Ask any question you want about Physics

a reply to: joelr

ImaFungi


How are two bar magnets forced to combine without touching?
"Wave functions being smeared?"

Meaningless.

"Probability adding and squaring?"

Meaningless.


"The fact that the uncertainty principle allows a virtual photon to produce a momentum that acts like an attractive force or a repulsive one."

Meaningless.


Your interpretation of reality, is a magicians fiction.

Uncertainty principle is not a description of reality!!!!!

Uncertainty principle is a description of HUMANS ability to measure reality!!!!!

If you do not get the difference, intelligence ought not speak to you.


Stuff exists in reality, stuff moves in reality. The concept of probability has nothing to do with bar magnets and their ability to attract. There is 100 percent probability I can move 2 bar magnets closer together if I want. There is a 0 percent probability I can move 2 bar magnets closer together if I do not want to; probability explains nothing here.

Wave function smearing; maybe....maybe, if that is a fancy way to refer to "things interacting with things"; but you are still failing to explain how. You are creating magic tricks because you have not yet grasped the true physics. You do not know what the material of the bar magnets are doing to the material which surrounds them, to cause them to combine. You do not know. You do not understand. You do not comprehend.

originally posted by: ImaFungi
a reply to: Arbitrageur

How do the iron fillings, and your comprehension of what a field is and how it works, tell you how 2 separate bar magnet objects, at distance A are not forced to combine, but at distance B are forced to combine?

I can't give you any better answer about ontology than I already did, but I will repeat this notion about force disappearing at a greater distance isn't really true. The magnetic field strength decreases with distance to the third power while the force between two magnets decreases with the distance to the fourth power so both fall off rapidly, but that doesn't means they go to zero exactly. If it takes 100 times the age of the universe for the amount of movement to become measurable by our instruments, I wouldn't argue with either the person who says that's zero nor the person who says that isn't zero because either argument can be supported.

Virtual particle theory and field theory, is some idea and attempt as to explain; What exists besides the bar magnets that forces them together?

Do the bar magnets have little invisible arms, which when brought close enough, can reach and grab onto the other bar magnet, and pull themselves together?

There must exist something, which surrounds the bar magnets, which the bar magnets interact with, which the result of that interaction, is the forcing of the bar magnets to combine.

I was going to say your guess is as good as mine, until I saw your comment about the little invisible arms...so maybe it's not.

I doubt that's it, and I don't know what the fields are "made of", but there has to be a reason our field based models make such accurate predictions, meaning I suspect rather than little arms there is probably some resemblance between the fields we model, and how nature actually works, and while that's only a guess, I think it's better than the "little invisible arms" guess. If you can picture invisible arms, why can't you picture invisible fields?

originally posted by: ImaFungi
a reply to: joelr

ImaFungi


How are two bar magnets forced to combine without touching?
"Wave functions being smeared?"

Meaningless.

"Probability adding and squaring?"

Meaningless.


"The fact that the uncertainty principle allows a virtual photon to produce a momentum that acts like an attractive force or a repulsive one."

Meaningless.

Rules of classical reality at the quantum realm:

Meaningless.

Your interpretation of reality, is a magicians fiction.

My interpretation? Are you a time traveller from 1800? It's not a magicians fiction it's a physicists fiction.

Uncertainty principle is not a description of reality!!!!!

Uncertainty principle is a description of HUMANS ability to measure reality!!!!!

If you do not get the difference, intelligence ought not speak to you.

The Uncertainty principle is a mathematical description of reality. Just like Ad Hom is a description of your ability to measure reality.

Wait, did you just say you wanted a non-human way to describe reality?

Stuff exists in reality, stuff moves in reality. The concept of probability has nothing to do with bar magnets and their ability to attract. There is 100 percent probability I can move 2 bar magnets closer together if I want. There is a 0 percent probability I can move 2 bar magnets closer together if I do not want to; probability explains nothing here.

It explains nothing, except what will probably happen. That is the only way it can be measured. The probability has nothing to do with human action, we're talking about what's happening at the subatomic level when they come close. You are mixing up 2 separate things.

Wave function smearing; maybe....maybe, if that is a fancy way to refer to "things interacting with things"; but you are still failing to explain how. You are creating magic tricks because you have not yet grasped the true physics. You do not know what the material of the bar magnets are doing to the material which surrounds them, to cause them to combine. You do not know. You do not understand. You do not comprehend.

Generally one synonym for "not know" is enough.

There is no deeper explanation right now. I thought you would have grasped quantum reality by now anyways?

A level exists beyond mass and energy that is just information or math. Probability math and such. Yes it's weird.
But since you want to make certain judgments, coming full force against it and then insulting people who explain it to you is high level ignorance and it speaks poorly of your intelligence.

a reply to: joelr

I know everything you know about theoretical fundamental physics, but more. I have all your understandings and perceptions of models and reality in my head, but the more intelligent progression of my thought, has resulted in viewing such stances as far from accurate/complete comprehensions of actual reality.

Google maps (not photo satellite view) is a model of reality, it may help us use and know reality, but there is a lot of information missing from it. I am interested in the existence of human ignorance, I am interested in the existence of human knowledge, and the relationship between the two, and how to diminish the former and advance the latter.

Me asking the questions I have been so clearly asking, and you pointing to the maps which I am well aware of, is not attempting to answer the question. There is no explanation as to how, 2 bar magnets are brought together.

Objects. Movement. How.

Bar magnets. At a distance without their bodies touching (with no arms to grab) are forced to combine. How, The electrons bump into particles that are non existent, and the non existent particles head to the back of the magnets and push the magnets together.


The only way an object can move is if something moves it. What is the something that moves the magnets together? What are all the somethings involved. The atoms of the magnet, the electrons. The intrinsic movement of the electrons. The invisible material which surrounds the magnets. The way the electrons interact with the invisible material that surrounds the magnets; causes the magnets to be forced together. What is the type of way, the electrons can interact with the invisible material that surrounds the magnets (and is inside the magnets apparently), so that the magnets are forced to combine? What type of physical motion, and physical reaction would cause such a result, as the forcing of two separate objects to combine without the objects grabbing onto one another and pulling one another closer? Einstein got gravity, who will get EM?

a reply to: Arbitrageur

Because I have not seen it expressed how the fields mechanically move bar magnets towards one another.

There was the problem with gravity, spooky action at a distance; Einstein said, there is probably invisible material in between earth and the moon, and earth and the moon cause the invisible material to warp in such a way that it is easier for the moon to continually approach the earth rather than anything else.

With complete ignorance, holding two bar magnets at a distance, and slowly bringing them together, there appears to be a similar problem, the magnets, spookily experience force at a distance. How to eliminate the magic/spooky and replace with mechanical physical understanding?

No one has been able to express the general physical mechanical principle as to how the interaction of the magnets parts with the 'field' surrounding it, forces the magnets together.

Virtual particles is bad enough, but then to say once the virtual particles are interacted with, they possess magical powers is enough to make Einstein warp in his grave.

We read in our textbooks that gravity is not really a 'force' but a shortest path geodesic, and a feature of, or distortion of space-time, and it's this which seems to 'bend' photons, mass-less wave-particles passing near massive objects, creating gravitational lensing.

Why, then, is there a search for (indirect) evidence of 'gravitons', as though there is a particle mediating this fundamental force...which is not a force?

Another question I have is why do most physics equations in books and in Wiki pages fail to have a 'key', denoting what the greek letters or constants are, in a table form. When we do physics problems and set up an equation, we are required to make such a table. Without it, various greek letters which have different meanings, or look almost identical to an italicized alphabetic character, most notably v and 'nu', or 'w' and a small Omega, are easily confused.

It would be nice to see textbook authors start doing this, since all students are required to do it:

Psi | Psi (character) | wave-function........|
versus:
Psi | Psi (character) | psion...................|
versus:
Psi | Psi (character) | polygamma function |

...since often the same character is used repeatedly but for different functions. If anything would help the 'student' it would be to include such a table.

It just seems careless, lazy and designed to be exclusionary of people who don't already -know- what it is. If physicists will recall, Feynman said that if you can't explain a physics concept so your grandmother can understand it you don't really know what it means. In fact, we see YT authors like minutephysics can do it, we see that lecturers like Professor Wolfson can do it.

Am I wrong to conclude that this is laziness on the part of book authors, or do they have some lame 'excuse', like 'it takes up too much space'?

TIA

originally posted by: Maverick7
We read in our textbooks that gravity is not really a 'force' but a shortest path geodesic, and a feature of, or distortion of space-time, and it's this which seems to 'bend' photons, mass-less wave-particles passing near massive objects, creating gravitational lensing.

Why, then, is there a search for (indirect) evidence of 'gravitons', as though there is a particle mediating this fundamental force...which is not a force?

Another question I have is why do most physics equations in books and in Wiki pages fail to have a 'key', denoting what the greek letters or constants are, in a table form. When we do physics problems and set up an equation, we are required to make such a table. Without it, various greek letters which have different meanings, or look almost identical to an italicized alphabetic character, most notably v and 'nu', or 'w' and a small Omega, are easily confused.

It would be nice to see textbook authors start doing this, since all students are required to do it:

Psi | Psi (character) | wave-function........|
versus:
Psi | Psi (character) | psion...................|
versus:
Psi | Psi (character) | polygamma function |

...since often the same character is used repeatedly but for different functions. If anything would help the 'student' it would be to include such a table.

It just seems careless, lazy and designed to be exclusionary of people who don't already -know- what it is. If physicists will recall, Feynman said that if you can't explain a physics concept so your grandmother can understand it you don't really know what it means. In fact, we see YT authors like minutephysics can do it, we see that lecturers like Professor Wolfson can do it.

Am I wrong to conclude that this is laziness on the part of book authors, or do they have some lame 'excuse', like 'it takes up too much space'?

TIA

Do you mean, why is there no universal key or symbol for all the measurements? That would be because memorizing all of the different symbols would become as difficult as remembering all of the different formulas they are connected to.

Also, the symbol used really doesn't matter they could be drawings of pokemon and still mean the same thing.

If you meant, why doesn't wikipedia provide a legend to understand what all these things are? IDK.

The symbols in textbooks are usually presented that way because that is how they were used in the proofs for the maths. To repeat a lot of these symbols repeat because in math a symbol is just a symbol and reusing the same symbol for a bunch of random stuff reinforces that and wears away at the idea of the squigglies on the page being anything more than an idea or concept.



Gravity.

They want to find some agent which would generate a field. I have seen people describe the "bending" as a density (but with all the other dimensions involved it doesn't really work) where large masses will cause a particle's path to curve similar to light passing through a lens.

You can't just say that something which is within space-time causes the space's 'shape' (or gradient) to change with no source or mechanism.

Also, a lot of physics uses set theory where the behaviour of interacting particles behaves the same as other interactions and so one can start "filling in the blanks" with particles they think would "fit" there and then they go off looking for them.

See quarks.
quark

The quark model was independently proposed by physicists Murray Gell-Mann and George Zweig in 1964.[5] Quarks were introduced as parts of an ordering scheme for hadrons, and there was little evidence for their physical existence until deep inelastic scattering experiments at the Stanford Linear Accelerator Center in 1968.[6][7] Accelerator experiments have provided evidence for all six flavors. The top quark was the last to be discovered at Fermilab in 1995.[5]

Basically the particles meet the reqs to be classified as a group so they have an identity element (add or multiply by another element and you always get that element), an inverse (anti-particles which will result in the identity element when multiplied/add/whatever by another element) and their relation is associative (to a degree order doesn't matter).

Just about all of observed physics fits the definition of a 'group' and so many physicists utilize group theory to search for phenomena. In addition just about all phenomena so far have had a particle/wave/field which explains them so it makes sense to continue that search for gravity.

-FBB

originally posted by: joelr


Yup.

Charge are the short range forces, similar to gravity except some repel rather than attract. The forces are electrical.
So the difference is the way each force effects the EM field. Or the way each one produces disturbances or our famous "virtual particles".

You would think virtual particles coming from one source and hitting another would cause repulsion but sometimes it adds up to attraction. So one force or charge ends up creating virtual particles that (in conjunction with an opposite charge creating it's own VP) causes an attraction.

The force split in two because nature is all about symmetry. That's a big thing worth reading about.

There must be an explanation somewhere about why some VP cause attraction, I don't remember the exact explanation.

As I understand it (we need Eros for confirmation), the notion of "virtual particles" comes about when you try to do many computations in quantum field theory, and you need to make a "perturbative expansion".

In principle, Nature solves the true underlying field equations in full nonlinear form. Which humans approximate up to a certain order of expansion (think of approximating a function by a series expansion in some region around a known value).

In this expansion there are terms which are identified as 'particles' by their mathematical structure and the connection to physical experiment. The real ones were identified, and then there are other terms, in the math which look like real particles (but aren't exactly), and these are called "virtual particles".

Down at the core, there is the underlying field theory which is the TRVTH as far as we know it. Then there are approximations so primates can connect to primate experimental results.

Analogy: to do Maxwellian classical electrodynamics, you don't need virtual particles. You just solve the underlying partial differential equations. But when you do it on a computer, you have to, in practice, make some grid of 'finite elements' and patches of 'fields'. These are the expansion functions, in a sense, of a practical electromagnetic simulation. They aren't the underlying truth, they are the computational convenience.

In a rough analogy, these are equivalent to real and virtual particles. In electromagnetic interactions, real particles (photons) correspond to radiation which can transmit energy & momentum out to far distances. The virtual particles are the expansion representation for non-radiative (near field, in the classical sense) electromagnetic forces like induction, etc.

originally posted by: Maverick7

Am I wrong to conclude that this is laziness on the part of book authors, or do they have some lame 'excuse', like 'it takes up too much space'?

Yeah, it's just lazy and it sucks.

When I read applied math/machine learning papers, I am enormously relieved and grateful when the authors provide a table with notation and explanation, and especially when they actually give the dimensions of every vector and matrix. As three different papers on the same subject which even reference each other often may have different notation for the same damn thing. Often there gets to be 'camps' of internally common but externally incompatible notation---the people who started out working on version A do it one way, and people who follow the results which started from notation B do it another way.

originally posted by: Maverick7
Why, then, is there a search for (indirect) evidence of 'gravitons', as though there is a particle mediating this fundamental force...which is not a force?

Because we don't have all the answers and we're still searching for them.

Where relativity theory produces singularities such as those in black holes, theoretical predictions such as infinite density are usually not considered tenable, hence the search for a better model which will produce a tenable solution to this problem, and perhaps also for the big bang "singularity".

originally posted by: Maverick7

Am I wrong to conclude that this is laziness on the part of book authors, or do they have some lame 'excuse', like 'it takes up too much space'?

originally posted by: FriedBabelBroccoli
If you meant, why doesn't wikipedia provide a legend to understand what all these things are? IDK.

originally posted by: mbkennel
Yeah, it's just lazy and it sucks.

When I read applied math/machine learning papers, I am enormously relieved and grateful when the authors provide a table with notation and explanation...

I agree use of notation without explanation is a problem in some papers.

However I can't recall cases in textbooks where symbols were introduced without defining them. Wikipedia does have a key of sorts:

Greek letters used in mathematics, science, and engineering

There's also this key, which is both entertaining and slightly silly like the cat symbol for Schrodinger's cat, though some of the symbols are serious.

My gripe is somewhat different, and it's not that symbols aren't defined in textbooks since I find they usually are, it's that sometimes there are different symbols used for the same thing.

For example E=hv and E=hf is the same formula for photon energy, where either v or f can mean frequency, with v in this case being the Greek letter "Nu". Why can't we just pick one?

I can't complain too much about the same symbol being used more than once for different things since there are more terms to define than there are letters, Greek or English. There are enough Chinese symbols, but I'm glad we didn't go there.

a reply to: Arbitrageur

Thanks for the quick answers. I suppose what I'm asking about gravity being a shortest path through the geodesic and gravity is not a force vs 'looking for gravitons and gravity waves' is that when ever a 'physics-spokesperson' says either one they say it as though it's unequivocal and as a physics student doing ToR in Modern Physics, it's confusing.

In fact I've seen two different ways of explaining why a photon, which is a massless particle is affected by a large mass. One uses 'the geodesic' and the other uses a quantum mechanical version of the force of gravity. Still another said it was 'Energy' not 'mass'. And it's as if each person explaining it their way doesn't know the other explanations exist and they're Physicists!

My modern physics instructor doesn't seem to know that there is a way to explain almost all of physics without using a big bunch of math. In fact he doesn't really teach 'physics', he just teaches Greek...looking at what he writes on the board. He is almost devoid of the ability to explain anything on physics without doing differential or integral calculus, and the whole class is missing the forest for that math tree. I asked one advanced student why there was Planck's Constant in almost every equation and when I said 'well it's related to 'one quanta' of the wave form' and he looked at me like I was from Mars!

THAT is something which should be fundamental and that every physics student should be able to know on an intuitive level by the time they are halfway through a level 200 course...but it's not.

I don't think there's a student or professor in the whole department who can actually explain 'angular momentum' the way 'minutephysics' does on YT.

In fact MY professor didn't know that a proton had a quark makeup of uud. He guessed that the number of Earths which would fit inside the sun was 3x10e3, and it's actually 1.3x10e6 and I knew that just as a hobbyist of astronomy.

He didn't know (denied) that GPS systems are affected by relativistic effects, and said a quark was not an elementary particle when we were making a list of them, including electrons, and neutrinos, but not, obviously protons and neutrons.

So I'm wondering if modern physics PhDs are just phoning it in or if they really are that myopic.

As to labeling the equations, I'm saying that EVERY TIME they 'drop' a NEW equation into the text, it should have a little embedded 'key'. That key should include the basics, JUST like they do (though not always) in the "Big Dummy" and "Complete Idiot" books, or just like they require when you turn in a homework assignment.

In fact, they don't even always label their units, as though it's OH SO EXHAUSTING to do that. But I suspect it's to keep their little group 'elite'. Why? Because almost all physicists suffer from a type of hubris. If you're not a Feynman, Dirac, Bohr, Einstein, and you don't have a Nobel then all you have to make you feel special or elite is your 'magical knowledge'.

And since it's publish or perish, sometimes I suspect they make stuff up just to try to get funding...iow, make it seem more difficult than it is.

There are a whole lot of physicists who are PhDs who really can't teach and know it, don't have any original ideas, and don't want to swell their ranks too easily. Even worse, I suspect there are those who know there's an easier way to teach physics, but they don't making you learn and do complex math, like 'integration in parts' just to be allowed to sit at the cool kids table.

Don't the physicist PhDs know there are guys out there like Wolfson (Great Courses) and Minutephysics who ARE teaching physics in a way that you can grasp it?

I think all physics instructors at the beginning of the class in all courses (outside of MIT or the hot physics universities) should ask each class 'do you want me to teach this class for 'teachers', or for non-math majors, or for PhD candidates, because in reality it's knowledge that's accessible to anyone of those groups', and then do it.

Physics is so 'hard' that it jumps the paradigm which is normally used for 'History or Biology Majors' which is learn taxonomy and regurgitate dates and names and labels, and the Instructors should really try to make sure that when every student completes his class they UNDERSTAND it at an intellectual and an intuitive level. Otherwise we're turning out a bunch of Physics-PhD-Morons and not finding or creating future Feynmans. And by understand I don't mean spoon-fed.

Instead of making us buy 20 year old books without 'labels and keys' why not assign 'Quantum Mechanics for Dummies', or "Complete Idiot's Guide to Theory of Relativity' by George Musser', both great books? It's because they are embarrassed to admit that current physics authors are incompetent at writing physics books. Either incompetent or lazy.

/rant. LOL

originally posted by: Maverick7
a reply to: Arbitrageur

Thanks for the quick answers. I suppose what I'm asking about gravity being a shortest path through the geodesic and gravity is not a force vs 'looking for gravitons and gravity waves' is that when ever a 'physics-spokesperson' says either one they say it as though it's unequivocal and as a physics student doing ToR in Modern Physics, it's confusing.

I don't think anybody should be teaching gravitons as more valid than relativity since gravity isn't even part of the standard model of particle physics, nor are gravitons, though they are part of an extended version of the model which has some difficult theoretical problems at high energies. I sort of agree with the following assessment of the two approaches, except for the fact it initially lends more credence to gravitons until it later explains the problem with this approach. The problem with the analogy to electromagnetism is, not only can we detect photons, but also quantum theory works with electromagnetism while it doesn't yet work with gravity at high energies:

Is gravity the exchange of gravitons, or the curvature of space-time?

Theorists believe that both of these descriptions are valid, in much the same way that we can think of the force of electromagnetism as being either the product of a continuous field, or the exchange of numerous force-carrying particles called photons. For certain 'classical' calculations, the description of electromagnetism as a field is more workable than its 'quantum' description, and vice versa. The problem is that, although physicists have a workable theory of gravity that involves the gravitational field, and gravitational forces as a curvature of space-time, there is no currently believable quantum theory of gravity involving 'gravitons'. We do not even know, a priori, whether there are such things as gravitons even though we have isolated the particles responsible for the other three forces in nature.

In fact I've seen two different ways of explaining why a photon, which is a massless particle is affected by a large mass. One uses 'the geodesic' and the other uses a quantum mechanical version of the force of gravity. Still another said it was 'Energy' not 'mass'.

I made a thread related to that last point. It's really the amount of energy included in both mass and momentum terms but most people have learned the simplified version of the equation as E=mc²

Is E=mc² right or wrong?
By the way I found a lot of physics was like that where you learn a simplified concept like E=mc², then later when you get into more depth, you learn the simplified concept was wrong or at least not exactly right in all cases. You may learn about the Hubble constant, then later find out it's not really a constant, especially at large distances or "lookback times", and there are plenty more cases like that.

I don't think there's a student or professor in the whole department who can actually explain 'angular momentum' the way 'minutephysics' does on YT.

Sorry to hear about your bad experience. I had my share of incompetent teachers before entering university, but I can't think of a single professor I had who wasn't competent. The closest to an exception I can recall is a brilliant man was teaching electromagnetism and he had such a thick accent that nobody could understand what he was saying, so only students who could read and understand the text on their own survived that course, of which I was one as I didn't have as much problem reading the material and teaching myself. I remember the curriculum administrators giving us an orientation saying half of us weren't going to survive the next two years, and then wondering if that EM course "taught" by a guy nobody could understand was part of the "weeding out" process they talked about. I also remember some people saying if you couldn't teach yourself from the texts the parts of physics the professors didn't teach well, you'd never make it in physics. Well I suspect that EM professor was a great researcher, but he wasn't a great teacher and I suspect he wouldn't have been even if he had spoken perfect English.

He didn't know (denied) that GPS systems are affected by relativistic effects, and said a quark was not an elementary particle when we were making a list of them

that's shocking, so what did he think quarks were composed of?

As to labeling the equations, I'm saying that EVERY TIME they 'drop' a NEW equation into the text, it should have a little embedded 'key'.

That sounds a bit extreme to me. What if the terms was just defined 4 pages ago and they show some variations of the equation on the next 4 pages? You want them to repeat that definition on each one of those 4 pages? I sort of got used to thumbing back to the point where the term was introduced if I forgot what it meant. The problem I have with some scientific papers is they will sometimes use terms that aren't defined at all anywhere in the paper, but maybe only in some of the referenced papers. To me that's a bit much to find another paper to see the definition of a term they are using.

There are a whole lot of physicists who are PhDs who really can't teach and know it, don't have any original ideas, and don't want to swell their ranks too easily.

There might be some truth to that, since there's already a lot of competition for teaching positions, but you'd think that competition would allow the better teachers to get the teaching jobs. Then there's the "on-line revolution" where supposedly the best lectures are videotaped and can be played by anybody anywhere with a small device, where you can pause or rewind and replay to get something you missed or that didn't sink in the first time, etc.

Don't the physicist PhDs know there are guys out there like Wolfson (Great Courses) and Minutephysics who ARE teaching physics in a way that you can grasp it?

Sure I love the course by Wolfson, and minutephysics is great too, but they intentionally omit the hard math. While that's a good way to gain popularity and understand simple concepts, you need better math to solve more difficult problems and you won't get it from those.

Instead of making us buy 20 year old books without 'labels and keys' why not assign 'Quantum Mechanics for Dummies', or "Complete Idiot's Guide to Theory of Relativity' by George Musser', both great books? It's because they are embarrassed to admit that current physics authors are incompetent at writing physics books. Either incompetent or lazy.

Yes there is probably a gap because they've spent maybe 8 years using that symbol, so maybe it doesn't occur to them that a new student isn't going to remember what it meant 4 pages later when the re-use the same symbol they defined 4 pages ago. But still I think the textbook would be cluttered if they did re-define it every time they used it. I haven't read 'Quantum Mechanics for Dummies' to see how that handles the symbol definitions. I have "Physics for dummies" though I haven't read it, I just glanced through it and it doesn't seem very good, and it doesn't provide a key every time it uses a symbol. Again I think it would be really cluttered if it did.

a reply to: Arbitrageur

OK, except you missed when I said each time they drop a 'new' equation into the text...

IOW, I don't mind thumbing back and in fact I could make up my own tabbed spreadsheet or MS document with a page for each of these major equations. We also bought a big whiteboard and would use that and this box to 'memorize' these terms and keys.

What's daunting and wastes a HUGE amount of our time (I'm working with a partner/spouse), is paging through a large number of books and Wiki pages trying to find these terms one at a time for fairly extensive equations, especially Schrodinger's, and some other complicated field equations and vectors and even then a few times it was two days before one of us would come upon one of them that was particularly hard to find.

Now having said that, I'm fine with having a set of base knowledge such that we know trigonometry having taken it in school, and we took calculus and algebra, so we know how to rearrange terms and substitute values, and we recognize Boltzmann's constant, Avogadro's number, Planck's constant, (h-bar was new, but we memorized that quickly and realizing that h/2π = h-bar had to do with the wave function. So we're not complete newbs, or English majors trying to jump into Physics 200 level course. We know various math constants, e, i, ln() and soforth.

But the last University Science course we took was many, many years ago.

We jumped right into Phys level 200 because we had kept up an interest and since we were both professional scientists with a science degree and computer experts we coped better than some of the sophomore and juniors taking the course, and in fact we 'retirees' have the highest grades in the class where the average is about 80 we both have 92% over the course of five homework assignments and three labs and two exams, EVEN THOUGH, we were made to miss the first three classes by the admissions office, where they bizarrely charge us about $500 each, but want to be sure the regular credit students get first dibs (we're auditing but decided to do all the work after the second week).

Now we were able to turn in formatted MS documents with headers, footers, formulas and I even did an Excel spreadsheet which does in-cell calculations to show the progression and graph of General Relativity wrt time-dilation, mass increase and length compression and even graphed it out.

ANYWAY, we used the struggle to bring us up in a 'quantum leap' to well above what was expected, and enjoyed the challenge.

Again, I don't expect a key every time the same equation appears, just once in the whole book for each new equation or perhaps an addendum if new terms are introduced, just like it's required to do for each problem in our homework or lab or exam (the standard 'rubric'). I just wondered if the writers of the books took courses with the same requirements why do they allow themselves to skip and cut corners. Now I don't expect very basics like π = 3.14159, to be keyed, but yes anything that is unusual, new, has duplicates or look-alikes.

In fact if you just had an equation above that used 'v' for velocity but as an italics, then below it used a 'nu' you MUST note that in a little box, otherwise you lead even a bright student astray.
----

OK, now for a new easy question, what would you say was the list of elementary particles.
Leptons and antimatter particles among the fermions:
electron-neutrinos and their anti
muon-neutrinos and their anit
Tau-neutrinos (and their antiparticles)
electrons
quarks and anti-quarks

(perhaps gluons are virtual particles so they don't count, not is it proven that quarks are made up of preons).
...

Elementary bosons
photons
gluons
W - Z bosons
graviton (hypothetical)
Scalar bosons - Higgs

What else?



Thanks again for bearing with me and putting up with a rant...

originally posted by: Maverick7
OK, now for a new easy question, what would you say was the list of elementary particles.
....
graviton (hypothetical)

Yes the graviton is hypothetical and not part of the standard model, so it's not included in this popular graphic of elementary particles:

Standard model

Some particles have anti-particles, while some like the gluon and photon are their own anti-particles, but the gluon can have 8 different "colors" so if you're counting you have to decide what to count. If you count all the colors and anti-particles you should come up with 61 (not including the graviton).

A particle physicist told me this is the standard reference he uses, but it contains non-elementary particles too like bosons:

2015 Review of Particle Physics

originally posted by: ImaFungi
a reply to: joelr

I know everything you know about theoretical fundamental physics, but more. I have all your understandings and perceptions of models and reality in my head, but the more intelligent progression of my thought, has resulted in viewing such stances as far from accurate/complete comprehensions of actual reality.

I get that your are dazzled by your intellect and want to share your fascination. Repeatedly. I have no idea how smart you are, maybe you are really smart?
But I am sure you do not know much about theoretical fundamental physics. Which is fine. That's why we ask questions, to learn new things.

First of all, all physicists already know that our theories are far from accurate/complete comprehensions of actual reality. That's one reason I know you don't know physics. That's old news. There is a great video of Feynman explaining this back in the 70's.

But fluffing it off as magic suggests you have no idea how powerful and accurate the mathematics describes the reality at that level. There are unexplained phenomena related to the electron that these theories were able to explain that involve calculations out to the 8th decimal point.

If you ever bother to learn quantum mechanics from the beginning it will be easier for you to stop trying to common sense the quantum realm.

Comparing the wave function of a human to the wave function of photons (100% certainty that a human will bring 2 magnets together if they choose) is another indication you do not recognize the basic elements of QM.
The wf of a human is trillions of times smaller than the human itself. Quantum effects begin to be seen when the wave is larger than the actual object.
An entire magnet has trillions of probability waves so the end result is that it's going to act classical trillions^trillions of times.

And you have not answered my questions about which thing you disagree with.

Google maps (not photo satellite view) is a model of reality, it may help us use and know reality, but there is a lot of information missing from it. I am interested in the existence of human ignorance, I am interested in the existence of human knowledge, and the relationship between the two, and how to diminish the former and advance the latter.

That's a good thing to be interested in. There is clearly much we don't know.

Me asking the questions I have been so clearly asking, and you pointing to the maps which I am well aware of, is not attempting to answer the question. There is no explanation as to how, 2 bar magnets are brought together.

Objects. Movement. How.

There is no classical explanation. Now as to something like hidden variables in quantum mechanics, that has been largely ruled out. See Bell/hidden variables if you are unaware.

I feel you are not giving quantum mechanics a fair shot. You should study it and go from there. You are right about some of the problems it has but you may move past the idea that there should be a classical reality to the quantum realm when you understand scientists were pushing that idea since the beginning.

Bar magnets. At a distance without their bodies touching (with no arms to grab) are forced to combine. How, The electrons bump into particles that are non existent, and the non existent particles head to the back of the magnets and push the magnets together.

It's weird that pure probabilities exist at that level and mass does not. Like I said when the wave function of an object extends beyond the object, the object is smeared out into probabilities and uncertainty.
That explanation works really well.

The only way an object can move is if something moves it. What is the something that moves the magnets together? What are all the somethings involved. The atoms of the magnet, the electrons. The intrinsic movement of the electrons. The invisible material which surrounds the magnets. The way the electrons interact with the invisible material that surrounds the magnets; causes the magnets to be forced together. What is the type of way, the electrons can interact with the invisible material that surrounds the magnets (and is inside the magnets apparently), so that the magnets are forced to combine? What type of physical motion, and physical reaction would cause such a result, as the forcing of two separate objects to combine without the objects grabbing onto one another and pulling one another closer? Einstein got gravity, who will get EM?

But are they separate objects? It's a field theory so energy is already moving around as slight disturbances in the field. When there is enough energy to make a particle the particles are then acted on by these disturbances and there is your movement, attraction of repulsion.

Einstein didn't get gravity though? Not in the way you are asking about, a deep fundamental level. If gravitons are discovered then we might have the same virtual graviton type explanation as EM.
Beyond that who knows?

how does the SLAC Undulator work?

originally posted by: BASSPLYR
how does the SLAC Undulator work?

Magnets polarize the light (EM wave) so that it is in phase or phase shifted to the desired waveform.

-FBB

originally posted by: FriedBabelBroccoli
Magnets polarize the light (EM wave) so that it is in phase or phase shifted to the desired waveform.

-FBB

The description in this video seems quite a bit different from that, since the whole point is to produce short bursts of X-rays by undulating (wiggling) focused small bunches of electrons as they travel down the accelerator, unless you're talking about a different apparatus than this video:

X-ray Laser Animated Fly-through

www.youtube.com...

LCLS produces pulses of X-rays more than a billion times brighter than the most powerful existing sources, the so-called synchrotron sources which are also based on large electron accelerators.

The ultrafast X-ray pulses are used much like flashes from a high-speed strobe light, enabling scientists to take stop-motion pictures of atoms and molecules in motion, shedding light on the fundamental processes of chemistry, technology, and life itself.

They refer to the X-rays as "light" in the video, but to me light implies IR, UV or visible light and these X-rays have much higher energy than that so it's more clear to me to call them X-rays. That's what they are, right?

The only role that light seems to have is to generate the electrons, but it's the electrons that get accelerated in the accelerator and in the undulator. They don't accelerate light.

a reply to: greenreflections

Air, detector components, anything really

In vacuum your flight time would be dictated by the lifetime of the object + the lorentz factor

that said, if you are talking about very high energies, it doesn't matter too much as the objects will decay before leaving the interaction point by a significant amount, and all you will see are high energy jets

originally posted by: Arbitrageur

originally posted by: FriedBabelBroccoli
Magnets polarize the light (EM wave) so that it is in phase or phase shifted to the desired waveform.

-FBB

The description in this video seems quite a bit different from that, since the whole point is to produce short bursts of X-rays by undulating (wiggling) focused small bunches of electrons as they travel down the accelerator, unless you're talking about a different apparatus than this video:

X-ray Laser Animated Fly-through

www.youtube.com...

LCLS produces pulses of X-rays more than a billion times brighter than the most powerful existing sources, the so-called synchrotron sources which are also based on large electron accelerators.

The ultrafast X-ray pulses are used much like flashes from a high-speed strobe light, enabling scientists to take stop-motion pictures of atoms and molecules in motion, shedding light on the fundamental processes of chemistry, technology, and life itself.

They refer to the X-rays as "light" in the video, but to me light implies IR, UV or visible light and these X-rays have much higher energy than that so it's more clear to me to call them X-rays. That's what they are, right?

The only role that light seems to have is to generate the electrons, but it's the electrons that get accelerated in the accelerator and in the undulator. They don't accelerate light.

They have polarize the x-rays and use phase shifting for constructive interference.

At least in the labs I have been associated with we usually just use magnets or a mesh for this because it is fairly simply and relatively cheap.

The constructive interference leads to an increased intensity that is directed, otherwise superposition reduces the intensity in the desired direction.


I also just skimmed some papers and was working on some projects so I might have misread so I will check back on it later this week.

-FBB