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Sue... science forum Guru
Joined: 08 May 2005
Posts: 2684

Posted: Sun Jul 09, 2006 8:53 am Post subject:
Re: Magnetic Idyll



Tom Roberts wrote:
Quote:  Edward Green wrote:
The formal simularity of the Coriolis force and the Lorentz force law
2w x v vs. qB x v
suggests that the magnetic field may correspond to a local rotation of
space (inertial coordinate system) as seen by charge vs. that seen by
mass.
Not really.
The Lorentz force law, written in terms of physical quantities in 4d
spacetime using the language of tensors is:
f = q F.U
Where f is the covariant force 4vector, F is the electromagnetic field
2form (includes both B and E), and U is the 4velocity of the particle
with charge q.
Using the same language, the "Coriolis force" is:
f = 0
I see no similarity here at all ().

Because you did your transformation wrong so why the
big grin ?
http://farside.ph.utexas.edu/teaching/jk1/lectures/node28.html
Quote: 
[Note, please, that "Coriolis force' is fictitious  merely
an artifact of one's coordinates (your formula applies only to
rotating coordinates). It is _not_ a tensor; Lorentz force is.]
Besides, if this were truly a good analogy there would be an
electromagnetic analog to "centrifugal force" (which is usually much
larger than the "Coriolis force"). With your identification above, the
EM analogy would be B x (B x r), which does not appear in any usual
formula of classical electrodynamics that I am aware of (one applies
"centrifugal force" to a particle sitting still on a carousel, but a
charge sitting still does not "feel" B at all).

What in the world do you think moves the currents toward
surface in this experiment ?
http://www.esa.int/SPECIALS/GSP/SEM0L6OVGJE_0.html
Oh! ... I forgot. That is probably something you'd really
rather not see isn't it.
Sue...
Quote: 
Bill Hobba wrote:
Cross products appear all over the place in physics. That does not imply
they are related any more than bacteria growth and monetary growth with
interest being exponential implies bacteria are related to money.
Lest anybody wonder why such different phenomena are described by
similar mathematics, let me point out that one makes similar
_approximations_ here: in the real world, the bacteria do not really
have exactly equal and constant reproduction rates, and the money does
not have exactly constant interest rate; by _approximating_ those as
constant one obtains similar differential equations with similar solutions.
Tom Roberts 


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Sorcerer1 science forum Guru
Joined: 09 Jun 2006
Posts: 410

Posted: Sun Jul 09, 2006 8:36 am Post subject:
Re: Magnetic Idyll



"Edward Green" <spamspamspam3@netzero.com> wrote in message
news:1152400330.145973.161020@s13g2000cwa.googlegroups.com...
 The formal simularity of the Coriolis force and the Lorentz force law

 2w x v vs. qB x v

 suggests that the magnetic field may correspond to a local rotation of
 space (inertial coordinate system) as seen by charge vs. that seen by
 mass.

 On the proside, one can easily list more hints that magentic effects
 have to so with something or other rotating. On the con side, there
 doesn't seem to be an obvious way in incorporate the centrifugal force
 into this analogy  for purposes of "magnetic rotation", the test
 particle is always on axis.

 Comments?
1) Coriolis is a change of reference frame, not a force.
The laws of physics in this frame of reference say the ball curves
without being accelerated:
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/gifs/coriolis.mov
2) Single phase induction motors normally rotate in either direction, they
have
a starting winding to determine which. The Lorentz force is nothing more
than the equivalent of squeezing a dough ball so that it spreads out, or
stretching it so that it spreads in. A pastry chef understands physics
better than Lorentz, he knows what to do with a rolling pin.
3) This bottle is juggled from Mickey's left hand to his right and
back again. No forces are involved. If there were friction between
the bottle and the Mickey's frame then the bottle frame and Mickey
frame would try to combine. Then you have force.
http://www.androcles01.pwp.blueyonder.co.uk/Wilson/RotateMickeyLarge.gif
Androcles. 

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Tom Roberts science forum Guru
Joined: 24 Mar 2005
Posts: 1399

Posted: Sun Jul 09, 2006 5:34 am Post subject:
Re: Magnetic Idyll



Edward Green wrote:
Quote:  The formal simularity of the Coriolis force and the Lorentz force law
2w x v vs. qB x v
suggests that the magnetic field may correspond to a local rotation of
space (inertial coordinate system) as seen by charge vs. that seen by
mass.

Not really.
The Lorentz force law, written in terms of physical quantities in 4d
spacetime using the language of tensors is:
f = q F.U
Where f is the covariant force 4vector, F is the electromagnetic field
2form (includes both B and E), and U is the 4velocity of the particle
with charge q.
Using the same language, the "Coriolis force" is:
f = 0
I see no similarity here at all ().
[Note, please, that "Coriolis force' is fictitious  merely
an artifact of one's coordinates (your formula applies only to
rotating coordinates). It is _not_ a tensor; Lorentz force is.]
Besides, if this were truly a good analogy there would be an
electromagnetic analog to "centrifugal force" (which is usually much
larger than the "Coriolis force"). With your identification above, the
EM analogy would be B x (B x r), which does not appear in any usual
formula of classical electrodynamics that I am aware of (one applies
"centrifugal force" to a particle sitting still on a carousel, but a
charge sitting still does not "feel" B at all).
Bill Hobba wrote:
Quote:  Cross products appear all over the place in physics. That does not imply
they are related any more than bacteria growth and monetary growth with
interest being exponential implies bacteria are related to money.

Lest anybody wonder why such different phenomena are described by
similar mathematics, let me point out that one makes similar
_approximations_ here: in the real world, the bacteria do not really
have exactly equal and constant reproduction rates, and the money does
not have exactly constant interest rate; by _approximating_ those as
constant one obtains similar differential equations with similar solutions.
Tom Roberts 

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Bill Hobba science forum Guru
Joined: 02 May 2005
Posts: 2138

Posted: Sun Jul 09, 2006 1:24 am Post subject:
Re: Magnetic Idyll



"Edward Green" <spamspamspam3@netzero.com> wrote in message
news:1152400330.145973.161020@s13g2000cwa.googlegroups.com...
Quote:  The formal simularity of the Coriolis force and the Lorentz force law
2w x v vs. qB x v
suggests that the magnetic field may correspond to a local rotation of
space (inertial coordinate system) as seen by charge vs. that seen by
mass.

Cross products appear all over the place in physics. That does not imply
they are related any more than bacteria growth and monetary growth with
interest being exponential implies bacteria are related to money.
Quote: 
On the proside, one can easily list more hints that magentic effects
have to so with something or other rotating.

Sure  usually electron spin or electrons 'rotating' around atoms. Of
course these are quantum effects but in a very crude way it is rotation.
Bill
Quote:  On the con side, there
doesn't seem to be an obvious way in incorporate the centrifugal force
into this analogy  for purposes of "magnetic rotation", the test
particle is always on axis.
Comments?



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Sue... science forum Guru
Joined: 08 May 2005
Posts: 2684

Posted: Sat Jul 08, 2006 11:33 pm Post subject:
Re: Magnetic Idyll



Edward Green wrote:
Quote:  The formal simularity of the Coriolis force and the Lorentz force law
2w x v vs. qB x v
suggests that the magnetic field may correspond to a local rotation of
space (inertial coordinate system) as seen by charge vs. that seen by
mass.
On the proside, one can easily list more hints that magentic effects
have to so with something or other rotating. On the con side, there
doesn't seem to be an obvious way in incorporate the centrifugal force
into this analogy  for purposes of "magnetic rotation", the test
particle is always on axis.
Comments?

What rotates is an ensemble of electric charges.
"The origin of permanent magnetism"
http://farside.ph.utexas.edu/teaching/302l/lectures/node62.html
"Visualizations"
http://web.mit.edu/8.02t/www/802TEAL3D/teal_tour.htm
If you take a Machian view of inertia, the the dielectric propeties
of free space don't make too bad an analogy to the gravitational/
inertial field established by nearby matter.
There are numerous way to incorporate the
magnetic force into gravity/inertia. You are building bricks
with little houses. Try it the other way round. )
http://www.esa.int/SPECIALS/GSP/SEM0L6OVGJE_0.html
http://www.mypage.bluewin.ch/Bizarre/GRAV.htm
Sue... 

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Edward Green science forum addict
Joined: 21 May 2005
Posts: 95

Posted: Sat Jul 08, 2006 11:12 pm Post subject:
Magnetic Idyll



The formal simularity of the Coriolis force and the Lorentz force law
2w x v vs. qB x v
suggests that the magnetic field may correspond to a local rotation of
space (inertial coordinate system) as seen by charge vs. that seen by
mass.
On the proside, one can easily list more hints that magentic effects
have to so with something or other rotating. On the con side, there
doesn't seem to be an obvious way in incorporate the centrifugal force
into this analogy  for purposes of "magnetic rotation", the test
particle is always on axis.
Comments? 

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