Why are physicists the electronics experts?

[TimFox]

The relativistic velocity of the electrons is important to the design of the accelerator.

[Berni]

GPS Satelites have to deal with the relativistic effects.

Firstly the atomic clocks up on the satellites run slightly fast due to being slightly out of earths gravity (also slightly slowed down due to going so fast, tho the effect is weaker so it looses out). But that is fixed by adjusting the trim on those clocks to match the ground clocks, not that it would matter since GPS would still work fine as long as all the clocks run slightly fast by the same amount.

The more observable effect of relativity is the fact that the GPS carrier signal varies by up to a few KHz due to the Doppler shift of the satellite moving towards or away. This relative frequency shift is measured by GPS receivers to get some extra information out of the signal on top of the usual CA code pseudorange measurement.

[Rick Law]

The relativistic velocity of the electrons is important to the design of the accelerator.

GPS Satelites have to deal with the relativistic effects.
...

Yeah, my initial reply there was poorly worded.  My point was, the electronics are not at relativistic speed, so the electronics themselves don't have to deal with the effect of traveling at that speed.

Neither the linear accelerator itself nor the detection system itself is traveling.  The xray (particle) is.  The accelerator of course is designed with that in mind so it knows where the particle is as it accelerates the particle.  But neither the accelerator nor detector themselves is traveling, the electronic components are stationary so they don't have to deal with relativistic effects on how the components work.

If the particle's energy level matters, then the particle's speed has to be factored in with energy calculation.  Other than that, the application is rather like a lux-meter, absorb photon which is actually traveling at light speed and tell you how bright it is at the point, but the electronics themselves doesn't need to deal with any relativistic effect regarding itself traveling at relativistic speed because it isn't.

GPS:   The electronics in the satellite are not traveling at relativistic speed, therefore the electronics doesn't have to deal with relativistic effect on its electronics due to traveling.  The electronics themselves will work as well stationary or moving.  However, the GPS application is one in timing, the timing calculation has to to deal with the time dilation.

[Buriedcode]

When I look up the answer to an electronics question online, it's often a physicist who is giving the answer.  Do they know more about electronics than someone who actually works with electronics?

Where exactly are you getting your "answer" from?  Online is a big place - with thousands willing to answer questions regardless of any experience or qualifications, so ultimately you have no real confidence in the accuracy of their answer.  Places like stackexchange and Quora are full of self-professed experts who can give wildly inaccurate answers with an air of arrogance - which really means nothing, they could be anyone.

It could be that the people who answer the most questions on the forums you ask, just so happen to be physicists who have retired, or you're asking the question on a forum/website that is frequented by physicists.  Also, the title of the thread implies that the answers you got are from physicists who call themselves experts in electronics.  Or did you just assume they were expects because they answered? It's another "lets post something controversial and see who bites" thread.

We've got three pages of replies, without a post from the OP.

[TimFox]

The electron velocity is relativistic;  x-ray photons, being massless, must travel at the speed of light.  When setting up the accelerating cavities and excitations, one uses the relativistic velocity of the electrons as they gain energy.
When I took freshman Electricity and Magnetism, we used a wonderful textbook by Purcell.  He introduced magnetic forces by showing that they resulted from relativistic effects on the motion of charged particles, even at the very low drift velocity of electrons in a conductor.  That textbook (which cost less than $10 back in the '60s) is stored now, but I found this (curmudgeonly) discussion of Purcell's demonstration online:
http://physics.weber.edu/schroeder/mrr/MRRtalk.html
One of his complaints is how much that book costs now.
There is Special Relativity in the real world;  General Relativity is less important to your day-to-day life.

[Rick Law]

...
There is Special Relativity in the real world;  General Relativity is less important to your day-to-day life.

We are on the same page.

Special relativity has not been the discussion here anyway.  Fast but sub-light speed is what we have been talking about, so only general relativity is applicable here.

I called it "a rounding error" in my original reply under discussion here, you call it "less important to your day-to-day life."  Not exact same wording, but in general agreement I would say.

I should however consider GPS further, but I wont.  That one really straddle the fence, but I gotta eat so I wont worry about GPS for the time being.

[Berni]

You are not going to see relativistic effects within the same blob of circuitry, no matter how fast it goes, that's sort of the point behind it that you can't detect your own absolute speed, only relative speed to something else.

GPS is one of the rare cases where you can see it happen because the fast moving satellite and slow moving receiver are communicating over a radio link. So even if they are not one physically connected circuit they are exchanging information. But even then all of this is only easily noticeable because the satellites have incredibly precise clocks in order to make such tiny timing differences show up (rather than getting lost under the clocks own natural drift)

If you wanted to see relativity within the same circuit then i suppose the best bet is to build a ring laser gyroscope using coax cable instead of fiber optics. Send a high frequency sine wave in a clockwise and a counterclockwise spool of coax and compare the timing while rotating the whole thing. Since its going along with the rotation and counter to the rotation you get a phase shift as if one of the cables got longer during rotation. Tho the effect is again really really tiny so they prefer using fiberoptics for actual gyros (fiber is tiny and light has a short wavelength).

[paulca]

Electronic Engineering.

Engineering = application of science to solve problems.

The physicists work out how things work, present that research to engineering who work out how to solve problems with it.

[FransW]

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.

There is a vast territory for a talented physicist to use his/hers abilities.
Not the physicists that copy, publish and summarise other physicists work.
The simplicity of the "Standard Model", "Big Bang" and "Dark Matter/Energy' always make
me feel uncomfortable.
The lack of abstraction is too strong. There is so much absent.
It is like the "-2x𝞼" from the median of the IQ-Gauss curve applied to the "highly gifted".

[TimFox]

...
There is Special Relativity in the real world;  General Relativity is less important to your day-to-day life.

We are on the same page.

Special relativity has not been the discussion here anyway.  Fast but sub-light speed is what we have been talking about, so only general relativity is applicable here.

I called it "a rounding error" in my original reply under discussion here, you call it "less important to your day-to-day life."  Not exact same wording, but in general agreement I would say.

I should however consider GPS further, but I wont.  That one really straddle the fence, but I gotta eat so I wont worry about GPS for the time being.

To clarify the discussion:  Special Relativity (the first of Einstein's theories) deals with "inertial" reference frames in uniform motion (constant velocity), and includes the dilation of time with velocity and the speed of light as a maximum.  Here, he introduced the Lorentz factor
 (1 - v²/c²)^-1/2  .
General Relativity (the later theory) deals with reference frames in non-uniform motion, including acceleration and gravitation.  Motion around a circular orbit, for example, involves acceleration.  As an undergraduate, one exam question involved a sealed boxcar with a helium balloon tethered to the floor.  When the train accelerates to the east, what direction does the balloon move (with no drafts from the outside air)?  The simplest answer is to invoke General Relativity.  (A gravitational field is equivalent to an accelerated reference frame.)

[Rick Law]

You are not going to see relativistic effects within the same blob of circuitry, no matter how fast it goes, that's sort of the point behind it that you can't detect your own absolute speed, only relative speed to something else.

GPS is one of the rare cases where you can see it happen because the fast moving satellite and slow moving receiver are communicating over a radio link. So even if they are not one physically connected circuit they are exchanging information. But even then all of this is only easily noticeable because the satellites have incredibly precise clocks in order to make such tiny timing differences show up (rather than getting lost under the clocks own natural drift)

If you wanted to see relativity within the same circuit then i suppose the best bet is to build a ring laser gyroscope using coax cable instead of fiber optics. Send a high frequency sine wave in a clockwise and a counterclockwise spool of coax and compare the timing while rotating the whole thing. Since its going along with the rotation and counter to the rotation you get a phase shift as if one of the cables got longer during rotation. Tho the effect is again really really tiny so they prefer using fiberoptics for actual gyros (fiber is tiny and light has a short wavelength).

Thank you!  That was the whole point I was making...  You wont see it within the same circuit. Anything/anyone traveling with the circuit wont see it.  And I pointed out the issues when sending signals off to someone not moving with the circuit.

That whole paragraph beginning with "Standard theory today is: if you are traveling with an electrical system..." seem to have been ignored.  Instead, the focus of the discussion was on the side comment paragraph that we really hasn't made things that go that fast.

I knew I could have worded it better in that initial reply, but at least you got what I was saying.  I'm pleased with that.

[TimFox]

A reasonable description of the (relativistic) Sagnac effect in the fiber-optic gyroscope:
https://link.springer.com/chapter/10.1007/978-3-540-39490-7_3