Impedance Matching (2017) | Hacker News Reader

Impedance Matching (2017)

edge.org

86 pointsmuti28 comments

I think concepts from impedance matching could also be loosely applied to other areas, for example:

- How veins in organisms branch out to give "energy" to different areas while being the right size for the required supplies

- How people can adapt and communicate with simpler words but taking more time. The optimum is when both parties are "matched"

- Information theory, data across a channel needs to be sent at a rate lower than its capacity, otherwise it's "rejected"

- In organizations, when a message needs to be passed from one area to another one, each impedance mismatch between individuals can lead to some "information bounce" and make it harder to get a message/idea across

- When politics adopt a measure, there's an impedance mismatch when people aren't fully onboard

It's a bit methaphorical but the overall idea is that efficient transfer across an interface requires compatibility between the source and destination. Incompatibilities produce some sort of "reflections", "distortions" or "backpressure".

> On a larger scale, we can think of atmospheric carbon dioxide as an undesired impedance matcher, coupling the infrared light waves of the sun into the planet. Someday, we may decide to cool our earth by adding tiny particles of dust to our stratosphere, tuning the optical surface to reflect away a tiny portion the infrared waves coming from the sun. The impedance mismatch between the atmosphere and sunlight would create a kind of half-silvered mirror to keep us cooler by reflecting away the unwanted energy flowing into our planet.

Good old geoengineering. The principle has been shown to work - in 536 AD [1], volcanic ashes and/or a cosmic impact event caused decades worth of cooling, causing or contributing to millions of deaths, pest spreads and massive migration movements.

The problem is... if we screw it up and overhit our target, we're in for a repeat, just this time with billions of deaths.

The question is... aren't we in for the same if we let human-caused climate change run its course anyway, just with us frying ourselves to death?

[1] https://en.wikipedia.org/wiki/Volcanic_winter_of_536

From your link, global temperature anomaly were -0,4°C. We are at +1,5°C. We would need something like 9 very big volcano injecting tons of sulfure in the upper atmosphere to cancel out the recent global warming.

And probably 3 meteor impact.

Would tiny airborne particles be safe for our lungs ?

Would they cool earth in such a way that it would offset carbon dioxide uniformly or would it lead to even more change ? Climate change is undesirable, wether or not Climate warming is invloved.

> Would tiny airborne particles be safe for our lungs ?

Almost certainly not. Pretty much anything inhaled in large amounts will cause pneumoconiosis including pollen. Some stuff like asbestos or coal dust are worse than others, but even biologically inert particles tend to cause health problems.

I think that depends a lot on what density of particles is required, and how they are distributed in the atmosphere. Intuitively actually turning the whole atmosphere into something like smog would also be pretty difficult, so I would not be surprised if they could have an effect while being pretty diffuse, and that would tend to reduce the health effects, perhaps to a trivial level.

IMO it's a very questionable solution anyway. Either you have to constantly replenish this dust, causing huge economic costs, or you have to engineer it in a way that keeps the dust airborne for long times, likely causing all kinds of health effects when breathing it and making it very difficult to remove it from the atmosphere in any significant amounts on short notice.

All of these side effects just disappear if we were to engineer this dust to emit a lot of radiation outside of the absorption spectra of water vapour and CO2, absorb a lot of light in the the absorption spectra of water and CO2, mix it as pigment into paint, rooftiles, road surfaces, and so on.

That way absorbed direct radiation gets its climate change contribution cut about in half and probably much more for diffuse radiation.

We could also biologically engineer e.g. grasses to have similar effects.

I'm a huge fan of engineering various plants to emit light in specific wavelengths anyway, and making sure that e.g. insects pollinate and birds spread them much more preferentially. That way you can outcompete or naturally cross invasive species with them and then you'll just look from satellites were the stuff you dislike is spreading and send in automated drones to highly selectively spray anything that has weirdly glowing pollen stuck to it. And after repeating that a few times, you get rid of your trojan-glowies.

who'd be in charge of the thermostat? if this followed my offices practices we'd be in ww3 before any heating/cooling had a chance to kill anyone

I was introduced to the need for impedance matching early as young self selected audiophile. Later got more serious during school for audio engineering, but then as my interest in sound got more serios when it concerned guitar amplifiers and a variety of magic smoke, impedance miss matching, became and remains a thing for me. Add in a german copy of a fender bassman that allowed for 5 different input voltages ,two levels of gain not counting three frequency gain controls and switching between two different, non standard speaker impedance settings, and well, it's the tone that counts, and there is nothing like an amp doing it's utmost to fry everything, but built just strong enough to take it. 99% acoustic these days as the tonal control is so imediate, and just going for it involves less police, who I might add are useualy quite relaxed and good about it. My point is that impedance miss matching can lead to resonance, and that can be a good thing, orrrrr it can create too much heat and let the magic white smoke out.

Coincidentally, I am reading 'Scale' by Geoffrey West where this concept of impedence matching is discussed (amongst many other things). It is fascinating how impedence matching was arrived at in biological systems viq evolutionary pressure to optimize energy usage.

As someone familiar with electrical impedance, I don't like this article. It's trying too hard to sound smart.

It's just the transformer example does not sit correctly inside the EE domain definition of impede. Once you understand that word is not locked up to the EE domain, everything is fine (except in the EE world of course).

The first three examples they use are filters.

The abstraction of impedance matching should be to "tune things to make them more efficient in their usability".

Their examples don't sit with impedance matching to me. They're all conversions or filters. The first thing was either not usable or they purely chopped off a part, not pointed it in the right direction.

In fact, the examples more or less all sit in a group in which impedance matching does not belong

Edit: the car transmission I'll give since there's a power vs speed decision that needs to be coupled

Upon further reflection, I realize there's two "impedance matching". I, and other EEs, will assume I mean the complex conjugate matching to redirect power toward load.

The author is making the argument about minimizing reflections across a medium. The trumpet, and AR coating land. The other points are more tortured. The transformer example in particular invites nitpicking.

I just find this an interesting comment. Having an electrical engineers education, there is this interesting repetition of formula which is unmistakable.

First you learn the physical equations, mostly applied to sound interestingly. Then at some point you learn about transmission line theory and maximum power transfer theory. Lastly, you get introduced to Maxwells equations, and how they produce the phenomena you’ve been learning about for years.

Unfortunately that is where my learning stopped, and I never got an answer to how quantum theory resolves with Maxwells equations, and how it interacts with standard model and special/general relativity.

Honestly I’d love an explanation of the standard model that wasn’t covered with mystery and math. It makes the idea of understanding particle physics impossible.

Unfortunately, in my experience the more advanced/nuanced/complete of an explanation of physical phenomenon you want, the more math heavy and abstract the "real answer" becomes. Quantum Electrodynamics is some beefy stuff, the math is gnarly, and it is built on an increasing pyramid of mathematical reasoning and intuition as well as the steps of physical reasoning and intuition that you mention.

Remembering my graduate physics days im astounded that i was able to understand it, and am unable to really follow it now, as that higher math has gotten preeeety rusty.

Feynman diagrams are the attempt to loop back around and represent this field without all the math, but my experience was you have to have done the math first otherwise they are just so much arcane heiroglyphs. the wikipedia illustrates this well, where you can see a relatively clear diagram and corresponding equation, but i recall whole pages of a notebook to get one _line_ of an equation down. https://en.wikipedia.org/wiki/Quantum_electrodynamics#Feynma...

I say all of this not to suggest a clear explanation is impossible, but it sure wouldn't be easy. Love to see it though.

Just read this article as well and thought the same. Quite a bit disappointed.

Anything from a funnel to a reduction gear on a ship is an example.

Does low verbalization imply that a concept isn't widely known?

Or is this blog post, itself, an example of impedance matching?

The whole article appears use a very loose philosophical definition of "impedance". As a mechanical engineer, none of the mechanical examples are correct either when there are real-world examples that actually meet the more strict technical definition of impedance matching, mass-damper systems in skyscrapers is immediate example that comes to mind.

Is gearing up or down, with a fixed power budget, a valid example in the strict sense? Genuinely asking.

That's a pretty decent example IMO.

No. A gear train is just a transfer of force/torque. It's analogous to a simple lever for rotational motion. Mechanical impedance is almost always referring to harmonic forces (think of spring systems and structural dynamics). Impedance in fluids also fall under mechanical impedance but it's usually classified separately as acoustic impedance.

I think what they're getting at, and is valid, is how the speed/torque relationship is similar to voltage/amperage. There's nuance which can separate those ideas.

Mass damper systems were really important in cars too before we had deep simulations of structures. Putting some loosely coupled weight in some spot to keep the whole thing from vibrating was a breakthrough.

Reading this was a relief, I've only got a hobbyist's knowledge of impedance matching in the electrical sense and felt like I was going crazy... Good to know I'm not alone

>"Some of the most interesting impedance matching occurs when energy comes in the form of a wave. You have probably noticed in a swimming pool that waves from a splash reflect off the sides of the wall. Because there is an impedance mismatch between the water and the wall, the wave energy is unable to couple into the wall, and so it reflects back."

Observation:

If:

Impedance Mismatch = Reflection Of Waves = No Fixed Wave Nodes (Wave Nodes Must Travel in Space and Time) = Dispersion Of Energy in Time, over Space

Then:

Impedance Matching = Creation Of Standing Waves (creation of fixed, non-moving wave node points in space) = Preservation Of Energy In Space, over Time = Capacitance

(Note that I'm not saying I'm right... I'm just saying that if A implies B (A->B), and B implies C (B->C), then there's a very strong possibility that A implies C through logical transitivity / chain of implications (i.e., A->B->C becomes A->C), in the above case that Impedance Matching strongly implies Capacitance (via Standing Waves)...

Also, it should be noted that Capacitance comes in many forms... Electric (electrostatic), Magnetic, and in theory, any type of electromagnetic wave should be subject to Capacitance under the right conditions...)

Anyway, great article!

Whatever happened to Edge? They haven't really published since 2018

Speculation, but Edge was John Brockman’s thing and he was heavily connected to Epstein, so probably has become a bit toxic for potential contributors. https://en.wikipedia.org/wiki/John_Brockman_(literary_agent)...

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