String theory is what?

[Farsight]

Hi, I have a newbie question on this subject (although on GR): how is it (if I'm not mistaken, which I probably am) that the space-time coordinates in GR can be treated as interchangeable? I.e. it doesn't matter which coordinate is which. This makes sense from the point of view that travelling through the 4-dimensions of space-time is limited by the upper speed limit of c, but is there really no difference between space and time?

No, there is a difference, and actually you travel through space, not spacetime. You then plot a worldline in spacetime where the "length" or "spacetime distance" ds² = - dt² + dx² + dy² + dz². There's a minus sign on the time coordinate. You can't move through the time dimension like you can move through space dimensions, because it's derived from motion through space.

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

It's a rather relative point that his maths was poor... he still formulated general relativity, the maths of which is hardly trivial. Whatever Einsteins shortcomings may have been, he was nonetheless able to put forward his theories mathematically, and subject them to experimental tests which produced results that validate them. Not only that, but they explained results which the prevailing ideas of the day could not.

The contrast between general relativity and string theory is quite marked in this respect. The initial verification of general relativity was in 1919, only three years after it was completed. Interestingly, some do say that Einstein lost his insight once his mathematics improved, and that he didn't achieve much after general relativity.

[lpetrich]

Like newolder said, trap a massless photon in a box, and the mass of the system is increased.

The masslessness refers to its zero rest mass.

This is essentially what Einstein said in Does the Inertia of a Body Depend Upon its Energy Content?". That's the paper that introduced E=mc², though Einstein used L instead of E, saying If a body gives off the energy L in the form of radiation, its mass diminishes by L/c².

We don't do physics by hero-thumping.

If you take a look at pair production and annihilation you can see this in extremis. In pair production we create two "bodies" with mass, the electron and the positron, out of a massless photon. (It has to be a pair for conservation of angular momentum etc). In annihilation, each body emits a photon, and then isn't there any more.

The pair-production interaction is essentially the interaction of an electron with a photon, except with a positron leaving instead of an electron entering. Likewise, the annihilation interaction has a positron entering instead of an electron leaving. Look at the Feynman diagram for the processes -- the positron, the virtual electron, and the real electron form one line with the photon lines coming off of it.

The electron has angular momentum, and magnetic dipole moment, so there's something going round and round.

Projecting classical intuitions onto quantum mechanics again. Electrons don't have gyroscopes attached to give them their spins. An electron field is a 4-component spinor field, and the spin resides in the spinorness. Likewise, a photon field is a 4-component vector field, and the spin resides in the vectorness.

To see why, let's rotate a vector [A+, A0, A-] and a spinor [X+,X-] by angle a around the z-axis:

[A+, A0, A-] -> [exp(i*a)*A+, A0, exp(-i*a)*A-]
[X+, X-] -> [exp(i*a/2)*X+, exp(-i*a/2)*X-]

Note: A+ = (Ax + i*Ay)/sqrt(2), A- = (Ax - i*Ay)/sqrt(2), A0 = Az

Since in quantum mechanics, rotation and angular momentum are closely related, it's easy to see where the angular momentum comes from.

[lpetrich]

(me on spin 0, 1/2, and 1 field equations)

Thanks for going to all that trouble.

Nice to see that appreciation for my efforts.

I see things a little differently because I have a different view of time. I see it as an emergent property of motion through space.

A spin-zero pion is however an unstable structure, it lasts for less than a microsecond.[/quote]
It's unstable because it is energetically favorable and quantum-number permitted for it to decay. A charged pion decays by the weak interaction into a muon and a neutrino, while a neutral pion decays by the electromagnetic interaction into two photons.

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

I've tried, and I'm still trying. The reaction is somewhat mixed. String theorists obviously hate it. Mathematical physicists dismiss it because there's a lack of rigor, and don't understand that I've analysed terms to try to explain what they really mean. The LQG guys are unhappy because I say you can't quantize gravity. The Beyond the Standard Model guys aren't too chuffed because I'm saying understand the electron before you dream up a whole new raft of supersymmetric particles. The HEP guys aren't too keen either because they feel they own a monopoly on this sort of thing, and massive stable particles are knots is somehow threatening. Even some of the relativity guys are unhappy, because I advance the Einstein interpretation rather than the modern interpretation, and say Misner/Thorne/Wheeler is wrong in some respects - see http://arxiv.org/abs/astro-ph/0703751 re George Ellis having a bit of ding-dong with Jo Maguijo re VSL. The people who do like it are the guys involved in photonics, condensed matter physics, and electromagnetics. But they have their own problems getting papers into top-flight journals. It's getting out there slowly, eg via an ad on the Institute of Physics PhysicsWorld website, and I fancy I'm seeing some movement. We'll see how it goes I suppose.

So you want to publish on some heterodox theory of particle physics by appealing to physicists in other fields? I hope that the journal editors catch that lame end run.

[lpetrich]

Hi, I have a newbie question on this subject (although on GR): how is it (if I'm not mistaken, which I probably am) that the space-time coordinates in GR can be treated as interchangeable? I.e. it doesn't matter which coordinate is which. This makes sense from the point of view that travelling through the 4-dimensions of space-time is limited by the upper speed limit of c, but is there really no difference between space and time?

No, there is a difference, and actually you travel through space, not spacetime. You then plot a worldline in spacetime where the "length" or "spacetime distance" ds² = - dt² + dx² + dy² + dz². There's a minus sign on the time coordinate. You can't move through the time dimension like you can move through space dimensions, because it's derived from motion through space.

That minus sign has nothing to do with it. That's because one can define in relativity a "4-velocity", which includes motion in time as well as in space.

Farsight, you are not going to become the next Einstein by making elementary mistake after elementary mistake after elementary mistake.

[Farsight]

The masslessness refers to its zero rest mass.

Because a photon isn't at rest. When you contrive things so that it is "at rest" in aggregate because it's moving back and forth or in a loop, then it confers mass to the system that it's in, or the system that it now is.

We don't do physics by hero-thumping.

Come off it. That's a perfectly valid reference to the original E=mc² paper.

The pair-production interaction is essentially the interaction of an electron with a photon, except with a positron leaving instead of an electron entering.

That sounds like a stretch. The interaction of an electron with a photon is Compton Scattering. You start with an electron and a photon, and that's what you're left with. Pair production is typically an interaction between a +1022keV photon and a nucleus. You start with a photon and a nucleus, and you end up with an electron, a positron, and a nucleus. OK it doesn't have to be a nucleus, but you can't perform pair production with a photon and an electron and be left with an electron and a positron.

Likewise, the annihilation interaction has a positron entering instead of an electron leaving. Look at the Feynman diagram for the processes -- the positron, the virtual electron, and the real electron form one line with the photon lines coming off of it.

Do you mean this one?



You can turn it upside down for a photon-photon interaction resulting in the creation of an electron and a positron, but that virtual electron is virtual, and I still can't see how the interactions are similar. Maybe I'm misunderstanding your point here?

Projecting classical intuitions onto quantum mechanics again. Electrons don't have gyroscopes attached to give them their spins. An electron field is a 4-component spinor field, and the spin resides in the spinorness. Likewise, a photon field is a 4-component vector field, and the spin resides in the vectorness.

And you can convert one photon into an electron and a positron. That "spinorness" came from somewhere, the energy/momentum isn't going past you at c any more, and you've now got two opposite chiral particles with angular momentum and mass. The spinor field is a real rotation of stress-energy in space, and because it's essentially "light" and light travels in straight lines, the space must now be curved.

To see why, let's rotate a vector [A+, A0, A-] and a spinor [X+,X-] by angle a around the z-axis:

[A+, A0, A-] -> [exp(i*a)*A+, A0, exp(-i*a)*A-]
[X+, X-] -> [exp(i*a/2)*X+, exp(-i*a/2)*X-]

Note: A+ = (Ax + i*Ay)/sqrt(2), A- = (Ax - i*Ay)/sqrt(2), A0 = Az

Since in quantum mechanics, rotation and angular momentum are closely related, it's easy to see where the angular momentum comes from.

I can't see your point here. The difference is the /2 for the spinor, a spinor is a rotating vector, and an electron has spin 1/2 like the moebius strip.
Sorry I must go, but re your comment:

So you want to publish on some heterodox theory of particle physics by appealing to physicists in other fields? I hope that the journal editors catch that lame end run.

No, I don't. I want people in particle physics to understand what I'm saying and make use of it. I know how gravity unifies. I'm really not kidding about that.

[colubridae]

So you want to publish on some heterodox theory of particle physics by appealing to physicists in other fields? I hope that the journal editors catch that lame end run.

No, I don't. I want people in particle physics to understand what I'm saying and make use of it. I know how gravity unifies. I'm really not kidding about that.

So why are you posting at every forum around except peer-reviewed publications like Nature?

You do sprinkle your stuff with real science, then mix it up with gibberish...

It's puzzling why... Do you derive somehting from mixing drivel with real science and confusing lesser mortals?
It's very reminiscent of mandelson.

I don't mean it nastily but what do you gain from these posts. Truly I am interested. You even accused me of being a creationist.

[lpetrich]

The masslessness refers to its zero rest mass.

Because a photon isn't at rest.

It doesn't have to ever be at rest. The relativistic energy-momentum relation is

E2 = p2 + m2

using c = 1, energy E, momentum p, and rest mass m. For a photon, E = |p|, meaning that m = 0. Farsight, you'll make professional physicists LOL.

We don't do physics by hero-thumping.

Come off it. That's a perfectly valid reference to the original E=mc² paper.

But what's so special about it? From the looks of it, it doesn't look like Einstein disagrees with other physicists about its interpretation.

The pair-production interaction is essentially the interaction of an electron with a photon, except with a positron leaving instead of an electron entering.

That sounds like a stretch. The interaction of an electron with a photon is Compton Scattering. You start with an electron and a photon, and that's what you're left with. Pair production is typically an interaction between a +1022keV photon and a nucleus. You start with a photon and a nucleus, and you end up with an electron, a positron, and a nucleus. OK it doesn't have to be a nucleus, but you can't perform pair production with a photon and an electron and be left with an electron and a positron.

Farsight, you need a course in Feynman Rules 101. The following are all equivalent on a particle level:
e + gam -> e
e -> e + gam
e* + gam -> e*
e* -> e* + gam
gam -> e + e*
e + e* -> gam

e = electron, e* = positron, gam = photon (gamma)

One similarly finds that pair production and pair annihilation are particle-level equivalents of Compton scattering.

Projecting classical intuitions onto quantum mechanics again. Electrons don't have gyroscopes attached to give them their spins. An electron field is a 4-component spinor field, and the spin resides in the spinorness. Likewise, a photon field is a 4-component vector field, and the spin resides in the vectorness.

And you can convert one photon into an electron and a positron.

Farsight, that is just plain irrelevant.

That "spinorness" came from somewhere,

The spinorness is a four-component structure, not some added-on gyroscope.

the energy/momentum isn't going past you at c any more,

Another irrelevant remark.

So you want to publish on some heterodox theory of particle physics by appealing to physicists in other fields? I hope that the journal editors catch that lame end run.

No, I don't. I want people in particle physics to understand what I'm saying and make use of it. I know how gravity unifies. I'm really not kidding about that.

You're not going to get particle physicists to take you seriously if you keep on making elementary mistakes and if you keep on refusing to accept that you have done so.

[Farsight]

So why are you posting at every forum around except peer-reviewed publications like Nature?

Because it's good to talk. And I like to stick my oar in when I see people talking about woo like time travel.

You do sprinkle your stuff with real science, then mix it up with gibberish.

There isn't any gibberish. It's all real science.

It's puzzling why... Do you derive somehting from mixing drivel with real science and confusing lesser mortals? It's very reminiscent of mandelson. I don't mean it nastily but what do you gain from these posts. Truly I am interested. You even accused me of being a creationist.

I get the satisfaction of knowing I'm doing my bit for physics. I accused you of behaving like a creationist, not being a creationist. Those guys just won't look at scientific evidence and they won't think things through because they suffer from deep-seated conviction. This behavioural trait is not unique to creationists. You see people who obviously know a bit about physics believing in time travel when there's absolutely no evidence for it whatsover. Try to tell them about time, try to get them to look at what a clock clocks up, and they just ain't having it. There's something similar going on with string theory. It's pseudoscience, it predicts nothing, there's no evidence for it, it's been going for forty years, and people believe in it.

[Farsight]

It doesn't have to ever be at rest. The relativistic energy-momentum relation is

E2 = p2 + m2

using c = 1, energy E, momentum p, and rest mass m. For a photon, E = |p|, meaning that m = 0. Farsight, you'll make professional physicists LOL.

LOL, lpetrich, you're being evasive and simplistic. Before pair production the mass term is zero, after pair production when you're comoving with the electron, the momentum term is zero. After annihilation the mass term is zero again. It's a flip-flop that gives an experimental demonstration of the symmetry between momentum and inertia.

But what's so special about it? From the looks of it, it doesn't look like Einstein disagrees with other physicists about its interpretation.

What's special about it is that you can apply it to the photon and the electron in pair production and annihilation, and understand mass. The difference between momentum and inertia depends only on motion. A self-trapped photon has mass instead of momentum because it isn't going anywhere.

Farsight, you need a course in Feynman Rules 101. The following are all equivalent on a particle level:
e + gam -> e
e -> e + gam
e* + gam -> e*
e* -> e* + gam
gam -> e + e*
e + e* -> gam

Compton, inverse Compton, positron Compton, positron Inverse Compton, pair production, and annihilation, where we usually see gam gam. Simple stuff. Sounds to me as if you're using mathematics as a shield to avoid understanding the electron.

One similarly finds that pair production and pair annihilation are particle-level equivalents of Compton scattering.

You're fooling yourself, and you are the easiest person to fool. They simply aren't the same, and in no way are they equivalent. Pair production creates your "spinorness". It creates the electron. It creates mass and charge, because the photon is no longer moving laterally at c. Instead it's going round at c. That's why the electron has its angular momentum and magnetic dipole moment. Chuck another photon at it and it acquires action and an additional velocity vector so the component photon then moves in a helical path. Keep on adding to it and you're straightening out the path more and more. Indeed, that means Compton scattering is the opposite of pair production.

Farsight, that is just plain irrelevant.

No, it isn't. It gets to the heart of it. Pair production is key, and you just can't see it.

The spinorness is a four-component structure, not some added-on gyroscope.

Make a photon spin in two orientations, and you've created a stable structure. The electron isn't some spinning billiard ball, it's a photon with two orientations of spin like a steering wheel and a smoke ring. Only we don't call it a photon any more, we call it an electron. Or a positron. Conservation of angular momentum applies, which is why you have to make a positron too.

the energy/momentum isn't going past you at c any more,

Another irrelevant remark.

This is how it works Ipetrich. Come on, wake up. The mass of a system is a measure of its energy content. A photon in a mirror-box really adds mass to that system, because its aggregate motion is zero. Then when you let it out of the box, the mass diminishes, just like that original Einstein paper. Annihilation lets the photons out of their "boxes", called the electron and the positron. Then there's nothing left, because the photon was trapped in a "box" of its own making. It's simple, come on man, think.

You're not going to get particle physicists to take you seriously if you keep on making elementary mistakes and if you keep on refusing to accept that you have done so.

I'm not making elementary mistakes, lpetrich. There is no motion in time. Now please go and read Time Explained,

[Farsight]

See how it works colubridae? You try to show a guy some crucial evidence, and he dismisses it and says it's irrelevant. Then when you ask him what's actually happening in pair production, he can't explain it himself, and all he does is throw runes at you.

[lpetrich]

(me on the relativistic energy-momentum relation...)

LOL, lpetrich, you're being evasive and simplistic. Before pair production the mass term is zero, after pair production when you're comoving with the electron, the momentum term is zero. After annihilation the mass term is zero again. It's a flip-flop that gives an experimental demonstration of the symmetry between momentum and inertia.

AN exercise in irrelevance.

Compton, inverse Compton, positron Compton, positron Inverse Compton, pair production, and annihilation, where we usually see gam gam. Simple stuff. Sounds to me as if you're using mathematics as a shield to avoid understanding the electron.

On the contrary, it gives a successful understanding of the electron, along with other elementary fermions. You've been evading the task of deriving Maxwell's equations, the Dirac equation, and the electron-photon vertex from your theories.

One similarly finds that pair production and pair annihilation are particle-level equivalents of Compton scattering.

You're fooling yourself, and you are the easiest person to fool. They simply aren't the same, and in no way are they equivalent. Pair production creates your "spinorness". It creates the electron. It creates mass and charge, because the photon is no longer moving laterally at c. Instead it's going round at c. That's why the electron has its angular momentum and magnetic dipole moment. Chuck another photon at it and it acquires action and an additional velocity vector so the component photon then moves in a helical path. Keep on adding to it and you're straightening out the path more and more. Indeed, that means Compton scattering is the opposite of pair production.

Farsight, you don't know what you are talking about. Pair production, pair annihilation, and scattering are all versions of one interaction, expressed with this term:

4-current: ji = (sum over elementary fermions) charge * (psi-bar . gammai . psi) + (similar terms for other sorts of particles)
Vertex: - ji Ai

psi = creates an elementary fermion or destroys its antiparticle.
psi-bar = destroys an elementary fermion or creates its antiparticle.
A = creates or destroys a photon.

Pair production is key, and you just can't see it.

Pair production is NO problem for mainstream quantum field theory.

The electron isn't some spinning billiard ball, it's a photon with two orientations of spin like a steering wheel and a smoke ring.

Empty assertion.

A photon in a mirror-box really adds mass to that system, because its aggregate motion is zero. Then when you let it out of the box, the mass diminishes, just like that original Einstein paper.

'
The extra mass of that box has nothing to do with the photon's "aggregate motion", whatever that is. It's due to that photon's energy content.

Annihilation lets the photons out of their "boxes", called the electron and the positron. Then there's nothing left, because the photon was trapped in a "box" of its own making. It's simple, come on man, think.

Empty assertion.

There is no motion in time. Now please go and read Time Explained,

I've never heard of that book.

[Twiglet]

Photons are electrons, and time doesn't exist.

This thread has some first class entertainment value

[Nautilidae]

Photons are electrons, and time doesn't exist.

This thread has some first class entertainment value

No, you imbecile; electrons are photons. It makes much more sense now.

[owtth]

Photons are electrons, and time doesn't exist.

This thread has some first class entertainment value

No, you imbecile; electrons are photons. It makes much more sense now.

Ah, I was getting all confused there for a second

[Farsight]

lpetrich: the extra mass of that box is due to the photon's energy/momentum content, which is trapped in the box. The photon is still moving at c, but back and forth, so it isn't going anywhere, so on aggregate its motion is zero. That's why the momentum now appears as inertia. And it's the same after pair production. The 511keV electron has mass because it's like a photon trapped in a box. Only there is no box. It's a photon that's trapped by itself.

But I suppose we'll have to agree to differ because you can't see the obvious. And won't.

Guys: time exists like heat exists.