也是一只自由泳的小鸟
Every particle in Nature has an amplitude to move backwards in time, and therefore has an anti-particle. […] I’d like to show you what this backwards-moving electron looks like to us, as we move forwards in time. […] We start at T0 with an electron moving toward a photon, which is moving in the opposite direction. All of a sudden—at T3—the photon turns into two particles, a positron and an electron. The positron doesn’t last very long: it soon runs into the electron—at T5, where they annihilate and produce a new photon. Meanwhile, the electron created earlier by the original photon continues on through space-time.
所以，电子是真的进行了时光倒流，只不过在随着时间正向流动的人眼里看来就成了正电子吗
还是说这是一个假说/理解方程的角度？
QED 这书读得我真的很想去看那本 Reasoning about Uncertainty... 那本 Introduction 里的引言就很吸引我：
"When one admits that nothing is certain one must, I think, also admit that some things are much more nearly certain than others. It is much more nearly certain that we are assembled here tonight than it is that this or that political party is in the right. Certainly there are degrees of certainty, and one should be very careful to emphasize that fact, because otherwise one is landed in an utter skepticism, and complete skepticism would, of course, be totally barren and completely useless."
— Bertrand Russell, Am I an Atheist or an Agnostic?
[...] Schwinger, Tomonaga, and I independently invented ways to make definite calculations to confirm that it is true (we got prizes for that).
然后我去查了，是 Nobel Prize
It was expected that only protons and neutrons would come out. But when the energies became sufficiently large, new particles came out. First there were pions, then lambdas, and sigmas, and rhos, and they ran out of the alphabet.
为何我联想到新冠。。。或者 run out of the alphabet 是常事吧
（向您安利中文（认真
啊？这就是你叫量子色动力学的原因？
In books it says that science is simple: you make up a theory and compare it to experiment; if the theory doesn’t work, you throw it away and make a new theory. Here we have a definite theory and hundreds of experiments, but we can’t compare them!
So when some fool physicist gives a lecture at UCLA in 1983 and says, “This is the way it works, and look how wonderfully similar the theories are,” it’s not because Nature is really similar; it’s because the physicists have only been able to think of the same damn thing, over and over again.
我又猜中了这个 fool 就是他自己
哇，看完了！费曼这本 QED: The Strange Theory of Light and Matter 出乎意料地简单好懂诶，也就集中读了两天吧！前两个 lectures 都是非常基础非常有逻辑衔接得也很好的内容，如果是工科生的话应该差不多在课本里都学过了，第三个 lecture 的后半部分和第四个 lecture 就突然神奇起来，更像科普了，读起来好像就是“我没法给你解释清楚但事情就是我讲的这个样子，虽然看起来一团糟，但 Nature 一直都是一团糟，只不过我们还在一步步寻找规律而已”，反正读完之后产生了强烈地去读一下正经教科书的兴趣
@unagi 这个可以叫做对数学上出现的“负能量解”的一种“诠释”吧，比如目前通用的 “正向时间拥有正能量的反粒子” 是 Feynman-Stückelberg interpretation（其实我也还没接触过别的合理诠释）
@QuantumBubbleTea 我就感觉这样来看的话真相就是“相对”的，反正我们也只能通过观测和推断来了解世界，而（在我的理解里）不存在直接了解到真相的途径，那么任何一种合理自洽的“诠释”都可以是对的。
@unagi 嗯就像量子力学也有多种诠释，只不过哥本哈根学派的诠释比较主流……但其实理论的诠释并不完全是物理学范围内的东西了，物理学只负责建模描述实验验证这些……
我好像是第一次看书的时候看 foreword preface 和 introduction 这么认真，因为我怀疑正文我都看不懂