The US Mint Denver produces 30 million coins a day. Denes, the tooling department manager, discusses with us how production at this scale functions.
Stephen is on the hunt for the next step in his electrical engineering career and shares the shifts in the industry and what employers are looking for.
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Parker is an Electrical Engineer with backgrounds in Embedded System Design and Digital Signal Processing. He got his start in 2005 by hacking Nintendo consoles into portable gaming units. The following year he designed and produced an Atari 2600 video mod to allow the Atari to display a crisp, RF fuzz free picture on newer TVs. Over a thousand Atari video mods where produced by Parker from 2006 to 2011 and the mod is still made by other enthusiasts in the Atari community.
In 2006, Parker enrolled at The University of Texas at Austin as a Petroleum Engineer. After realizing electronics was his passion he switched majors in 2007 to Electrical and Computer Engineering. Following his previous background in making the Atari 2600 video mod, Parker decided to take more board layout classes and circuit design classes. Other areas of study include robotics, microcontroller theory and design, FPGA development with VHDL and Verilog, and image and signal processing with DSPs. In 2010, Parker won a Ti sponsored Launchpad programming and design contest that was held by the IEEE CS chapter at the University. Parker graduated with a BS in Electrical and Computer Engineering in the Spring of 2012.
In the Summer of 2012, Parker was hired on as an Electrical Engineer at Dynamic Perception to design and prototype new electronic products. Here, Parker learned about full product development cycles and honed his board layout skills. Seeing the difficulties in managing operations and FCC/CE compliance testing, Parker thought there had to be a better way for small electronic companies to get their product out in customer's hands.
Parker also runs the blog, longhornengineer.com, where he posts his personal projects, technical guides, and appnotes about board layout design and components.
Stephen Kraig began his electronics career by building musical oriented circuits in 2003. Stephen is an avid guitar player and, in his down time, manufactures audio electronics including guitar amplifiers, pedals, and pro audio gear. Stephen graduated with a BS in Electrical Engineering from Texas A&M University.
Special thanks to whixr over at Tymkrs for the intro and outro!
Welcome to the macro fat engineering podcast a weekly show about all things engineering, DIY projects, manufacturing industry news, and this week quantum mechanics. Where are your host logical engineers Parker, Dolman. And Steven Craig. This is episode 328. And our guest this week is Colin Anderson. Colin is a computer scientist turned electrical engineer who has worked on things as varied as quantum key distribution at Los Alamos National Laboratory, a tool to help decipher glyphs of classical Mayan civilization, and FPGA firmware at the IceCube Neutrino Observatory. He is currently an engineer and co founder of orthogonal systems and engineering and software development firms specializing in custom test and measurement hardware databases and data analysis.
Thank you so much, Colin, for coming on our podcast. Oh, thank you for having me. I'm really excited. You know, before we start, I have to ask, what is the IceCube Neutrino Observatory?
It's, it's kind of like a Bond villain layer. It's this cubic mile of sensors in the ice at the at exactly the South Pole and in Antarctica. And,
and that's where they make sharks with lasers. Right.
I mean, I would hope so. But
it's because neutrinos, they,
they sometimes though, the only way they really interact is they release like a little photon of light. But they, they don't hit things very often. So you just need this huge volume of water usually. And so they have a cubic mile of it. And all these sensor nodes just buried in the ice that talk to each other. And try to make scene you see the universe using neutrinos, basically. So Oh, that's cool. I'm curious, what's the goal with that whole device?
to learn neutrinos, I guess.
So I mean, so like, it's all about, we know, our understanding of physics is incomplete, because we have this thing called the standard model. And it doesn't include gravity and
doesn't explain dark matter and all this other stuff. And so we thought maybe neutrinos might be like, like, partly what dark matter is, and.
And there's, it was like, it was potential new physics, but now, I mean, I'm not I'm not sure what they're doing now. Because that that ended up being kind of a dead end, I think.
so yeah, neutrinos are not dark matter. They're not
not that exciting.
I don't mean to like, crap.
I mean, I just don't know what they're what the goal is now. But yeah, sure. I just, I just love the idea of this huge, like science project that involves things like a mile of, you know, scientific equipment at the South Pole, to just like, for what purpose? I don't know, like as fun.
Well, I mean, general research is like really important, even if just to see what I mean. That's kind of like we build these huge particle accelerators. But it's not with any well, okay, what they like to do is to find the Higgs boson. But typically, there's not like a specific goal. It's just general research to see what we find, right? I do like the I, the idea behind like particle accelerator accelerators is we don't know what we're going to be looking for. But we're just going to smash things at really high speed together and see what happens.
Yeah, the same thing with the neutrinos is like, there's these particles, we have no idea what they do. They don't seem to interact with anything. What are they?
Yeah, well, there's, I, if you're, like, average, like six foot tall person, I think it's, we calculated it out. It's like, it's like every 14 years is your neutrino birthday, which is when you will have on average interacted once with a neutrino. And just the mean, surely there's interactions. Yeah, but there's trillions of them passing through you right now. Every second
don't they have to hit the nucleus of an atom directly? And the nucleus is, I mean atoms, mostly empty space. They just don't hit anything very often.
Is that because one there's not a lot of space in? Well, there's a lot of space in atoms. But is it too that neutrinos also very tiny? Like it? Yeah. Yeah, it's okay. Yeah.
And the neutrino has neutral charge. Am I right on that? Yeah, it has it only interacts via the weak force, the.
And, yeah, it has no charge, electrical charge. And we, we thought there might be, and there's three of three kinds of them. And they oscillate between those three types, for some reason. And
well, it sounds like we need to experiment just to find out the reason. Yeah, let's they're just so hard to detect. So I also thought there might be a
colliders I love the fact that like, every time we build a collider, it's always one more step where it's like, this one goes 99%, the speed of light, this one was 99.9, the speed of light, like it just keeps going. Well, it's, it's, it's all about the electron volts. And that you can accelerate stuff too, because when they hit, I mean, if there's enough energy to make a particle, this much mass an electron volts, then they'll get created, just probabilistically. And so like the Higgs, Higgs Boson is really massive. So that's why we had to build the LHC, just to find it and that kind of thing. It's also
not just smashing electrons together, or particles together, I should say, but like thinking about the design, and how you're going to measure that stuff, because first of all, you don't even know like, what you're looking for, potentially. And then you're like, we had to measure that somehow. And we don't know what it is. If you've ever seen those pictures, where it's like a little guy standing next to this huge thing, just packed with equipment, like this huge cylinder. I mean, that's, that's the detector, it measures all the paths of these particles that move through it. And it and it produces like, gigabytes of data per second. Just the computer, they're like competing. Like, just to save the information is like a problem. So it's, I would totally binge watch a whole series on just the design of the sensors in Yeah, at CERN. That would be amazing.
I mean, well, yeah, that would, that'd be cool.
I mean, now they have like, the future collider plan, which is, I think it's the ring is 100 100 kilometers. Oh, geez, what's it called? The future?
The future circular collider FCC. And
I mean, this is called the extra large collider.
I don't know.
Visitors aren't the best at naming things sometimes. Yeah.
Use it was the problem that like kind of like Nintendo had with their game consoles, they called the first one, you know, the tendo. And then there was the Super Nintendo. And they're like, Okay, what's more than Super and you actually weren't going to call the ultra Nintendo and then they ended up doing that and I descended 64 But the codename was like the ultra Nintendo. And that's just a funny just pat like and then what's after Ultra then giga,
giga intend to But same thing is like the already called one like the large one. So it's like
next one's gonna be bigger guys. What? Yeah, and then and then as soon as the future circular collider is like old news, and they're building the next one. Like, seems like that's not the best name for it.
Although just changed the past collider and make you feel like that?
There was a video
that we wanted. Yeah.
I mean, you had you guys touched on it a while ago that the video Veritasium put out about energy and where it flows and that kind of thing, I think taught how electricity war actually works. Yeah. And he got a ton of blowback
Just about all the IE YouTubers, and you know, and so he put out a new video
titled how electricity actually works.
But I guess actually, more than the last video, I don't know,
the title of the first video is energy, a big misconception about electricity. And the the splash image says energy doesn't flow in wires, which is a pretty bold statement. Right? And at I mean, okay, he he's technically wasn't wrong about that it is mostly in the fields. But he was arguing that it mostly just went through the air like like just directly telephones.
And I mean that does happen but we all just known as near field effects, right like electrostatic fields, magnetic fields like induction, that's that's what he was talking about. And yeah, and if you have a transformer and you like, like, very specifically construct it to, like optimize for this, then yeah, you can transfer like a ton of energy, like through the air. But I mean, it's like, barely through the air. It's a tiny, tiny air gap, usually, but
But what the thing is, is, like for DC, like that transit, like nearfield stuff is gonna transfer almost none of the power. And
if, if you actually look at, let's call it the pointing vector, which he talks about in this new video,
which is just a vector that it's gives you the energy flux through
field. So it's in watts per square meter. And it just tells you where the energy is flowing. And you can simulate it or do whatever. But I mean, at all, like, it's in like a little cylinder like around the wire, it flows along the wire and partly in the wire.
It only is completely external to the wire if the wire superconducting, but just any conductor, it's partly in the wire as well. And that is what transfers the bulk of the energy. Unless it's so fast that you're like using a coax cable. And in that case, it's in the dielectric, but I mean, that's, and he, he
so he has the I like the second video is much better, like I don't have any of the issues I had with with it that I had with the first one. But um,
And I think it's funny too, because at the at the beginning of this new video, he kind of addresses where it's like, okay, I need to really, like revisit this and go a little bit more in depth, because he really did kind of
ruffle some feathers a little bit.
And I don't know, he's still he, he measured he does measure the effect. And it's, and it's such this tiny transient from just flipping the switch on. Like it's a resistor connected to a battery and some long wires. And it trend, the power is like 14 milliwatts, which is enough to light an LED.
But the thing is the trend that transient was three nanoseconds long. So and I it was like 40 pico joules that it transferred. So you say it was enough to light up an LED, but probably not enough for us to register that led even lit up. Yeah. So what was the experiment that he was doing there? Like, how was that all set up?
Um, he just he had
two really long wires. I can't remember how long but they were I think they're a meter apart. And he had a $20,000 oscilloscope balanced on top of a ladder until like
and he you know, was measuring the characteristic impedance and all this other stuff. And but yeah, he had a battery and like a resistor, or maybe there's a light bulb I can't remember. And you flip a switch and you have the oscilloscope hooked up across the resistor. And oh yeah, you see a transient from when the switch turns on. Like that's like near field
propagation, and then a bit later after the time you would expect it to take for the current to go all the way around the wire. You see
A much higher voltage, which is the actual current flowing. And so that's what where most of the energy comes from.
And, and that's flowing effectively in the wires, right? Well, I mean,
it depends on the current, but it's in the wire and around the wire. It's a long, that's the most of it is just outside the wire like, Well, yeah. And he said,
Oh, no, no. Oh, well, the that field falls off whether square root of two or something like that. Yeah, so like Inverse Square Inverse Square. That's it.
And because of that, like, yeah, it doesn't propagate too far out. So
it's still with the wire, though.
Yeah, yeah, it follows the the pointing vector like
they it goes out from the battery or whatever, then almost immediately bends around to follow the wire. That's what he didn't show really in the first video. Well, and I think that's the misconception, because in the first video, the pointing vector, the way that it was described, is that it goes from the battery directly to the source almost magically, yeah, yeah. And, sure, a tiny, tiny amount of energy does flow that way. But he was just showing the vectors and not the actual, like, energy density. So yeah, I think a better experiment for this would be, set it up how you had it, but then also set up like 40 More of the scopes that are measuring that, like all along the wire, because then you could actually probably measure, you could see that wave come around.
So to speak, yeah, you'd have to trigger them all at the same time.
And, I mean, this this might like, this, this is open to like, debate, but
it's actually not like 100% accepted that the pointing vector at, like, the can be interpreted how they're interpreting it for us static fields? Because
not that's going to be a whole can of worms, but um, you know, let's go right into it. Yeah, open an argument that you can make an argument that it strictly only applies to propagating electromagnetic waves. And that
it also when you're in steady state, it's not actually radiating out it. And when you're in steady state it, you could interpret it as saying the, the inner the energy flux is instead the rate that that field is just changing in, in the in space or in a vacuum, rather than the energy flowing through it, essentially.
And it's called the dispersion relation, I think.
I mean, but it's one of those things where it really, it doesn't really matter. It's philosophy sounds like how you interpret. Yeah, it's how you want to decide that the way it's what the numbers mean. Like you can you can choose a few different things, but they're the same numbers, you know, so.
Oh, I'm going over Collins nose. Yeah, I am
looking at SilverStar for the for the for the blank here.
so I don't know it'd be cool. If.
So, I did want to talk about kind of
the what, what electrical current really is like, and flowing in the wire
is in that second video, he's described the electrons as well, you know, these little particles and they, they hit stuff, and transfer energy kinetically and that's joule heating and resistance and that kind of thing.
It's, that's something called the Drude model.
It's really old. It's useful for a few things, but it's not a it's not what's really physically happening.
but to do that, have to go kind of deep
Let's do it. I'm calling you 40 minutes. So we got it.
Man. So. So there's this thing called quantum field theory. It's,
it's, it's quantum mechanics after we're unified it with special relativity. And what and
the really important thing to understand is that particles are like made up. They don't exist. Well,
we still talk about particles, but they're not particles, how we think of a particle, like they're not these, like berries flying through space. Yeah, whatever. When you ask, when you say something, as a particle, people immediately think sand, or dust.
Yeah, or, I just think of like, you know, alien geographic would like write an article about how hunter gatherers have berry based physics or something, because they're like, I don't know, where we're in that phase of, of evolution, right.
But, um, so And there's been this whole, I don't know, disservice maybe to,
to people's understanding of quantum physics, quantum mechanics, because, because we're so so hung up on this idea of particles. But the thing is, quantum mechanics is really just waves doing wave stuff. Like, it's nothing that any engineer would be unfamiliar with.
And the only weird thing is that these waves are quantized, which means they can only have like, integer multiples of, of energy. So that's why we were what we call particles are just these quantized waves that have to only have this certain energy, but they can move around. And so but they're still waves.
And that's what so the quantum quantum fields are just the the,
the medium that,
that these particles, quote, unquote, propagate through. And so there's, there's, you know, there's like an electron field and there's a photon field. And there's,
by Higgs Boson, the Higgs field, there's a field for all the different elementary particles. And you can think of a particle as just a vibrational mode in these in one of those fields.
If Have you seen those YouTube videos of it's like a speaker that vibrates a plate of metal, and you put sand on it? And it makes these weird? Yeah, patterns that resonance? Yeah. That's those patterns in it. It quickly shifts between them as you increase the frequency. Those that's kind of what's going on with, with the particles, it's these these vibrational modes in the quantum field, but But isn't it? Isn't it such that with a field of like, sick electron field or, or whatever, that if you look at the mathematical model, and I'm, I'm asking question here, but it's like a value of zero, where the electron doesn't exist, and then it grows to some value where the electron does exist? Is it? Am I interested? Yeah.
Oh, yeah. So it's still a way what you're talking about? Yeah, what you're talking about is what is quantum wave function as we call them,
but and it's just a complex valued function. So it's a wave that is oscillating, and kind of to two different degrees of freedom, and one of them is complex. And, you know, just it's not that much different than impedance like that.
And the, if you square the magnitude of this wave function at any particular spot, you get what's called the probability amplitude, which is the probability of an interaction taking place with that, that particle.
so in this is where the whole quantum internet or the interpretations of quantum mechanics comes into play, because people are like, they really want to think about what does that mean? Like, what is the wavefunction? What what physical thing is actually going on? And I mean, we don't know and it
I mean, I would argue it doesn't really matter.
Fineman that that physicist was a big proponent of just saying the math works like,
I mean, why are we arguing about what it what it means physically, because it's nothing we can we can't like you can tell that you can't observe this part of reality directly, you can only just see the results. So it's kind of a black box in that way. And
so you know, that's that's where you get the Copenhagen interpretation or like the many worlds interpretation, all these different ways of looking at it, but they, the math and everything else is, is exactly the same. It's just, it's philosophy essentially. And so I would just encourage people to just pick the one they liked the most.
I like that. Yeah, cuz sometimes it can feel like you're separating, like, this idea of the physical reality, and putting a blanket of mathematics that just kind of defines it, or at least explains it slightly on top of it, but I suppose that if the math like works out, then you can, in a way, just trust that?
Well, I mean, I should be clarify something. So
we are more sure about the correctness of quantum field theory than we are about any other like, thing that we know, as a species. The, it has made the most accurate prediction of the most precisely measured thing that we've ever measured, which is some really, it's something really specific about the electron.
how its angular momentum is distributed compared to its mass, but
so we are like, we are more sure that this is this theory works than we are about, essentially anything like the sun rising the next day the,
like, general relativity, which is also very successful, but so it's not it's, I'd say it's a little more than just,
I mean, it works, it works really well.
it's incomplete. And I and I, sometimes I think, what if this is just, what if there's another like, kind of set of equations that that could be shown to be equivalent to this, that that would be that would be interpreted in a completely different way or something? So
who knows? If this is like, the only way that you can, like, solve for reality or whatever? But oh, yeah, I mean,
just saw fourth reality? Well, those were you getting out, because we have a set of equations that what Stephens covered talk about is blanketing
this this section of our reality. And but there's a gap there. And having a instead of trying to
expand the current set, maybe looking at it at a different viewpoint to see if there's something else that can also explain, you know, the math, what's going on, and then also bridges the gap is a completely different kind of way, I guess. And there's there's definitely, so that I mean, there's a few theories that extend quantum field theory. And there's several theories that are doing something else completely, like theoretical physics is there's a it's a very
idea rich landscape, as I'll put it, but there
The reason there's so many theories is the only way to test test if they're right, is essentially building larger and larger particle accelerators. And that takes a lot of time. And yes, people have theoretical physicists have more thought time than experimental time.
but on the other hand, you have these this crazy thing where,
you know, one, one person predicts this entire particle and field like 60 years in advance, like with the Higgs field and Higgs boson.
So that's, you know, we're doing something right. But we're also missing
something because like quantum field theory does not like gravity is just missing like it just does not like, account for it at all.
So that's that's a problem. And, and also recently, because this is the same thing, the standard model is like experimental particle physics, it's a quantum, the standard model is a quantum field theory. And as usually what we what we mean when we say quantum field theory, so that's interchangeable. But recently,
we've determined that the mass of this one LM elementary particle, is just is wrong.
Or is rather, what we predict is wrong. And so the standard model is, is probably wrong.
But we don't know exactly how or like, because it's really, right. It's, it's great about everything else except the mass of this one. One. It's the W, Ws, which is on I think, yeah. And, and there's one other thing, which is some interaction cross section, which is how likely a reaction will occur.
Between I think it's the top quark,
it's one of the quarks. And these two things are like off enough that it's a big problem. And then gravity, I mean, yeah, and grab the problem. And so, so but I mean, all of this stuff, it's usually how so far, it's always been the we find a more fundamental theory. And then the earlier theory is just a limiting case of that theory. So, so I mean, I'm not, we'll see, like, it's totally possible, this could all be just like, just happened to almost work. And there's something code totally different. But at least so far, what usually happens is we find out that what we know now is just a, it's still kind of, it's not wrong, it's just not the whole picture is an edge case.
Yeah, a limited limiting case. Kind of like how, you know, Newtonian mechanics is the limiting case of relative Special Relativity for like, low speeds, essentially, that kind of thing.
But oh, yeah, well, back to the Yeah, how does this all relate to current?
so it's important to understand, okay, so
now that we know that or can think of like particles as being these waves or wave packets.
Now, all of it, a lot of stuff in quantum mechanics makes a lot more sense. Like you can unmute intuitive, you intuitively understand it. So let me ask you this. Let's imagine just a single tone pure sine wave, like on the oscilloscope or whatever.
Where is it?
Like, where is the wave? Where did where does it start? Where does it end?
That's, that's, I mean, that's incredibly difficult to answer, right? Oh, no, the thing is, that's it's not I would argue, it's not even a valid question, right? It doesn't have a location. It just, you could say it just extends to infinity in both directions or whatever.
And so but what if you wanted to take that wave and like, make give it I do have an answer, though. Start turning. It starts when you turn it on and turn it off.
All right. All right. But
but in like mathematical theory land,
yeah. It has no start. No finish. Right. Correct. I mean, our Yeah, I mean, we're, like, the land that engineers hate.
But, um, it's
so but so what if you wanted to?
Well, no, let's just, like think about it on the oscilloscope still, like,
I mean, okay. Yeah, it starts when you turn it on and turn it off. But, you know, that could be
you. You don't necessarily know when you're going to turn off the oscilloscope.
And so it's still kind of the important thing is it's not, it's poorly defined. Now, if you wanted to turn to this into a very localized moment in time.
What how, how would you do that?
You would start adding harmonics. Oh,
Um, so you, you would start that would constructively and destructively interfere, and you start adding, like energy or harmonics. And you know, you get something that looks like the sync function.
It just like ripples that spike in the middle and then slowly fade on either side. And you keep adding more and more harmonics, this thing, this pulse will get narrower and narrower and be taller and taller spike, or rather a shorter and shorter spike, I can impulse.
Yeah, and so.
and these are like frequency is, and momentum in waves is proportional, like, energy, momentum, frequency, it's all kind of the same thing.
it's, and these two things like
the end, we're just talking about the frequency domain and the time domain, and they're related by a Fourier transform, you can.
And that is what the Heisenberg uncertainty principle actually is, though, there's like, a constant that it has to always be, it never goes to infinity, it's always like, these two, two things multiplied to always equal this constant or less than it.
But so the position of like an electron and its momentum or energy, are, you can, it's a Fourier transform to convert one to the other. And so if, if you have a very localized electron, it's in a very like, specific spot. That means there's a ton of these, like harmonics of other possible energies this electron could be at that are all interfering with each other, to make it that local, and then vice versa, if you, if it's like, has a very specific energy, then it has a very large position that it could be.
that is this make any sense? actually visualizing it as the impulse?
No, it makes it that's actually starting to make some sense. I mean, so you can think of this as if you had like a slit, and you're shining light through it. And you start narrowing the slit, the light has to be in more a smaller and smaller position, you're like making localizing it to squeeze through that slit. And
that, because of that, its momentum becomes more uncertain. And the what you see that as you narrow the slit, the beam of light, what it hits will widen it. diffuses yeah, as you do that, and that, but that's just like, wave propagation to like this. This is this is common to all waves, like everything I've just talked about, but it just gets weird when you're talking about, you know, these actual physical things and the berries, but yeah, the berries. But this is bringing nightmares of H. H bar and all that good. Oh, yeah. That's the constant Planck's constant. Yep. But it's not it's not as like weird and scary as people think and when
and when, like, it, it but it's quantized. So at the end, like, of the photon, or the electron, it's just hits at one spot, because that's all the energy it has still, I can only do that one interaction.
But up until then, it's probably going to be like a wave and interfere with itself and all this other stuff. And that's the wave particle duality. But it's, I don't know, I feel like that is a little more accessible, maybe
when you think about is like wave mechanics or whatever.
But uh, okay, I don't know. Let's see. Where was I going with this? Oh, yeah.
So the reason I'm talking about all this is,
we, in in a wire, these electrons, the conduction band, you know, like, if semiconductors are conductors, that's a band of energy levels that the electrons can be at. And
that means they're at very well defined momentum. So they're D localized to a large degree and behave like waves inside the wire. And what conduction is is these electrons actually the when they see the lattice of metal ions or whatever, they they don't hit the atoms, they tunnel right around
Random. And when something tunnels, it's basically just part of part of the wave function goes through it and part of it is reflected back.
Don't ask me what physically that means like, I don't know. But that's good.
But this, this reflection actually forms a standing wave with the instant electrons wave function. And that allows the electron to propagate through the metal almost unimpeded. Like there's just because it's metals really are like, very good conductors. Like that's not like a normal property of, of most things to be to be able to do that. And,
but what resistance is in that case is, you know, the lattice isn't perfect, there's dislocations, there's impurities, and also there's vibration, which changes stretches the lattice, and then it's not in the right spot, like the, for the standing wave of the electron to to be a standing wave. And that causes some losses. And so that's why metals resistance goes up with heat, because there's more more vibration. And then
other than other things, semiconductors, there, it's kind of the reverse, and rather, the their resistance tends to go down with temperature.
And that is because they their conduction band is only partially filled. And the extra heat is boosting more electrons from the valence band up to the conduction band. And they still have that, that
increase in resistance from temperature, but it's much less than the boost, they're given in conductivity from the extra electrons. And
so that's what's called the free electron model of electricity. And that's,
there's a slightly newer one, but it doesn't conceptually really change anything.
But oh, I'm almost forgetting. I mean, is this is this still? Is this interesting? Or is this
really remain reminded by the
logical physics like 201, or something like that?
Yeah, the free the free electron model was the one that my school taught. Yeah, no, I think that's like, that's it's a good model, it can predict almost all the properties of metals.
And including things like the Seebeck effect, and that kind of thing. So works very well. Now, one thing I
think this might be an interesting question, or might be stupid dowel, no, yet.
We'll talk about so the standing wave that gets formed, the more perfect the metal is, the less impedance it will have. Because of it, basically hitting stuff.
Now, is that one is,
is an electron making its own Wave? Or are we seeing a wave of multiple electrons going? Like, do they follow each other
zillion waves of all each electron?
Yeah, it's, it's each electron guy be individually with itself and not the so don't have that have a lot of interaction with each other? Because I know they're all that's a very good question. That's exactly what I was wanting to get to is so electrons are fermions, which is
I do not type of particle.
Though there's, there's it's named after Enrico Fermi.
And there's bosons and fermions with the other classes of particles. And it refers to if their spin, which is an angular momentum, but quantized if it's
integer, which is Bose on or half integer, which is fermion. So it could be like a boson could have a spin of two or zero or one. But a fermion would have what, what would a half integer be?
One half, okay, okay. I'm just making sure like exactly what. Yeah, I just like to know, yeah, no, that's a good that's good to
to specify. Again, this is all really abstract. Spin is a whole whole thing.
its own right?
Because it's not like familiar like just things rotating. But I'm not gonna get into that. But so electrons are what's called anti parallel, or errno, anti symmetric.
you can't, if you shift the wave 360 degrees, it will not be in phase with itself,
you have to shift it 720 degrees. And the result of this is that
any electron, if you try to shove it into the same like energy level, or quantum state, as we call it,
it's going to completely destructively interfere with the electron that's already there. And so fermions and well, it doesn't have to be electrons, it's any Fermi on but what it means that they cannot be in the same state, they can't be in the same energy level. So, so the electrons actually, they do not interact with each other electromagnetically. Now, I'm a huge fan of the like, tube filled with ping pong balls model of electricity. And that was that was my motivation for the original packets we have with about this topic was like a conga line of particles. Yeah. And I mean, it, it works like, for basically anything that we would ever have to do. So don't you know, don't think you have to abandon this like description.
But I'm hoping.
Okay, well, I mean, I'm just so improve or okay, it is sad set, it is kind of a satisfying, what, what is actually happening? So.
So these are like, the electrons don't interact with each other like electromagnetically? Because they're kind of just in the sea of positive charge. Like, you know, there's no metal generally, I mean, isn't doesn't have like a net charge, it's neutral.
Which means the fields are cancelling each other out. And so the electrons, there's no, there's so much positive, it's just cancelling that's called a dressed electron. And it's just it's field is canceled out by all the positive ions nearby. And they don't really feel and I guess they're also density so low, that they are not close enough to each other to repel each other.
With that, well, we think about I mean, well, no, there I kind of, but it's also that they're not they're spread out. They don't have like, positions. They don't exist that like that specific.
back towards the slit experiment and talking about, yeah, field probably. So they're delocalized just assume they're like waves. And so but so they really just superimposed on each other.
But they, they're also isolated from each other because they're take a ton of energy, the energy of like two electrons, basically, to force them into the same energy level when you're actually and when you're actually sorry to interrupt again. So when you're measuring stuff, you're actually
not just, it's a weird way to think about because usually you're like, oh, it's blah, blah, blah, amps, right? The flow, you're actually technically measuring all these individual waves just kind of sum together. Well.
Yeah, so that's what that's
this is exactly what I what I'm trying to get at is, um, so this,
what I've described is called what's called a Fermi gas, it's like, behaves kind of like a gas made of fermions fermions. And there's a pressure that results from these, all these energy states and the electrons not wanting to, to be in the same state. And in fact, this is part this is a huge contributor to the, like, the rigidity of metals is this.
It's sorry, I should have said what this is, it's called the Pauli exclusion principle.
Not wanting to inhabit the same state for fermions. But um, so what do you have a bunch of these states filled with electrons? There's a pressure and it's like an actual mechanical pressure. And so what when, when a current is propagating, it's propagating as a pressure wave through this Fermi gas. So it's essentially a sound wave
but in a very through, but in through, but it's propagating in the form of
the density of states of these electrons. So very, very Okay, so, yeah, okay. Okay.
It's a pressure, density fluctuation of the electrons. Yeah, I mean conductor.
Yes. And it's very, it's analogous to just sound traveling through a, you know, a solid.
But it's for it's for very quantum quantum II abstract reasons. But I mean, that doesn't really matter. It's still like at the high level, it's, it's a pressure wave. And it's very, it's a very real thing, like, the Pauli exclusion principle is what makes things solid. That's why you're not falling through your chair right now. It's not electrical repulsion, because, again, the that might work if everything was like ionized, and had a charge, and there was Nate could repel. But atoms are, you know, for the most part neutral. And it's because the electrons, there's orbitals, those are the different energy levels, and they don't want to, they can't overlap. That's why things are solid, too. It's a mechanical pressure.
And so it's the same thing, that conduction band is just those orbitals of atoms have taken to a huge extreme. So there's a ton of different states. But I mean, that's what's flowing through a wire, is this Fermi gas made of electrons? And
so I don't know if that was. See, that's not this is why it's not necessarily an improvement, because it's harder to understand for like, no good reason. Unless you're doing like condensed matter physics. So no, I kind of I kind of love that this is sort of the exact opposite, in a way where like, instead of trying to, like, take this concept that was difficult to understand, and say, Let's boil it down to something simpler, that is more practical, we take it and we go the other way. And like, let's make it even more not difficult to understand. But like, let's make our understanding. even wider. But but in a in a different kind of way. And so yeah, this pressure, this pressure wave on Fermi gas,
how does that respond? Or how does that look like at static conditions like DC conditions? Because like I've been, perhaps I'm thinking about it
differently, because we're saying the word wave, but is it a constant pressure in a way because it is static?
Yeah, so it's,
they, the, you know, at the end of the day, there are like electrons like, flowing into the positive terminal, or whatever of the voltage source, and there are electrons flowing out of the negative one. And they, they're being pushed into, you know, they have to push their way and onto the wire and they make generate this pressure, and then on the other end there, so in a way it actually kind of is the paif tube filled with ping pong balls, but in a very abstract way. I guess. That's it. Oh, go ahead. Sorry.
Oh, no, no. Um, yeah, that's one thing I wanted to touch on this with here is the so voltage, voltage is
how they teach it in school is it's the potential that makes electrons move. So it is out. So the voltage potential is causing this pressure wave to happen then, because it is it is wanting to shove
or gobble I guess, because how you want to think about it the electrons off the wire.
Yeah, well, I mean, and it's also the surface charges, surface charges on the wire.
that are that are kind of squeezing these things in, in one direction.
It actually a better analogy might be squeezing like, toothpaste out of a tube. And the surface charges that put on the wire outside of the wire or the field around it is like your hand pushing it.
Okay? They're squeezing it. That's, that's the best I could it's, it's uh, all ends up being
the same thing looked at in different ways, I guess. Because you can get the same result just with Maxwell's equations like, this is
this is on
Talking about becomes important. Like,
if you're doing, like maybe semiconductor stuff or condensed matter stuff, but for like actually modeling a conductor, it's, you know, it's just, you know, Maxwell's equations with extra steps.
So one question I have here is because we were talking about it as a standing wave, similar to sound. Could you technically model a conductor? That way, though, we're using sound equations? How sound propagates through material? Just as a high? We don't have to go way into it? No, no, yes, you absolutely can. In fact,
if you I think if you go on the Wikipedia page for Fermi gas, it has a really nice, like, derivation where at the end, you what you end up with is the same equation you get for, like, gas, like pressure and a gas. Like you get the you can derive the exact same math from from this very kind of exotic
model of like, all these states interacting, which I think is really cool. But
yeah, you absolutely can.
Yes, I think we're a good takeaway from this conversation is, there's a lot of different ways to explain the same thing. Different equations to do the same thing. It? Well, yeah, I think
I, how I would put it is,
deeper explanation of something
is a good way to like check if it's right is if you can recover, like the earlier model out of it. Because, you know, we know it works. Like empirically it works. So, like anything, if
it can't answer, like, it can't predict, like all the properties of metals or whatever. Whereas this free electron model can, except for I think,
couple I can't remember which, but then there's a newer model that I think, can predict, like, more or less all the properties of a metal. And, but it the model is, I mean, at the end of the day, it just lets you predict those properties. Like that's what you're getting out of it.
But the earlier models, they, they they worked just fine. And so
and at the All of these are just models, because
the there's so many like particles interacting and stuff like you know, it's like the three body problem times a quintet, quadrillion,
or by probably more with how much the electrons are in like an amp.
There's, it's just
we can't do the the math is too hard. So we come up with these models that, you know, kind of simplify that out.
Yeah. So I want I count on keep talking about this standing wave idea, because we talked about how resistance would work,
which is the imperfections in the metal and
vibrations, but like basically reflections of the wave caused that problem to happen. Actually, can I can I do one quick tangent real quick. I had a question about that specifically, is that is that some kind of it? Can we define superconductivity in that way in terms of if if some conductor is exhibit superconductivity is that just the wave function of the electrons and the wave function of the material? Not interacting? Yes, caught well. Okay, so there's two kinds of superconductivity, but the the cleverly named type one, superconductivity that's exactly how it works. If you've probably heard of Cooper pairs, heard that term be okay.
Okay, it's superconductors. Let these electrons actually pair up
in these things called Cooper pairs, and to become bosons, because now they have integer spin when you had two halves together, and that means they can have it the same energy state and then some crazy quantum math stuff happens and that lets them propagate. Like without you know what
without any energy loss like perfect, perfect conduction. Now, I mean, I mean that like, I don't know, I just don't know. I know. But conceptually, that's, that's how it's supposed to work. Yeah, what's going? Yeah. And it's something that's also has to do with the shape of like the, because usually it's like these sports?
Oh, no, no, no, I'm thinking of type two.
But yeah, I mean, it has to be really cold because I assume just the vibrations can still mess that up. And so you'd have to get it.
Then there's type two Sun superconductivity we don't, we don't know how it works really. It's much weirder, it's the electrons seem to be forming like a super fluid,
which is a fluid that has no viscosity. That's one giant wave function. And
it's weird. So it's a function that describes all of the electrons.
Rather, all the electrons collapse into a single wave function.
This can happen with helium, if you cool it below four degrees Kelvin, it becomes a super fluid, and it is one macroscopic quantum wavefunction. That and it's, it's nuts, like, you can move your hand through it, and there's no resistance to the flow. It's like it's a vacuum that has no viscosity. And it flows without any
this energy loss or, or like resistance, so like, super fluid, like superconductor.
Great. So resistance, we were talking about.
Basically just imperfections for the metal, which hampers the wave. Now, there's there's two other
what we call like fundamental electronic electrical things, because you have resistance, right? We talked about voltage, but then we have an impedance, nine impedance inductance. And we have capacitance.
So how does impedance now keep saying impedance? How does that didn't
work with this wave? Because it's a all this great.
In they're all they're all related? And so that's how I was asked, like, how does it relate to this idea of this, this standing wave of electric so.
So I mean, there is still like, overall movement of because the electrons aren't, there's a spread out, but or a single electron is kind of spread out. But it's still like, you know, it, overall, there's this dense, there's movement of these charges.
well, it's all back to the fields.
So the light capacitance is basically a measure of the energy that will get stored in an electric field. And inductance is the same, but for current in a magnetic field.
so I just thrown it out there. So would would inductance be kind of like how stretchy
the wave can be.
No, so inductance would just is just on how much energy will be stored per per amp. And in a magnetic field, okay. And so impedance,
the reactive component of impedance, or that rather the complex component is it's still in ohms. It's just uses imaginary numbers. And then it's like resistance, but instead of the energy being dissipated, it's just temporary, it comes back into the circuit. So it's, so it's resistance due to energy being stored rather than dissipated. And, and so
it's so when you think of capacitance and inductance, as really measures measuring
the propensity of something, you know, coil geometry, whatever, to store energy in these fields, then then it makes that whole relation between capacitance inductance, the reactive component of impedance, all that make a lot more sense. It's just it's all about the energy. And that's so that's why like, when you just have like DC current,
you just you have to spend that bit of energy to make that static electric field MC that static magnetic field after that, you know, you're done. Like, no more energy has to go into it. So and
That's why you want your wires like, why you want your like, traces to, or why the current flows right under the trace on like a PCB, because that's the easiest spot for it to flow because it's cancelling out that magnetic field from the current on top because it's going the opposite direction. And that means it doesn't have to store that energy in that field. And so the impedance is less, there's less energy going to that to the storage part. So
well, and I guess, if you're asking just like what the magnetism is, it's,
I mean, that's a, that's kind of a can of worms. It's a, it's relativity. I mean, it's due to like length contraction. Like, there's a magnetic field is just an electric field in a certain frame of reference. But from a moving frame of reference, it looks like a magnetic field.
But there's no, that just makes the math harder for no reason, like, so. I just want to really relate and you answered it quite well. So.
Okay. Oh, sorry.
I kind of maybe rambled a bit.
So yeah, that's, uh,
I guess what, you know, a kind of gist of what we think is going on in the wire. So, for better or worse, I like how all of this culminates to us just asking something that's pretty fundamental, when we're talking about just like electrical engineering as a whole is this like, what is current? And I feel like we could talk for another 12 hours on this, and still be like, just asking a whole bunch of questions.
Oh, yeah. Like, I mean,
the thing is, there's just, physics is really complicated and really hard. And,
but the part I find it fun to just, you know,
think of it and like, conceptually, because it's, you know, it's like the engineer, you know, that that desire to like know how things work. Like taking stuff apart. Maybe putting it back together. That kind of goes back together.
Just bits like that. But for reality. I don't know. That seems kind of cool. That's amazing. It kind of reminds me of the Carl Sagan quote, if you wish to make an apple pie from scratch, you first have to invent the universe.
If you wish to measure current, you first have to invent the universe.
I mean, it's true. on a desert island. Yeah.
Well, Colin, thank you so much for coming on to our podcast and basically describing how this stuff actually works.
I mean, I, there's gonna be a lot of people that are probably going to like write you, right? So you could say like, I don't know, I did my best though. I thank you for having me is a ton of fun. So, Colin, where can people find more about you or talk or get a hold of you?
So everything I do is under medical, and that's with a E T. A, and then a Colin with two L's that just under that handle? I have stuff on GitHub.
Also, you can
the my design company, it's just orthogonal systems.com.
But I'm also very active on Stack Exchange.
So you can look at my profile there. I have a lot of like, kind of physics related answers, but I mean, mostly in the electrical engineering, Stack Exchange.
see. Yeah, I mean, that yeah, you can if it's on there, it's under that web handle.
So also medical clinics on the Mac fan Slack channel versus virtually 24/7.
Well, yeah, I don't know. It's, it's an addiction. I don't know.
Yeah, I think um, funny enough, I ran across your posts about printing, 3d printing polycarbonate.
i That's why I use your tips and tricks. Oh, yeah. I did. How did they work? How do they work out for you? Indestructible?
Awesome. Yeah. It's good. It's good. Great stuff. I love polycarbonate.
So again, thank you again, Colin. Colin, for being on our podcast. Thank you. And
Colin will defend his positions on quantum mechanics in the macro app Slack channel.
or I'll change my mind. Oh yeah, I'm all about being wrong.
So that was the macro engineering podcast. We're your hosts Parker Dolman and Steven Craig later everyone take it easy
Thank you. Yes, you are a listener for downloading our podcasts if you have a cool idea, project or topic or know more about quantum mechanics and Steve and I do let us know Tweet us at macro at Longhorn engineer at analog EEG or emails at podcasts at macro rev.com Also, check out our Slack channel you can find at macro hub.com/slack