Author Topic: Why are physicists the electronics experts?  (Read 6108 times)

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Offline Nominal Animal

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Re: Why are physicists the electronics experts?
« Reply #25 on: August 21, 2020, 06:56:41 pm »
Seriously, if you can't find places online where EEs would usually not be able to answer EE questions, but physicists would, then you're probably looking in the wrong places.
I was referring to willingness, definitely not ability, though.

I don't think that professionals like to volunteer on the net on things they do at their day job.  For example, although I was quite active on Stack Exchange for a few years, I never went to the matter modeling (materials.stackexchange.com) site at all.  Math, electronics, and POSIX C programming are basically just my hobbies, and I kinda like to help with those.

So, if I had to guess, I'd say that the overwhelming majority of people answering questions online do so on topics they have as a hobby, not as a day job.  If indeed physicists do answer electronics questions often (which I'm not sure about, it could be just a coincidence in OP's topics), I would guess it is because many physicists like doing electronics as a hobby, and also like to answer questions.

Like they say: Those that can, do; those that can't, teach.  :P
« Last Edit: August 21, 2020, 06:58:49 pm by Nominal Animal »
 

Offline fourfathom

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Re: Why are physicists the electronics experts?
« Reply #26 on: August 21, 2020, 07:27:31 pm »
I don't think that professionals like to volunteer on the net on things they do at their day job.

I think you're probably wrong about that.

I don't think Stack Exchange even existed when I retired from my engineering career (almost 20 years ago), but I was trying to help out on-line in my areas of expertise as far back as the USENET days.  I'm definitely a practical hands-on engineer, not a deep theory guy, so I'm happy that the physicists and physicist-engineers are here to answer those deeper questions.  I do try to help when I think I know what I'm talking about, and would certainly have done so when I was working full-time (assuming I could have found the free time).
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Offline SiliconWizard

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Re: Why are physicists the electronics experts?
« Reply #27 on: August 21, 2020, 09:13:54 pm »
I don't think that professionals like to volunteer on the net on things they do at their day job.  For example, although I was quite active on Stack Exchange for a few years, I never went to the matter modeling (materials.stackexchange.com) site at all.  Math, electronics, and POSIX C programming are basically just my hobbies, and I kinda like to help with those.

So, if I had to guess, I'd say that the overwhelming majority of people answering questions online do so on topics they have as a hobby, not as a day job.  If indeed physicists do answer electronics questions often (which I'm not sure about, it could be just a coincidence in OP's topics), I would guess it is because many physicists like doing electronics as a hobby, and also like to answer questions.

Whereas there may be some truth to that, you can't generalize. Again, this forum is a counter-example. Sure there are some retired people and hobbyists on here, but there also are MANY active professionals that do help on a regular basis.

To elaborate a bit, I think professionals actually attract professionals. The fact Dave (Jones) was an active professional for many years before starting EEVBlog was a big part of it. That did attract a lot of other professionals, and not just hobbyists. OTOH, there are many other forums out there that are not created/run by professionals and will mainly attract hobbyists.

Like they say: Those that can, do; those that can't, teach.  :P

Whereas that's kind of true when people choose a career path, that's not an absolute truth in general. Many professionals will teach/share their knowledge and experience, especially as they get more advanced in their career. So getting back to EEVBlog's forum, your statement is even kind of insulting. There are again a lot of people on here that have done a lot (and many that still do) and help or teach when they get a chance.

As to what motivates professionals: yes many experienced engineers actually like to help/share (as fourfathom said.) But many also do this for expanding their network/get some exposure, and that's fine too.
« Last Edit: August 21, 2020, 09:19:25 pm by SiliconWizard »
 

Offline TimFox

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Re: Why are physicists the electronics experts?
« Reply #28 on: August 21, 2020, 09:22:59 pm »
My examplar is the Clerk from Chaucer's Canterbury Tales:
"Sownynge in moral vertu was his speche,
And gladly wolde he lerne, and gladly teche."
 

Online tszaboo

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Re: Why are physicists the electronics experts?
« Reply #29 on: August 21, 2020, 09:33:27 pm »
Well, thats normal. If you ask an " I=U/R" question, you are not going to get an answer online from an engineer, because he will be busy navigating to a different webpage that is actually interesting. Its not that we dont know the answer, but it is probably just to elementary.

Now, ask the physicist, to recommend an opamp with low offset voltage for battery powered electronics. Or with the previous example, I=U/R is interesting, if you need to do Monte Carlo on the resistor values, the U changes based on the battery voltage, the resistance has to be from the E24 table, cheaper than  cent, and the current has to be kept below the safety limits of a harmonized standard.

Besides, engineering is all about problem solving. If you can google your question, and solve the problem that way, do that.
 

Offline Sal Ammoniac

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Re: Why are physicists the electronics experts?
« Reply #30 on: August 21, 2020, 09:46:48 pm »
From what I have seen by working with universities around the world that used to be the case (and often still is) is Europe (Italy, Germany, etc.). Here the traditional teaching order is bottom up, starting with lots of math (complex functional analysis, linear algebra etc) physics, electromagnetism in particular, then device physics (pn junctions, BJT’s, MOS) and on from there.

Unfortunately it’s been some time that we are importing the Top down approach from the US (the UK has been the first, however it is not the only one now). This starts from system level and goes down from there, often times completely neglecting physics, math and even how semiconductor devices work. In a “makery “ type of way.

I went to university in the US and it was definitely what you describe as "bottom up".
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Offline Nominal Animal

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Re: Why are physicists the electronics experts?
« Reply #31 on: August 21, 2020, 11:25:17 pm »
Whereas there may be some truth to that, you can't generalize. Again, this forum is a counter-example.
No facts in my post, just vague guesses as to why one might make the statement OP did in the initial post.

To elaborate a bit, I think professionals actually attract professionals.
Sure, I agree; but I think you're reading something in/from my post that wasn't there (or if it is, it is in error).

I was not talking about hard rules that apply to all sites, as in defining characteristics that are common to all discussion sites.  I was thinking about all the Q&A sites out there, and how the discussions and questions I most commonly see are hobbyist-level and not professional-level stuff.  Because there are lots more hobbyists than professionals out there babbling on the intertubes – and I'm not talking about EEVBlog here, or any specific site, but rather in statistical terms – on a random site, you're much more likely to engage with a hobbyist than a professional.

(So, to repeat, if one asks an electronics related question on some random Q&A site, and if it turns out you are more likely to get a response from a physicist than an EE professional, I think it could be because there are more talkative physicists who do electronics as a hobby than EE professionals on typical sites.  I am not even sure if that actually happens.  On EEVBlog, the situation is completely different.)

If we switch to discussing EEVBlog, then I absolutely love to read about real world experiences and advice.  That level of information and experience is not easy to get access to in general on the intertubes; EEVBlog is definitely unique in that sense.  (And I wouldn't want anyone to think that the net is full of sites like EEVBlog, because it isn't; there are not that many sites where professionals engage so much with hobbyists.)

Like they say: Those that can, do; those that can't, teach.  :P
Whereas that's kind of true when people choose a career path, that's not an absolute truth in general.
No!  That was a self-referential joke.  As in, I try to teach, even though I'm just an uncle bumblespork.  I've been told it is in my blood.

So getting back to EEVBlog's forum, your statement is even kind of insulting.
Why would you consider it that way?

I've reread my posts in this thread, and can't see a reason why one would think that.  It certainly wasn't my intention.
« Last Edit: August 21, 2020, 11:32:17 pm by Nominal Animal »
 

Offline eti

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Re: Why are physicists the electronics experts?
« Reply #32 on: August 21, 2020, 11:31:52 pm »
Here's my very simplified understanding of this:

All physicists will generally (I should HOPE so, anyway) know electrons, protons, neutrons etc and how they behave, so electronics is just a practical manipulation/physical realm engineering of solutions based around those behaviours.

Not all electronics engineers will, or will need to know the above, depending on their area of focus. They know that electrons flow, in current, and they know that for X potential across Y resistance, Z current will flow, and all the variations of that. If you can solder, measure, test and diagnose, one isn't required to know all the aspects of the molecular realm that a physicist would generally know (at a bare minimum level, I'd think).

What I am trying to say is that, if I seek an expert on soldering, faultfinding, circuit repair and measurement of signals, I'd ask an electronics engineer. However, if I wanted a fine grained explanation of electrons and the molecular level behaviour of that kinda thing, I'd seek a physicist.

You get my drift?
 

Offline Rick Law

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Re: Why are physicists the electronics experts?
« Reply #33 on: August 22, 2020, 05:01:03 am »
There are so many branches in Physics and many of them use electronics.  Electronics is a "must learn" if you are a Physics major.

Before I get into it, first some background.  There is Experimental Physics and Theoretical Physics, this is a function focused description.  Then there is the subject field focused description such as Particle Physics, Plasma Physics, Astrophysics, etc., etc.

A.  Why Physicist learns lot of electronics

Experimental Physicist uses a lot electronics and much of it custom designed by the Experimental Physicist themselves.  The equipment's function and manner of operations are designed by Physicist.  The electronics may be designed in collaboration with Electronic Engineers as needed.  As Physicist participate in such activities, they learn more EE stuff because whatever experiment they designed, EE may be the "what" that makes it happens.  After it happens, EE is likely the "what" that takes the measurement.  So they must understand EE to know how far they can push -- you don't want to design an experiment that cannot possibly be done.  Budgetary constrains also pushes more work to be done "in-house."  That is, have a Physics graduate assistant do the work and have him/her get advice from an EE guy.

A good example may be CERN/LHC (Large Hadron Collider).  There you have some of the most advanced electronics used by Physicist - In this case, Experimental Particle Physicist mostly but not all.  All custom designed by Physicist, again, in collaboration with Electronic Engineers as needed.

Another example is Carbon Dioxide, used in lasers.  Experiment Physicist working in that field (and other Physicist using lasers heavily) would know as much about Carbon Dioxide as most Climatologist.  They are the ones who like to argue with Climatologist about Carbon Dioxide's role in warming of the globe[1].  One more example is Computer Science, every Physicist has to use computer in one way or another.  So some Physicist became good computer programmers as the need arises.

B. Why Physicist is more likely to answer questions

Now above perhaps explained why Physicist typically understand some electronics, but that doesn't explain why Physicist tend to answer questions.  My opinion is: May be that is just a (self) selection bias.  Those going into Physics like to understand things instead of just applying things.  And liking to understand would likely lead to liking others to understand it too.  Hence, they are likely to take time to answer questions.  May be...

[c] What is a physicist

As to the question "What is a Physicist?"  From the perspective of someone with a mere master degree in Physics and having done some research as a graduate assistant...  I would say a Physicist is one who works in the field of Physicist.

Many would say a PhD in Physics is necessary to be called a Physicist.  But I think that would be unfair to those who is working in the field doing active research but without a PhD.  It would be rather hard to find work as a Physicist without a PhD, but if that person is good enough for others to pay him/her to do Physics, that person is good enough to be called a Physicist.

Footnote:
[1]  Princeton University Professor of Physics William Happer

At time mark 5:11 is the question posted by the interviewer "...What do you mean CO2 doesn't make much difference [with climate]...".
At time mark 5:20, he answered "...I know a lot about CO2 compare to most Climate Scientist because we make  CO2 lasers.   CO2  is a very interesting molecule..."
« Last Edit: August 22, 2020, 05:07:28 am by Rick Law »
 

Offline FransW

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Re: Why are physicists the electronics experts?
« Reply #34 on: August 22, 2020, 09:39:04 am »
I would say that there exists a lot of self-induced occupational myopia.
One sees what one wants to see. It often can be compared with the
difference between a pigeons intuition and occupational intuition, based
on knowledge and experience.
Knowledge and/or intuition often is present in a compiled version.
Reconstruction into parts can be quite a task.

I did like the contribution of "Rick Law".
He describes the fields in question in a broader context, without too much
limitations and an open view to whatever can influence any observations and/or
measurements.

Being aware of one's own limitations the question: "what do you not know"
(a silly question if put in this way) can be answered by oneself.
Curiosity is a gift, the brains to use it as well.

The solution for many questions is to reduce complexity.
When someone describes a problem as complex, chances are that the understanding
is still far away. The question that remains is: did you really understand the subject.
Calling it complex is not contributing to a solution.

Frans
« Last Edit: August 22, 2020, 09:50:02 am by FransW »
PE1CCN, Systems Engineering, HP, Philips, TEK, BRYMAN, Fluke, Keithley
 
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Online EEVblog

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Re: Why are physicists the electronics experts?
« Reply #35 on: August 22, 2020, 09:52:30 am »
What question did you ask them?

If it is something along the lines of "What kind of circuit should i use to transfer power and bidirectonal communication simultaneously over 2 wires" or "How do i make the switchmode regulator <Insert part no. here> output be digitally adjustable" you are very unlikely to get any sort of even remotely useful answer out of a physicist.

If you instead ask something along the lines of "How does a bipolar transistor work?" or "How does an LED work?" or "Why do resistors make thermal noise?" then you are indeed more likely to get a much better answer out of a physicist. The electronics engineers just simply don't care what the electrons are doing inside of that transistor. They can't poke and touch those electrons in there to make them do anything else than what they normally do. They care about the transistors functionality of amplifying current, so they instead know how the transistor behaves and how to use that behavior to do something useful in a circuit. But physicists are way more interested in those electrons whizzing around inside trough those funky energy levels of the junction, while not really caring about what that transistor could do in a useful circuit.

This leads to things like the much debated topic around Dr. Lewin and Kirchhoffs circuit rules.

Yes, that was a absolutely classic case of the way an electronics engineer sees things, and how a physicist sees things. In essence both of them were "right".
« Last Edit: August 22, 2020, 10:28:05 am by EEVblog »
 

Offline coppice

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Re: Why are physicists the electronics experts?
« Reply #36 on: August 22, 2020, 10:21:24 am »
There are so many branches in Physics and many of them use electronics.  Electronics is a "must learn" if you are a Physics major.
When I was at college doing my electronics degree the material used for the physics people's circuit design course was basically the same as ours. Their course was presented with a more instrumentation focus, but it covered roughly the same ground.
 

Offline iteratee

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Re: Why are physicists the electronics experts?
« Reply #37 on: August 22, 2020, 12:38:37 pm »
Having understood the underlying physics helps to deal with many real-life electronics problems. Like EMC, noise, interference, efficiency, signal integrity, ...
You don't think an engineering degree covers that in great detail?
In 4 years? With half of courses being irrelivent bullshit and the rest being tought via a process that could only be conceived by an alien that doesn't understand human learning?

Nope. No chance.

*disclaimer: I'm part-alien and don't understand normal human learning either. As evidenced by the fact that normal people claim education works for them, for incomprehensible reasons.
« Last Edit: August 22, 2020, 12:52:07 pm by iteratee »
 

Offline pidcon

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Re: Why are physicists the electronics experts?
« Reply #38 on: August 22, 2020, 03:11:58 pm »
I would imagine that physicists work in an academia-like environment and would be more open to communicating their ideas and definitely will take the time to explain how things work from their perspective. Maybe the engineer was too busy to write out a long explanation.
 

Offline SiliconWizard

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Re: Why are physicists the electronics experts?
« Reply #39 on: August 22, 2020, 05:56:24 pm »
Like they say: Those that can, do; those that can't, teach.  :P
Whereas that's kind of true when people choose a career path, that's not an absolute truth in general.
No!  That was a self-referential joke.  As in, I try to teach, even though I'm just an uncle bumblespork.  I've been told it is in my blood.

So getting back to EEVBlog's forum, your statement is even kind of insulting.
Why would you consider it that way?

I've reread my posts in this thread, and can't see a reason why one would think that.  It certainly wasn't my intention.

Oh nevermind, I likely overinterpreted what you wrote. But in the context of the thread and of what you said above, it was kind of conveying the idea that most people helping others out on tech forums must just be hobbyists or people who haven't achieved anything much, which was backed by your "I'd say that the overwhelming majority of people answering questions online do so on topics they have as a hobby, not as a day job." sentence. So the "teachers are not doers" part that followed just looked like a nail in the coffin. Re-read better, I guess you'll have to admit it was a gross generalization and could be misinterpreted.

Of course generalizations are just that. "Online" is a pretty big place with a lot of different things happening. I'd personally be hard-pressed to say what a "majority" of people do "online" and why.

But back to the topic, the OP's statement IME is certainly NOT true.
 

Offline SiliconWizard

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Re: Why are physicists the electronics experts?
« Reply #40 on: August 22, 2020, 06:20:49 pm »
Well, thats normal. If you ask an " I=U/R" question, you are not going to get an answer online from an engineer, because he will be busy navigating to a different webpage that is actually interesting. Its not that we dont know the answer, but it is probably just to elementary.

Now, ask the physicist, to recommend an opamp with low offset voltage for battery powered electronics. Or with the previous example, I=U/R is interesting, if you need to do Monte Carlo on the resistor values, the U changes based on the battery voltage, the resistance has to be from the E24 table, cheaper than  cent, and the current has to be kept below the safety limits of a harmonized standard.

Besides, engineering is all about problem solving. If you can google your question, and solve the problem that way, do that.

I second this.

Several of us asked what kind of questions the OP was referring to. And apart from the kind of forums they visit, I think this is the key point here.

If you ask a fundamental question about electronics - it could be either pretty advanced, in which case a typical engineer may not be comfortable answering, and a physicist will be better at that - but as I said earlier, you may not understand your own question after they have fully answered ;D . As Dave just mentioned, the whole thread about Kirchhoff's laws was a good example. Is that kind of questions what the OP had in mind (and calls people able to answer them properly "electronics experts")? Frankly as several of us already said, you'd need to ponder what engineering is all about.

Or, it could be a very basic question, as NANDBlog just said, in which case many professional engineers will just pass - they usually have better things to do than teach elementary things to typical students (or hobbyists). So obviously it's not because they are not expert enough in that case, just that they have better things to do. The value of an experienced engineer on an online forum is their experience and practical knowledge, it's not teaching random people very basic things that anyone can find in a textbook.
 

Offline richard.cs

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Re: Why are physicists the electronics experts?
« Reply #41 on: August 22, 2020, 06:37:14 pm »
I have heard from some UK academics that health and safety plus cost issues means lab work is mostly matlab work these days.

Someone with an electronics degree who has little understanding of basic components is not necessarily a bad thing. Electronics is now a big topic, and every engineer is a specialist of some kind, For example, many careers in electronic engineering can be entirely based on the maths of communications.

For this particular university the cause seems to be more related to internal politics.

And yes of course some engineers specialising in comms theory is good and necessary. I am not sure however that a masters in electronics should focus so heavily on it to the detriment of everything else. Or to put it another way, the kind of engineer that my employer requires aligns poorly with many UK university electronics courses, to the extent that when they apply for an electronics engineering position we are starting to count an electronics degree as a possible negative. I don't think our needs are that weird and oddball that this should be the case.

We've also become a bit suspicious of top grades - it seems to correlate heavily with the kind of student who is very good at exam technique and studies very narrowly to optimise academic results at the expense of subject understanding.
 

Offline Rick Law

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Re: Why are physicists the electronics experts?
« Reply #42 on: August 22, 2020, 06:41:18 pm »
I would imagine that physicists work in an academia-like environment and would be more open to communicating their ideas and definitely will take the time to explain how things work from their perspective. Maybe the engineer was too busy to write out a long explanation.

RE:"...physicists work in an academia-like environment and would be more open to communicating their ideas..."

That would be the ideal, but that is not the real world.  A lot of careers and money are on the line.

Say for example, Dark Energy.  It is the current accepted "standard model".  A lot of money is on the line.  You have to search really hard to find Astrophysicists who openly voice their doubt.  Doing so will pretty much limit your grants and career rather quickly.  You have some "voices in the wilderness" and that is about it.  If your publication submission doesn't agree with the "standard model", good luck getting it published.  It can be done, but certainly not easily.  Should their objection of Dark Energy be proven truth, a lot of "heavy weights" (establishment, including Nobel Laureates) will be handed a good size serving of humble-pies.

But, the world of Physics is changing...

First a quick fact: LHC found the Higgs particle, but absolutely nothing else!  Super Symmetry is now in doubt -- All the SUSY particles we hoped for, no SUSY particles found at all!  Not a one.  Proposals exist to upgrade LHC (14TeV, about 27km ring) to about 8x (110TeV) by adding another ring at about 100km radius - hoping may be we will find some (SUSY and the likes).  Tons on money there for everyone to get a piece of that pie.

The fallout of no SUSY: Physics today is in crisis or in an era of great opportunities.  String Theory have been sucking all the top brains of Theoretical Physics for the last few decades, but it is now in great doubt.  The Standard Model for Particle Physics while works but too much seem like patch-work, is therefore lacking a way to get out of that patch-work construct.

It is now finally the time to call some "standard models" into question.  You can still have a career if you openly question "Standard Model for Particle Physics" or the validity of String Theory today.

EDIT - missed the re:"... ..." in the first line.  Corrected a "could" to a "can" in the last line.
« Last Edit: August 22, 2020, 06:47:52 pm by Rick Law »
 

Offline Nominal Animal

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Re: Why are physicists the electronics experts?
« Reply #43 on: August 22, 2020, 07:58:55 pm »
But in the context of the thread and of what you said above, it was kind of conveying the idea that most people helping others out on tech forums must just be hobbyists or people who haven't achieved anything much, which was backed by your "I'd say that the overwhelming majority of people answering questions online do so on topics they have as a hobby, not as a day job." sentence.
I see.  I definitely didn't intend it that way.  Again, I am horribly bad at expressing non-technical things in English; the non-technical undercurrents escape me, and in my own written output tend to be just noise.

There are a lot of professionals on the net.  I tried to convey a guess that perhaps hobbyists find it difficult to express their questions and problems in a way that attracts the interest of a professional to answer; that many questions instead get answered by other hobbyists.

I am not claiming that those who answer are hobbyists, just wondering aloud that it could be possible that when asking vague, not-very-well formed questions, to get answers from other hobbyists, because professionals find the hardest part is to understand what is the actual problem the asker is trying to solve, or something along such lines.  So, when asking questions about electronics, it perhaps could be that some questions attract answers from hobbyists that happen to be physicists, because a lot of physicists with electronics as hobbies (I know about half a dozen or so) also like to ask and answer questions (the ones I know that have electronics as a hobby happen to also be that way, myself included – and I am aware that I oftentimes seem to have a "teacherly tone" and seem like I know more than I do, as just a hobbyist in electronics, which lead to the attempt at a self-deprecating joke).  And all this assumes that OP's observation is correct, which I am not at all sure about; I think it more likely that it is just confirmation bias, or a complete coincidence.

On a completely different track, human minds are not at all good at discerning if something happens often or not.  We have exceptionally strong perception "filters" or "lenses".   Consider the following attention test:

and you'll understand what I mean: our conscious perception is highly selective.

The scientific principle about repeatable experiments is the best tool I know of of overcoming those.  Practical experience, in the best case, falls into the same category, unless done by rote.  People who have acquired experience on how to keep things working in a dynamic experience have a lot to teach; and electronics, especially electronic design, is a complex subject where nothing is "perfect", and that makes EE experience such valuable to me personally.  So, if you read anything written by me that seems disparaging of EE or practical engineering, let me know so I can fix, because that is an error, categorically.  (I do often wail against people who do not do the work, and produce shoddy work, but even that's not about ability, that's about effort or exploitation.)

I personally like to answer very specific types of questions that also interest me, and in those cases can get quite in-depth even if I have no idea of the actual answer myself beforehand.  Among those questions, and other answers to the ones I've tried to answer, there are roughly three categories: drive-by-statements (that either give a formula, link, or statement) without any reasoning, often basing the answer on authority; other hobbyists (either having solved the same beforehand, found an answer elsewhere, or happen to know the answer, or how to find the answer); and professionals.  It is my feeling, without any actual statistics, only based on my "gut feeling" related to the thousand or two questions I've (tried to) answer on the net, that the middle category, hobbyists, is in the majority.
I do not place much value on that feeling at all, because the questions were on very specific topics.  To me, it is barely enough to speculate on.

So, if anybody felt slighted about any of my statements in this thread, I do apologise: no slight was intended.  I don't see any real way to find out if OP is right or wrong, and it does not really matter enough to more than idly speculate on.
 

Offline bsfeechannel

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Re: Why are physicists the electronics experts?
« Reply #44 on: August 23, 2020, 12:34:54 am »

This leads to things like the much debated topic around Dr. Lewin and Kirchhoffs circuit rules.

Yes, that was a absolutely classic case of the way an electronics engineer sees things, and how a physicist sees things. In essence both of them were "right".

Unfortunately, that's not true.

Tom Lee, that you interviewed on The Amp Hour Electronics Podcast, says the following in his book, Planar Microwave Engineering: A Practical Guide to Theory, Measurement, and Circuits, a book that every wannabe microwave engineer should read:

As we noted early in this book, it is important to remember that conventional lumped circuit theory results from appproximating the way the universe behaves (in particular, from setting to zero some terms in Maxwell's equations [i.e. using special cases of those equations], effectively treating the speed of light as infinite). The much vaunted "laws" of Kirchhoff are not really laws at all; they are consequences of making simplifying approximations, and so they ultimately break down

² Failure to acknowledge this fact is the source of an infinite variety of false conundrums, many of which are debated
ad nauseam on various internet chat sites ("proof that physics is broken" [or that engineers see things different than physicists] and that sort of thing, written by folks who are often wrong but never in doubt).

Chapter 21 "Antennas", p. 688.

The bold letters and quotes between brackets [] are mine.

Tom Lee is an engineer.

.

He published this in 2004.

And that's the whole point of the engineering degree: make you see things the way a physicist sees so that you know exactly what the consequences of your simplifications are. Engineers need to simplify things for practical reasons, but they can't afford to see things in a different way. Engineering is not an amusement park. It is serious business.

So the truth is that some engineers insist that the simplified way the see the world are the fundamentals, get puzzled when it fails and are proud of their ignorance, while a lot of other engineers endeavor to see the world exactly as physicists do, know that their simplifications are prone to break down, and thank the physicists who point that out to them.
« Last Edit: August 23, 2020, 12:43:11 am by bsfeechannel »
 
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Online EEVblog

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Re: Why are physicists the electronics experts?
« Reply #45 on: August 23, 2020, 12:49:25 am »

This leads to things like the much debated topic around Dr. Lewin and Kirchhoffs circuit rules.

Yes, that was a absolutely classic case of the way an electronics engineer sees things, and how a physicist sees things. In essence both of them were "right".
Unfortunately, that's not true.

I used quote marks around the word "right" for a reason.
 

Offline iteratee

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Re: Why are physicists the electronics experts?
« Reply #46 on: August 23, 2020, 05:36:55 am »

This leads to things like the much debated topic around Dr. Lewin and Kirchhoffs circuit rules.

Yes, that was a absolutely classic case of the way an electronics engineer sees things, and how a physicist sees things. In essence both of them were "right".

Unfortunately, that's not true.

Tom Lee, that you interviewed on The Amp Hour Electronics Podcast, says the following in his book, Planar Microwave Engineering: A Practical Guide to Theory, Measurement, and Circuits, a book that every wannabe microwave engineer should read:

As we noted early in this book, it is important to remember that conventional lumped circuit theory results from appproximating the way the universe behaves (in particular, from setting to zero some terms in Maxwell's equations [i.e. using special cases of those equations], effectively treating the speed of light as infinite). The much vaunted "laws" of Kirchhoff are not really laws at all; they are consequences of making simplifying approximations, and so they ultimately break down

² Failure to acknowledge this fact is the source of an infinite variety of false conundrums, many of which are debated
ad nauseam on various internet chat sites ("proof that physics is broken" [or that engineers see things different than physicists] and that sort of thing, written by folks who are often wrong but never in doubt).
Erm is this not sort of obvious common-sense? I knew this prior to any study of electronics and zero physics education. I'd suspect anyone that's pondered this will have noted the issue.

The manual distributed by S.I. IIRC explicitly disclaims that relativity is essentially ignored throughout. Meaning the basic definition of voltage as an instantanious measurement across space necessarily violates your light cone (duh). I recall this being explained rather dismissively as a niche detail applicible only to "specialized fields". Well it's pretty damn fundamental to everyday electronics.

Any geek kid with hilarious gamer P.C. laced with fruit loopy LEDs has tweaked their memory timings, has intuition of phase velocity, and can tell you how many picoseconds apart their DRAM slots lie from CPU.
« Last Edit: August 23, 2020, 05:56:54 am by iteratee »
 

Offline Rick Law

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Re: Why are physicists the electronics experts?
« Reply #47 on: August 23, 2020, 06:43:59 pm »
Standard theory today is: if you are traveling with an electrical system (say, a PC on a space craft) at relativistic speed, everything should work just fine.  If you are using wireless to send signal from your space craft off to something not traveling with you, that is where you will run into trouble -- apart from your getting out of range within milliseconds, the signal will be frequency-shifted.  Another space craft traveling along side at similar speed should however receive the signals just fine.

But,  I can't think of anything we are doing where relativistic effect becomes significant...  The fastest thing we ever made was the Juno probe.  Back in 2016 when it was about to go into Jupiter orbit, with Jupiter's gravity helping, it was traveling at about 266,000 km/h (0.00025c).  That was about 2.5x the speed we are orbiting the sun.  At 0.00025c,  relativistic effect is tiny rounding error.

As to Kirchhoff's Law or issues regarding the simplification...  Let me put it this way:

What is the conductivity of an electron?

That question doesn't even make sense.  But it is a reminder of something we often forget: electricity (voltage/current) is a statistical emergent phenomenon - emerged from a flow of a large number of charged particles.  Rather like heat/temperature emerging from random vibrations of molecules.

As such, electronics and electrical rules applies only in the "normal world" where the statistical models were compiled and thus can apply.

When you deal with statistics, there is no meaningful exact solutions.  You only get probabilities. 

EDIT:

The initial writing (above), I was trying not to be too direct.  That risk offending people.  But re-reading the post, I think I did not get the point across.  So I am adding this few more direct statement.  Hope I am not offending anyone.

Don't fool yourself into thinking we can solve those problem analytically with exactness.  Even today, we cannot solve Three-Body gravitational problems exactly.  We do that with approximations.   We cannot solve relativistic equations analytically with two black holes orbiting each other (when they get very close, there is where it counts), we have to solve it numerically.

That didn't stop us from going to moon (moon + spacecraft + earth = 3 bodies), that we can't deal with orbiting black holes didn't stop us (LIGO) from detecting a black hole merger with gravitational waves.

So there is nothing wrong with approximations.  They are just fine.  And as always, we need to apply solutions knowing the limitation, and all solutions are limited in domain(s).

« Last Edit: August 23, 2020, 07:24:57 pm by Rick Law »
 

Offline TimFox

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Re: Why are physicists the electronics experts?
« Reply #48 on: August 23, 2020, 07:11:33 pm »
A simple example of everyday things with relativistic features.
Linear-accelerator x-ray sources (used for radiography and radiotherapy) achieve electron kinetic energies from 2 MeV up to over 20 MeV.  The rest mass is 0.511 MeV.
 

Offline Rick Law

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Re: Why are physicists the electronics experts?
« Reply #49 on: August 23, 2020, 07:35:02 pm »
A simple example of everyday things with relativistic features.
Linear-accelerator x-ray sources (used for radiography and radiotherapy) achieve electron kinetic energies from 2 MeV up to over 20 MeV.  The rest mass is 0.511 MeV.

But the electronic equipment themselves are not traveling.  So we need not deal with the relativistic effects of electronic.  The radiography detecting/capturing part of it will need to think about the relativistic effects to the extend necessary.

Is it presence/absence or does the gradation of energy level matters? 
 


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