# Magnetism

Magnetism is a class of physical phenomena that are mediated by magnetic fields. Electric currents and the fundamental magnetic moments of elementary particles give rise to a magnetic field, which acts on other currents and magnetic moments.

## Quotes

* Magnetism, as you recall from physics class, is a powerful force that causes certain items to be attracted to refrigerators.
** Dave Barry, quoted in Bobby Mercer, How Do You Light a Fart?: And 150 Other Essential Things Every Guy Should Know about Science (2009).
* MAGNET, n. Something acted upon by magnetism. MAGNETISM, n. Something acting upon a magnet. The two definitions immediately foregoing are condensed from the works of one thousand eminent scientists, who have illuminated the subject with a great white light, to the inexpressible advancement of human knowledge.
** Ambrose Bierce in: The Cynic's Dictionary, Interactive Media (January 15, 2014), p. 112.
* I must reject fluids and ethers of all kinds, magnetical, electrical, and universal, to whatever quintessential thinness they may be treble distilled, and (as it were) super-substantiated.
** Samuel Taylor Coleridge in: The Complete Works of Samuel Taylor Coleridge: With an ..., Volume 1, University Microfilms (1884), p. 382.
* El imán humilla al hierro. Es una teoría sobre el amor.
** Translation: Magnets humiliate iron. It's a theory about love.
** Marco Denevi, Falsificaciones (1977).
* More than the diamond Koh-i-noor, which glitters among their crown jewels, they prize the dull pebble which is wiser than a man, whose poles turn themselves to the poles of the world, and whose axis is parallel to the axis of the world. Now, their toys are steam and galvanism.
** Ralph Waldo Emerson in: John Telford, Benjamin Aquila Barber The London Quarterly Review, Volume 7 , J.A. Sharp (1857), p. 390.
* I have been driven to assume for some time, especially in relation to the gases, a sort of conducting power for magnetism. Mere space is Zero. One substance being made to occupy a given portion of space will cause more lines of force to pass through that space than before, and another substance will cause less to pass. The former I now call Paramagnetic & the latter are the diamagnetic. The former need not of necessity assume a polarity of particles such as iron has with magnetic, and the latter do not assume any such polarity either direct or reverse. I do not say more to you just now because my own thoughts are only in the act of formation, but this I may say: that the atmosphere has an extraordinary magnetic constitution, & I hope & expect to find in it the cause of the annual & diurnal variations, but keep this to yourself until I have time to see what harvest will spring from my growing ideas.
** Michael Faraday in: Peter Day The Philosopher's Tree: A Selection of Michael Faraday's Writings, CRC Press, Feb 1, 1999CRC Press (February 1, 1999), p. 100.
* In any atom there are, generally speaking, several electrons and some combination of spin and orbit rotations which builds up a total angular momentum and a total magnetic moment. Although there is no classical reason why it should be so, it is always true in quantum mechanics that (for an isolated atom) the direction of the magnetic moment is exactly opposite to the direction of the angular momentum.
** Richard Feynman: (1964). 34–2. Magnetic moments and angular momentum in Chapter 34. The Magnetism of Matter, Vol. II, The Feynman Lectures in Physics.
* In like manner, the loadstone has from nature its two poles, a northern and a southern; fixed, definite points in the stone, which are the primary termini of the movements and effects, and the limits and regulators of the several actions and properties. It is to be understood, however, that not from a mathematical point does the force of the stone emanate, but from the parts themselves; and all these parts in the whole—while they belong to the whole—the nearer they are to the poles of the stone the stronger virtues do they acquire and pour out on other bodies. These poles look toward the poles of the earth, and move toward them, and are subject to them. The magnetic poles may be found in very loadstone, whether strong and powerful (male, as the term was in antiquity) or faint, weak, and female; whether its shape is due to design or to chance, and whether it be long, or flat, or four-square, or three-cornered or polished; whether it be rough, broken-off, or unpolished: the loadstone ever has and ever shows its poles.
** William Gilbert in: Kate Aughterson The English Renaissance: An Anthology of Sources and Documents, Psychology Press (August 23, 2001), p. 376.
* Might and wrong combined, like iron magnetized, are endowed with irresistible attraction.
** Nathaniel Hawthorne, The House of the Seven Gables (1851).
* Ohm found that the results could be summed up in such a simple law that he who runs may read it, and a schoolboy now can predict what a Faraday then could only guess at roughly. By Ohm's discovery a large part of the domain of electricity became annexed by Coulomb's discovery of the law of inverse squares, and completely annexed by Green's investigations. Poisson attacked the difficult problem of induced magnetisation, and his results, though differently expressed, are still the theory, as a most important first approximation. Ampere brought a multitude of phenomena into theory by his investigations of the mechanical forces between conductors supporting currents and magnets. Then there were the remarkable researches of Faraday, the prince of experimentalists, on electrostatics and electrodynamics and the induction of currents. These were rather long in being brought from the crude experimental state to a compact system, expressing the real essence. Unfortunately, in my opinion, Faraday was not a mathematician. It can scarcely be doubted that had he been one, he would have anticipated much later work. He would, for instance, knowing Ampere's theory, by his own results have readily been led to Neumann's theory, and the connected work of Helmholtzand Thomson. But it is perhaps too much to expect a man to be both the prince of experimentalists and a competent mathematician.”
** Oliver Heaviside in: Electromagnetic Theory, Volume 1, he Electrician" printing and publishing Company, limited (1893), p. 13.
* Phonons are displacements of atoms around their rest positions in a crystalline solid. They carry sound and heat, but are not classically associated with magnetism. Here, we show that phonons are, in fact, sensitive to magnetic fields, even in diamagnetic materials. We do so by demonstrating experimentally that acoustic phonons in a diamagnetic semiconductor (InSb) scatter more strongly from one another when a magnetic field is applied. We attribute this observation to the magnetic-field sensitivity of the anharmonicity of the interatomic bonds that govern the probability of phonon-phonon interactions.
** Jin H, Restrepo OD, Antolin N, Boona SR, Windl W, Myers RC, Heremans JP, "Phonon-induced diamagnetic force and its effect on the lattice thermal conductivity", Nature Materials. 2015 Jun;14(6):601-6.
* My aim is to say that the machinery of the heavens is not like a divine animal but like a clock (and anyone who believes a clock has a soul gives the work the honour due to its maker) and that in it almost all the variety of motions is from one very simple magnetic force acting on bodies, as in the clock all motions are from a very simple weight.
** Johannes Kepler in: Vincent Wilmot New Science Theory, Lulu.com (2019), p. 68.
* Despite the growing interest in the ﬁeld of ultracold chemistry, experimental progress has been hampered by a lack of appropriate methods to trap and cool molecules. Laser cooling, while very successful, is limited to a small number of atoms in the Periodic Table because few atoms and no molecules have closed cycling transitions. The main methods to produce cold molecules of chemical interest can be divided into two groups. Buffer gas cooling relies on collisions with cold helium in a dilution refrigerator to cool paramagnetic molecules and trap them in a magnetic trap. Super-sonic expansion is used by other methods to precool the molecules. The resulting cold molecular beams have been slowed and trapped in some experiments by interactions with pulsed electric ﬁelds Stark decelerator, by interactions with pulsed optical ﬁelds, by spinning the nozzle, and by billiardlike collisions. Finally, laser-cooled alkali-metal atoms are used to produce cold molecules via photoassociation. None of these methods have, to date, achieved the phase space densities required to observe reaction dynamics at ultracold temperatures. We recently demonstrated a general method to stop and eventually trap paramagnetic atoms. Our method is based on the interaction of a paramagnetic particle with pulsed magnetic ﬁelds. It operates in analogy with the Stark decelerator by reducing the kinetic energy of a para-magnetic atom passing through a series of pulsed electro-magnetic coils. The amount of kinetic energy removed by each stage is equal to the Zeeman energy shift that the atom experiences at the time the ﬁelds are switched off.
* Future work will extend the coilgun method to trap molecules of chemical interest. Once they are in a magnetic trap, they can be cooled to near the single photon recoil limit using the method of single photon cooling, as demonstrated recently with trapped atoms. The application of this method to cooling of molecules is particularly promising.
   * Edvardas Narevicius, Adam Libson, Christian G. Parthey, Isaac Chavez, Julia Narevicius, Uzi Even, and Mark G. Raizen; "Stopping supersonic oxygen with a series of pulsed electromagnetic coils: A molecular coilgun" in Physical Review A 77(5) (May 2008).
* Mariners at sea, when, through cloudy weather in the day which hides the sun, or through the darkness of night, they lose knowlege of the quarter of the world to which they are sailing, touch a needle with a magnet, which will turn round till, on its motion ceasing, its point will be directed towards the north.
** Alexander Neckam in : Joseph Mayer A Library of National Antiquities, D. Marples (1857), p. 17.
* Water, fire, air and dirt Fucking magnets, how do they work? And I don't wanna talk to a scientist Y'all motherfuckers lying, and getting me pissed.
** Insane Clown Posse, "Miracles" (2009).
* The fact that a magnet draws iron towards it was noticed by the ancients, but no attention was paid to the force with which the iron attracts the magnet. Newton, however, by placing the magnet in one vessel and the iron in another, and floating both vessels in water so as to touch each other, showed experimentally that as neither vessel was able to propel the other along with itself through the water, the attraction of the iron on the magnet must be equal and opposite to that of the magnet on the iron, both being equal to the pressure between the two vessels.
** James Clerk Maxwell, Matter and Motion (1876).
* For decades, new-energy researchers talked about the possibility of treating a magnet so that its magnetic field would continuously shake or vibrate. On rare occasions, Sweet saw this effect, called self-oscillation, occur in electric transformers. He felt it could be coaxed into doing something useful, such as producing energy. Sweet thought that if he could find the precise way to shake or disturb a magnet's force field, the field would continue to shake by itself. It would be similar to striking a bell and having the bell keep on ringing. Sweet - who said his ideas came to him in dreams - turned for inspiration to his expertise in magnets. He knew magnets could be used to produce electricity, and wanted to see if he could get power out of a magnet by something other than the standard induction process. What Sweet wanted to do was to keep the magnet still and just shake its magnetic field. This shaking, in turn, would create an electric current. One new-energy researcher compares self-oscillation to a leaf on a tree waving in a gentle breeze. While the breeze itself isn't moving back and forth, it sets the leaf into that kind of motion. Sweet thought that if cosmic energy could be captured to serve as the breeze, then the magnetic field would serve as the leaf. Sweet would just have to supply a small amount of energy to set the magnetic field in motion, and space energy would keep it moving.
** Jeane Manning in: The Coming Energy Revolution: The Search for Free Energy, Avery Publishing Group (1996), p. 72.
* The magnetism as exhibited in iron is an isolated phenomenon in nature. What it is that makes this metal behave so radically different from all other materials in this respect has not yet been ascertained, though many theories have been suggested. As regards magnetism, the molecules of the various bodies behave like hollow beams partly filled with a heavy fluid and balanced in the middle in the manner of a see-saw. Evidently some disturbing influence exists in nature which causes each molecule, like such a beam, to tilt either one or the other way. If the molecules are tilted one way, the body is magnetic; if they are tilted the other way, the body is non-magnetic; but both positions are stable, as they would be in the case of the hollow beam, owing to the rush of the fluid to the lower end. Now, the wonderful thing is that the molecules of all known bodies went one way, while those of iron went the other way. This metal, it would seem, has an origin entirely different from that of the rest of the globe. It is highly improbable that we shall discover some other and cheaper material which will equal or surpass iron in magnetic qualities.
** Nikola Tesla, "The Problem of Increasing Human Energy with Special References to the Harnessing of the Sun's Energy" in Century Illustrated Magazine (June 1900).
* His [Faraday's] third great discovery is the Magnetization of Light, which I should liken to the Weisshorn among mountains-high, beautiful, and alone.
** John Tyndall in: Faraday as a discoverer, Longmans, Green, and Co. (1894), p. 171.
* ... one can still say that quantum mechanics is the key to understanding magnetism. When one enters the first room with this key there are unexpected rooms beyond, but it is always the master key that unlocks each door.
** John Hasbrouck van Vleck, Quantum Mechanics, The Key to Understanding Magnetism, Nobel Lecture (December 8, 1977).