台湾记者可恶

2010.03.13

这几天看两会新闻，本来以为《京华时报》的那个记者是最可恶的，结果发现台湾东森电视台的记者更可恶。

人家本来只是为人民服务，可是给他这么一问，搞得来好像真的是司马昭之心，路人皆知的样子。

台湾是个新闻记者无法无天的地方，大陆可不是。

新闻自由真的要不得！要不得！

经验主义与理性主义

2010.03.13

中国学术界过去几十年受不靠谱的哲学思想毒害太深，搞自然科学的的人居然不得不抱着《反杜林论》这种东西翻来复去。其实在科学思想史上，这玩意儿的重要性恐怕最多跟方舟子和科学文化人之间的激烈争论一样，不能说一点价值没有，长远价值及其有限。

建议大家还是老老实实地去研究一下哲学中的经验主义（Empiricism）和理性主义（Rationalism）。要做一个象样的科学家和学者，首先要坚定地接受经验主义，在此基础上还要接受理性主义，而且不要把顺序搞反了。

下面是wiki百科上有关经验主义和理性主义的英文信息。

wiki百科上Empiricism介绍链接：http://en.wikipedia.org/wiki/Empiricism

wiki百科上Rationalism介绍链接：http://en.wikipedia.org/wiki/Rationalism

《论语》偶得

2010.03.13

夫子谓仁曰：己所不欲，勿施于人。

由是观之：为人民服务，属巧言令色，鲜亦仁。

The Nautilus curiosity shop in Torino, Italy describes this as “A very nice French conformateur, a device for registering the shape of a head so that a precisely-fitting hat may be made.”

The most basic explanation of Pi is that it is the ratio of the circumference to the diameter for a circle. That seems simple enough, but it turns out that Pi is an irrational number - so you can't just write it down. Oh, I know that you are an uber-geek and you could recite the first 80 digits of Pi. But the question is - how many digits are enough?

In this post, I am going to assume that we don't know the true value of Pi (which is essentially true). I can then use propagation of error techniques to see how dependent different calculations are on the value of Pi.

I still can't believe I haven't put a post together on the basics of measurement and uncertainty. Add that to the todo list. The most important idea in measurements is that they are not exact values. Let me start with my favorite example. Suppose I have a table that I want to know the area of. To do this, I measure the length and the width. The value I come up with for the length is 133.2 cm. But what does this mean? Is this the exact length of the table? No. Two problems.

• The table doesn't have an exact length. What does the length mean for a table? Is it a perfect rectangle? No. Is it even straight on the edges - probably not.
• Even if it were a perfect table, would my measurement be perfect? No.

Maybe I measured this length a whole bunch of times and at different locations. This would give me an estimate of how the measurements are spread out. If I do the same for the width, I might get something like:

This means that the length of the table is almost certainly between 133.0 cm and 133.4 cm. If a similar thing can be said about the width, then this diagram could represent the area.

The point I would like to make - since the width and the length have uncertainty, the calculated area would have uncertainty. How do you determine this calculated uncertainty? I have three ways:

• Use the extreme values of length and width to calculate the extreme values of the area (in this case the smallest area uses the smallest length and width). This is the method I use for my algebra-based physics labs.
• Assume the error is small, linear, and normally distributed. In this case, you can use the partial derivatives of the functions to determine the relationship of the uncertainty for the measured stuff on the calculated stuff. Here is wikipedia's page on this, but I am not really going to go into the details.
• Assume that if you measure the stuff a whole bunch of times, the data would be normally distributed. Write a program that generates normal data and use that to calculate tons of times the calculated value. Look at the spread of all these calculations to determine the uncertainty. I am not going to do this right now.

Archimedes used 96 sided polygons to estimate the value of Pi. He showed that Pi was greater than 3 and 10/71 and less than 3 and 1/7th. This gives a decimal value from 3.14084507 to 3.142857143 (with no rounding). I could write this as an average and an uncertainty of about:

That is not too bad of a value. But what about pi = 3? Is that bad? First - according to Snopes, no state has ever proposed a law that would officially change Pi to 3. It is still a fun story. Anyway, in this case I could perhaps say:

I chose the uncertainty in this fictional Pi to be +/- 0.2 so that the range would cover the true value of Pi. Really, though you could in general write Pi as:

Where Delta pi is the uncertainty in pi.

So what effect does the uncertainty in Pi have on different uses of Pi? Let me start with something practical - the speedometer in your car. Basically, your speedometer needs Pi to make the conversion between angular velocity and linear velocity using:

I know, there is no pi in that equation. But, how do you know the angular velocity (omega)? If this is measured in revolutions per second (or minute) then you have to convert units. Let me write this as:

Now, I will assume that omega, r, and pi all have uncertainty. Then the uncertainty in the velocity would be (using the max-min method from above for simplicity):

And I would do a similar thing for the minimum value. I could average the difference between average and the max and the average and the min. (I will put these calculations in a spreadsheet for you).

What about the volume of a sphere? This same thing is used for calculating things such as - the volume of the sun or the volume of a spherical cow. Here is the volume of a sphere:

These two uses of Pi seem boring - but really this is the basis for many applications of pi. There are tons of others, but they are maybe more abstract (but just as important). Now, on the to the spreadsheet. I will put in some values for the stuff, but you can change them if you like.

Note - I don't know how to change the number of digits presented in google docs. Also, I seem to have hit a creative wall with uses of pi. How about you list your favorite use of Pi in the comments?

每个人从刚生下来睁开眼睛开始，就要评估自己的家庭出身，父母社会地位怎样，家底怎么样，兄弟姐妹（如果有的话）怎样，父母偏心谁。而且在成长的阶段要不断地重新评估以更新资料。同时，也要趁早评估自己所在的城市或山区农村，评估自己所在的省、自己所在的国家，乃至自己所在的星球的目前状况。了解所有的东西，来决定你的人生最有戏的程度到哪里。人生的任何事情都是通过个人努力所达到的，通过个人努力达不到，只能怨自己活该。

这就是精英。所以这些人如果看到其他人在怨天尤人，就会忍不住去贬低——你好意思怨天尤人？你生在什么家庭你又不是今天才知道，你生在什么国家你又不是今天才知道，那你早干嘛来了？你不要跟我说你对你控制不了的世界抱有什么希望啊——这样很愚蠢。

所以，一个精英主义者就算是个种田农民，他说话的口气也会很像既得利益者。因为按照精英主义的上述思想，他今天的一切都是既得利益，都是经过精心评估和设计所能达到的人生最有戏程度，心态跟一个既得利益者没有区别了。只是大家喜欢攻击的精英主义者总是任志强那类，而不会是种田农民，因为大家并不羡幕种田农民，一个种田农民大秀少壮不努力之活该，没有人会气愤。

这就是所谓精英与草根的永恒矛盾：精英遇到什么不幸一律从自己身上找原因，草根遇到什么不幸一律从人家身上找原因。精英和草根与社会地位和个人财富无关。

站着说话不腰疼是非常爽的一件事，而且这么做我也感受不到任何道德和良心上的谴责，做个贱人很可能比老实人长寿。科学新闻最近“策划”了一个“深度”：博士“呼救”——中国博士生心理现状调查，点击该链接可以看到该专题的各篇文章。首先整个专题华尔街日报体到不行我就先不讲了，我看完所有的文章，持续在我脑中浮现的一句话就是“活该”。

我要分析一下，当初是谁或什么东西逼他们读博士的？因为读博士导致这些所有问题，如果早前愿意去想去了解的话，都可以了解个80%，那么多的师兄师姐。如果是早前没有了解就是活该没得说；如果是早前有了解，但还是选择了跳进这个火坑，那一定是有原因的，被迫的，无奈的。我就想分析一下读博士是为什么所迫。生活吗？不读博士没饭吃，读了才有？显然情况相反。前途吗？既然了解过，应该知道博士的前途就是继续读博士。自从读博士开始，你就已经走上你一生的职业了——科研。所以如果科研没饭吃，你就从读博士开始一辈子没饭吃。如果科研没老婆，你就从读博士开始一辈子没老婆。当然这只是打个比方，科研不至于没饭吃和没老婆，但都是要讲条件的。总之你读博士你就等于选择了科研，科研有什么不好你就都选择了。事后才在那里怨天尤人，不是活该是什么？

所以有很多人认为读博并不等于将来要做科研？那做什么？混学位吗？抱着这种心态，不是不可以，但是你要评估一个学位所带来的回报与你浪费的三五年时间相比是得大于失还是失大于得。不知道怎么评估？不好评估？那你就是没有答案啦。没答案你做什么决定？而且你连可能的最坏情况都不了解，你做什么决定？你不是活该是什么？而且你混学位你还要考虑你老板高不高兴。你老板不高兴你为什么不会延期？你以为全世界都是你父母吗？

总之一句话：

谁叫你忽视职业规划？活该！

你现在延期，老婆失业，房租交不起，已经活该。而且如果你继续不进行将来的职业和人生规划，你将继续活该。你的人生到头来只会有两个字——活该！

我猜之所以偏偏近几年才听到所谓“博士呼救”，是因为现在读博的都是80后独生子女，以为世界是围绕他们而设计的，他们只要“相信自己”一定会“一分耕耘一分收获”。80后的蜗居蚁族全部什么乱七八糟都是活该。这个宇宙的终极定律不是你来设计的，什么事情请只怨自己或者接受“活该”。可悲的独生子女们，那些成功学畅销书作者正在一边向你们抛媚眼一边在说：活该！

Wonjoon Choi, Seunghyun Hong, Joel T. Abrahamson,
Jae-Hee Han, Changsik Song, Nitish Nair, Seunghyun Baik &
Michael S. Strano
Nature Materials, Published online: 7 March 2010
doi: 10.1038/nmat2714

还是精英害国比较好

2010.03.13

王邦进《肉食者鄙 未能远谋——答王鸿飞》博文链接：http://www.sciencenet.cn/m/user_content.aspx?id=302198

我所谓的“精英误国论”，是指目前中国精英独裁制度下，精英们为了自己的私利的害国，和少数完全和大众脱离的精英，依靠自己的狭隘的认识，根本没有考虑全面因素的治国理念的误国。