String theory is what?

[lpetrich]

Spontaneous parametric down conversion.
Bosons: Blue + antiblue → 2 red + (some rubbish).
Fermions: Beauty meets antibeauty and more matter than its anti emerges. CP violation. Observed.

References, please?

SPDC has no classical analogy. Maxwell could not have seen this one coming.

Have I not posted the A. Steinberg refs?
http://arxiv.org/PS_cache/hep-ph/pdf/0510/0510076v2.pdf

It doesn't fit that description. It's aiming three extremely intense laser beams at each other and attempting to detect a light beam that comes from their intersection. They are confident that some lab facilities can detect it if it's at the quantum-electrodynamics predicted value.

QED photon-photon scattering goes like this: two photons meet and create a virtual electron-positron pair. They then annihilate, creating two new photons. The rate is proportional to (elementary charge)^4 / (electron mass)^4 with whatever hbars and c's are necessary to get into ordinary units. The next strongest contribution is from the muon, a flavor of electron about 200 times more massive than ordinary electrons. It's easy to show that muons will make a contribution about 1.6 billion times weaker.

and day1, lhc@50% and stable, crossing beams, 30th March, 2010 - present. The lhc is a beauty factory, some of the time.

But the LHC has not been making collisions long enough to get anything but the most cursory particle-physics results, like overall hadron production.

As to observing CP violation, the favorite place to do so has been in the decays of neutral mesons. These are the K0 (ds*), D0 (cu*), B0 (db*), and Bs0 (sb*). The top quark does not form any hadrons because it decays before it can hadronize. Due to weak interactions, these particles convert to their antiparticles and back again. This also makes the K0 and its antiparticle split into two states, one that lasts about 5*10-8 s, and one that lasts about 9*10-11 s. It's also been observed in the D0, the B0, and the Bs0. For the B0, it can be observed by looking for two B0's or two B0*'s emerging, since the interactions that produce bottom quarks always produce them in particle-antiparticle pairs. To date, CP violation has been observed in the K0, the D0, and the B0.

The LHCb team evidently hopes that the LHC will make a lot of B0's and Bs0's and their antiparticles, thus getting good statistics.

Particle Data Group'

[newolder]

But the LHC has not been making collisions long enough to get anything but the most cursory particle-physics results, like overall hadron production.

I know. The cursory results displayed by the lhc-b guy on day 1 need statistical tightening that will come from more collisions. I've probably got over-excited about those early results – this too will pass.

As to observing CP violation, the favorite place to do so has been in the decays of neutral mesons. 

Yes. The collision I have in mind takes a bѢ as input (equal amounts of matter and antimatter in a neutral meson) and produces 2 b (plus some other rubbish) as output, like this:

Isn't that what I'm seeing here? http://cdsweb.cern.ch/record/1255400?ln=en

[Farsight]

"Pointlike" in the sense of having "no internal structure except for their spins and quantum numbers".

They aren't pointlike at all. A point cannot exhibit angular momentum.

This is lame. Why are stability and trappability supposed to be fundamental properties?

It isn't lame at all. Setting neutrinos aside, the only stable particles with mass that we actually observe are electrons, protons, and their antiparticles. The rest are either hypothetical or ephemera.

Because there's no independent evidence of vortons. That's why they have been dismissed as unnecessary hypotheses

The evidence is spin, angular momentum, magnetic dipole moment, etc. That rotation is real. Don't dismiss it.

Farsight, why don't you try writing a paper and submitting it to some particle-physics journal? Like Physical Review D or Physical Review Letters. However, I seriously suspect that the journal editors will be so overcome with laughter that they won't get much business done that day.

I did. Foundations of Physics had the paper for three months, then eventually Gerard t'Hooft rejected it with an editors comment saying "This manuscript lacks sufficient foundational quality. We must advise the author to submit his manuscript somewhere else." I tried another half-dozen journals with variants and had similar results.

What mismatches between the Standard Model and experimental evidence?

Intrinsic spin and elementary particles.

Free neutrons decay into protons because it is energetically favorable for them to do so. But bound nuclei are a different story. What makes stable nuclei stable is that it's energetically unfavorable for a neutron to decay into a proton. But when it is energetically favorable, a neutron can decay into a proton -- and a proton into a neutron.

Beta plus "decay" is hardly a decay.

But you are advocating them.

Yes, because they fit the evidence. Charge is not fundamental. It can be created and destroyed.

The electron's observed anomalous magnetic moment agrees VERY well with calculations - it's a triumph for Quantum Electrodynamics, a part of the Standard Model.

QED is solid. The issue with it has always been understanding the underlying physical reality. It's very simple.

If one calls word-drool coherent.

What a shame that people cannot continue a discussion without resorting to abuse.

Elementary particles do NOT work like macroscopic objects.

I'm afraid they do.

Given what Einstein had worked on, it must be a VERY simplified level of understanding.

It's horribly simple. You'll be shocked.

Is that all you can say? With that sort of dismissiveness, you aren't going to get a QFT 101 course.

You still can't explain it.

Yes, you must do it all, and do it without whining "Why should I have to show that my pet theories agree with the Standard Model to within experimental limits?"

I'm not whining. But you are reacting emotionally. So let's leave it at that.

[lpetrich]

"Pointlike" in the sense of having "no internal structure except for their spins and quantum numbers".

They aren't pointlike at all. A point cannot exhibit angular momentum.

Farsight, you're being too literal-minded. The particles are not little billiard balls or whatever, but quantum fields that follow field equations.

Photons and abelian gauge fields in general: Maxwell's equations.
Nonabelian gauge fields: Yang-Mills equations (generalization of Maxwell's equations for the nonabelian case)
Elementary fermions: the Dirac equation
Elementary scalars: the Klein-Gordon equation
Etc.

Because there's no independent evidence of vortons. That's why they have been dismissed as unnecessary hypotheses

The evidence is spin, angular momentum, magnetic dipole moment, etc. That rotation is real. Don't dismiss it.

Elementary-particle fields can have spin, in case you didn't know.

Farsight, why don't you try writing a paper and submitting it to some particle-physics journal? Like Physical Review D or Physical Review Letters. However, I seriously suspect that the journal editors will be so overcome with laughter that they won't get much business done that day.

I did. Foundations of Physics had the paper for three months, then eventually Gerard t'Hooft rejected it with an editors comment saying "This manuscript lacks sufficient foundational quality. We must advise the author to submit his manuscript somewhere else." I tried another half-dozen journals with variants and had similar results.

Farsight, it's great that you did that.

But it's not so great that you had not taken seriously those physicists' criticisms and considered what might be wrong with your theories.

What mismatches between the Standard Model and experimental evidence?

Intrinsic spin and elementary particles.

Why are they mismatches? There is no problem in the Standard Model with either.

The electron's observed anomalous magnetic moment agrees VERY well with calculations - it's a triumph for Quantum Electrodynamics, a part of the Standard Model.

QED is solid. The issue with it has always been understanding the underlying physical reality. It's very simple.

Farsight, hasn't it ever occurred to you that there need not be some underlying quasi-classical physical reality?

Elementary particles do NOT work like macroscopic objects.

I'm afraid they do.

Demonstrably false.

Given what Einstein had worked on, it must be a VERY simplified level of understanding.

It's horribly simple. You'll be shocked.

Try explaining relativity to your grandmother some time and see how successful you are. Especially general relativity.

BTW, Albert Einstein - Wikiquote states that that grandmother quote is misattributed.

Is that all you can say? With that sort of dismissiveness, you aren't going to get a QFT 101 course.

You still can't explain it.

Farsight, I'll give you some links on quantum field theory, to save myself the trouble of writing something lengthy that may or may not get some appreciation.

Quantum field theory - Wikipedia, the free encyclopedia - a nontechnical explanation with LOTS of references.
Arthur Jaffe's Introduction to Quantum Field Theory - rather technical.

[Twiglet]

This is a good illustration of why a solid understanding of maths is needed to discuss these topics for more than illustration. As Paul Dirac said "I understand an equation when I have a good idea of the results it will produce before performing the calculation". Much can be lost in the translation from a mathematically forumalated idea into English, and the process of communicating it is typically one way. There is not much point in attacking an explanation of a theory with linguistic tricks - all it usually identifies are a weakness in the explanation, or a failure to understand the explanation.

If you want to think outside the box, you need to know whats inside it to begin with, otherwise you are just building a house of cards.

The mailboxes of physics departments and science journals are full of submissions from people with a "Grand Theory of Everything", and most generally those submissions would be better directed to the screenwriters of Star Trek, but even they have quality control.

[Farsight]

Farsight, you're being too literal-minded. The particles are not little billiard balls or whatever, but quantum fields that follow field equations.

Photons and abelian gauge fields in general: Maxwell's equations.
Nonabelian gauge fields: Yang-Mills equations (generalization of Maxwell's equations for the nonabelian case)
Elementary fermions: the Dirac equation
Elementary scalars: the Klein-Gordon equation
Etc.

I'm glad you said that lpetrich. It's something we agree upon. But sadly I have had numerous conversations with people who consider themselves to be educated and knowledgeable in physics, who are utterly convinced that electrons and quarks are pointlike. I wish people like you would attempt to persuade them that this is not the case. Unfortunately the myth persists, such as on the wiki article, see http://en.wikipedia.org/wiki/Electron#F ... properties where it says "The electron has no known substructure.[2][71] Hence, it is defined or assumed to be a point particle with a point charge and no spatial extent."

Elementary-particle fields can have spin, in case you didn't know.

I know this. And I also know that they aren't elementary in the sense that they're fundamental. They're only elementary in the sense that they are elements or components of something else.

Farsight, it's great that you did that. But it's not so great that you had not taken seriously those physicists' criticisms and considered what might be wrong with your theories.

I have. And I've also talked at length to physicists who have struggled for years to get a paper published. These are real physicists, with ample rigor, and even they have difficulty. It's far more competitive than I ever imagined.

Why are they mismatches? There is no problem in the Standard Model with either.

See the wiki article on elementary particles?

http://en.wikipedia.org/wiki/Elementary_particle

I know this is only wiki, but it says "If an elementary particle truly has no substructure, then it is one of the basic building blocks of the universe from which all other particles are made." This is misleading. The electron does have a structure, that's why it exhibits charge, and it isn't a "basic building block". You can destroy it via annihilation, and get something more basic. Ditto for the proton. And note that one nanosecond after low-energy proton/antiproton annihilation, the quarks have gone.

Farsight, hasn't it ever occurred to you that there need not be some underlying quasi-classical physical reality?

Yes, of course. I thought that for years. Then I started giving online homework help, and struggled to explain certain things, then started coming across papers and articles that don't receive much attention. Then I developed a picture of the underlying reality. Like I said, it is horribly simple. In some respects it's too simple for some people to understand. They're absolutely convinced it can't be that simple. As an example, see what I said in Time Explained.

Demonstrably false.

It isn't. Elementary particles really do work like macroscopic objects. The Stern-Gerlach experiment is a good example. I was talking about this elsewhere last week, so I'll repeat it here:

See the Stern-Gerlach article which says:

"If the particles are classical, "spinning" particles, then the distribution of their spin angular momentum vectors is taken to be truly random and each particle would be deflected up or down by a different amount...

The experiment shows that this doesn't happen, so we know the particles aren't spinning spheres. However the article goes on to say:

"Electrons are spin-1⁄2 particles. These have only two possible spin angular momentum values, called spin-up and spin-down. The exact value in the z direction is +ħ/2 or −ħ/2. If this value arises as a result of the particles rotating the way a planet rotates, then the individual particles would have to be spinning impossibly fast."

There's actually nothing wrong with that, but watch carefully, and you can see the non-sequitur:

"The speed of rotation would be in excess of the speed of light, 2.998×108 m/s, and is thus impossible".[2] Thus, the spin angular momentum has nothing to do with rotation and is a purely quantum mechanical phenomenon. That is why it is sometimes known as the "intrinsic angular momentum."

We've established that the particle isn't rotating like a planet, but why can't it be rotating in some other fashion? There is no justification here for asserting that spin angular momentum has nothing to do with rotation. Imagine a globe, like you'd find in a geography class. (The electron isn't solid and it isn't a globe, but go with the flow). Give the globe an earth-style spin to give yourself a classical particle, then throw it through the inhomogeneous magnetic field. Repeat with a variety of globes with different spin orientations and you'd see a line on the screen as per the classical prediction:



Now take your spinning globe, and give it another spin with a different orientation. Spin the spin axis. You have two choices as regards this new spin direction, this way ↓O↑ or that way ↑O↓. Now throw it through the inhomogeneous magnetic field repeatedly and ask yourself what you'd see. This spheres example doesn't cover the spin 1/2 of course. You need one spin to be twice the rate of the other for that. A moebius strip is an everyday example of this, where two rotations around the strip occur for every rotation of the strip.

Try explaining relativity to your grandmother some time and see how successful you are. Especially general relativity.

I have. I'm the relativity+ guy. I wouldn't say I've set the world on fire yet, but I'm off to a TV studio for a documentary in a couple of weeks.

BTW, Albert Einstein - Wikiquote states that that grandmother quote is misattributed.

Noted. It says it's often attributed to Richard Feynman, the "great explainer". Whoever said it, I hope you agree that if one is unable to give a simplified explanation, there is an issue.

Farsight, I'll give you some links on quantum field theory, to save myself the trouble of writing something lengthy that may or may not get some appreciation. Quantum field theory - Wikipedia, the free encyclopedia - a nontechnical explanation with LOTS of references.

I read that long ago lpetrich. See the Axiomatic approaches section and note this:

"During the 1980s, a second set of axioms based on geometric ideas was proposed. This line of investigation, which restricts its attention to a particular class of quantum field theories known as topological quantum field theories, is associated most closely with Michael Atiyah and Graeme Segal, and was notably expanded upon by Edward Witten, Richard Borcherds, and Maxim Kontsevich. However, most physically-relevant quantum field theories, such as the Standard Model, are not topological quantum field theories;"

Arthur Jaffe's Introduction to Quantum Field Theory - rather technical.

Thanks. Looks interesting. I've saved it. My first check was to search on electron, but the word isn't mentioned. Photon is only mentioned once in passing. And I see there's a Why Quantization? section but the proof involves a by definition, and he seems to miss the quantum of quantum mechanics. I should read it I suppose. But this bit of the introduction caught my eye:

"One should mention right at the start that one still does not understand whether quantum mechanics and special relativity are compatible at a fundamental level in our Minkowski four-space world. One generally assumes that this means finding a complete Yang-Mills gauge theory or the interaction of gauge fields with fermionic matter fields, the simplest form being quantum chromodynamics (QCD). Associated with this picture is the belief that the fundamental vector meson excitations are massive (as opposed to photons, which arise in the limiting case of an abelian gauge symmetry. The proof of the existence of a “mass gap” appears a necessary integral part of solving the entire puzzle".

I ask myself whether he understands the fundamentals like mass. Maybe that's unfair, yes I should read on, especially since http://physics.harvard.edu/people/facpages/jaffe.html looks interesting. Non-commutative geometry is what Joy Christian was talking about in his disproof of Bell's Theorem. But anyway: a photon in a mirror-box adds mass to that system. Pair production and electron angular momentum tell us the electron is like a photon in a box, only it's going round and round rather than back and forth. And there ain't no box.

And what's this?

"This question remains one of the deepest open issues in theoretical physics, as well as in mathematics. Basically the question remains: can one give a mathematical foundation to the theory of fields in four-dimensions? In other words, can do quantum mechanics and special relativity lie on the same footing as the classical physics of Newton, Maxwell, Einstein, or Schrodinger—all of which fits into a mathematical framework that we describe as the language of physics. This glaring gap in our fundamental knowledge even dwarfs questions of whether there are other more complicated and sophisticated approaches to physics..."

This is where I come in. What people have a blind spot about is that you cannot explain the maths with maths. By the way, if you're game for a laugh, see http://www.advfn.com/cmn/fbb/thread.php3?id=2724522. That's a shares website, where I started using the name "Farsight". In 2002.

[oddmanout]

Hey Farsight, oddman from RD.net here.

But anyway: a photon in a mirror-box adds mass to that system. Pair production and electron angular momentum tell us the electron is like a photon in a box, only it's going round and round rather than back and forth. And there ain't no box.

Could you elaborate on this?

And, preferably, someone else too? It struck me as important, not sure why.

[newolder]

Hey Farsight, oddman from RD.net here.

But anyway: a photon in a mirror-box adds mass to that system. Pair production and electron angular momentum tell us the electron is like a photon in a box, only it's going round and round rather than back and forth. And there ain't no box.

Could you elaborate on this?

And, preferably, someone else too? It struck me as important, not sure why.

To map (□ + hυ) to [e- with non-zero rest mass and orientable spin] requires some absurd mathematics. Electrons moving in circles, trefoils or square-dance hooleries emit radiation whilst orientable and spinning, point-like charges in QFT do not.

[oddmanout]

Hey Farsight, oddman from RD.net here.

But anyway: a photon in a mirror-box adds mass to that system. Pair production and electron angular momentum tell us the electron is like a photon in a box, only it's going round and round rather than back and forth. And there ain't no box.

Could you elaborate on this?

And, preferably, someone else too? It struck me as important, not sure why.

To map (□ + hυ) to [e- with non-zero rest mass and orientable spin] requires some absurd mathematics. Electrons moving in circles, trefoils or square-dance hooleries emit radiation whilst orientable and spinning, point-like charges in QFT do not.

Umm..

So what you're saying is; a photon in a mirror-box does not add mass to "that system", according to quantum field theory? If the answer is yes, then what does this mean in the "bigger picture of things"? (I.e. could this be a limitation of the QFT, or is it an observed fact?).

[newolder]

Hey Farsight, oddman from RD.net here.

But anyway: a photon in a mirror-box adds mass to that system. Pair production and electron angular momentum tell us the electron is like a photon in a box, only it's going round and round rather than back and forth. And there ain't no box.

Could you elaborate on this?

And, preferably, someone else too? It struck me as important, not sure why.

To map (□ + hυ) to [e- with non-zero rest mass and orientable spin] requires some absurd mathematics. Electrons moving in circles, trefoils or square-dance hooleries emit radiation whilst orientable and spinning, point-like charges in QFT do not.

Umm..

So what you're saying is; a photon in a mirror-box does not add mass to "that system", according to quantum field theory? If the answer is yes, then what does this mean in the "bigger picture of things"? (I.e. could this be a limitation of the QFT, or is it an observed fact?).

No, the photon adds mass alright. The mirror-box to electron, 'there ain't no box' analogy does not work.

[oddmanout]

No, the photon adds mass alright. The mirror-box to electron, 'there ain't no box' analogy does not work.

Ah, you were talking about the electron!

OK, so the photon does add mass to "the system". Could you explain this, in layman's terms, please? Light / photons is something that has been confusing me for a while. So, the photon is a massless particle, yet it is also a wave. If you confine "it" (the "wave-particle"?) into a mirror-box it adds to the total mass of the box. What does this mean?

If I'm not mistaken, a common thing is to consider light quantified; light as quanta. But I feel like I'm missing something here, an important part of the puzzle. I'm quite aware that light is "bent" in gravitational fields, but this because of the curved space, is it not? And not because of interactions with (the supposed) gravitons? Or is that two ways of looking at the same thing; from either a GR or a QM point of view?

[newolder]

No, the photon adds mass alright. The mirror-box to electron, 'there ain't no box' analogy does not work.

Ah, you were talking about the electron!

OK, so the photon does add mass to "the system". Could you explain this, in layman's terms, please? Light / photons is something that has been confusing me for a while. So, the photon is a massless particle, yet it is also a wave. If you confine "it" (the "wave-particle"?) into a mirror-box it adds to the total mass of the box. What does this mean?

If I'm not mistaken, a common thing is to consider light quantified; light as quanta. But I feel like I'm missing something here, an important part of the puzzle. I'm quite aware that light is "bent" in gravitational fields, but this because of the curved space, is it not? And not because of interactions with (the supposed) gravitons? Or is that two ways of looking at the same thing; from either a GR or a QM point of view?

In layman's terms boxes that carry surplus or injected wave energy weigh more than utterly dark ones and the bluer the wave being carried, the heavier the box. The gravitational nature of massless entities is described by their effect on local curvature in space-time.

The Weyl curvature represents such gravitational effects as tidal fields and gravitational radiation.

[lpetrich]

Farsight, you're being too literal-minded. The particles are not little billiard balls or whatever, but quantum fields that follow field equations.

Photons and abelian gauge fields in general: Maxwell's equations.
Nonabelian gauge fields: Yang-Mills equations (generalization of Maxwell's equations for the nonabelian case)
Elementary fermions: the Dirac equation
Elementary scalars: the Klein-Gordon equation
Etc.

I'm glad you said that lpetrich. It's something we agree upon. But sadly I have had numerous conversations with people who consider themselves to be educated and knowledgeable in physics, who are utterly convinced that electrons and quarks are pointlike. I wish people like you would attempt to persuade them that this is not the case. Unfortunately the myth persists, such as on the wiki article, see http://en.wikipedia.org/wiki/Electron#F ... properties where it says "The electron has no known substructure.[2][71] Hence, it is defined or assumed to be a point particle with a point charge and no spatial extent."

That's a misunderstanding about particle spin, that it's like some added gyroscope. In reality, it's built into the spatial structure of the particle field. Here goes:

Spin-0: Klein-Gordon equation

Di - partial-differential operator with respect to variable xi.
gij - raised-index space-time metric

A simple space-time wave equation:

Field: f
Potential: V(f)
Equation: gijDiDif = V'(f)

Spin-1: Maxwell's equations

Electromagnetic potential: Ai
Electromagnetic field: Fij = DiAj - DjAi
Raised indices: Fij = gikgjlFkl

Maxwell's equations:
DiFjk + DjFki + DkFij = 0
DjFij = Ji

Spin-1/2: Dirac equation

Dirac matrices gmi:
Time: [I 0; 0 -I]
where I is the 2*2 identity matrix.
Space [0 sg; -sg 0]
where sg is the Pauli matrices.
The gm's have dimension 4*4.

Field: f (dimension 4)
Mass: m
Equation -i * gmiDif + m*f = 0

The particles' spins is a result of their space-time structure. 0: scalar, 1: vector, and 1/2: spinor.

I know this is only wiki, but it says "If an elementary particle truly has no substructure, then it is one of the basic building blocks of the universe from which all other particles are made." This is misleading. The electron does have a structure, that's why it exhibits charge, and it isn't a "basic building block". You can destroy it via annihilation, and get something more basic. Ditto for the proton. And note that one nanosecond after low-energy proton/antiproton annihilation, the quarks have gone.

All bad arguments against elementariness. Spin is not some sort of gyroscope added to a particle. Decay and annihilation happen because they are permitted by energy conservation and conservation of various quantum numbers and its nonabelian analog.

Demonstrably false.

It isn't. Elementary particles really do work like macroscopic objects. The Stern-Gerlach experiment is a good example.

Don't make me laugh. That's a quantum-mechanical effect without a classical counterpart. A stream of particles with angular momentum j gets split by a magnetic field into (2j+1) equally-spaced streams around where the original stream would be in the absence of a magnetic field.

It happens because the angular-momentum operator J projected onto any direction will have eigenvalues -j, -j+1, ..., j-1, j.

Try explaining relativity to your grandmother some time and see how successful you are. Especially general relativity.

I have. I'm the relativity+ guy. I wouldn't say I've set the world on fire yet, but I'm off to a TV studio for a documentary in a couple of weeks.

Why not try to take it to the mainstream scientific community?

Whoever said it, I hope you agree that if one is unable to give a simplified explanation, there is an issue.

I don't.

[lpetrich]

This is a good illustration of why a solid understanding of maths is needed to discuss these topics for more than illustration. As Paul Dirac said "I understand an equation when I have a good idea of the results it will produce before performing the calculation". Much can be lost in the translation from a mathematically forumalated idea into English, and the process of communicating it is typically one way. There is not much point in attacking an explanation of a theory with linguistic tricks - all it usually identifies are a weakness in the explanation, or a failure to understand the explanation.

That's so true. The mathematics is there for a reason - not necessarily to produce grandiose qualitative claims but testable quantitative claims -- and sometimes very precisely testable quantitative claims at that.

[hackenslash]

And what of Einstein, whose understanding was visceral, and whose mathematics was poor?