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Author Topic: Do we really know how magnetism works?  (Read 11852 times)

Offline Joe L. Ogan

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Do we really know how magnetism works?
« on: 15/12/2009 00:01:04 »
Do we really know why Magnetism works?  There is a similarity between Magnetism and Gravity.  Both attract under certain conditions.  Although some have said that we have Negative Gravity, I do not believe anyone has ever proven it.  Like poles in Magnetism repel each other?  Opposite poles in Magnetism attract each other.  Why?
Does Magnetism do any work.  I believe it does.  Is it possible that there is some connection between Gravity and Magnetism?  Both are intriguing topics to me.  Thanks for comments.  Joe L. Ogan
« Last Edit: 15/12/2009 19:09:45 by chris »


 

Offline Nizzle

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Re: Do we really know how magnetism works?
« Reply #1 on: 15/12/2009 09:25:45 »
Gravity might be a "monopole" kind of magnet, but one that responds to mass instead of charge..
 

Offline Soul Surfer

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Re: Do we really know how magnetism works?
« Reply #2 on: 15/12/2009 18:21:45 »
Electricity and magnetism are very well understood and the predictions of behaviour among the most accurate in all of science. this includes classical, relativistic and quantum mechanical models in their areas of relevance.  Why should you consider that there was any lack of understanding in this area?
 

Offline Joe L. Ogan

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Do we really know how magnetism works?
« Reply #3 on: 15/12/2009 19:14:37 »
Yes, we do understand how it works.  My question was "Why?" it works.  I believe that is a different thing.  We understand how Gravity works but we do not understand "Why' it works. Thanks. Joe L. Ogan
 

Offline Geezer

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Do we really know how magnetism works?
« Reply #4 on: 15/12/2009 20:27:19 »
I think Joe is asking how magnetism manages to communicate its invisible force. It's a good question!
 

Offline Soul Surfer

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Do we really know how magnetism works?
« Reply #5 on: 15/12/2009 23:17:46 »
Yes we do know why magnetism works it is a result of moving electrical charges.  It gan also be shown that applying relativistic analysis to moving charges creates the effects.  There is also a similar effect with moving gravitating bodies called gravitomagnetism or frame dragging.  A space probe is currently trying to determine this very difficult to detect effect.

The precise process for generating static electrical charges is less well proven but there are several hypotheses relating to multidimensional processes and string theories that can produce the effects but deciding which one is most likely to be correct is very difficult
 

Offline Geezer

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Do we really know how magnetism works?
« Reply #6 on: 16/12/2009 01:56:27 »
Yes we do know why magnetism works it is a result of moving electrical charges.  It gan also be shown that applying relativistic analysis to moving charges creates the effects.  There is also a similar effect with moving gravitating bodies called gravitomagnetism or frame dragging.  A space probe is currently trying to determine this very difficult to detect effect.

The precise process for generating static electrical charges is less well proven but there are several hypotheses relating to multidimensional processes and string theories that can produce the effects but deciding which one is most likely to be correct is very difficult

Soul Surfer,

Can you break that down for us in terms of what has been demonstrated experimentally versus theories that have not been demonstrated by experiment? Thanks!
 

Offline Soul Surfer

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Do we really know how magnetism works?
« Reply #7 on: 16/12/2009 12:40:57 »
Geezer, I thought that I had?!! I wanted to give a short answer.  A lot of the details are elsewhere on this site
 

Offline Pmb

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Do we really know how magnetism works?
« Reply #8 on: 16/12/2009 12:53:31 »
Do we really know why Magnetism works?  There is a similarity between Magnetism and Gravity.  Both attract under certain conditions.  Although some have said that we have Negative Gravity, I do not believe anyone has ever proven it. 
Science is concerned with evidence, verification etc. Not proof. There is evidence of negative gravity if by "negative gravity" you mean anti-gravity, i.e. repulsive gravity. The observed accelerating expansion of the universe is evidence of repulsive gravity.
 

Offline lightarrow

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Do we really know how magnetism works?
« Reply #9 on: 16/12/2009 14:43:32 »
Do we really know why Magnetism works?  There is a similarity between Magnetism and Gravity.  Both attract under certain conditions.  Although some have said that we have Negative Gravity, I do not believe anyone has ever proven it.  Like poles in Magnetism repel each other?  Opposite poles in Magnetism attract each other.  Why?
Because magnetic field is nothing else than an electric field measured in a different frame of reference (see special relativity and how electric field change in a Lorentz transformation).

Quote
Does Magnetism do any work.  I believe it does.
Of course it does make work: put two electromagnets close to eachother and switch on the current: you will see them be shooted apart... :)
 

Offline Geezer

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Do we really know how magnetism works?
« Reply #10 on: 16/12/2009 17:29:40 »
Geezer, I thought that I had?!! I wanted to give a short answer.  A lot of the details are elsewhere on this site

SS, you have introduced several other topics here. I just think it would be helpful to newer posters if we make it clear what is proven by experiment versus theoretical. I was not looking for much more detail. No problem if you don't want to though.

Thanks, G
 

Offline JP

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Do we really know how magnetism works?
« Reply #11 on: 16/12/2009 21:13:02 »
Just my 2 cents, expanding on what SS mentioned, magnetism is classically a force generated by moving charges.  In relativity, since the laws of physics shouldn't depend on how fast you're moving, the magnetic force can be explained as part of a combined electromagnetic force that works to keep the forces the same whether you're moving or not--hence why it's created by moving charges.  Quantum mechanically, this electromagnetic field is modeled by field theory, which uses photons as the basic elements of the field.  So in some sense, the most fundamental explanation we have of the force is by using photons.  The quantum model of the electric field is one of the most accurate physical models we have as far as agreement with experiment.

A big difference between gravity and electromagnetism is that gravity is only attractive and electromagnetism is both attractive and repulsive.  There isn't evidence of "anti-gravity" and I don't think many physicists are considering it seriously.  I'm not an expert, but I've heard it said that it's partly due to this fact that its hard to come up with a quantum mechanical gravitational theory. 
 

Offline Farsight

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Do we really know how magnetism works?
« Reply #12 on: 16/12/2009 23:27:17 »
Do we really know why Magnetism works?
I believe some of us do, but that it's not yet accepted as mainstream physics.

There is a similarity between Magnetism and Gravity. Both attract under certain conditions. Although some have said that we have Negative Gravity, I do not believe anyone has ever proven it. Like poles in Magnetism repel each other? Opposite poles in Magnetism attract each other. Why?
There certainly some similarity between magnetism and gravitomagnetism, but I'd say there not so much similarity between gravity amd magnetism. I know of no negative gravity either. Anti-gravity can be thought of as being the result of two opposing gravitational forces which cancel to zero, as at a Lagrangian point, but this isn't the same as negative gravity.

Does Magnetism do any work. I believe it does. Is it possible that there is some connection between Gravity and Magnetism? Both are intriguing topics to me. Thanks for comments.
I'd say magnetism can do work, but a magnet stuck to the underside of a steel bridge isn't doing any work. I'd also say there is no major connection between gravity and magnetism, but that magnetism is merely one aspect of electromagnetism, and gravity does have an electromagnetic basis. I feel I can explain all the forces in adequate detail, but since it isn't yet mainstream physics, doing so would create issues, so I won't volunteer it.
 

Offline Joe L. Ogan

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Do we really know how magnetism works?
« Reply #13 on: 16/12/2009 23:38:42 »
A magnet stuck to the underside of anything is holding itself from dropping.  Is that not work?  Just asking.  Joe L. Ogan
 

Offline Geezer

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Do we really know how magnetism works?
« Reply #14 on: 17/12/2009 00:23:16 »
A magnet stuck to the underside of anything is holding itself from dropping.  Is that not work?  Just asking.  Joe L. Ogan

Joe, not according to the classic definition of work. The magnet is responsible for producing a force that attracts the magnet to, say, a steel plate. Work is only done by the magnetic force if something is displaced by that force.

When the magnet is moved close enough to the steel plate that it pulls itself onto the plate, work is done by the magnet on the mass of the magnet for that short distance, but as long as the magnet remains attached to the plate, no work is being done and no energy is being expended.

 

Offline Farsight

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Do we really know how magnetism works?
« Reply #15 on: 17/12/2009 00:23:16 »
No Joe. It can stick there forever. See wiki where it says "work is the amount of energy transferred by a force acting through a distance". Nothing's moving, so whilst the force is there it doesn't go the distance, hence no work.
 

Offline Joe L. Ogan

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Do we really know how magnetism works?
« Reply #16 on: 17/12/2009 00:39:22 »
A magnet stuck to the underside of anything is holding itself from dropping.  Is that not work?  Just asking.  Joe L. Ogan
OK, I understand you.  According to the definition of work , no work is being done.  But, If I am holding myself up to the steel, I sure feel that I am doing work.  But I am not arguing the definition.  Thanks, Joe L. Ogan

Joe, not according to the classic definition of work. The magnet is responsible for producing a force that attracts the magnet to, say, a steel plate. Work is only done by the magnetic force if something is displaced by that force.

When the magnet is moved close enough to the steel plate that it pulls itself onto the plate, work is done by the magnet on the mass of the magnet for that short distance, but as long as the magnet remains attached to the plate, no work is being done and no energy is being expended.


 

Offline Joe L. Ogan

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Do we really know how magnetism works?
« Reply #17 on: 17/12/2009 00:42:39 »
No Joe. It can stick there forever. See wiki where it says "work is the amount of energy transferred by a force acting through a distance". Nothing's moving, so whilst the force is there it doesn't go the distance, hence no work.

OK. I understand your definition.  But, If I am holding myself up against the steel, I feel sure that I am doing some work in spite of the definition.  But I do understand. Thanks, Joe L. Ogan
 

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Do we really know how magnetism works?
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