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

.

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

.

.

.

2010.06.12 Saturday ACHK

讀書與睡眠

這段改篇自 2010 年 2 月 7 日的對話。

(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?)

個個人也不同。你應該做實驗:兩個方法也試一試,看看哪一個對你比較好。

(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。)

所以我說「個個人也不同」。你一定要做實驗才知道。例如,我中學時期(1998),當企圖早起溫習時,次次都會失敗。所以,我後來放棄了「早起大計」,每晚也溫完書才睡。兩年多前(2007),我重新讀書時,因為日間要上班,晚上回家後實在十分疲倦,不能集中精神溫習,唯有每天早上四時起來溫習。

(LWT:為什麼你那時就可以早起呢?)

比喻說,一個人當生命安全受到威脅時,就什麼事情也可以做到。

那時,我沒有其他選擇。如果不早起的話,就完全沒有時間溫習。那樣,「我要得到一個物理學位」的夢想就要放棄。

— Me@2010.06.11

2010.06.12 Saturday (c) All rights reserved by ACHK