Author Topic: Veritasium -- How Special Relativity Makes Magnets Work.  (Read 25679 times)

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Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #150 on: April 09, 2022, 06:38:32 am »
Yes.  There are commercial sources for vacuum-compatible search coils that can sense a pulsed beam of charged particles flowing through the hole in the coil.
Here is one commercial source with several different coil configurations built into vacuum flanges:  https://www.bergoz.com/products/
A coil senses the time-derivative of the magnetic field around the beam, dBdt, as the pulsed beam goes through it.
Here is a tutorial from Fermilab about various "beam diagnostics", including measuring the field induced by the beam current, similar to how clamp-on ammeters measure normal AC through an insulated wire.
https://lss.fnal.gov/archive/2000/conf/Conf-00-119.pdf
It looks to me that sensing a pulsed beam is a measure of the change in magnetic field, rather than the measure or detection of a steady magnetic field. However, for a change in magnetic field then there has to be a magnetic field, & if so then mission accomplished i suppose. I will have to have a think.

Would one of thems gizmos detect a magnetic field around a wire carrying steady DC?
Has one?

If u made a steady electric DC circuit including a CRT type of device & wires, then the gizmo should detect the same magnetic field everywhere along the circuit.
Has this ever been done?
« Last Edit: April 09, 2022, 06:46:22 am by aetherist »
 

Offline thinkfat

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #151 on: April 09, 2022, 08:02:55 am »
Well, just expose the steady beam to a magnetic field of known strength and look at how it's deflected. Like, how a CRT works.
Everybody likes gadgets. Until they try to make them.
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #152 on: April 09, 2022, 02:08:35 pm »
Yes.  There are commercial sources for vacuum-compatible search coils that can sense a pulsed beam of charged particles flowing through the hole in the coil.
Here is one commercial source with several different coil configurations built into vacuum flanges:  https://www.bergoz.com/products/
A coil senses the time-derivative of the magnetic field around the beam, dBdt, as the pulsed beam goes through it.
Here is a tutorial from Fermilab about various "beam diagnostics", including measuring the field induced by the beam current, similar to how clamp-on ammeters measure normal AC through an insulated wire.
https://lss.fnal.gov/archive/2000/conf/Conf-00-119.pdf
It looks to me that sensing a pulsed beam is a measure of the change in magnetic field, rather than the measure or detection of a steady magnetic field. However, for a change in magnetic field then there has to be a magnetic field, & if so then mission accomplished i suppose. I will have to have a think.

Would one of thems gizmos detect a magnetic field around a wire carrying steady DC?
Has one?

If u made a steady electric DC circuit including a CRT type of device & wires, then the gizmo should detect the same magnetic field everywhere along the circuit.
Has this ever been done?

The usual clamp-on ammeter or current transformer is useful for AC current measurement.  The electrical circuit formed is basically a transformer, where the wire being sensed is the primary and the surrounding coil is a secondary.  Of course, transformer response does not extend down to DC.  The coils used to sense beam current are used in the same way, with the beam going through the center of the coil, like the wire in the current transformer case.  Note that the manufacturer I cited makes different models, one optimized for low frequencies and another optimized for fast pulse response.

To measure DC current in a non-contact manner there are two normal methods:  Hall effect sensor or flux-gate sensor.  The former uses the deflection of the drifting electrons in an external conductor from the magnetic field from the wire, and the latter is similar to a current transformer, but there are extra coils that excite the magnetic hysteresis of a ferromagnetic core and detect the second harmonic of the excitation frequency due to the magnetic flux from the current in the wire.  My classic -hp- 428A "clip-on milliammeter" is a good example of the flux gate.
« Last Edit: April 09, 2022, 02:13:15 pm by TimFox »
 

Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #153 on: April 09, 2022, 09:08:17 pm »
Yes.  There are commercial sources for vacuum-compatible search coils that can sense a pulsed beam of charged particles flowing through the hole in the coil.
Here is one commercial source with several different coil configurations built into vacuum flanges:  https://www.bergoz.com/products/
A coil senses the time-derivative of the magnetic field around the beam, dBdt, as the pulsed beam goes through it.
Here is a tutorial from Fermilab about various "beam diagnostics", including measuring the field induced by the beam current, similar to how clamp-on ammeters measure normal AC through an insulated wire.
https://lss.fnal.gov/archive/2000/conf/Conf-00-119.pdf
It looks to me that sensing a pulsed beam is a measure of the change in magnetic field, rather than the measure or detection of a steady magnetic field. However, for a change in magnetic field then there has to be a magnetic field, & if so then mission accomplished i suppose. I will have to have a think.

Would one of thems gizmos detect a magnetic field around a wire carrying steady DC?
Has one?

If u made a steady electric DC circuit including a CRT type of device & wires, then the gizmo should detect the same magnetic field everywhere along the circuit.
Has this ever been done?
The usual clamp-on ammeter or current transformer is useful for AC current measurement.  The electrical circuit formed is basically a transformer, where the wire being sensed is the primary and the surrounding coil is a secondary.  Of course, transformer response does not extend down to DC.  The coils used to sense beam current are used in the same way, with the beam going through the center of the coil, like the wire in the current transformer case.  Note that the manufacturer I cited makes different models, one optimized for low frequencies and another optimized for fast pulse response.

To measure DC current in a non-contact manner there are two normal methods:  Hall effect sensor or flux-gate sensor.  The former uses the deflection of the drifting electrons in an external conductor from the magnetic field from the wire, and the latter is similar to a current transformer, but there are extra coils that excite the magnetic hysteresis of a ferromagnetic core and detect the second harmonic of the excitation frequency due to the magnetic flux from the current in the wire.  My classic -hp- 428A "clip-on milliammeter" is a good example of the flux gate.
But, ignoring AC, ignoring wires, ignoring pulses – has a magnetic field ever been measured around an electron beam?
Here i am thinking an electron beam in a long glass tube.
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #154 on: April 09, 2022, 09:10:17 pm »
Yes:  using the appropriate coils around an electron beam in linear accelerators.  The vacuum chamber for the beam is usually metallic, not glass, but the coil can be placed inside the vacuum.  Note that the manufacturer I cited places his coils inside standard "ConFlat" high-vacuum flanges.
Re-reading the Bergoz catalog, I find one unit that goes down to DC, the "NPCT", which I assume is a flux-gate based instrument.  Its specs:
    Full Scale Range ±20 mA, ±200 mA, ±2 A and ±20 A
    Resolution down to 0.5 µA rms/√(Hz)
    Output Bandwidth from DC to 10 kHz (-3dB)
    Linearity error ≤ 0.1 %
It can be mounted outside the chamber, or supplied on ConFlat flanges to go inside the chamber.  (If outside a metallic chamber, there must be a gap to pass the magnetic field to the coil.)
Another unit, the "ACCT" is AC-coupled.  Its specs:
    Full Scale Range from ±1 mA to ±2 A
    Single Range or 3 Selectable-Range
    Resolution ≤ 1.5 µArms
    Droop ≤ 2 %/ms
    Bandwidth from 3 Hz to 1 MHz (-3dB)
The linear accelerator to accelerate electrons to a high kinetic energy is a mature field.  Industrial and medical units go up to around 25 MeV kinetic energy, but the big guys such as SLAC (3 km long) go up to 50 GeV.
« Last Edit: April 09, 2022, 09:20:41 pm by TimFox »
 

Offline penfold

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #155 on: April 09, 2022, 10:01:48 pm »
[...]
But, ignoring AC, ignoring wires, ignoring pulses – has a magnetic field ever been measured around an electron beam?
Here i am thinking an electron beam in a long glass tube.

Please (for your own sake) tread cautiously on this one, regardless of whether you approach it from a relativistic or pure-Maxwell, you must remember that there is an entire loop of circuit to consider. Remember that the total force on a charge (having velocity) near a beam of electrons is, in a Maxwellian sense, the sum of the forces due to the magnetic "field" and electric "field" whereas in the relativistic sense it is the total electric force from the charge's perspective. It adds up to the quantity in both cases, but it is not a simple sum to do in your head. In either case, it is an important distinction between, philosophically, whether you are considering the field, force or trajectory in, of, or around the beam.
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #156 on: April 09, 2022, 10:07:54 pm »
The probe coils used in electron-beam accelerators are shielded against electrostatic fields, and sense the magnetic field induced by the current passing through the center of the coil.
 

Offline penfold

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #157 on: April 09, 2022, 11:37:28 pm »
Ahh, yes, but the sheild must be transparant to the relativiistic effects as there is no relative motion wrt the fixed charges of the sensor of those of the hard-wired "fabric" elements of the electron beam's circuit... I think... its a bit late for me to be thinking about reference frames.
If the shield were a rotating disc or a cylinder rotating about an axis that intercepts that of the electron beam (but not parallel to and the geometry of the cylinder allowing passage of electrons through), the continuous motion of the cylinder (or disc) with facets of it passing through an apparently varying electric field (seeing, relatively, a non-linear beam current), the constant redistribution of charges would constitude a current visible in all reference frames... which might make an aetherist's head explode (the rate of redistribution being higher than drift velocity), but might make for an alternative interpretation of the Faraday disc.
 

Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #158 on: April 11, 2022, 10:22:56 pm »
Ahh, yes, but the sheild must be transparant to the relativiistic effects as there is no relative motion wrt the fixed charges of the sensor of those of the hard-wired "fabric" elements of the electron beam's circuit... I think... its a bit late for me to be thinking about reference frames.
If the shield were a rotating disc or a cylinder rotating about an axis that intercepts that of the electron beam (but not parallel to and the geometry of the cylinder allowing passage of electrons through), the continuous motion of the cylinder (or disc) with facets of it passing through an apparently varying electric field (seeing, relatively, a non-linear beam current), the constant redistribution of charges would constitude a current visible in all reference frames... which might make an aetherist's head explode (the rate of redistribution being higher than drift velocity), but might make for an alternative interpretation of the Faraday disc.
A DC beam in a long glass tube would be simpler.

But the spinning disc or cylinder reminds me of Kennard's version of the Faraday disc X where Kennard shows a falsification of the STR explanation for mmf around a current carrying wire.
http://www.conspiracyoflight.com/Kennard.pdf

Attached below are pages of Kennard's 1912 paper.
« Last Edit: April 12, 2022, 01:37:16 am by aetherist »
 

Offline penfold

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #159 on: April 12, 2022, 09:40:54 am »
Ahh, yes, but the sheild must be transparant to the relativiistic effects as there is no relative motion wrt the fixed charges of the sensor of those of the hard-wired "fabric" elements of the electron beam's circuit... I think... its a bit late for me to be thinking about reference frames.
If the shield were a rotating disc or a cylinder rotating about an axis that intercepts that of the electron beam (but not parallel to and the geometry of the cylinder allowing passage of electrons through), the continuous motion of the cylinder (or disc) with facets of it passing through an apparently varying electric field (seeing, relatively, a non-linear beam current), the constant redistribution of charges would constitude a current visible in all reference frames... which might make an aetherist's head explode (the rate of redistribution being higher than drift velocity), but might make for an alternative interpretation of the Faraday disc.
A DC beam in a long glass tube would be simpler.
[...]

That it would, but would it really show anything interesting?
The reason I suggested the off-axis rotating sheild is that it doesn't rely on metal-metal sliding contacts, so it is an experiment that may (or may not) operate on a similar underlying principal as the classic Faraday disc, but has a very different physical makeup and so relys on different sources of error and discrepancy.
 

Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #160 on: April 12, 2022, 08:04:26 pm »
Ahh, yes, but the sheild must be transparant to the relativiistic effects as there is no relative motion wrt the fixed charges of the sensor of those of the hard-wired "fabric" elements of the electron beam's circuit... I think... its a bit late for me to be thinking about reference frames.
If the shield were a rotating disc or a cylinder rotating about an axis that intercepts that of the electron beam (but not parallel to and the geometry of the cylinder allowing passage of electrons through), the continuous motion of the cylinder (or disc) with facets of it passing through an apparently varying electric field (seeing, relatively, a non-linear beam current), the constant redistribution of charges would constitude a current visible in all reference frames... which might make an aetherist's head explode (the rate of redistribution being higher than drift velocity), but might make for an alternative interpretation of the Faraday disc.
A DC beam in a long glass tube would be simpler.[...]
That it would, but would it really show anything interesting?
The reason I suggested the off-axis rotating sheild is that it doesn't rely on metal-metal sliding contacts, so it is an experiment that may (or may not) operate on a similar underlying principal as the classic Faraday disc, but has a very different physical makeup and so relys on different sources of error and discrepancy.
(1) A glass tube would show whether an electron beam makes a similar mmf to what is found around a wire carrying an electric current. Talking bout steady DC current.

(2a) A glass tube would show whether an electron beam makes an identical mmf to (2b) what is found around a wire carrying an electric current, if the wire is a part of that circuit. Talking bout steady DC current.

Apparently neither test has ever been done. We can be sure of that, koz, if it (one ovem)(or both) had ever been done, then thems who reckon that the sun shines out of Einstein's bum would be crowing about it from rooftops, but they aint, so it haznt.

No, i am wrong. They might be crowing if (1) shows an mmf. But they would not be crowing if (2a) equals (2b), koz (2a) has no protons that can length contract.
And, if they think about it, they shouldn’t be crowing re (1).
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #161 on: April 12, 2022, 08:12:07 pm »
The manufacturer of magnetic-field probes for beam diagnostics that I cited above makes probes for both use inside a vacuum chamber and outside a vacuum chamber.
I suggest you check their website   https://www.bergoz.com/products/  which is quite detailed, or the Fermilab tutorial on how to do such things that I cited  https://lss.fnal.gov/archive/2000/conf/Conf-00-119.pdf
before you assert that "neither test has ever been done".
Locally, you can call the Australian Synchrotron Laboratory  https://www.ansto.gov.au/research/facilities/australian-synchrotron/overview  and ask how they do beam diagnostics.
In large-scale labs, linear electron accelerators are no longer fashionable, but there are quite a few electron synchrotrons about, since they are useful for generating intense x-ray beams, and are good examples of special relativity in action.
Serious scientists and engineers do not "crow" about the application of settled physics to practical results, just if they discover something new or contrary to settled physics.  Were you expecting a YouTube video:  "As expected and predicted, magnetic field detected around high-current charged-particle beam in accelerator!"?
Particle accelerators, both linear and circular, are a very mature technology, dating back to Cockroft and Walton (1932) and Lawrence (1929).  There are commercial firms that supply instrumentation to the laboratories.
« Last Edit: April 12, 2022, 08:44:23 pm by TimFox »
 

Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #162 on: April 12, 2022, 09:08:52 pm »
The manufacturer of magnetic-field probes for beam diagnostics that I cited above makes probes for both use inside a vacuum chamber and outside a vacuum chamber.
I suggest you check their website   https://www.bergoz.com/products/  which is quite detailed, or the Fermilab tutorial on how to do such things that I cited  https://lss.fnal.gov/archive/2000/conf/Conf-00-119.pdf
before you assert that "neither test has ever been done".
Locally, you can call the Australian Synchrotron Laboratory  https://www.ansto.gov.au/research/facilities/australian-synchrotron/overview  and ask how they do beam diagnostics.
In large-scale labs, linear electron accelerators are no longer fashionable, but there are quite a few electron synchrotrons about, since they are useful for generating intense x-ray beams, and are good examples of special relativity in action.
Serious scientists and engineers do not "crow" about the application of settled physics to practical results, just if they discover something new or contrary to settled physics.  Were you expecting a YouTube video:  "As expected and predicted, magnetic field detected around high-current charged-particle beam in accelerator!"?
Particle accelerators, both linear and circular, are a very mature technology, dating back to Cockroft and Walton (1932) and Lawrence (1929).  There are commercial firms that supply instrumentation to the laboratories.
Faraday (Faraday Disc) proved that STR was wrong back in say 1831, 74 yrs before STR was invented in 1905.
Michelson & Morley (MMX) proved that STR was wrong in 1887, 18 yrs before 1905.
Kennard (Kennard coil version of Faraday Disc) proved that STR was wrong in 1912.

And if an aetherist (or anyone else) ever does that there (2a)(2b)(electron beam in glass tube) experiment then that too will prove that STR is wrong. 
Funny, there is no way that (2a)(2b) can confirm STR, it can only falsify STR.
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #163 on: April 12, 2022, 09:20:53 pm »
Once again, you are wrong.  The diagnostic equipment and beam testing procedures that I suggested you read clearly show that the magnetic field outside a beam of charged particles is identical to that outside a wire.
In a particle accelerator, one can compare the current with these magnetic sensors to the current that hits a Faraday cup (which suppresses the effect of secondary emission from the target).
Have you ever seen a particle accelerator, or read anything about them?
What do your countrymen at the Australian Synchrotron Lab say?

PS:  doing some elementary Googling, I found an interesting engineering thesis from Georgia Tech back in 1962:  https://smartech.gatech.edu/bitstream/handle/1853/14924/lineberger_william_c_196212_ms_69818.pdf?sequence=3&isAllowed=y 
The author discusses practical methods for measuring the magnetic field induced by a beam of charged particles without interrupting the beam.  Since this was already a physical phenomenon applied to practice in engineering, no one needed to crow about it.
« Last Edit: April 12, 2022, 10:13:41 pm by TimFox »
 

Offline PlainName

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #164 on: April 12, 2022, 10:12:47 pm »
Once again, you are wrong.

I have to say that I admire your patience and and continued good humour when engaging with aetherist, who clearly isn't here to learn but merely to tell everyone they are wrong about everything. A lesser person would have said harsh words and/or left to pursue an actual worthy cause many, many pages ago.

In fact, the only reason I am still watching this is to find out exactly where your limit is  >:D
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #165 on: April 12, 2022, 10:14:10 pm »
I'm approaching my limit rapidly.
I made my recent posts because I feared that a reader not familiar with the topic might believe that his un-supported statements that no one had measured the magnetic field around a charged-particle beam had any truth to them.
« Last Edit: April 12, 2022, 10:19:36 pm by TimFox »
 
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Offline YurkshireLad

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #166 on: April 12, 2022, 10:39:29 pm »
Once again, you are wrong.

I have to say that I admire your patience and and continued good humour when engaging with aetherist, who clearly isn't here to learn but merely to tell everyone they are wrong about everything. A lesser person would have said harsh words and/or left to pursue an actual worthy cause many, many pages ago.

In fact, the only reason I am still watching this is to find out exactly where your limit is  >:D

I'm waiting for the announcement of the published paper on the electon, this new world changing discovery, and also whether tin foil will protect me from aetherwind. Though maybe I simply need to change my diet.  :popcorn:
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #167 on: April 12, 2022, 11:09:08 pm »
It may be a while before it gets through normal peer review, unless they use abnormal peers.
 

Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #168 on: April 13, 2022, 12:47:34 am »
Once again, you are wrong.  The diagnostic equipment and beam testing procedures that I suggested you read clearly show that the magnetic field outside a beam of charged particles is identical to that outside a wire.
In a particle accelerator, one can compare the current with these magnetic sensors to the current that hits a Faraday cup (which suppresses the effect of secondary emission from the target).
Have you ever seen a particle accelerator, or read anything about them?
What do your countrymen at the Australian Synchrotron Lab say?

PS:  doing some elementary Googling, I found an interesting engineering thesis from Georgia Tech back in 1962:  https://smartech.gatech.edu/bitstream/handle/1853/14924/lineberger_william_c_196212_ms_69818.pdf?sequence=3&isAllowed=y 
The author discusses practical methods for measuring the magnetic field induced by a beam of charged particles without interrupting the beam.  Since this was already a physical phenomenon applied to practice in engineering, no one needed to crow about it.
But, if the magnetic field of a steady DC electron beam in vacuo (in a glass tube) is equal to the magnetic field of the wire supplying the steady DC, then this falsifies the STR explanation (ie that it is due to the length contraction of the wire), because there is no wire for the electron beam, there is only vacuum.
The vacuum contains spacetime, & i suppose that Einsteinists could claim that the space of the spacetime contracts, but that would i think require that the electrons spacings also contract, which would give the beam a double dose of negative charge, which is the opposite of what Einsteinists are looking for.
 

Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #169 on: April 13, 2022, 12:57:49 am »
Once again, you are wrong.
I have to say that I admire your patience and and continued good humour when engaging with aetherist, who clearly isn't here to learn but merely to tell everyone they are wrong about everything. A lesser person would have said harsh words and/or left to pursue an actual worthy cause many, many pages ago.

In fact, the only reason I am still watching this is to find out exactly where your limit is  >:D
I'm waiting for the announcement of the published paper on the electon, this new world changing discovery, and also whether tin foil will protect me from aetherwind. Though maybe I simply need to change my diet.  :popcorn:
A 2 page paper would do the job. Based on one little X involving the speed of electricity along a threaded rod compared to a plain rod. I would do it if i had access to a good scope.

Electons also hug a nucleus. Electons "orbit" a nucleus, electrons dont orbit.
Here the hugging force is due to the slowing of em forces near matter (ie protons & neutrons of the nucleus here)(the Cu of the wire in the case of the wire), plus the attraction of the protons (in the nucleus here).
« Last Edit: April 13, 2022, 12:59:32 am by aetherist »
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #170 on: April 13, 2022, 05:24:33 pm »
Once again, you are wrong.  The diagnostic equipment and beam testing procedures that I suggested you read clearly show that the magnetic field outside a beam of charged particles is identical to that outside a wire.
In a particle accelerator, one can compare the current with these magnetic sensors to the current that hits a Faraday cup (which suppresses the effect of secondary emission from the target).
Have you ever seen a particle accelerator, or read anything about them?
What do your countrymen at the Australian Synchrotron Lab say?

PS:  doing some elementary Googling, I found an interesting engineering thesis from Georgia Tech back in 1962:  https://smartech.gatech.edu/bitstream/handle/1853/14924/lineberger_william_c_196212_ms_69818.pdf?sequence=3&isAllowed=y 
The author discusses practical methods for measuring the magnetic field induced by a beam of charged particles without interrupting the beam.  Since this was already a physical phenomenon applied to practice in engineering, no one needed to crow about it.
But, if the magnetic field of a steady DC electron beam in vacuo (in a glass tube) is equal to the magnetic field of the wire supplying the steady DC, then this falsifies the STR explanation (ie that it is due to the length contraction of the wire), because there is no wire for the electron beam, there is only vacuum.
The vacuum contains spacetime, & i suppose that Einsteinists could claim that the space of the spacetime contracts, but that would i think require that the electrons spacings also contract, which would give the beam a double dose of negative charge, which is the opposite of what Einsteinists are looking for.

Your logic here is fallacious.
1.  It is well-established experimentally that current through a wire and current in a beam of charged particles induce a magnetic field B, according to the law of Biot and Savart that is later incorporated into Maxwell's Equations.
2.  Purcell published an explanation for a particular common case of current flowing through a metallic conductor, where the substantial magnetic field is induced despite the wire being electrically neutral.  There is some controversy about his derivation, some of which suggests that it is only useful as a pedagogical explanation.  However, quantitatively, it agrees with experiment.  He did not discuss this as an explanation for other situations of current, although he does say elsewhere in his textbook that there are other forms of current besides that in a wire.
3.  The case of a charged particle beam is a different configuration, since the beam itself is not electrically neutral and the velocity can easily be "relativistic" or "very relativistic" for an electron beam at a reasonable kinetic energy, while the drift velocity in Purcell's explanation is not so large.
4.  The experimental evidence for case 3 does not refute case 2, since the basic situations are different but the current is the same.

I can make fun of your logic with this analogy:
1.  Visible light is that portion of the electromagnetic spectrum that can be sensed by human vision.
2.  A common source of visible light is an incandescent light bulb, where current through the filament heats it to incandescence and much of the electromagnetic radiation emitted by the hot filament is visible.
3.  Another source of visible light is bioluminesence, produced by chemical processes within a living organism.  There is no external source of electricity to the firefly, and the firefly is not heated to incandescent temperatures.
4.  The experimental evidence of case 3 does not mean that case 2 does not emit visible light.

Note that one form of bioluminesence is "foxfire" in forest fungi.  I could claim that it was named in my honor, but it probably comes from the French "faux" for false.  An interesting coincidence is that the same phenomenon is named after foxes ("kitsunebi") in Japanese folklore.  See the Hiroshige print "New Year's Eve Foxfires at the Changing Tree, Oji, No. 118 from One Hundred Famous Views of Edo"  https://www.brooklynmuseum.org/opencollection/objects/121730
I tried to obtain a copy of this print, but had to settle for a museum-quality reproduction.
« Last Edit: April 13, 2022, 06:20:52 pm by TimFox »
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #171 on: April 13, 2022, 08:40:29 pm »
"A 2 page paper would do the job. Based on one little X involving the speed of electricity along a threaded rod compared to a plain rod. I would do it if i had access to a good scope."

In olden days, when impedances were higher (for use with vacuum tubes) and speeds were more leisurely, delay lines were made from coaxial cables where the solid center conductor was replaced by a tightly-wound helical coil.
As a transmission line, this increased the inductance per unit length substantially, with some increase in the capacitance due to dimensions.  This increased the characteristic impedance and the delay time per unit length, following the usual equations for coax cable.

Specifically, RG-65/U (still available in a later version) has:
     Polyethylene dielectric:  OD = 0.285 in
     Center conductor:  helix with ID = 0.11 in, 112 turns/in of AWG 32 (0.008 in diameter) wire.
     Core inside helix:  0.11 in diameter polyethylene.

Parameters:  Z0 = 950 ohms, velocity factor 29 time slower than solid polyethylene coax, delay time = 130 ns/m.

With such a slow, high-impedance construction, you shouldn't need a very expensive oscilloscope to compare it to a conventional coaxial cable.

Note that in 1965, more extreme cables were available that included a ferromagnetic core inside the helix (to increase the inductance) and lower-capacitance (thicker) dielectric.  Examples included:
(HH-1500A) 1500 ohms, 230 ns/m;  (RG-176/U) 2200 ohms, 9360 ns/m (?);  (DL1100) 1100 ohms, 1800 ns/m; (HH-4000) 3900 ohms, 3350 ns/m.

See:  J Millman and H Taub, Pulse, Digital, and Switching Waveforms, McGraw-Hill 1965.  Appendix B, pp 798 to 799.
 
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Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #172 on: April 13, 2022, 09:47:02 pm »
Once again, you are wrong.  The diagnostic equipment and beam testing procedures that I suggested you read clearly show that the magnetic field outside a beam of charged particles is identical to that outside a wire.
In a particle accelerator, one can compare the current with these magnetic sensors to the current that hits a Faraday cup (which suppresses the effect of secondary emission from the target).
Have you ever seen a particle accelerator, or read anything about them?
What do your countrymen at the Australian Synchrotron Lab say?

PS:  doing some elementary Googling, I found an interesting engineering thesis from Georgia Tech back in 1962:  https://smartech.gatech.edu/bitstream/handle/1853/14924/lineberger_william_c_196212_ms_69818.pdf?sequence=3&isAllowed=y 
The author discusses practical methods for measuring the magnetic field induced by a beam of charged particles without interrupting the beam.  Since this was already a physical phenomenon applied to practice in engineering, no one needed to crow about it.
But, if the magnetic field of a steady DC electron beam in vacuo (in a glass tube) is equal to the magnetic field of the wire supplying the steady DC, then this falsifies the STR explanation (ie that it is due to the length contraction of the wire), because there is no wire for the electron beam, there is only vacuum.
The vacuum contains spacetime, & i suppose that Einsteinists could claim that the space of the spacetime contracts, but that would i think require that the electrons spacings also contract, which would give the beam a double dose of negative charge, which is the opposite of what Einsteinists are looking for.

Your logic here is fallacious.
1.  It is well-established experimentally that current through a wire and current in a beam of charged particles induce a magnetic field B, according to the law of Biot and Savart that is later incorporated into Maxwell's Equations.
2.  Purcell published an explanation for a particular common case of current flowing through a metallic conductor, where the substantial magnetic field is induced despite the wire being electrically neutral.  There is some controversy about his derivation, some of which suggests that it is only useful as a pedagogical explanation.  However, quantitatively, it agrees with experiment.  He did not discuss this as an explanation for other situations of current, although he does say elsewhere in his textbook that there are other forms of current besides that in a wire.
3.  The case of a charged particle beam is a different configuration, since the beam itself is not electrically neutral and the velocity can easily be "relativistic" or "very relativistic" for an electron beam at a reasonable kinetic energy, while the drift velocity in Purcell's explanation is not so large.
4.  The experimental evidence for case 3 does not refute case 2, since the basic situations are different but the current is the same.

I can make fun of your logic with this analogy:
1.  Visible light is that portion of the electromagnetic spectrum that can be sensed by human vision.
2.  A common source of visible light is an incandescent light bulb, where current through the filament heats it to incandescence and much of the electromagnetic radiation emitted by the hot filament is visible.
3.  Another source of visible light is bioluminesence, produced by chemical processes within a living organism.  There is no external source of electricity to the firefly, and the firefly is not heated to incandescent temperatures.
4.  The experimental evidence of case 3 does not mean that case 2 does not emit visible light.

Note that one form of bioluminesence is "foxfire" in forest fungi.  I could claim that it was named in my honor, but it probably comes from the French "faux" for false.  An interesting coincidence is that the same phenomenon is named after foxes ("kitsunebi") in Japanese folklore.  See the Hiroshige print "New Year's Eve Foxfires at the Changing Tree, Oji, No. 118 from One Hundred Famous Views of Edo"  https://www.brooklynmuseum.org/opencollection/objects/121730
I tried to obtain a copy of this print, but had to settle for a museum-quality reproduction.
I don’t see any reason to change one word of anything i have written on this thread.

Re Purcell's STR explanation. I will now add that in his final step (of his derivation of the equation) he invokes a relativistic change in the Coulomb force to correct the force to a value seen in the stationary lab frame. However, in STR, charge has the same value in every frame, ie Einsteinists say that charge is invariant. But Purcell says that the force (due to charge) is not invariant. Smells fishy to me.

Earlier i pointed out Purcell's mistake/push that he did in his first step, & it looks to me that he adds another in his final step. I think that the 2 pushes are in the same direction, ie they don’t negate each other. If they negated then he would not need them.

Anyhow, its amazing how any kind of such STR analysis can get anywhere near the correct number.

If an aetherist applied a (neoLorentz) relativistic length contraction to the wire (instead of the silly Einsteinian length contraction) then nothing much would result.  The wire suffers a length contraction (& width contraction)(& so duz the observer) due to the aetherwind passing throo the wire (& throo the observer). This physical real absolute contraction affects everything in & on the wire, which duznt much affect or explain any charge or voltage or amperage etc. The observer might need to correct her numbers depending on her velocity & the velocity of the wire, but this kind of correction due to change of frame could never be invoked to explain any phenomenon (that i can think of).
« Last Edit: April 13, 2022, 09:51:04 pm by aetherist »
 

Offline TimFox

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #173 on: April 13, 2022, 10:08:22 pm »
I didn't think you would change anything.
I just preach to the choir.
« Last Edit: April 13, 2022, 10:13:32 pm by TimFox »
 

Offline aetheristTopic starter

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Re: Veritasium -- How Special Relativity Makes Magnets Work.
« Reply #174 on: April 13, 2022, 10:40:34 pm »
"A 2 page paper would do the job. Based on one little X involving the speed of electricity along a threaded rod compared to a plain rod. I would do it if i had access to a good scope."

In olden days, when impedances were higher (for use with vacuum tubes) and speeds were more leisurely, delay lines were made from coaxial cables where the solid center conductor was replaced by a tightly-wound helical coil.
As a transmission line, this increased the inductance per unit length substantially, with some increase in the capacitance due to dimensions.  This increased the characteristic impedance and the delay time per unit length, following the usual equations for coax cable.

Specifically, RG-65/U (still available in a later version) has:
     Polyethylene dielectric:  OD = 0.285 in
     Center conductor:  helix with ID = 0.11 in, 112 turns/in of AWG 32 (0.008 in diameter) wire.
     Core inside helix:  0.11 in diameter polyethylene.

Parameters:  Z0 = 950 ohms, velocity factor 29 time slower than solid polyethylene coax, delay time = 130 ns/m.

With such a slow, high-impedance construction, you shouldn't need a very expensive oscilloscope to compare it to a conventional coaxial cable.

Note that in 1965, more extreme cables were available that included a ferromagnetic core inside the helix (to increase the inductance) and lower-capacitance (thicker) dielectric.  Examples included:
(HH-1500A) 1500 ohms, 230 ns/m;  (RG-176/U) 2200 ohms, 9360 ns/m (?);  (DL1100) 1100 ohms, 1800 ns/m; (HH-4000) 3900 ohms, 3350 ns/m.

See:  J Millman and H Taub, Pulse, Digital, and Switching Waveforms, McGraw-Hill 1965.  Appendix B, pp 798 to 799.
Interesting. Elektons hugging the AWG32 would need to propagate 39 helical ft per lineal ft of coax, which would take 39 ns/ft at c, or 60 ns/ft at 2c/3 in the insulation (if wires are coated), or 180 ns/yd, or 198 ns/m.
U mention 130 ns/m, which is much faster than my 198 ns/m. I would have expected it to be slower than my 198 ns/m.

But when i mention an X using threaded rod, my elektons hugging the surface would go up&down&up over the threads, elektons would not go the long way around&around.  Hence a helical kind of wire would not do the trick.

X1.  Elektons going along a 10 ft plain rod would take 10 ns to go to the end & 10 ns to reflect back to the start.
For a 10 ft threaded rod that 20 ns might double to 40 ns, koz of the extra distance up&down&up.
A 350 MHz scope can detect say  3 ns, hence it could detect the 20 ns diff tween 20 ns & 40 ns.

X2. If the rods were then painted, the times would increase to 30 ns & 60 ns, a diff of 30 ns.
« Last Edit: April 29, 2023, 06:12:48 am by aetherist »
 


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