撰文 | Frank Wilczek澳门娱乐官网

翻译 | 胡风、梁丁当

汉文版

在量子物理中，只须对粒子的动量信息保持无知，才有可能获取它的位置信息。

在乔治·奥威尔（George Orwell）的演义《1984》中，有一句造作的口号“无知即力量”。这句口号是乔治 · 奥威尔笔下陈腐狞恶的政权的深入缩影。如若把它奥密地调理一下，改成“无知或为力量”，那这句新的口号就成了如今科技前沿的纯真写真。如若咱们能机灵地行使无知，它不错成为一种超才能，使咱们的感官更机敏（通过测量仪器），念念维更晴明（通过估计机）。

这条口号看似首尾乖互，其根源却在于量子现实的实质，它从根底上对咱们所了解的猖狂物体的特点施加了收场。如若咱们掌执所斟酌于物体现象的表面常识，那么咱们就能够准确地策动，在测量物体的位置与畅通速率时，它出咫尺某个所在以及具有某个速率的概率。可是，证明量子表面，位置的拖拉度与动量的拖拉度的乘积必须大于一个极限值。这即是海森堡省略情味旨趣。

咫尺，假定咱们要精准地测量某个物体的位置，以探伤引力波引起的轻微的时空曲解。为了最大限制地减少位置测量的舛误，同期不违抗海森堡旨趣，咱们需要尽可能地增多动量的拖拉度。这种测量艺术被称为“量子压缩”，它是面前热点的前沿盘考范畴。

要想制造出性能优胜的量子估计机，最主要的辛勤在于如何让它历久保持对我方的现象一无所知。经典估计机在运行经过中会经过一系列的“位置”，每个位置由一串0和1构成的字符所编码,其中的0和1代表晶体管的两种现象。与之相对的是，量子估计机的估计单位就像量子粒子相通，它不错同期处在系数这些位置上。

要想确保量子估计机能够可靠地运行，这种位置的拖拉性是必要的。因为只须这么，估计机才能在动量拖拉度较小的情况下准确地践诺下一步才能。如若估计机不测露馅了位置散播的信息，就会缩小位置的拖拉度。证明省略情味旨趣，这势必会导致动量拖拉度升高，从而龙套才能践诺的可靠性。

在我刚初始念念考如何行使量子宇宙的省略情味——某种进程上，也不错被称为“无知”——的时期，我一经以为这是量子宇宙独到的奇特步地。但我逐渐领路到这是一个更为正常的成见，它明晰地揭示了咱们与周围宇宙疏通的许多阵势其实并不简单。

比如，让咱们想一想咱们经常是怎样辩别出某个东谈主的。当光子投射到视网膜上，此后经大脑处理产生的图像会受到诸多身分的影响，比如这个东谈主的位置、朝向、她是否被其它物体装束、她的一稔等等。尽管如斯，咱们仍然能够判断出“这是贝茜”。泄露，在这个经过中咱们遴荐性地忽略了许多细节，而这么作念是有利的。

还有一个问题也浮现着无知的价值 ：为什么不是系数东谈主都有好意思满的音准呢？在咱们的内耳中，有一双小小的“反向钢琴”。它们通过拨动特定的键（现实上是特定的毛发）来对特定的曲调产生反应。通过这种阵势，耳朵不错齐集到系数的信息，但只须少量一部分东谈主能够王人备行使它们。关于咱们这些莫得好意思满音准的东谈主来说，八成大脑在运作时，无矍铄地“遴荐”了无知——惨酷那些曲调的信息，好让咱们专注于愈加灵验的信息上。

在圣经故事中，亚当和夏娃因为吃了“离别善恶树”上的果实而受到措置。不管你怎样看待这个故事，它都纯真地领导咱们 ：无知是一项值得钟情的遴荐。

英文版

The Scientific Value of Ignorance

In quantum physics, maximizing knowledge of a particle’s location requires fuzziness about its momentum, and vice versa.

In George Orwell’s novel “1984,” “Ignorance is Strength” is a shocking slogan that epitomizes a corrupt and sinister regime. But in a more nuanced form, “Ignorance can be Strength,” it is an apt slogan for some cutting-edge science. Used wisely, ignorance can be a superpower that makes our senses more acute and our minds more capacious(through measuring devices and computers, respectively).

This seeming paradox is rooted in the nature of quantum reality, which imposes a fundamental limitation on our knowledge of the properties of any object. Given perfect theoretical knowledge of an object’s state, we can predict probabilities for where it will be found and how fast it will be seen to move, if we measure those things. But according to quantum theory, when we multiply the fuzziness in predicted position by the fuzziness in predicted momentum, the product cannot get below a definite limit. That is Heisenberg’s uncertainty principle.

Now suppose that we’d like to measure the position of a test body very precisely, so that we can detect the tiny distortions of space caused by gravitational waves. To minimize the fuzziness in its position, while remaining in Heisenberg’s good graces, we need to crank up the fuzziness in its momentum. The art of doing this is called “squeezing,” and it is a hot frontier of research.

The main difficulty in making good quantum computers is keeping nature ignorant about what they’re doing. A classical computer runs through a sequence of definite “positions,” each consisting of a series of 0s and 1s that represent the states of its transistors. A quantum computer, like a quantum particle, allows all these positions to coexist.

Fuzziness in position is necessary so that the computer can move reliably, with small fuzziness in “momentum,” to execute the next step in its program. If the computer inadvertently betrays information about its distribution of positions, it will reduce that distribution’s fuzziness and necessarily inject fuzziness into the corresponding momentum, thus making the program’s execution unreliable.

When I first began to think about leveraging ignorance in the quantum world, I considered it to be one of that world’s weird special features. But I’ve come to see it as a much broader idea that illuminates many things about how we deal with the everyday world.

Consider, for example, what it means to recognize someone. The underlying pattern of photons that arrives at our retina will be quite different depending on where that person is, how they’re oriented, whether they’re partially hidden behind other objects, what they’re wearing and many other factors. But in concluding “It’s Betsy,” we choose to ignore all that, and that’s obviously a useful thing to do.

Why don’t we all have perfect pitch? Within our inner ears we have little inverse pianos that move specific keys(actually, specialized hairs)in response to specific tones. The information is there, but few of us can access it. Those of us who don’t have perfect pitch may have “chosen” ignorance—unconsciously, as our brains got wired up—in order to focus on more generally useful relationships.

Advertisement - Scroll to Continue

Adam and Eve were punished for eating from “the tree of the knowledge of good and evil.” However you take that story, it is a vivid reminder that ignorance is an option worth keeping in mind.

Frank Wilczek

弗兰克·维尔切克是麻省理工学院物理学解说、量子色能源学的奠基东谈主之一。因发现了量子色能源学的渐近摆脱步地，他在2004年取得了诺贝尔物理学奖。

本文经授权转载自微信公众号“蔻享学术”。

特 别 提 示

皇冠体育hg86a

1. 干涉『返朴』微信公众号底部菜单“杰作专栏“，可查阅不同主题系列科普著述。

2. 『返朴』提供按月检索著述功能。温雅公众号，答谢四位数构成的年份+月份，如“1903”，可获取2019年3月的著述索引，依此类推。