# Einstein field equations

Einstein’s equation in plain English:

Given a small ball of freely falling test particles initially at rest with respect to each other, the rate at which it begins to shrink is proportional to its volume times: the energy density at the center of the ball, plus the pressure in the x direction at that point, plus the pressure in the y direction, plus the pressure in the z direction.

— John Baez

2010.06.12 Saturday ACHK

# Pianist

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An expert pianist can play notes faster than the brain can send signals to his hand. Likewise an artist, after a while, can make visual perception flow in through his eye and out through his hand as automatically as someone tapping his foot to a beat.

— Paul Graham

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2010.06.12 Saturday $ACHK$

# 讀書與睡眠

（LWT：我有有關睡眠的問題。如果要溫了書的話，就會很晚才可以睡。所以我會想，究竟應該溫了書才睡，還是早點睡，第二天才早起來溫習？）

（LWT：但是呢 … 早睡的話，可能第二天早上仍然不能早起。結果都是沒有溫習。）

（LWT：為什麼你那時就可以早起呢？）

— Me@2010.06.11