# Kaluza–Klein theory

In physics, Kaluza–Klein theory (KK theory) is a model that seeks to unify the two fundamental forces of gravitation and electromagnetism. The theory was first published in 1921. It was proposed by the mathematician Theodor Kaluza who extended general relativity to a five-dimensional spacetime. The resulting equations can be separated into further sets of equations, one of which is equivalent to Einstein field equations, another set equivalent to Maxwell’s equations for the electromagnetic field and the final part an extra scalar field now termed the “radion”.

— Wikipedia on Kaluza–Klein theory

2010.07.26 Monday ACHK

# Customers

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Customers Don’t Know What They Want. Stop Expecting Customers to Know What They Want. It’s just never going to happen. Get over it.

— The Iceberg Secret, Revealed

— Joel Spolsky

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2010.07.26 Monday $ACHK$

# 難能可貴

Rare 2

— Me@2010.07.21

How would it be possible, if salvation were ready to our hand, and could without great labour be found, that should be by almost all men neglected? But all excellent things are as difficult as they are rare.

— Spinoza