Transcript · English → Chinese
Quantum Physics and Wave-Particle Duality
如果我们随机向屏幕发射一个小物 体，比如弹珠，
我们会看到它们穿过狭缝 并击中后墙所留下的图案。
现在，如果我们加入第二个狭缝，
我们会预料到右侧会出现 一条复制出来的第二条条纹。
现在，让我们来看看波。
波击中狭缝并向外辐射，撞击后墙，
在与狭缝直接对齐的地方强度最大。
后屏幕上的亮线显示了这一强度。
这与弹珠留下的线条类似。
但是，当我们加入第二个狭缝时， 发生了一些不同的事情。
如果一个波的波峰与另一个波的波 谷相遇，
它们就会相互抵消。
所以现在，后墙上出现了一个干涉图 样。
两个波峰相遇的地方强度最高，即亮 线，
而在它们相互抵消的地方，什么都没 有。
所以，当我们把物体，也就是物质， 投过双缝时，就会得到这个。
两条撞击条纹。
而对于波，我们会得到 由许多条纹组成的干涉图样。
目前为止还挺顺利。
现在，让我们进入量子世界。
电子是极小极小的物质， 就像一颗微型弹珠。
让我们发射一束电子流穿过单缝。
它的表现就像弹珠一样，只有一条条 纹。
所以，如果我们把这些微小的粒子 射向双缝，
我们应该像弹珠那样，得到两条条纹 。
什么？干涉图样！
我们发射了电子，也就是微小的物质 ，让它们穿过。
我们得到的却是像波一样的图样， 而不是像小弹珠那样。
怎么会这样？
物质微粒怎么会产生 像波一样的干涉图样？
这根本说不通。
但是，物理学家们很聪明。
他们想，也许那些小球在互相碰撞， 从而产生了那种图案。
于是，他们决定 一次只发射一个电子。
这样它们绝对不可能 互相干扰。
但是，在持续一个小时后， 依然出现了相同的干涉图案。
这个结论是不可避免的。
单个电子以粒子形式发射， 变成概率波，
穿过两个狭缝，并与自身干涉， 像粒子一样撞击墙壁。
但在数学上， 这甚至更加诡异。
它穿过了两个狭缝， 又好像哪个都没穿过。
它只穿过了其中一个， 又只穿过了另一个。
所有这些可能性 都处于彼此叠加的状态。
但这让物理学家们 彻底困惑了。
于是，他们决定偷看一眼， 看看它到底穿过了哪个缝隙。
他们在其中一个缝隙旁放了测量仪 器， 想看看它穿过哪个，然后让它飞过去 。
但量子世界远比他们想象的要神秘 得多。
当他们进行观测时， 电子又恢复了像小弹珠一样的行为。
它产生了两条条纹的图案， 而不是多条条纹的干涉图样。
仅仅是测量或观测它穿过哪个缝隙 的行为，
就意味着它只穿过了一个，而不是两 个。
电子决定做出不同的表现。
仿佛它知道自己正在被注视着一样。
End of transcript · 527 words · machine translated
Original transcript (English)
If we randomly shoot a small object, say a marble, at the screen, we see a pattern on the back wall where they went through the slit and hit. Now, if we add a second slit, we would expect to see a second band duplicated to the right. Now, let's look at waves.
The waves hit the slit and radiate out, striking the back wall with the most intensity directly in line with the slit. The line of brightness on the back screen shows that intensity. This is similar to the line the marbles make. But, when we add the second slit, something different happens.
If the top of one wave meets the bottom of another wave, they cancel each other out. So now, there is an interference pattern on the back wall. Places where the two tops meet are the highest intensity, the bright lines, and where they cancel, there is nothing.
So, when we throw things, that is, matter, through two slits, we get this. Two bands of hits. And with waves, we get an interference pattern of many bands. Good so far. Now, let's go quantum.
An electron is a tiny, tiny bit of matter, like a tiny marble. Let's fire a stream through one slit. It behaves just like the marble, a single band. So, if we shoot these tiny bits through two slits, we should get, like the marbles, two bands.
What? An interference pattern! We fired electrons, tiny bits of matter, through. We get a pattern like waves, not like little marbles. How? How could pieces of matter create an interference pattern like a wave?
It doesn't make sense. But, physicists are clever. They thought, maybe those little balls are bouncing off each other and creating that pattern. So, they decide to shoot electrons through one at a time. There is no way they could interfere with each other.
But, after an hour of this, the same interference pattern is seen to emerge. The conclusion is inescapable. The single electron leaves as a particle, becomes a wave of potentials, goes through both slits, and interferes with itself to hit the wall like a particle. But mathematically, it's even stranger.
It goes through both slits, and it goes through neither. And it goes through just one, and it goes through just the other. All of these possibilities are in superposition with each other. But physicists were completely baffled by this. So, they decided to peek and see which slit it actually goes through.
They put a measuring device by one slit to see which one it went through and let it fly. But the quantum world is far more mysterious than they could have imagined. When they observed, the electron went back to behaving like a little marble. It produced a pattern of two bands, not an interference pattern of many. The very act of measuring, or observing, which slit it went through,
meant it only went through one, not both. The electron decided to act differently. As though it was aware it was being watched.
