not
Speaker 1: gonna force it to break apart. You'd have to use
Speaker 1: more force than that. Pushing a kid at just the
Speaker 1: right moment in the swings arc gives the kid a
Speaker 1: significant boost, but you do have to push. You can't
Speaker 1: just you know, like tap, it's not gonna do anything.
Speaker 1: So the source of the vibrations have to produce waves
Speaker 1: of significant amplitude to affect something like a building. Same
Speaker 1: thing with the wine glass. Right, If you can produce
Speaker 1: the right note, but you're not producing it at a
Speaker 1: high enough volume, the glass won't break. It will vibrate.
Speaker 1: If you put something like a piece of paper inside
Speaker 1: the glass, you'll see the paper jump around because the
Speaker 1: glass will be vibrating, but it won't be enough to
Speaker 1: cause the glass to deform to the point where it breaks.
Speaker 1: So I just doubt that Tesla's oscillator would be able
Speaker 1: to do it, particularly the way he was describing it.
Speaker 1: In his later descriptions of the technology, he said that
Speaker 1: he had as an air powered one that could fit
Speaker 1: in your pocket. So it was like a smaller version
Speaker 1: of the oscillating electric generator. So technically, yes, I think
Speaker 1: you could do this if you had something that was
Speaker 1: significantly powerful enough to introduce vibrations that would ultimately cause destruction.
Speaker 1: I just don't think Tesla's did it. I don't think so,
Speaker 1: but I could be wrong. It's it's the hard thing
Speaker 1: is that there just aren't any reliable sources outside of Tesla,
Speaker 1: and Tesla was not a reliable source. He made a
Speaker 1: lot of claims that have been unsubstantiated, and many of
Speaker 1: them I believe were really meant to help keep him
Speaker 1: in the public eye so that he could, you know,
Speaker 1: live out his life with as little hardship as he could. Again,
Speaker 1: he lived rather tortured existence, So no hard feelings against
Speaker 1: the guy. He was just trying to get through life
Speaker 1: under frustrating, to say the least circumstances. I mean, I
Speaker 1: could go into the whole story about Tesla and Marconi.
Speaker 1: If you think Tesla and Edison is one of those
Speaker 1: big tales of two people, you know, posed against each other,
Speaker 1: which really I would say Edison Westinghouse really is that story.
Speaker 1: That's nothing compared to Marconi and and Tesla in my mind.
Speaker 1: But that's the story for another time. Anyway, hope you
Speaker 1: enjoyed this discussion about resonant frequencies and how a Janet
Speaker 1: Jackson music video was shutting down computers left and right
Speaker 1: in two thousand five. I found it interesting. I hope
Speaker 1: you did too. If you would like me to cover
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