The Bearden MEG

[Bob Smith]

 I accept Smudge's description, understanding the negative resistor as a source through which energy enters the system, rather than a source from which this happens. I would venture that this is what Smudge is implying.

While resistors dissipate energy from a circuit in the form of heat - an exothermic process, negative resistors cohere energy from the electrostatic environment, and generally run cold - an endothermic process.  While Farmhand is technically correct in pointing out that a negative resistor is not a source of energy, it is a coherer of energy from the environment, a conduit of sorts, through which energy enters the system from the environment.  This is the sense in which I believe Smudge's reference to the neg resistance in the MEG is made.

It would be great to explore this aspect of the MEG further.  Most, if not all agree there is tremendous unlimited energy in the environment around us. I find the idea of a simple, yet effective way to tap this energy using negative resistance to be very encouraging.

Looking forward to your next posts, Smudge!
FWIW Bob

[Smudge]

Hi Farmhand,

The answer is in your quote from Wikipedia, "current through a negative resistance implies a source of energy just as current through positive resistance implies that energy is being dissipated".  Generally there are active devices producing the negative resistance and the energy then comes from their power source.  But not always!  Bob Smith puts it quite nicely that if you have a system that entrains energy from some external source, that can appear as a negative resistance.  Note that this is likely to be an absolute negative resistance rather than the more well known differential negative resistance. ("Absolute negative resistance" or "absolute negative conductance" are good search terms to use).

Take for example a column of electron gas that is within a magnetic field that is directed along the column.  The electrons are not stationary, they are all jiggling about (thermal motion) at Fermi velocity.  And because of the presence of the magnetic field their motions tend to be cyclic at cyclotron frequency.  An applied electic field along the column will cause the electrons to drift, the column has a resistance.  Now supply a microwave field that is close to the cyclotron frequency.  This coherence between applied microwave and cyclotron frequency allows the microwaves to pump the electrons in a given direction along the column. and the microwaves can pump the electrons the wrong way, against the electric field.  The column then appears to exhibit absolute negative resistance.  Of course in this scenario the DC energy gained from the column comes from the microwaves doing the pumping.

The electrons all have spin that will either be in spin-up (trying to align with the field) or spin-down (trying to align in the opposite direction).  I say "trying" because quantum rules do not allow alignment, they all precess at Larmor frequency about their nominal alignment.  If the magnetic field is uniform thay all precess at notionally the same frequency, but at random phases so there is no net observable effect from the precessions.  However they can be forced into phase by the application of an external RF field at the Larmor frequency (this is electron spin resonance, ESR).  And it just so happens that the Larmor frequency is the same as the cyclotron frequency.  So maybe it is possible that, given the right conditions, the quantum driven precessions could supply the microwave energy needed to do the pumping.  Note that conduction electrons within a permanent magnet or within magnetised ferromagnetic material can be considered as an electron gas.

Cheers

[Smudge]

Here is another of my old papers on the topic of precession energy as a charge pump.  This gives references to other papers on the subject of charge pumps and quantum ratchets.