kanex
发表文章数: 860
武功等级: 弹指神通
(第六重)
内力值: 343/343
完了，完了
我们系没有人做理论方面，系主任推荐我去写信给李淼教授，结果我不小心说了些crackpot理论，被认为是不懂QFT被强烈鄙视，越解释越被认为不懂 -_-
江畔何人初见月`江月何年初照人`
| 发表时间：2005-12-12, 03:53:44 |
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弱力三千
发表文章数: 143
武功等级: 罗汉拳
(第六重)
内力值: 169/169
Re: 完了，完了
真懂就不怕被暂时误会嘛~多写几次信就说得清了~
当华美的叶片落尽，生命的脉络才历历可见
弱水三千，只取一瓢饮
娇玫万朵，独摘一枝怜
| 发表时间：2005-12-12, 06:07:55 |
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kanex
发表文章数: 860
武功等级: 弹指神通
(第六重)
内力值: 343/343
Re: 完了，完了
误解很深，只好写封超级长信，从最头说起。
江畔何人初见月`江月何年初照人`
| 发表时间：2005-12-12, 06:08:40 |
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弱力三千
发表文章数: 143
武功等级: 罗汉拳
(第六重)
内力值: 169/169
Re: 完了，完了
哈哈，和这种人打交道，第一要避免过于数学化的论述
第二就是要单刀直入，展示最精华的部分
当华美的叶片落尽，生命的脉络才历历可见
弱水三千，只取一瓢饮
娇玫万朵，独摘一枝怜
| 发表时间：2005-12-12, 06:19:48 |
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sage
发表文章数: 1125
武功等级: 天山六阳掌
(第六重)
内力值: 535/535
Re: 完了，完了
would you share your crack-pot ideas with us? maybe we could help you sharpen it.
It is always good to start contacting a professor with questions, not with your own big theory.
| 发表时间：2005-12-12, 15:27:02 |
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元江
发表文章数: 228
武功等级: 逍遥拳
(第五重)
内力值: 200/200
Re: 完了，完了
sage 这个说得有道理：-)有学问得人都是喜欢别人向他请教的：-)
道可道非常道
名可名非常名
| 发表时间：2005-12-12, 18:31:31 |
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kanex
发表文章数: 860
武功等级: 弹指神通
(第六重)
内力值: 343/343
Re: 完了，完了
没错，如果哪天有个毛头小子跑上来就说一大堆奇谈怪论，一定会让你非常愤怒。
The central issue is that I don’t think the probability interpretation, the operator + Hilbert / Fock space approach, or even the idea of field itself in quantum theories should take any role in a fundamental theory of the universe [but I forget to mention this clearly in any of my email, so Prof. Li became very angry and thought I know nothing about quantum theories]. I will briefly explain the reasons.
The most common interpretation of QFT is: the quantum fields are the only things that matters [in some sense, path integral formalism is more powerful than the canonical approach, for we are able to derive some non-perturbative results from it. But, we shall notice that none of these “topological” solutions are observed. Some people hold the belief that due to some black magic we will get miracles if we know all the non-perturbative features of the theory, but I have to disagree]. It is always said that "particles" are localized Gaussian wave packets of the field [we can map the field to a vector in the Fock space, and have a more “relevant” picture of the particles in the field. But this really does not change anything]. However this is just the principle. We do not need this principle for doing any calculations. And we do not need this principle for making any predictions of the real universe.
I have to say that the only usage of this “principle” is to bring endless confusions.
We just do a functional integral over field histories, and get the only “observable”: the S-matrix [Unfortunately, it is not well-defined when we have the big bang. We do not even know what a vacuum is in that case]. Everything is encoded in it. And, we have huge troubles decoding them. It is very discouraging.
What is worse is that we do not know how to do the integral directly. It is ill-defined from the start. We do a perturbative expansion of the exponential, and get a series. We use funny diagrams to help us remembering the coefficients in the series, and we call them Feynman diagrams. For some deep reason [check john baez’s website. I wont go through it here], Feynman diagrams look superficially close to some “real process”, however it is perfectly legal [and a wide-spread idea] to regard them as merely a tool for doing perturbative calculations and hand-waving arguments.
The integral is still ill-defined because we did not choose the correct measure. We get infinities. Then we have regularization + renormalization. The real mathematics behind them is to replace the Lebesgue measure by Gaussian measure. “Particles” are Gaussian! After all this mess, we finally get some physical results.
Are we satisfied? Is it the end of the story? No.
[to be continue.]
江畔何人初见月`江月何年初照人`
| 发表时间：2005-12-12, 19:43:17 |
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kanex
发表文章数: 860
武功等级: 弹指神通
(第六重)
内力值: 343/343
Re: 完了，完了
Please ignore the above post. It is early in the morning and I got something wrong in my brain.
江畔何人初见月`江月何年初照人`
| 发表时间：2005-12-12, 20:36:55 |
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