Daily Archives: February 11, 2010

Multiple time dimensions

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Two dimensional time 6.1

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Physics

Special relativity describes spacetime as a manifold whose metric tensor has a negative eigenvalue. This corresponds to the existence of a “time-like” direction. A metric with multiple negative eigenvalues would correspondingly imply several timelike directions, i.e. multiple time dimensions, but there is no consensus regarding the relationship of these extra “times” to time as conventionally understood.

Philosophy

An Experiment with Time by J.W. Dunne (1927) describes an ontology in which there is an infinite hierarchy of conscious minds, each with its own dimension of time and able to view events in lower time dimensions from outside. His theory was often criticised as exhibiting an unnecessary infinite regress.

— Wikipedia on Multiple time dimensions

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2010.02.11 Thursday ACHK

The Open Cage

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Have you ever noticed that when animals are let out of cages, they don’t always realize at first that the door’s open? Often they have to be poked with a stick to get them out. Something similar happened with blogs. People could have been publishing online in 1995, and yet blogging has only really taken off in the last couple years. … it just took eight years for everyone to realize the cage was open.

— Paul Graham

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2010.02.11 Thursday ACHK

兩種天份

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超凡的人（時常）會以為自己無困難的東西是理所當然地無困難的。他們以為其他人都和他們一樣，所以其他人並不需要特意向他們學習。有時，超凡的才能甚至成為了超凡的人潛意識的一部分。他們運用才能時，連想也不用想，導致他們運用了超凡的才能也不知道。

例如，我以前有一科的老師本身學科的知識學養很出眾。但是，很多時候，我問他問題時，他一開始答，就答（例如）第十二步的東西。他沒有講開頭的十一步，導致我很難理解他的答案。哪為什麼他不說之前的十一步？是不是他特意為難我呢？

不是。我估計原因是，他覺得頭十一步太明顯，不需要教。

（安：甚至他不知道有頭十一步。你的第十二步，其實是他的第一步。）

我以前教書時都有這個現象。所以教學經驗很重要。它可以令你知道其他人其實感受不到你以為很明顯的東西。教學天份和學術天份本身是兩樣東西。例如教物理，要教得好的話，是需要兩種天份合在一起，變成一種完整的 “教物理” 天份。我是教了一年書後，才可以有辦法知道你層次在哪裏、你在哪一步開始不明白、對你來說怎才算是 “一步”。然後，將那些步驟拆到足夠細小，適合你吸收為止。

（安：所以如果用這個準則在衡量老師的好壞，根據自然定律，好的老師是極少數。那是因為要一個人本身學養高，機會已經很小。而同時要他教學技巧好，機會就更小。）

我以前也向學生講過類似的說話。如果每一萬人有一個人物理好。而每一萬人有一個人教學好。那樣，教物理教得好的人，每一億人就只有一個。

— Me@2010.02.10

2010.02.10 Wednesday (c) All rights reserved by ACHK