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形形色色(6)  

2009-11-08 14:18:08|  分类: 默认分类 |  标签: |举报 |字号 订阅

  下载LOFTER 我的照片书  |

1、隐身斗篷的故事

电磁隐身斗篷现在成了热门研究领域。

我受葛墨林老师的影响关注这个方向,最后终于和苗荣欣、庞毅建议用metamaterials模拟宇宙,特别是de Sitter空间。

Invisibility Uncloaked是一篇较长的讲这个故事的文章。

它从Leonhardt如何将一篇建议共形变换研究隐身斗篷的文章投到Science,Nature, PRL的故事开始(开头是悲剧,最后是喜剧),一直谈到最近的进展。

摘录:

Leonhardt’s role in the cloaking field’s rise to respectability did not get off to an encouraging start. The details of his initial frustration and eventual triumph illustrate the swiftness with which the field entered the mainstream — even surprising some experts. “I began my work at a time when invisibility was not fashionable at all,” he says. That was about a decade ago. After years of quiet work with a few colleagues, he wrote a paper titled “Optical conformal mapping.” The abstract’s first words come right to the point: “An invisibility device should guide light around an object as if nothing were there.”

这一段说隐身斗篷如何迅速成为研究主流的。

我希望用超颖材料模拟宇宙学也迅速进入大家视野。

2、LHC要加速面包?

当然不是。

在帮助LHC制冷的设备中,人们发现了一坨面包,致使LHC暂时停顿。

有人故意捣乱吗?不知道。

Efforts to get the Large Hadron Collider up and running just encountered a temporary snag, reports yesterday’s online edition of The Times of London. A crusty chunk of bread “paralysed a high voltage installation that should have been powering the cooling unit.” That cryogenic facility, guarded by high-security fences, is designed to super-chill the LHC to temperatures approaching absolute zero.

And the official explanation for the out-of-place chunk of starch?

“Nobody knows,” a spokewoman for the CERN particle physics laboratory in Geneva told The Times. “The best guess is that it was dropped by a bird, either that or it was thrown out of a passing aeroplane.” Then again, that doesn’t seem to quite comport with the news organization’s explanation about where the bread was found: on an electrical connection inside one of eight above-ground buildings at the site.

以上是Large Hadron Collider suffers carb attack的全文。

3、计算动物智力

动物的智力能计算吗?可能。Calculating Animal Intelligence告诉我们John Evans找到一个公式。

John’s formula is simple: C (complexity) = logN * (1 + 2logZ) where N is the number of units and Z is the average number of interactions. (If you would like to see his logic, you can read the paper cited below.) In the paper, we tested the formula by calculating C for the nervous systems of animals ranging from nematodes (N = 302 neurons, Z ~ 10) through insects and frogs and finally a series of mammalian brains.

4、人生的意义

越来越多的人怀疑人生,不知道人活着为了什么?有人说是为了自私的基因,有人说是为了生产更多的生命。

The purpose of life的作者认为生命的目的其实更加无私,是为了保护更多的生命。例如他说

The process at work is the universal tendency of all life to produce, protect, and nurture life. Differences between life forms do not seem to affect this tendency. We humans for example, like to keep pets and nurture plants not just because we enjoy doing so - we feel a need to have other life forms nearby and to interact with them. But this impulse is not restricted to humans. Instances of animals adopting the young of other species are well documented. These behaviours exist because organisms in their natural state feel a need to contribute to the greater good.

所以,我们应该对那些怀疑人生的人说,好好活着吧,因为别人和别的生命需要你。

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