(Fig.1) An electron is a meaningless "letter" in quantum mechanics !
The present basic quantum mechanics was introduced in very old 1920s, so it cannot handle actual complicated physical phenomena ( though all the media is hiding it ! )
First, it can express the basic electron particle as only "nonphysical letters (= c†, c )" with NO actual figure. That's all it can do, so useless.
The is the reason the quantum mechanics is useless, just pursues "fantasy".
(Fig.2) Just "three abstract letters" (= JSS ) mean actual ferromagnet ?
How does the present quantum mechanics describe the actual ferromagnetism in iron magnet ? In fact, quantum mechanics has NO ability to explain actual phenomena.
They just put three simple letters side by side to express each metal.
This spin model is too abstract to deal with actual complicated phenomena !
Here, "S" denotes "electron spin" at each atomic position, and "J" means the strength of their spin-spin interaction. That's all.
This spin interaction parameter J is freely chosen and adjustable ( NOT gotten from the original spin postulate ! ), so useless and can predict nothing.
(Fig.3) Real metal → real structure → quantum useless model !
A recent Harvard paper is very unclear about what they are aiming at. Because they themselves knows their research is useless, and trying to hide it from people.
They try to simulate metallic many-body phenomena using some quantum quasi-model ( ← "quasi" means NOT actual model ).
Schrodinger equation introduced in ancient 1920 cannot handle multi-electron atoms, so all they can do is fabricate artificial pseudo-model and pseudo-particle.
They forcedly try to describe complicated many-body actual phenomena using fake quasi-1d model ( this p.2 this p.2 )
(Fig.4) ↓ Why the current academia remain useless, harmful to people ?
The current solid-state physics is based on ancient quantum mechanics in 1920s, where each metal is expressed by "oversimplified" 1d spin model.
In this Harvard paper ( this p.2 ), they just use three oversimplified letters (= JSS ) as an actual metallic model. S denotes unrealistic electron spin.
"J" is just an artificial parameter, which they can freely adjust, so it's meaningless and useless as an actual physical model.
These spin models disagree with the experimental results such as ferromagnetism. This is the reason why the current basic science stops advancing, remains useless for us.
(Fig.5) Solid-physics → faster-than-light entangle → black hole ?
Unfortunately, all the present basic physics is going in the wrong fantasy science ! This Harvard paper tries to connect solid-physics with unreal entanglement entropy.
Entanlement is fantasy faster-than-light action between particles. But we cannot send faster-than-light signals, so entangle is an useless, meaningless fiction.
So their new concept "entanglement entropy" is just an "imaginary concept" to mislead us into fanasy black hole and extradimension ( this p.13 ).
2016/12/23 updated. Feel free to link to this site.