Cosmic string

String theory and cosmic strings

There is no direct connection between string theory and the theory of cosmic strings (the names were chosen independently by analogy with ordinary string).

However, work in string theory revived interest in cosmic strings in the early 2000s. In 2002 Henry Tye and collaborators observed the production of cosmic strings during the last stages of brane inflation. It was also pointed out by string theorist Joseph Polchinski that the expanding Universe could have stretched a “fundamental” string (the sort which superstring theory considers) until it was of intergalactic size. Such a stretched string would exhibit many of the properties of the old “cosmic” string variety, making the older calculations useful again. Furthermore, modern superstring theories offer other objects which could feasibly resemble cosmic strings, such as highly elongated one-dimensional D-branes (known as “D-strings”). As theorist Tom Kibble remarks, “string theory cosmologists have discovered cosmic strings lurking everywhere in the undergrowth”. Older proposals for detecting cosmic strings could now be used to investigate superstring theory.

— Wikipedia on Cosmic string

2010.06.28 Monday ACHK

Isaac Newton

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To do really great things, you have to seek out questions people didn’t even realize were questions.

You only get one life. Why not do something huge?

And you know more are out there, separated from us by what will later seem a surprisingly thin wall of laziness and stupidity.

— Paul Graham

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2010.06.28 Monday ACHK

專利

「專利制度」表面上,主要是為了保障新產品發明者的利益而設的。那是大眾的誤解。實情是,「專利制度」的存在,主要是為了社會的整體利益。文明社會確立「專利制度」,是「兩害取其輕」的結果。

在有「專利制度」之前,新產品發明者為了保障自己的利益,往往會隱藏新產品的建構方法,導致很多新創見隨著發明者的離世而失傳。為了避免這種情形,人們創立了「專利制度」,容許新產品發明者為自己的新設計申請「專利」。申請成功的話,社會就賦予發明者長達大約 17 年的特權:只有他可以使用該設計來製造產品。

為什麼那就可以避免「新創見失傳」呢?

申請「專利」的先決條件是,發明者不單要公開自己新產品的建構方法,而且還要鉅細無遺地描述,哪些地方是全新的意念。在 17 年過後,全人類可以共同擁有使用那些新意念。

— Me@2010.06.28

2010.06.28 Monday (c) All rights reserved by ACHK