"Shocking" unification reduces a lot of tough physics problems to just one

[Thomas the Tank Engine]

 

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It's the sort of physics advance that Sauron might appreciate. The villain in J. R. R. Tolkien's fantasy trilogy, The Lord of the Rings, gives the kings of men, elves, and dwarves magic rings, but then forges a single ring that controls all the others. In a similar way, a duo of theoretical physicists has come up with a way to transform all the disparate members of a vast family of complex systems known as spin models into different shades of a single simple model, which now serves as the one to rule them all.

 

That "Ising model" is the simplest spin model and already has a legendary history. The advance could have implications well beyond physics, as spin models have been used to simulate everything from stock markets to protein folding. "I find it pretty shocking," says David Perez, a mathematician at the Complutense University of Madrid (UCM), who was not involved with the work. "What is surprising is not that there is a universal model, but that it is so simple."

 

Spin models were invented to explain magnetic materials, such as iron and nickel. Those metals can be magnetized because each of their atoms acts like a tiny bar magnet. At high temperatures, the jiggling atoms point in random directions and their magnetic fields cancel one another. However, below the so-called Curie temperature, the material undergoes a "phase transition" much like water freezing into ice, and all the atoms suddenly point in the same direction. That alignment reduces the atoms' total energy and makes their magnetic fields add together. Because each atom's magnetism originates from the spin of an unpaired electron within it, models of how magnetism arises are known as spin models.

 

The Ising model was the first spin model, invented in 1920 by German physicist Wilhelm Lenz, who gave it to his student Ernst Ising to analyze. In it, each atom is a simple object that can point either up or down. Each spin flips randomly with thermal energy, but it interacts with its neighbors so that each pair of spins can lower its energy by pointing in the same direction. Each spin can also lower its energy by aligning with an externally applied magnetic field. The coupling between each pair of spins can be different, as can be the external field applied to each spin.

 

Ising hoped to show that below a certain temperature the spins would undergo a magnetic phase transition. However, he could "solve" only the 1D Ising model—a single string of spins—and found it had no phase transition. Ising speculated that the 2- and 3D cases wouldn't, either. Then in 1944 the enigmatic Norwegian-American chemist Lars Onsager solved the Ising model with uniform couplings and no external fields on a 2D square pattern of spin. The famously incomprehensible Onsager, who won the 1968 Nobel Prize in Chemistry for earlier work but also lost two faculty jobs, showed that the 2D Ising model does have a phase transition—the first seen in a theoretical model. Onsager's tour de force calculation is now legendary, although he published it only 2 years after the fact. The 3D Ising model is still unsolved.

 

Meanwhile, spurred in part by Ising's difficulties, physicists invented plenty of other spin models. Instead of up and down, the spins can have, say, five possible settings, or like compass needles can point in any direction. The spins might also interact in groups larger than pairs and with spins far beyond their neighbors. Spin models have found use outside physics. For example, the spread of an epidemic might be simulated on a spin model with spins having three states corresponding to well, sick, and recovered. "Spin model is a really bad name for something that's a lot more general," says Gemma De las Cuevas, a theoretical physicist at the Max Planck Institute of Quantum Optics in Garching, Germany.

 

 

 

 

 

 

 

 

 

Read the rest: http://www.sciencemag.org/news/2016/03/shocking-unification-reduces-lot-tough-physics-problems-just-one

[Unobscured Vision]

Oh holy hell, that's huge news. It's actually a bigger discovery than Gravitational Waves -- and that one was already the "great discovery" of the 21st Century, slightly higher up the food chain than the Higgs Boson a couple of years ago (which in of itself was the "great discovery" of the 21st Century).

 

Spin-states determining the phase of whatever particle being observed ... well folks, there's the basis for Quantum Realities right there. The higher up your D value is, you gain an additional spin-value for each of your fundamental particles that make up that bit of matter?

 

Damn. They just proved Multi-Dimensional Spacetime, Quantum Realities, and Spin-State Phasing in one shot. That's a hell of an accomplishment.

 

16 years into the 21st Century and we're a Quantum Leap (teehee!) ahead of where we were on January 1, 2000 regarding Scientific Understanding.

 

Nice job, Science.