Spin

[Mike Smith Cosmos]

Are we not arriving at the difficulty of facing the crossing over from classical to quantum as if it were a different realm and out of bounds apart from the few. Surely the whole universe "exists" from the smallest point to the whole shebang . All that changes are different rules or approaches as we move through the scales. Maths does have a habit of becoming a barrier for many who approach this crossover territory. Surely it relies on those who have crossed over to make the understanding of the quantum region accessible. Otherwise we are surely in danger of sounding like priests who tell the lay people of old that the "deeper things" are our province only .

 

Roger Penrose one of the great current gurus of maths, gave a lecture to one of the American universities ( Princetown I think ) where he described it as classical above the waterline and quantum below the waterline. Different medium, different rules , different experience but still approachable none the less.

 

I appreciate the maths in whatever form will be a new pair of underwater goggles. But you that have gone there , tell us what you see !

Edited February 26, 2011 by Mike Smith Cosmos

[ajb]

But you that have gone there , tell us what you see !

 

Casimir operators of the Lie algebra of the Lorentz group...

[Mike Smith Cosmos]

AJB

 

Have you a book or two ( name and author) that you can give me that I can order up , or was that the one you referred to a few days ago .

 

And can you possibly tell me how to attatch my comments to other peoples, as I seem to be making statements in isolation. ?

[ajb]

Have you a book or two ( name and author) that you can give me that I can order up , or was that the one you referred to a few days ago.

 

Any book on QFT will say something about this.

 

I recommend Ryder as he does devote a few pages to this. Kaku 's book on QFT also talks about this, but I think it is much more hurried.

 

The point to my quite flippant reply is that one will have to look into the mathematics in order to get a real understanding. Analogies and metaphors are great and very useful, but no replacement for mathematics.

 

And can you possibly tell me how to attatch my comments to other peoples, as I seem to be making statements in isolation. ?

 

Use the reply button.

[Mike Smith Cosmos]

Thanks ! But there must be some overlay to the maths, unless you are saying like Mr Tegg that Maths is the bedrock rather than human constructs.

[ajb]

But there must be some overlay to the maths, unless you are saying like Mr Tegg that Maths is the bedrock rather than human constructs.

 

The overlay is really in the physical interpretation of the mathematics. Spin is due to a rotation, but it is not as simple as rotation of a particle about some axis. This "extra rotation" manifests itself in nature as the intrinsic spin of a particle.

 

More generally, you are asking if mathematics is invented or discovered? This has been discussed on these forums before, have a search. The question is rather philosophical in nature. I doubt it would shed much light on the question of spin.

Edited February 26, 2011 by ajb

[swansont]

So if I take one electron and one positron and put them together, they will generate two low energy gamma rays, and according to theoretical physics, this is happening everywhere all the time. But, whats the frequency of this happening? If my entire room was filled with these gamma-rays forming from matter-anti matter pairs, why wouldn't I get some kind of cancer easily? One of those low energy gamma rays would certainly be enough to accidentally ionize something.

 

Sometimes you get three photons. It depends on (wait for it…) the spin orientation of the electrons. If the spins are anti-aligned, there's no net angular momentum, so you get two anti-aligned photons (technically, any even number, but by far the most likely outcome is two). But if the spins are aligned, the total spin is 1, and you can't get that with two photons — you have to have three (or any larger odd number). A single photon conserves angular momentum, but is not allowed by conservation of linear momentum.

 

And since this phenomena produces energy which doesn't disappear, doesn't that violate the conservation of matter and energy? I have two particles which are creating out of the nothingness of space, but then they annihilate each other and they get converted into energy which then goes about the universe...that doesn't seem right.

 

Matter isn't a conserved quantity. Pair annihilation converts mass into another form of energy, because in the rest frame E=mc^2

[lemur]

I don't know what you mean by objects being made of particle-fields.

Protons create a positively charged electrostatic field around the nucleus. Electrons have negative charge and move around the nucleus, attracted by it while repelling each other. The interaction between these particle fields account for the force-resistance observed in physical objects, as far as I can model it based on what I've learned.

 

 

The electron may be a physical object, depending on your interpretation, but it's still not spinning.

Then how does its magnetic force emerge from its electric charge? I thought magnetic fields emerge from moving electric charges (current) and this occurred at the atomic level because the atomic electrons are moving.

 

The point of quantum mechanics is that the electron, for most of the time, has no defined location. It is merely somewhere, with the probability of finding it at a given point given by the square of the wavefunction. It's not that it's a small particle that pops from one place to the next -- it has no single location.

This is where it seems like QM starts confounding empirical observation and modeling. I understand that due to the uncertainty principle, it is impossible to observe the speed and location of an electron simultaneously, which impairs the possibility of inductive modeling. So if inductive modeling is obstructed by constraints on empirical observation, why wouldn't you just focus on deductive modeling?

 

 

[Mike Smith Cosmos]

The overlay is really in the physical interpretation of the mathematics. Spin is due to a rotation, but it is not as simple as rotation of a particle about some axis. This "extra rotation" manifests itself in nature as the intrinsic spin of a particle.

 

More generally, you are asking if mathematics is invented or discovered? This has been discussed on these forums before, have a search. The question is rather philosophical in nature. I doubt it would shed much light on the question of spin.

 

Yes I like that expression " the physical interpretation of the mathematics. Yes by all means we need to venture into the depths to gain an quantitative or predictive view but in the end the maths has to provide some mechanism for physical reality.

 

WHAT REALLY is going on at the Electron level. Be it that you chaps know the deep maths but what is the physical interpretation of the maths , and don't just say angular momentum and spin , because there is charge involved , there is some mass, there are some abilities for movement, and swapping with photons. Draw me a mental picture of whats going on down there. Wolfgang Paul and Hans Dehmelt Nobel prize winners 1989( not Pauli ) trapped an electron in a TRAP, it didn't like it. They kept it trapped for an hour then a few days , a month, finally a year, then it got out. May be it was quantum tunneling by the wave function ! Loose, trapped in atoms, ionized, converted to photons, full of charge ,conducting all sorts of Spin, happy in pairs within the shells. What kind of a tethered animal have we got here?

[swansont]

Protons create a positively charged electrostatic field around the nucleus. Electrons have negative charge and move around the nucleus, attracted by it while repelling each other. The interaction between these particle fields account for the force-resistance observed in physical objects, as far as I can model it based on what I've learned.

 

Fields are mathematical abstractions, which give us a model of how charged particles behave. What you want to call "real" is a matter of debate.

 

This is where it seems like QM starts confounding empirical observation and modeling. I understand that due to the uncertainty principle, it is impossible to observe the speed and location of an electron simultaneously, which impairs the possibility of inductive modeling. So if inductive modeling is obstructed by constraints on empirical observation, why wouldn't you just focus on deductive modeling?

 

On what principles would one deduce anything? Science describes how nature behaves. You can't remove that from the process.

 

WHAT REALLY is going on at the Electron level. Be it that you chaps know the deep maths but what is the physical interpretation of the maths , and don't just say angular momentum and spin , because there is charge involved , there is some mass, there are some abilities for movement, and swapping with photons. Draw me a mental picture of whats going on down there. Wolfgang Paul and Hans Dehmelt Nobel prize winners 1989( not Pauli ) trapped an electron in a TRAP, it didn't like it. They kept it trapped for an hour then a few days , a month, finally a year, then it got out. May be it was quantum tunneling by the wave function ! Loose, trapped in atoms, ionized, converted to photons, full of charge ,conducting all sorts of Spin, happy in pairs within the shells. What kind of a tethered animal have we got here?

 

http://abstrusegoose.com/342

[steevey]

Matter isn't a conserved quantity. Pair annihilation converts mass into another form of energy, because in the rest frame E=mc^2

 

So then the once established idea of "matter cannot be created nor destroyed" is completely irrelevant and eventually the universe will contain twice as much energy as it does now since matter keeps getting created from nothing but then gets converted into energy and stays in the universe? It seems like that time travel paradox where because you keep traveling in time in the past in the future, there will be an infinitely increasing number of the time traveler.

Edited February 26, 2011 by steevey

[Mike Smith Cosmos]

Wave particle duality as applicable to Electrons and Photons. In all this talk of spin and the electron together with the issue of magnetism from spin being discussed in another thread on theoretical physics, there is a need to not forget the wave aspect of particles like electrons. One feature I have been a little unclear on is: - Is the wave introduced by de Broglie namely the probability wave which tends to have a central peak with waves going off on either side decreasing in amplitude, considered to be related to, identical with , another feature of , or nothing to do with the conventional sine wave of fairly constant amplitude or gently decreasing amplitude that we normally think of as EM waves of light or radio waves etc.? I did ask this once to a visiting professor speaker as he was talking about the LHC and he coughed and spluttered to the effect they were the same thing. But they look nothing like each other ! Unless they are facets of the same thing. I am interested to know which of the waves is concerned with the statement " wave particle duality " , particularly as it applies to the electron , its motion , its spin and its conversion to a photon . ?

Edited February 26, 2011 by Mike Smith Cosmos

[swansont]

So then the once established idea of "matter cannot be created nor destroyed" is completely irrelevant and eventually the universe will contain twice as much energy as it does now since matter keeps getting created from nothing but then gets converted into energy and stays in the universe? It seems like that time travel paradox where because you keep traveling in time in the past in the future, there will be an infinitely increasing number of the time traveler.

 

Established where, and by whom? Energy can't be created or destroyed. Matter and energy are not the same thing, nor are they interchangeable.

[steevey]

Established where, and by whom? Energy can't be created or destroyed. Matter and energy are not the same thing, nor are they interchangeable.

 

So your saying I can create matter, and destroy matter but not energy, and that matter can't be converted into energy? Because "matter cannot be created nor destroyed" is one of the foundations of chemistry and the ability of matter to be converted into energy is one of the corner-stones of physics. Not even a black hole is predicted to "destroy" matter, only convert it into energy or a super-dense form. And according to Einstein, matter is a form of energy and vice versa since E=mc^2, where m=mass, which mass is a quantitative amount of matter.

Edited February 26, 2011 by steevey

[StringJunky]

So your saying I can create matter, and destroy matter but not energy, and that matter can't be converted into energy? Because "matter cannot be created nor destroyed" is one of the foundations of chemistry and the ability of matter to be converted into energy is one of the corner-stones of physics. Not even a black hole is predicted to "destroy" matter, only convert it into energy or a super-dense form. And according to Einstein, matter is a form of energy and vice versa since E=mc^2, where m=mass, which mass is a quantitative amount of matter.

 

Mass–energy equivalence does not imply that mass may be "converted" to energy, and indeed implies the opposite. Modern theory holds that neither mass nor energy may be destroyed, but only moved from one location to another. In physics, mass must be differentiated from matter, a more poorly defined idea in the physical sciences. Matter, when seen as certain types of particles, can be created and destroyed, but the precursors and products of such reactions retain both the original mass and energy, both of which remain unchanged (conserved) throughout the process. Letting the m in E = mc2 stand for a quantity of "matter" may lead to incorrect results, depending on which of several varying definitions of "matter" are chosen..................... According to the theory of relativity, mass and energy as commonly understood, are two names for the same thing, and neither one is changed or transformed into the other. Rather, neither one appears without the other. Rather than mass being changed into energy, the view of relativity is that rest mass has been changed to a more mobile form of mass, but remains mass. In this process, neither the amount of mass nor the amount of energy changes. Thus, if energy changes type and leaves a system, it simply takes its mass with it. If either mass or energy disappears from a system, it will always be found that both have simply moved off to another place. (My bold)

 

http://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence

 

Is this right Swansont?

Edited February 26, 2011 by StringJunky

[steevey]

Mass–energy equivalence does not imply that mass may be "converted" to energy, and indeed implies the opposite. Modern theory holds that neither mass nor energy may be destroyed, but only moved from one location to another. In physics, mass must be differentiated from matter, a more poorly defined idea in the physical sciences. Matter, when seen as certain types of particles, can be created and destroyed, but the precursors and products of such reactions retain both the original mass and energy, both of which remain unchanged (conserved) throughout the process. Letting the m in E = mc2 stand for a quantity of "matter" may lead to incorrect results, depending on which of several varying definitions of "matter" are chosen..................... According to the theory of relativity, mass and energy as commonly understood, are two names for the same thing, and neither one is changed or transformed into the other. Rather, neither one appears without the other. Rather than mass being changed into energy, the view of relativity is that rest mass has been changed to a more mobile form of mass, but remains mass. In this process, neither the amount of mass nor the amount of energy changes. Thus, if energy changes type and leaves a system, it simply takes its mass with it. If either mass or energy disappears from a system, it will always be found that both have simply moved off to another place. (My bold)

 

http://en.wikipedia....rgy_equivalence

 

Is this right Swansont?

 

 

So its saying that because matter and energy can't be created or destroyed, that whenever you have something like a pair particle system colliding, its simply the location of the matter and energy that gets changed? But in modern physics, there's missing matter in colliding particle experiments, which could only be explained by the fact that matter is equivalent to energy. In fact, I think it was something like 5% of the mass of a proton is quarks, and the rest of the mass is energy since gluons don't have mass, and mass is a measure of the amount of matter, so if the mass is also the energy, then matter and energy must be the same thing? It's essentially this: amount of energy=Mass=amount of matter

Edited February 27, 2011 by steevey

[swansont]

Mass–energy equivalence does not imply that mass may be "converted" to energy, and indeed implies the opposite. Modern theory holds that neither mass nor energy may be destroyed, but only moved from one location to another. In physics, mass must be differentiated from matter, a more poorly defined idea in the physical sciences. Matter, when seen as certain types of particles, can be created and destroyed, but the precursors and products of such reactions retain both the original mass and energy, both of which remain unchanged (conserved) throughout the process. Letting the m in E = mc2 stand for a quantity of "matter" may lead to incorrect results, depending on which of several varying definitions of "matter" are chosen..................... According to the theory of relativity, mass and energy as commonly understood, are two names for the same thing, and neither one is changed or transformed into the other. Rather, neither one appears without the other. Rather than mass being changed into energy, the view of relativity is that rest mass has been changed to a more mobile form of mass, but remains mass. In this process, neither the amount of mass nor the amount of energy changes. Thus, if energy changes type and leaves a system, it simply takes its mass with it. If either mass or energy disappears from a system, it will always be found that both have simply moved off to another place. (My bold)

 

http://en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence

 

Is this right Swansont?

 

The wikipedia article is kinda crappy, but then there's a lot of conflicting information in popular science; one needs to take a consistent view. Mass is not a conserved quantity. [imath]E^2=m^2c^4 + p^2c^2[/imath] The total energy of a particle (or system) is the mass energy added to the kinetic energy. You can convert between the two. If you add (subtract) energy and the kinetic energy doesn't change, the mass increases (decreases)

 

So your saying I can create matter, and destroy matter but not energy, and that matter can't be converted into energy? Because "matter cannot be created nor destroyed" is one of the foundations of chemistry and the ability of matter to be converted into energy is one of the corner-stones of physics. Not even a black hole is predicted to "destroy" matter, only convert it into energy or a super-dense form. And according to Einstein, matter is a form of energy and vice versa since E=mc^2, where m=mass, which mass is a quantitative amount of matter.

 

mass ≠ matter

 

And your act of telling people that they are wrong, in discussions where you are out of your depth, has really worn thin.

[steevey]

mass ≠ matter

 

I didn't say mass itself is matter, I said mass is a measurement of matter. Thats why when I put something on a gram scale, I get some amount of grams, which is telling me the quantitative amount of matter thats in it. So energy equals some quantitative amount of matter times the speed of light squared. I don't see how matter and energy aren't some form of the same thing according to that unless you forgot to mention that

because matter and energy can't be created or destroyed, that whenever you have something like a pair particle system colliding, its simply the location of the matter and energy that gets changed

 

is correct.

 

And I'm not necessarily saying your wrong, just pointing out something that doesn't make sense to me or contradicts what I've been told, since with that, its basically your word as an expert against the word of someone else who also claims to be an expert.

Edited February 27, 2011 by steevey

[lemur]

Fields are mathematical abstractions, which give us a model of how charged particles behave. What you want to call "real" is a matter of debate.

And "particles" are more real and less mathematic abstractions than fields then? What basis is there for that claim? An empirical one?

 

On what principles would one deduce anything? Science describes how nature behaves. You can't remove that from the process.

Induction moves from empirical observations to theory. Deductive theory begins with a theory and then deduces methods of testing the theory. If you observe that electrons appear and disappear or "tunnel" or whatever you call it within areas of varying probability, inductive modeling would seek to generate a theory to explain this behavior as it is observed. Deductive theory could move toward considering some alternative explanation for the reason electron behavior appears as it does and, as a result, could formulate a model that could be tested according to existing or new data. E.g. the Bohr model began with a model based on planetary motion and eventually deduced tests that proved itself wrong. It is possible to construct new models and deduce tests for them.

 

 

[Mike Smith Cosmos]

The overlay is really in the physical interpretation of the mathematics. Spin is due to a rotation, but it is not as simple as rotation of a particle about some axis. This "extra rotation" manifests itself in nature as the intrinsic spin of a particle.

 

More generally, you are asking if mathematics is invented or discovered? This has been discussed on these forums before, have a search. The question is rather philosophical in nature. I doubt it would shed much light on the question of spin.

 

Overnight I have read some of Marcus Chown's comment in his book "Quantum theory cannot hurt you " chap 6 . Here he quotes Feynman in connection with spin , as saying " This seems to be one of the few places in physics where there is a rule which can be stated very simply but for which no one has found an easy explanation. It probably means that we do not have a complete understanding of the fundamental problems involved" . Chown reasons that the main difference in spin between a boson, Photon style particle having quantum spin in the range 0,1,2 and a Fermion , electron style particle having a similar one value change quantum spin in the range 1/2, 2/3, 5/3. is that :- The electron being a fermion takes part in probability wave "waveflipping" which does not affect the probability of the event , as this depends on the square of the amplitude ( always positive ) , but it only takes part in interference in a certain way, if it has waveflipped in a collision.

 

This area of collision, waveflipping, spin up - spin down , angular momentum change , boson - fermion difference , and the link between electron and photon during radiation and absorption sounds interesting. Can you shed any light on this ?

Edited February 27, 2011 by Mike Smith Cosmos

[swansont]

I didn't say mass itself is matter, I said mass is a measurement of matter. Thats why when I put something on a gram scale, I get some amount of grams, which is telling me the quantitative amount of matter thats in it. So energy equals some quantitative amount of matter times the speed of light squared. I don't see how matter and energy aren't some form of the same thing according to that unless you forgot to mention that

 

Mass is not conserved, so why would matter be conserved?

 

is correct.

 

And I'm not necessarily saying your wrong, just pointing out something that doesn't make sense to me or contradicts what I've been told, since with that, its basically your word as an expert against the word of someone else who also claims to be an expert.

 

See, you just did it again. Claimed to be right, but you have given no supporting evidence. No physics argument, no link. Consider the possibility that your understanding of what you heard is wrong or your memory is wrong. Come up with e-v-i-d-e-n-c-e as a rebuttal, not just contrariness.

 

And "particles" are more real and less mathematic abstractions than fields then? What basis is there for that claim? An empirical one?

 

I will reiterate: what you want to call "real" is a matter of debate. In another thread.

 

Induction moves from empirical observations to theory. Deductive theory begins with a theory and then deduces methods of testing the theory. If you observe that electrons appear and disappear or "tunnel" or whatever you call it within areas of varying probability, inductive modeling would seek to generate a theory to explain this behavior as it is observed. Deductive theory could move toward considering some alternative explanation for the reason electron behavior appears as it does and, as a result, could formulate a model that could be tested according to existing or new data. E.g. the Bohr model began with a model based on planetary motion and eventually deduced tests that proved itself wrong. It is possible to construct new models and deduce tests for them.

 

Where does the theory come from, from which one would apply deduction? How would one test to see it is correct, without making an observation? That was my point. You had proposed to remove empirical observation from the process. You can't do it. Even the application of deduction within a theory, as you describe, must be followed by observation in order to confirm it.

[lemur]

I will reiterate: what you want to call "real" is a matter of debate. In another thread.

Then why did you raise it in this thread by claiming force-fields are unreal abstractions? But I will open another thread, because I would actually like to pursue this issue more extensively.

 

Where does the theory come from, from which one would apply deduction?

Someone has to come up with based on some rigorous reasoning about what could explain diverse data while providing a basis for further theorizing and testing.

 

How would one test to see it is correct, without making an observation?

You can seek new data or rely on existing data. You don't necessarily need new data to test a new theory. It could just be a question of interpreting old data in a new way or reasoning about it in a new way.

 

That was my point. You had proposed to remove empirical observation from the process. You can't do it. Even the application of deduction within a theory, as you describe, must be followed by observation in order to confirm it.

No, I wouldn't propose to avoid empiricism. That would completely diverge from the most fundamental basis for science. But there is nothing unscientific/anti-empirical about thinking in new ways about empirical data and/or generating new ideas for how to apply empirical observation to the task of deductively testing whatever model. Science, imo, is ultimately the philosophical reasoning that brings empiricism and knowledge to bear on each other.

 

 

 

[Mike Smith Cosmos]

 

 

 

Edited February 27, 2011 by Mike Smith Cosmos

[steevey]

Mr /mrs/miss Lemur

 

Do you have any model of the electron that you could share ?

 

The reason an electron acts the way it does is because its a wave, where existence itself is waving. As a result of this property, it has no specific location.

[Mike Smith Cosmos]

The reason an electron acts the way it does is because its a wave, where existence itself is waving. As a result of this property, it has no specific location.

Edited February 27, 2011 by Mike Smith Cosmos