Author Topic: Rotating magnetic fields  (Read 10564 times)

Offline Bob012345

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Re: Rotating magnetic fields
« Reply #20 on: 08/10/2019 04:07 pm »
We were discussing only the B field - hence vxB=E not E+vxB=E.  The E field from the B field is a separate entity as that of a charge's, what I call its "non-relativistic electric field".  I don't disagree there.
Can you see the difference between the letter "E", and the letter "F"? Let me repeat that in lower case (although lower case variables normally would mean something different.) The difference between the letter "e" and the letter "f"

The equation you just wrote is nonsensical. You have the same variable E on both sides, so just subtract it off and you are left with v x B = 0. This is only true in the special cases that v = 0, B  = 0, or v and B are parallel. The correct equation, (using lower case for e and f, since you failed to read it correctly in the previous post, or in the links provided, is  f = q*e +q* (vxB) The magnetic field directly generates a force, it doesn't generate some pseudo E-field to do its work for it. That wouldn't even make sense.

When you are saying you "don't disagree," you are actually saying that you understood nothing of 1's post, because 1 stated that the E field and B field are completely separate and unrelated in this (quasi-static) case. You are saying that the B -field generates an E-Field, and you are claiming so in a fundamentally inconsistent way. (In non-quasi-static cases, it is changing B fields that generate an E-Field, but before I try to explain what these words mean, you need to recognize the algebraic mistakes you are making.)

With that said, it doesn't sound like you understood a single word of 1's post. Hopefully now that I cleared up what seems to be some confusion with variables on your part, you will understand it better, so go back and re-read 1's post again, At least until you comprehend the fact that your equations are completely wrong, and any prediction that spinning a magnet on its axis of symmetry should do anything is a complete misapplication of the theory, and that is over a century old news.
I think the problem is rather your desire to see a lack of understanding.  It was already made clear in the rest of the text it was understood E_q+vxB=E_full such that  E_q is not the same as E_full.  Maybe it was lazy to lack the annotation at that point but the rest of the text makes it clear.

Yes an electron moving relative to a magnetic source does observe an E field in it's moving frame and the reason for the force.  The magnetic field being a velocity dependent dipole electric field.

It would help if you would use Feynman's notation in the reference I sent you. I think you are talking about fields
in different reference frames but you should be clear. If that's the case, you are missing the gamma factor. Your equation is close to

 E_y' = gamma ( E + vX B)_y

where gamma is 1/SQRT(1-beta^2) and beta is v/c.

Is this what you mean by E_full?
« Last Edit: 08/10/2019 04:08 pm by Bob012345 »

Offline dustinthewind

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Re: Rotating magnetic fields
« Reply #21 on: 08/11/2019 04:03 pm »
We were discussing only the B field - hence vxB=E not E+vxB=E.  The E field from the B field is a separate entity as that of a charge's, what I call its "non-relativistic electric field".  I don't disagree there.
Can you see the difference between the letter "E", and the letter "F"? Let me repeat that in lower case (although lower case variables normally would mean something different.) The difference between the letter "e" and the letter "f"

The equation you just wrote is nonsensical. You have the same variable E on both sides, so just subtract it off and you are left with v x B = 0. This is only true in the special cases that v = 0, B  = 0, or v and B are parallel. The correct equation, (using lower case for e and f, since you failed to read it correctly in the previous post, or in the links provided, is  f = q*e +q* (vxB) The magnetic field directly generates a force, it doesn't generate some pseudo E-field to do its work for it. That wouldn't even make sense.

When you are saying you "don't disagree," you are actually saying that you understood nothing of 1's post, because 1 stated that the E field and B field are completely separate and unrelated in this (quasi-static) case. You are saying that the B -field generates an E-Field, and you are claiming so in a fundamentally inconsistent way. (In non-quasi-static cases, it is changing B fields that generate an E-Field, but before I try to explain what these words mean, you need to recognize the algebraic mistakes you are making.)

With that said, it doesn't sound like you understood a single word of 1's post. Hopefully now that I cleared up what seems to be some confusion with variables on your part, you will understand it better, so go back and re-read 1's post again, At least until you comprehend the fact that your equations are completely wrong, and any prediction that spinning a magnet on its axis of symmetry should do anything is a complete misapplication of the theory, and that is over a century old news.
I think the problem is rather your desire to see a lack of understanding.  It was already made clear in the rest of the text it was understood E_q+vxB=E_full such that  E_q is not the same as E_full.  Maybe it was lazy to lack the annotation at that point but the rest of the text makes it clear.

Yes an electron moving relative to a magnetic source does observe an E field in it's moving frame and the reason for the force.  The magnetic field being a velocity dependent dipole electric field.

It would help if you would use Feynman's notation in the reference I sent you. I think you are talking about fields
in different reference frames but you should be clear. If that's the case, you are missing the gamma factor. Your equation is close to

 E_y' = gamma ( E + vX B)_y

where gamma is 1/SQRT(1-beta^2) and beta is v/c.

Is this what you mean by E_full?

Yes you are correct.  Most of the time they refer to the low velocity approximation because gamma can be neglected.
http://www.feynmanlectures.caltech.edu/II_26.html
If we are talking Lorentz contracted electric fields then we need to include gamma.  These also appear in Edward Purcell's book.  Don't have a lot of time for these forums.  Surprised I do this as much as I do. 

Anyways the point was just to point out reasons why the magnetic field doesn't actually rotate, that it radiates.  I think the discussion got a bit sidetracked. 

Here is something for the original poster that may be related to what he is interested in.
https://www.researchgate.net/publication/323935548_General_Relativistic_Gravity_Machine_using_Electromagneto-Torsion_Field
« Last Edit: 08/11/2019 04:50 pm by dustinthewind »

Offline meberbs

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Re: Rotating magnetic fields
« Reply #22 on: 08/11/2019 04:56 pm »
Yes you are correct.  Most of the time they refer to the low velocity approximation because gamma can be neglected.
http://www.feynmanlectures.caltech.edu/II_26.html
If we are talking Lorentz contracted electric fields then we need to include gamma.  These also appear in Edward Purcell's book.  Don't have a lot of time for these forums.  Surprised I do this as much as I do.
Please do not call it E_full then, it is simply the electric field in another reference frame, usually denoted E' (and the magnetic field in that frame would not in general go away.)

It seems like you keep trying to apply these equations in the lab frame, which is an incorrect thing to do. If you are going to the calculations in another frame, you have to shift everything into that frame. This is part of why jumping between frames is a good way to get confused. Since you are talking about experiments that naturally have multiple charges moving in different directions at different speeds, it is impossible to simultaneously work in a reference frame where all of the charges are stationary so that you can neglect the B field. Even if you did, the E field present in that frame would cause the charges to accelerate making the charge no longer stationary.

Offline MathewOrman

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Re: Rotating magnetic fields
« Reply #23 on: 08/17/2019 11:55 am »
Hi,

I've been interested in reactionless propulsion for a long time now, and one concept that seems to crop up a lot is rotating magnetic fields.

Whether it's Searl, Podkletnov, the Marcus device , it seems to be a recurring concept that (perhaps) a rotating magnetic field (particularly one that is rotating very fast or uses superconductors) *may* be able to affect the space-time fabric and hence create a reactionless force. 

I'm a rational guy and I don't have much time for the pseudoscience, but I think we have to keep an open mind.

So I was wondering what you folks thought about this as a propulsion concept, are you aware of any recent experiments, have you done any experiments yourself, does this have potential.

Very interested to hear any replies,
Thank you.
Time does not exist and space has no fabric... :-)   

Offline meberbs

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Re: Rotating magnetic fields
« Reply #24 on: 08/17/2019 10:38 pm »
Time does not exist and space has no fabric... :-)
You seem to have missed the part of the OP where he doesn't have time for pseudoscience.

Linking to some random person on youtube doesn't give you any credibility. Especially when that person doesn't understand physics It looks like you already found that site and posted some comments where you failed to address any of the points made in the blog post, and refused to answer questions about your supposed experiment. Meanwhile, and unsurprisingly flat earthers seem to like the video you linked to, which is more than enough reason for me to not waste my time with it.

As to your claim that time does not exist, the fact the objects move says otherwise. If there was no such thing as time, then how do you explain that when I walked through the same spot in the grocery store as someone else we did not run in to each other? (The standard answer is that we were there at different times.) Likewise for the fabric of space-time. If you have an actual alternative to general relativity that can replicate all of its predictions that have been verified by experiment, please share it. "Fabric of space-time" is just one metaphor used to explain what GR says in a way that helps human intuition understand it better.

https://xkcd.com/895/

Offline MathewOrman

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Re: Rotating magnetic fields
« Reply #25 on: 08/18/2019 02:32 pm »
Time does not exist and space has no fabric... :-)
You seem to have missed the part of the OP where he doesn't have time for pseudoscience.

Linking to some random person on youtube doesn't give you any credibility. Especially when that person doesn't understand physics It looks like you already found that site and posted some comments where you failed to address any of the points made in the blog post, and refused to answer questions about your supposed experiment. Meanwhile, and unsurprisingly flat earthers seem to like the video you linked to, which is more than enough reason for me to not waste my time with it.

As to your claim that time does not exist, the fact the objects move says otherwise. If there was no such thing as time, then how do you explain that when I walked through the same spot in the grocery store as someone else we did not run in to each other? (The standard answer is that we were there at different times.) Likewise for the fabric of space-time. If you have an actual alternative to general relativity that can replicate all of its predictions that have been verified by experiment, please share it. "Fabric of space-time" is just one metaphor used to explain what GR says in a way that helps human intuition understand it better.

https://xkcd.com/895/


Time is the method of measuring speed of motion of matter in space which has no property other than containment of matter...

Offline meberbs

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Re: Rotating magnetic fields
« Reply #26 on: 08/18/2019 03:55 pm »
Time is the method of measuring speed of motion of matter in space which has no property other than containment of matter...
So you contradict yourself by now saying that time has a use when you previously claim that it doesn't exist, and you otherwise ignore everything I wrote.

Offline RSE

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Re: Rotating magnetic fields
« Reply #27 on: 08/18/2019 04:55 pm »
The only way to create a reactionless drive would be to find a way to distort the fabric of Spacetime, other than gravity. (From a geometrical view of spacetime, either building a hump or a valley in spacetime.)

To date, no such method is known to exist. (For thoroughness, I note that Mill's GUT-CP allows such. I am not coming out in favor or against said theory, merely noting its existence.)

Offline MathewOrman

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Re: Rotating magnetic fields
« Reply #28 on: 08/20/2019 11:17 pm »
Time is the method of measuring speed of motion of matter in space which has no property other than containment of matter...
So you contradict yourself by now saying that time has a use when you previously claim that it doesn't exist, and you otherwise ignore everything I wrote.
You like twisting things:
 Time is abstract quantity thus does not exist... It is a method of measuring speed of motion of matter in space... It was invented to help synchronize life events in human culture...  Just like energy is to describe how much of matter is in motion...

Offline meberbs

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Re: Rotating magnetic fields
« Reply #29 on: 08/20/2019 11:40 pm »
You like twisting things:
No, I prefer things untwisted so, please try responding to what I actually wrote.

Time is abstract quantity thus does not exist... It is a method of measuring speed of motion of matter in space... It was invented to help synchronize life events in human culture...  Just like energy is to describe how much of matter is in motion...
You posted a video with a title about how philosophy is corrupting science, and while based on minimal research into who made that video, the contents are likely nonsense, the title has a point, pure science has no need to waste time on purely philosophical questions like "does something exist if you can't put it in a box." What you are doing here is that, you are pushing a specific philosophical definition for the word "exist" while ignoring the fact that the concept of time in physics is a rigorous, well-defined, and measurable thing.

Your definition of energy here is not correct, but I see no relevance in providing a better definition.

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