AXensen

Now, the coulomb is a fixed amount of charge in terms of a certain number of electrons, and mu0 is what changes with improved measurements. The whole point is to choose which things to define and which things to measure based on which measurements are most precise to minimize how much our values change over time

So the definition of the coulomb was subject to change over time as measurements of this current, and the resulting charge, became more precise

you make it sound like this is a "bad" thing, but the whole point of the 2019 redefintion is that it's less bad than the previous definition. In the previous definition, mu0 had a fixed value, which meant that the ampere was "whatever amount of current exerts this particular force," and since the coulomb was 1 amp times one second, the coulomb was "whatever amount of charge is exchanged by the current which exerts a certain force".

You have correctly pointed out that mu0 used to have a definitional value, and now it has a measured value that can change with time. but do you understand that this will always be true for something in any system?

I've never heard of someone being anti-2019 SI unit redefinition.

@uhoh if the ball's radius is negiligible compared to the radius of the earth, and if the center of mass of the system is not significantly perturbed from the center of the earth, this is a duplicate. The earth's surface is not "slightly perturbed" away from being an equipotential. The reason for the oblateness is to ensure that the surface of the earth is an equipotential. The ball will not roll for the exact same reason as the oceans don't flow toward the poles. However, if we're considering a ball that is comparable in size to the earth, this question may have a nontrivial answer.

Another possible duplicate (referring to air instead of water unlike qmechanic's linked questions, and this time not closed as a duplicate) physics.stackexchange.com/q/761424

Physics stack exchange often uses the description "personal theory" as a euphemism, a reason to close questions without getting into arguments. This is not a theory. There are no coherent predictions, there is no understanding of well-established facts, it runs dramatically counter to essentially every piece of evidence ever produced. It is nonsense. Words strung together to form a make-believe version of things you have heard physicists say. You should not continue to pursue it. If you want to ask serious questions about how things work, please do so in a new question.

@JoshuaTalsma I have skimmed some of it. All of it is nonsense. Both your and chat GPT's statements. There is no serious application of any concepts of well established physics or astrophysics. I don't mean to be rude. This really is the only thing that can be accurately said about what you have produced here. I encourage you to learn physics, and not try to invent physics without understanding any of our current knowledge about the universe.

You want us to wade through "the beginning is rough" so that we can read chat GPT's new theories, when chat GPT has been proven countless time to output mindless nonsense about physics. All of this effort so that we can explain why something is wrong that wasn't even a coherent idea generated by an intelligent human. Seems like a waste of time to me.

@mikestone Say a gas in a container of volume V is suddenly exposed to a second chamber of volume V. The gas gains kinetic energy, which may initially be isentropic. But there's no way it remains isentropic in the long term. The only way I could think of is if it somehow is retained as waves ripping through the gas forever. But even in the absence of friction, over time from the complex shape of the container the waves will turn into just heat. I think this is why my link just says outright that free expansion of gasses is not reversible. They're thinking of the equilibria before vs after.

@mikestone I wasn't entirely sure there... but after some googling it seems the definition of free expansion in thermodynamics, especially WRT ideal gasses, conforms to my understanding. "The free expansion of a gas is an irreversible process" from: chem.libretexts.org/Bookshelves/…

It looks like there are a few misunderstandings. (1) It seems like you think the internal energy of a gas is constant when it adiabatically expands. This is just wrong. When a gas adiabatically expands internal energy of the gas turns into work. (2) It seems like you think "free expansion" can also be adiabatic. It's not entirely clear to me what free expansion means to you, but usually it is essentially the opposite of adiabatic. Gas is suddenly exposed to a region of lower pressure and allowed to expand into it, and the adiabatic equations do not apply.

A gravitational field does not define a frame of reference. Within our current understanding of gravity, this is nonsense. And surely even you can see that "frequency's configured alignment" is just nonsense. I really strongly encourage you to learn our current understanding of physics - rigorously and mathematically - before you continue trying to suggest new alternative theories. Physics needs creative minds, but it doesn't need creative minds who have zero physics education and think that their nonsensical combination of words is just as valid as mathematical ideas tested with experiments.

I'm trying to help you make your thoughts more concrete. If you want to question general relativity, you should learn it as a mathematical model, then formulate your own model, and compare the predictions made by each theory to see which is more accurate. This is meaningless word salad that sounds to you like things you see written about science. But here there isn't an underlying mathematical model that the words are describing. A clear example-"time difference equates to the speed/distance travelled"-a difference in time (s) cannot equal a speed (m/s) or distance (m).

instead of leanring the mathematical description of an antenna?

you think they should build an antenna and do some observations on it instead of what...

I'm not really seeing your vision of a new, better version of physics education

blue sky is an excellent example of something "basic" that a physics student unfortunately has to learn much later in life because the explanation from fundamental physics (in my sense of the word fundamental) is difficult

again. two senses of the word fundamental. you mean one, and typically I mean the other. neither sense is wrong

I want to give you credit though, I have theorists friends who can't explain why a rainbow appears through the edge of a piece of glass... and frankly that makes me lose respect for them and doubt the validity of their work. I think something along the lines of "if you have that poor physical intuition, it seems unlikely that you can correctly interpret the physical consequences of these advanced mathematical theories you're working on"

it kind of sounds like you're insisting "everybody needs to be interested in the aspects of physics that im interested in, and everybody who is interested in the beginning of hte universe is a moron because that's not what im interested in"

well the people who do physics majors don't want to build circuits, they want to contribute to fundamental physics. It sounds like maybe you want to throw fundamental physics in the trash but there are a lot of people who are interested in that and want to work on it

for example conductors are, I think, chapter 7 or so of Griffiths E+M

but explaining how you get from laplace's equation to the behavior of circuits is not that simple...

you can say "touch this wire to this thing" to anybody in the world at any age

I personally absolutely do see physics all around me. But I'm an experimental physicist. I acknowledge there are theorist professors who are pretty weak with "everyday physics" and might struggle to light the bulb... but I appreciate the time they've spent learning enough math to contribute to such a technically difficult field. They have a different skill-set than me

If you wanted to be an electrical engineer you would learn a lot earlier, because there's a functional description of circuits that ignores a lot of E+M justification for why circuits work like that that can be taught a lot sooner.

as for this light bulb business... I'm working on my phd in physics and I've been generally happy with the order in which things were taught. If you want to rework all of physics education to teach things in the order they were discovered be my guest and write that cirriculum. I was taught how circuits work pretty late in that process, because circuits are actually pretty hard to explain to a physicist.

NOBODY says einstein's field equations are the last word in the physics of gravity

I'm really not all that interested in the philosophy of science discussion about "what does it mean for something to cause something"... when I say "more fundamental" I mean "X can be derived as a limit of Y" and nothing else. And I'm pretty sure that's what most physicists mean.

galileos results can be derived from newton (and not vice versa). And newton's from einstein

and you can understand E+M without understanding circuits... because the E+M taught in a first semester course is actually a lot simpler and easier to understand than circuits

when we say "fundamental physics" we mean it in the latter sense.

I'm trying to make the point that there are two possible senses of the word "fundamental" or the phrase "more fundamental"... it can either be "this should be understood first for pedagogical purposes" or it can mean "this is the underlying reason that something happens"

I guess my point is... everybody who knows how the muon decays probably also knows laplace's equation (more "basic" in my terminology). Not everybody who knows how the muon decays knows which outlet hole is neutral. I don't consider that to be a great tragedy, and it doesn't make me question their ability to do physics research.

But I don't agree that it proves some grand failure of physics education... a physics major gets courses in physics... there isn't any course where they just teach you a bunch of basic common sense things about household appliances and simple technologies.

as for the light bulbs... I'm not really astonished. They weren't physcis majors but even if they were I wouldn't be all that surprised - most physics majors have one semester of circuits, which doesn't necessarily include household light bulbs.

If I wanted to be pedantically perfect I might say "more basic phenomena like the behavior of circuits can be derived (with great difficulty) from the the laws that govern high energy particle physics, but not vice versa" But this is the comment section to a question about limitations of synchrotrons... not really meant to be a philosophy of science discussion.

I'm not sure what the distinction is between "cause X" and "origin of X"

@JohnDoty I'm just trying to use commonly accepted terminology. Do you really think this comment section is the right place to debate this? In some sense "fundamental physics" is the perfect expression, because we understand these concepts to be the underlying cause of all other kinds of physics - still "fundamental", but in a different sense than you're using. Besides, I'm not sure which fundamentals exactly you think "we" aren't teaching. Every physics major's first course is basic Newtonian mechanics, then usually the second course is basic E+M. Nobody is teaching high energy physics first.

@JohnDoty I googled "what is fundamental physics" and the first page of links all gave definitions that are basically what I meant to describe, not what you're describing which I would call "basic or introductory physics." For example imperial.ac.uk/physics/research/themes/fundamental-physics

@JohnDoty Thanks for the comment. I have edited to include the isochronous cyclotron. And I suppose I meant high energy accelerators meant to discover new fundamental physics... indeed there are still cyclotrons all over the word that are used as injectors for synchrotrons, rare isotope production, biological and materials research, etc.

@JohnDoty You might be right. I'll have to think about this. I'll leave my comments up because I thing I might be right.

@JohnDoty the oversampled example is the situation I described in my comment. Two different measurements happening one after the other. Possibly with an additional caveat regarding the fact that many measurements on many particles can give a measurement precision on the distribution that is much better. I wasn't necessarily saying you were wrong, but your first sentence could really use some clarification that the two measurements at arbitrary precision do not happen simultaneously, and do not describe the state of the particle at any one time. Also not clear what report vs measure are here

@hyportnex I said "cannot simultaneously measure the position and momentum of a particle to any precision". I did not say "cannot simultaneously measure the position and momentum." Perhaps you thought I meant "to any precision whatsoever". I meant "cannot... to an arbitrarily high precision" (this answer seemed to imply that you could)

I feel this is confusingly phrased. One single detector cannot simultaneously measure the position and momentum of a particle to any precision. One detector could measure the position to a precision $\sigma_{x1}$, and then the momentum uncertainty becomes $\sigma_{p1}\geq \hbar/2\sigma_{x1}$. A second detector can measure the momentum to a higher precision than $\sigma_{p1}$ (call it $\sigma_{p2}$), then the particle will be more spread out than before ($\sigma_{x2}\geq \hbar/(2\sigma_{p2})>\sigma_{x1}$). There was no moment where the particle was in a state with $\sigma_x\sigma_p<\hbar/2$

Strong disagree with "sensitive to suggestions that physics isn't the way to understand the universe." Physics isn't a particular way for the universe to work. It's just the study of how the universe works. So the only way that physics wouldn't be the way to understand the universe is if the universe... doesn't work in any particular way. I in particular downvoted because this is a very often discussed topic in physics, and a google search would have given many of answers. If you still have questions after that, perhaps one could formulate a more specific question.

See the discussion in this question: physics.stackexchange.com/q/387

Nobody has done this. It's up to you to figure it out. You're also going to need a lot more knowledge than you can get from physics stack exchange. I'd recommend you start reading review papers to find out what essential parts are required and for which kind of Wakefield accelerators