量子力学阅读笔记(3)｜多维空间

手头的书还没看完，不过最近看了几篇文章，突然发现用多维空间来理解量子力学的“既…又…”叠加现象很有帮助～（只是个人一种特别简单粗暴的思考方式）

多维空间又是另一个范畴的东西了，没法考虑超弦理论、黎曼几何和空间曲率这些，从最最简单的四维说起。（此文借鉴了知乎niyoul对《为什么人类想象不出四维的空间》的回答）

通常意义上理解的四维空间，也就是三个空间维度（上下、左右、前后）加上时间这一维度。

一维空间是直线（X轴），二维是平面（X轴、Y轴），三围是空间（X轴、Y轴Z）。

如果我们把一维空间的直线在二维空间上进行扭曲，那么A点和B点就重叠了，很好理解吧？

然而，一维的人就会觉得，这个物体同时出现在了A点和B点。

再加入时间维度（t1 t2)，那不就是说明它同时处于两种状态？既死又生，既是光又是波，既爱又不爱？

当然，量子叠加不仅仅是空间位置的重叠，而是状态的叠加，两者本质不同。

但至少可以从这角度想，是不是可以类比我们三维世界的人，其实看到是四维（或更高维）空间投影在三维空间的粒子（高维空间投影到低维时产生的信息压缩），能否这么理解同时出现这个现象？

在四维时空的观点中，时间就像空间一样是整体存在的。

我们可以先把时间也看成一个坐标轴。（我知道，时间维度与空间维度虽然在形式上类似，但本质上有重要区别。此外在我们这个世界根据热力学第二定律，时间具有单向性）

那么我们这个三维空间就是在时间Y轴上运行，你作为一个三维物体，只能感受Y轴一个个瞬间。

“现在”只是我们的感知，实际上过去、现在、未来都同样真实存在。

好了，我这里必须要把爱因斯坦搬出来了。

1955年，爱因斯坦给好友米歇尔·贝索（Michele Besso）去世后写信悼念时写道：“过去、现在和未来的区别只是一种幻觉，尽管这是一种持久的幻觉”。

这是一种基于广义相对论的宇宙观，"块宇宙"（Block Universe）理论：

时空是一个统一的整体，所有事件——无论是过去、现在还是未来——都以同样的方式存在于这个四维连续体中。

所有的时间点同时存在。时间流逝是人类的错觉，也就是说，未来其实已经存在。

这就牵扯到自由意志的问题了。关于这个哲学困境至今仍在争论，这是另一个话题了。

但是，量子力学的不确定性，叠加和塌缩又撬动了这个观点，认为微观世界具有概率性，与块宇宙的确定性冲突。

P.S.目前有观点认为两者可通过多世界（平行宇宙）诠释调和，所有可能性都可以实现。

好吧，我还得再学习。。。

此外，之前看《死神永生》时，蓝色空间号的人从翘曲点进入第四维，再潜入万有用力号那段描写特别精彩。但是后来我查了下资料发现这应该不可能？

人类的身体是由分子、原子构成的，而分子、原子构成是因为原子核与电子之间的电磁力。分子、原子进入四维空间后物质的基本相互作用力如何表现不得而知，但肯定不会维系现有状态。。。。

这是（2）https://www.douban.com/note/872129560/?_i=5738342KZGV8y-

0428 update:

This morning while running, Lou Reed's "Pale Blue Eyes" kept echoing in my mind. Sometimes I feel so happy

Sometimes I feel so sad

Sometimes I feel so lonely

But mostly you just make me mad

Baby, you just make me mad

Then when I got home and checked the lyrics, I realized that the song actually doesn't have the word "lonely".

And of course, there is no such things (or no one who) that should be thought of as my mountain top or the peak.

So I guess that's just the way it is.Maybe I should be used to those, and the way interact and maintain a safe distance.Accept that it's okay to feel upset or disappointed sometimes.

I don't believe in fate or destiny or horoscopes, but when you appeared, I thought you may be the one. That's unfair, one must face oneself, no matter you or me, although sometimes I fxcking asked for it.

I can't say I'm surprised things turned out this way.I have been there before and I still want to be with you. I know It's impossible for someone to precisely meet all your ideals.what I worry about is that it never happened.

I always felt there was something kind of pulling me back to darkness. I believe that’s why I've been absorbed in studying Quantum Mechanics recently.

I need to feel something BIGGER than myself. So how about cosmic mattering?

“A human being is a part of the whole, called by us “Universe”, a part limited in time and space. He experiences himself, his thoughts and feelings as something separated from the rest — a kind of optical delusion of his consciousness.……Nobody is able to achieve this completely, but the striving for such achievement is in itself a part of the liberation and a foundation for inner security.”

We always have choice, choose to love, to comfort, to understand, to forgive, and to face difficulties bravely.

A monk once said that if we think of spiritual practice as climbing Mount Everest, "meditation" helps us build a base camp along the way. We can return to it to rest whenever we encounter difficulties.

These ideas are valuable, but I believe practice isn't just about staying in the base camp and being content. That’s not enough.

Maybe the goal is to reach the summit, which represents transcendence—surpassing our limitations or merging with something BIGGER than ourselves.

"Fitter, happier, more productive" "Comfortable (not drinking too much)" "Regular exercise at the gym (three days a week)"