Merged Relativity+ / Farsight

[ben m]

When Farsight gets back perhaps he could address one of the more interesting particle-like properties of fermions and bosons: The Hanbury Brown and Twiss effect. This can only happen for objects with spin (i.e. not waves!).

RC, this is 100% wrong. The HBT effect for light, though usually explained in terms of photon correlation functions, was already known from pure classical electromagnetism---it CAN happen for waves. The connection to "spin" is that the HBT bunching effect is present only for bosons; contrary to your assertion not all bosons have nonzero spin. It's been observed with light (spin 1) and with neutral pions (spin 0).

 

[Senex]

Sorry, Senex, but you have obviously not read anything in that thread .
The contents have little to do with the topic. It is the pseudo-astrology fantasies of the thread creator (Dutch) who in 7 years has not even been able to describe "Hyper" "Dimensional " or even "Design" coherently or his actual "HDDesign" theory. Dutch basically makes dates up out of thin air and associates them with news stories that he thinks are important to him. For example one of his "predictions" is "Death of the Sun King" happening every so often where he does not get it right (he had Mandela dead months before his death) and death is not even death (some politician got ill)!

OK, I'll grant Dutch falls under the same category.

So successful trolling is your measure of merit?
Whatever floats your boat, I guess, but there's no reason for the rest of us to be impressed by it.

Ask not for whom the boat floats -- for it floats for thee.

That's my aggravating way of saying you've posted on this thread more than I have.

In light of this, further down in your post: "Myself, I have a gift for aggravating people. Really. I can read almost any post and know how to reply in a way that will catch someone's attention. I've showed that ability off. " you'll understand, I'm sure, why your 'marketing fluff' (or is it 'snake oil sales spin'?) left me somewhat unconvinced.

It's woo-woo. I like to shorten it to woo myself.

Sorry, I'm not buying it, not even for a millisecond.

However, in case any other reader doesn't understand what I mean, here's the outline of an example:

Imagine you're teaching electromagnetism, perhaps somewhat similarly to the example W.D.Clinger provided upthread. As an exercise to really make the material sink in, you get a volunteer (among your students) to prepare a rebuttal of a selection of Farsight's material on electromagnetism (there's plenty in this thread to choose from), and present it to the class. In order to do a good job, the volunteer needs to have really understood what you taught, to be able to find the relevant source material (e.g. Maxwell's papers), and show mastery of the key underlying physics and mathematics (oh, and be able to present well too).

There are many variations: a small group project (rather than a single volunteer); invite Farsight to join in the presentation (via Skype?); task specified very tightly or in a quite open fashion; add historical context (e.g. mathematics of Maxwell's day -> full tensor etc treatment); ...

Yes, now I understand. Unlike W.D.Clinger's experience my experience has been teaching inner-city English and history to middle school children. They aren't ready for Farsight yet.

 

[DeiRenDopa]

Yes, now I understand. Unlike W.D.Clinger's experience my experience has been teaching inner-city English and history to middle school children. They aren't ready for Farsight yet.

OK.

Why not try a variant of this 'strange' multiple choice question then?

What is the electron? Is it
a) a wave?
b) a particle?
c) neither a wave nor a particle?
d) both a wave and a particle?
e) none of the above?
f) all of the above?

Good for teaching logic and the role of definitions in physics (though of course you don't need to go that deep for your students). Farsight has written much on this topic, so you have a lot of pseudoscience material for your students to work with, in terms of rebuttal.

And if, perchance, you yourself don't know the answer, then finding out (and understanding it well enough so you could teach it) would be a great learning experience for you, wouldn't it?

 

[Senex]

OK.

Why not try a variant of this 'strange' multiple choice question then?

What is the electron? Is it
a) a wave?
b) a particle?
c) neither a wave nor a particle?
d) both a wave and a particle?
e) none of the above?
f) all of the above?

Good for teaching logic and the role of definitions in physics (though of course you don't need to go that deep for your students). Farsight has written much on this topic, so you have a lot of pseudoscience material for your students to work with, in terms of rebuttal.

And if, perchance, you yourself don't know the answer, then finding out (and understanding it well enough so you could teach it) would be a great learning experience for you, wouldn't it?

You are not the first person who has seen the benefits of teaching the scientific method to children. I have a laundry detergent comparison test they have to pass before they move on to physics, however.

 

[Reality Check]

RC, this is 100% wrong.

Perhaps I can put that better:
The The Hanbury Brown and Twiss effect is that there is bunching of bosons (an enhanced probability of detection coincidences) and anti-bunching (a decreased probability of detection coincidences) of fermions compared to the result for classical particles.
It has been observed for photons (spin 1), neutral pions (spin 0) and electrons (spin 1/2).

If you have single particle sources then in QM you get photon antibunching where there is a gap between detecting photons. But this cannot be explained using waves.
More fully explained in Why Antibunching Equals Photons.

Thus photons are not classical particles and are not classical waves.

The position with electrons does not seem as clear. HBT says they are not classical particles. I cannot find any theory or experiments for electron "antibunching" for single particle sources.

 

[ben m]

Thus photons are not classical particles and are not classical waves.

You're not too far from the truth, in that:

a) You've stated agreement at the conclusion you expected to agree with ("there is evidence for QM"), which happens to be correct

b) You seem to have learned some information from sources about real phenomena, from sources which happen to be correct

but I don't think you are anything close to correct in deriving (a) from (b). You are talking about experiments with photon detectors---i.e., energy that propagated in a wavelike manner, arrived at the detectors in a quantized manner---which is already sufficient justification for rejecting the classical-wave and classical-particle explanations.

On the other hand, I could build a classical particle source with either sub-Poissonian, or Poissonian, or super-Poissonian particle-particle correlation statistics. I can build a classical wave source with either Poissonian or super-Poissonian intensity-intensity correlation statistics, depending on the choice of what type of noise I modulate with. (Sub-Poissonian sounds impossible at first glance.)

Yes, it's true that the complete experiments are done in fully-QM systems, and explained using QM, and the results are compatible with QM, including compatibility with the (already well-tested) spin-statistics theorem which was an early success of QFT. But

My general point is: it is not true that you can look up random modern physics results, read an explanation that uses QM, and say "this result is evidence for QM." There's plenty of clear evidence for QM, spin, spin-statistics, etc., in the world of experiments that I'm sure you understand correctly (and can attempt to explain to Farsight if you feel like it). I'm happy to talk more about HBT but would not recommend your attempting to explain it to Farsight.

 

[ctamblyn]

(Replying to a post from another thread, since it is on the topic of this thread.)

Yes we will. Now go and find out about the screw nature of electromagnetism and the right-hand rule and the relationship between electromagnetism and gravitomagnetism and electromagnetic geometry. Don't try to portray it all as "my crackpot idea" and dismiss/censor all the references and quotes just because you don't know about it. OK? Right, I've said my piece on this. Over and out.

How about you provide some credible references that support your assertion that the electromagnetic field is due to a twisting/turning of three dimensional space, instead of (a) references that don't support that assertion (but perhaps contain a couple of "magic words" like "screw" and "magnet"), (b) mere repetition of your unsupported assertions, and (c) Google search results?

And since I'm bumping this thread anyway, perhaps you could answer this question from earlier?

To return to another sub-topic which I'd prefer didn't get dropped just yet - perhaps when you return from your 2-week suspension you could get around to addressing the lack of predictive power of these loopy photon models?

 

[Farsight]

I have to go, but for now: Do you accept that gravitomagnetism involves twisted space?

I will remind you that this NASA gravitomagnetism article includes this sentence:

"But if space is twisted, the direction of the gyroscope's axis should drift over time".

I'll talk more about toroidal-photon electron models another time.

 

[ctamblyn]

I have to go, but for now: Do you accept that gravitomagnetism involves twisted space?

First, note that it involves curved space-time, not just "twisted space".

Second, I hope you appreciate that what you're talking about is a sometimes-useful approximation and analogy, and definitely not something equivalent to GR in its full gory detail. It has about the same level of fundamental physical significance as the river analogy for black holes that you objected to some time back.

A bit of background, if anyone's interested: for sufficiently small disturbances to a given background gravitational field, you can come up with a set of approximate but easy-to-handle equations for how those disturbances evolve (ignoring things like the waves carrying energy and thus themselves acting as sources of fields). If you fiddle with these a little you can obtain a set of equations which bear quite a resemblance to Maxwell's equations, albeit with a couple of significant sign differences, and the Lorentz force law.

The couple of significant differences I mentioned are to do with the fact that gravity is always attractive between two "charges" (i.e. masses), while electromagnetism can be repulsive. There are several other significant differences between the two theories; a couple of key ones are:

1. In full GR, gravitational waves can interact directly with each other in complex ways that electromagnetic waves cannot. This is due to the non-linearity of Einstein's theory (Maxwell's equations, on the other hand, are linear).
2. All gravitational test "charges" (i.e. very tiny masses) fall at the same rate through a gravitational field, as famously demonstrated by Galileo. This is not remotely true of test charges in an electromagnetic field, which instead experience accelerations proportional to their charges.

 

[Reality Check]

I have to go, but for now: Do you accept that gravitomagnetism involves twisted space? \

Farsight:
You need to not lie about the contents of the news release NASA Announces Results of Epic Space-Time Experiment

May 4, 2011: Einstein was right again. There is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity.

Researchers confirmed these points at a press conference today at NASA headquarters where they announced the long-awaited results of Gravity Probe B (GP-B).

"The space-time around Earth appears to be distorted just as general relativity predicts," says Stanford University physicist Francis Everitt, principal investigator of the Gravity Probe B mission

No mention of gravitomagnetism appears there.
The simple fact is that frame dragging "twists" spacetime in GR.

Gravitomagnetism is merely the observation that in limited cases the equations of GR have an analogy with the equations of EM. Gravity Probe B happens to be such a situation so the general case of frame dragging reduces to the special case of gravitomagnetism. This is easily found in the literature or even NASA press releases !

Is the electron a photon with toroidal topology? (PDF) has been discussed here before. so there is no need to go over your obsession with this debunked model yet again .

 

[ctamblyn]

...
Is the electron a photon with toroidal topology? (PDF) has been discussed here before. so there is no need to go over your obsession with this debunked model yet again .

Well, there's still a little more to address. I'm still waiting for Farsight's answer to this request from about four weeks back:

To return to another sub-topic which I'd prefer didn't get dropped just yet - perhaps when you return from your 2-week suspension you could get around to addressing the lack of predictive power of these loopy photon models?

 

[Farsight]

Please can somebody do the decent thing and put Reality Check straight? As usual.

First, note that it involves curved space-time, not just "twisted space".

I know all about curved space-time. And I think we maybe need to talk about that, because I'm thinking you misunderstand it.

Second, I hope you appreciate that what you're talking about is a sometimes-useful approximation and analogy, and definitely not something equivalent to GR in its full gory detail.

Oh I do. I've referred to Heaviside's 1893 paper A gravitational and electromagnetic analogy and quoted bits at you like this: "Then in the electrical case the magnetic force follows the lines of latitude with positive rotation about the axis".

It has about the same level of fundamental physical significance as the river analogy for black holes that you objected to some time back.

The waterfall analogy is utter trash. Heaviside's analogy isn't.

A bit of background, if anyone's interested: for sufficiently small disturbances to a given background gravitational field, you can come up with a set of approximate but easy-to-handle equations for how those disturbances evolve (ignoring things like the waves carrying energy and thus themselves acting as sources of fields). If you fiddle with these a little you can obtain a set of equations which bear quite a resemblance to Maxwell's equations, albeit with a couple of significant sign differences, and the Lorentz force law.

The couple of significant differences I mentioned are to do with the fact that gravity is always attractive between two "charges" (i.e. masses), while electromagnetism can be repulsive.

I'm not fond of the concept of "gravitational charge".

There are several other significant differences between the two theories; a couple of key ones are:

1. In full GR, gravitational waves can interact directly with each other in complex ways that electromagnetic waves cannot. This is due to the non-linearity of Einstein's theory (Maxwell's equations, on the other hand, are linear).
2. All gravitational test "charges" (i.e. very tiny masses) fall at the same rate through a gravitational field, as famously demonstrated by Galileo. This is not remotely true of test charges in an electromagnetic field, which instead experience accelerations proportional to their charges.

All good stuff. But I was referring to the relationship between electromagnetism and gravitomagnetism, not to the relationship between electromagnetism and gravity.

Hmmn. You know, I think we need to talk about gravity. We need to further your ed-u-cay-shun on that before we can teach you about gravitomagnetism and electromagnetism. But JREF is going slow and I have to go. Bye for now. Meanwhile don't go into denial about that twisted space. I didn't make it up.

 

[edd]

Including a bit of extra context in the usual quotation due to the thread-jump here.

Originally Posted by edd
"The expansion (or not) of a universe is not governed by the mechanical action of pressure. Regardless of whatever analogy Phil might have made to such a thing."
It's a combination of pressure and tension edd. Perhaps you'd like to start a thread on that and we can talk further about it. But not now, I really have to go.

If we started a thread every time we disagreed there'd be a lot of threads, so I'll stick to this old one.
The large scale evolution of the universe is controlled by gravity, as can be seen in the Friedmann equations and their evolution. A pressure term does enter, but not due to its mechanical action on other matter nearby. Saying

In an infinite universe the pressure at one location is counterbalanced by the pressure at another location. At all locations. So the pressure remains confined and the universe doesn't expand.

is just wrong.

 

[ctamblyn]

...
I know all about curved space-time.
...

I think your arguments really do tend to suggest otherwise.

Second, I hope you appreciate that what you're talking about is a sometimes-useful approximation and analogy, and definitely not something equivalent to GR in its full gory detail.

Oh I do.
...

Great!

The waterfall analogy is utter trash. Heaviside's analogy isn't.

Heaviside's interesting (at the time) speculations have of course been superceded by the approximation scheme in GR which I described above. Let's not muddy the waters with his outdated model, and just stick to gravitoelectromagnetism (henceforth "GEM", and I'll abbreviate plain electromagnetism to "EM").

That aside, I find it very interesting that you cleave so tightly to the analogy which is only ever an approximation, but reject with such vehemence the one which is actually exact in the few situations where it applies. I have to wonder whether you have properly grasped either.

I'm not fond of the concept of "gravitational charge".

Hmm, I think that calls your claim to understand the GEM-EM analogy into serious doubt. Did you realise that your sentence above is exactly synonymous with "I'm not fond of the concept of mass"?

(ETA: And I have to ask this general question: why would your fondness for an idea have any relevance at all in a rational argument about its value?)

All good stuff. But I was referring to the relationship between electromagnetism and gravitomagnetism, not to the relationship between electromagnetism and gravity.

Ah, you think the differences I mentioned are irrelevant to the GEM-EM analogy. Let me clarify.

Let's start with the second difference. The fact that test masses all fall at the same rate in gravitational fields while test charges accelerate at different rates in electromagnetic fields is just as valid in GEM as it is in full GR. My apologies - I assumed you would already know this.

Now for the first difference (the non-linearity of GR vs. the linearity of EM). This should serve to remind us that what underlies GEM is radically different from what underlies EM, and that the equations of GEM (unlike those of EM) are applicable only to small perturbations of a background field. An amusing aside: to be consistent with your comments on local flatness earlier in this thread (e.g. see the last paragraph of this post), perhaps you should now be proclaiming that "this means they don't apply at all!"

Both differences (and there are also many others) demonstrate that the GEM analogy is, like all analogies, limited. It would be unwise to take it too seriously, just as it would be unwise to take the waterfall analogy too seriously (a statement with which I'm sure you agree).

 

[W.D.Clinger]

First let me apologize to Farsight for underestimating his knowledge of vector calculus. Although his level of maths was A level in 2007, he has assured me he now understands the mathematical notations employed by Maxwell's equations.

We need to further your ed-u-cay-shun

Fantastic. I'm hoping you can help me to understand this paper you're citing:

Second, I hope you appreciate that what you're talking about is a sometimes-useful approximation and analogy, and definitely not something equivalent to GR in its full gory detail.

Oh I do. I've referred to Heaviside's 1893 paper A gravitational and electromagnetic analogy and quoted bits at you

Oliver Heaviside was notoriously cavalier in his attitude toward rigor in mathematics, so I checked his equations as I read the paper. I don't see how he gets from equation (8) to equation (9):

Now if we multiply (5) by e, we obtain

e∙(∇×h) = e∙(ρu) - e∙c ∂_te, (8)​

or, which is the same,

∇∙(e×h) = F∙u - ∂_tU, (9)​

if U = ce²/2.

For those who lack Farsight's familiarity with this paper,

e∙(ρu) = F∙u​

follows immediately from equation (1) and

e∙c ∂_te = ∂_tU​

follows from the chain rule, so Heaviside is claiming

e∙(∇×h) = ∇∙(e×h)​

I'm sure you see the problem. Applying the identity

∇∙(A×B) = B∙(∇×A) - A∙(∇×B)​

to the right hand side tells me Heaviside's claim is incorrect unless

h∙(∇×e) = 2 e∙(∇×h)​

I'm just not seeing why that must be so.

The waterfall analogy is utter trash. Heaviside's analogy isn't.

I'm not saying Heaviside's paper is trash. I'm asking for your help in seeing why this step of Heaviside's derivation isn't trash.

The vector field h does bear a relationship to the vector field e that might somehow justify Heaviside's claim. I'm hoping your knowledge of this particular paper, combined with your knowledge of vector calculus and willingness to educate us, will save me from concluding that Heaviside made a mistake at this critical step of his derivation.

 

[ben m]

Here's a statement from Heaviside that may interest Farsight:

It is not known that there are no magnetons, but rather that, if there be any, they are in pairs like the ions and cannot dissociate as far as can be concluded from div.B = 0. ... I think it wise not to be overhasty in rejecting terms in the circuital equations because magnetons do not exist.

What are magnetons? So-far-undiscovered particles which, if they exist, would cause div.B != 0? They're what we now call magnetic monopoles. Heaviside proceeds to write some electromagnetic wave calculations including the familiar monopole term.

 

[Vorpal]

A somewhat more faithful transcription of Heaviside's paper follows (Ụ should have dot above):

(2) e = ∇P​

...

(5) curl h = ρu - cė​

... Now if we multiplify (5) by e, we obtain

(8) e curl h = eρu - ecė,​

or, which is the same,

(9) conv Veh = Fu - Ụ,​

if U = ½ce². ... Consequently, the vector Veh expresses the flux of gravitational energy. More strictly, any circuital flux that may be added. This Veh is analogous to the electromagnetic VEH found by Poynting and myself. But there is a reversal of direction. ...

What's conv? Convergence is just the negative of divergence:

Let R denote the electrostatic force, and ρ the volume density of electricity then we may say 4πρ = -conv. R, or, = div. R, where we use conv. and div. as abbreviations...

Finally, the appearance of V is to indicate that vector product that follows it is the vector (i.e., cross) product rather than the scalar product, which is also consistent with the statement that VEH is the electromagnetic Poynting vector, S = E×H in modern notation. Therefore, the transcribed equation (9) should probably read

(9) -∇·(e×h) = F∙u - ∂U/∂t,​

which would be correct. The "reversal of direction" that Heaviside refers to would be that in the electromagnetic version has a different sign:

-∇·(E×H) = J∙E + ∂u/∂t.​

So Heaviside was not quite that careless after all. The transcribers of his paper, however, are somewhat more disappointing.

 

[W.D.Clinger]

I was hoping Farsight would take advantage of this opportunity to demonstrate his knowledge of vector calculus, but I guess he's been too busy promoting crackpottery in other threads. Vorpal answered first:

Therefore, the transcribed equation (9) should probably read

(9) -∇·(e×h) = F∙u - ∂U/∂t,​

which would be correct. The "reversal of direction" that Heaviside refers to would be that in the electromagnetic version has a different sign:

-∇·(E×H) = J∙E + ∂u/∂t.​

So Heaviside was not quite that careless after all. The transcribers of his paper, however, are somewhat more disappointing.

I knew equation (9) was wrong and strongly suspected it was missing a minus on its left hand side (becoming certain of that within ten minutes of asking Farsight's help), but I still wasn't sure whether the mistake was Heaviside's or Jefimenko's. I thank you for answering that question.

Farsight, as evidence for his mastery of electromagnetism and vector calculus, has often referred to his many quotations of a single sentence from page 558 of John David Jackson's Classical Electrodynamics, third edition. To return the favor he has done me by not responding to my request for the education he offered, I'll direct his attention to section 6.7 and equation (6.108), which is Jackson's statement of the electromagnetic equation Vorpal wrote above.

With that background, let's return to the out-of-context sentence fragment Farsight quoted to demonstrate his appreciation of ctamblyn's remark that gravitomagnetism "is a sometimes-useful approximation and analogy, and definitely not something equivalent to GR in its full gory detail." In this expanded quotation from Heaviside's paper, I have highlighted the missing minus sign in red, highlighted Farsight's quote-mine in brown, and highlighted the more important parts of that paragraph in blue:

Now if we multiply (5) by e, we obtain

e∙(∇×h) = e∙(ρu) - e∙c ∂_te, (8)​

or, which is the same,

= - ∇∙(e×h) = F∙u - ∂_tU, (9)​

if U = ce²/2. But ∂_tU represents the rate of exhaustion of potential energy, so - ∂_tU represents its rate of increase, whilst F∙u represents the activity of the force on ρ, increasing its kinetic energy. Consequently, the vector e×h expresses the flux of gravitational energy. More strictly, any circuital flux whatever may be added. This e×h is analogous to the electromagnetic E×H found by Poynting and myself. But there is a reversal of direction. Thus, comparing a single moving particle of matter with a similarly-moving electric charge, describe a sphere round each. Let the direction of motion be the axis, the positive pole being at the forward end. Then in the electrical case the magnetic force follows the lines of latitude with positive rotation about the axis, and the flux of energy coincides with the lines of longitude from the negative pole to the positive. But in the gravitational case, although h still follows the lines of latitude positively, yet since the radial e is directed to instead of from the centre, the flux of energy is along the lines of longitude from the positive pole to the negative. This reversal arises from all matter being alike and attractive, whereas like electrifications repel one another.

In Heaviside's inexact (pre-relativistic) analogy, the vector field e is analogous to the electric field E, and the vector field h is analogous to the magnetic field H.

Farsight continues to reject the legitimacy of E and H, even to the point of saying they are not fields. It is therefore extremely difficult for me to understand how Farsight could accept Heaviside's analogy.

I hope Farsight will explain whether he rejects the legitimacy of Heaviside's e and h in the same way he rejects E and H. If he does reject e and h, I hope he will explain why he accepts an analogy based upon fields he rejects. If he does not reject e and h, then I hope he will explain why Heaviside regards e and h as analogous to the vector fields Farsight rejects.

I doubt whether Farsight is any more willing to provide that requested explanation than he has been to demonstrate his mastery of vector calculus, but we can hope. This is, after all, an opportunity for him to teach us something about physics.

 

[ctamblyn]

A somewhat more faithful transcription of Heaviside's paper follows (Ụ should have dot above):
...

Brief aside: I found a slightly nicer electronic version here:

https://archive.org/stream/electromagnetict01heavrich#page/454/mode/2up

The section of interest begins on page 455.

 

[Farsight]

...The large scale evolution of the universe is controlled by gravity, as can be seen in the Friedmann equations and their evolution.

No it isn't. Absolutely not. Gravity alters the motion of light and matter through space, but it doesn't suck space in. And in a flat universe, there is no overall gravity.

A pressure term does enter, but not due to its mechanical action on other matter nearby. Saying

In an infinite universe the pressure at one location is counterbalanced by the pressure at another location. At all locations. So the pressure remains confined and the universe doesn't expand.

is just wrong.

No it isn't, edd. You're wrong.

If we started a thread every time we disagreed there'd be a lot of threads, so I'll stick to this old one.

It will be too confusing to discuss multiple topics in this thread. If you want to talk about this, start a thread and I'll explain what I can.