撰文 | Frank Wilczek第二银河官网

海淀区共有6所学校上榜，共59人获得一等奖，具体是：

再问问，以前没多久就得去西单转悠一趟，是不？

翻译 | 胡风、梁丁当

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汉文版

在量子物理中，只消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，有一句作假的口号“无知即力量”。这句口号是乔治 · 奥威尔笔下退步荼毒的政权的深刻缩影。淌若把它好意思妙地营救一下，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。淌若咱们能聪敏地哄骗无知，它不错成为一种超才智，使咱们的感官更敏锐（通过测量仪器），念念维更豁达（通过策动机）。

这条口号看似针锋相对，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苟且物体的特点施加了为止。淌若咱们掌捏所联系于物体现象的表面常识，那么咱们就能够准确地瞻望，在测量物体的位置与领路速率时，它出面前某个所在以及具有某个速率的概率。然则，把柄量子表面，位置的粗率度与动量的粗率度的乘积必须大于一个极限值。这等于海森堡省略情味旨趣。

面前，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细小的时空诬蔑。为了最大适度地减少位置测量的舛错，同期不违犯海森堡旨趣，咱们需要尽可能地增多动量的粗率度。这种测量艺术被称为“量子压缩”，它是面前热点的前沿征询限度。

要想制造出性能优厚的量子策动机，最主要的不毛在于若何让它持久保持对我方的现象一无所知。经典策动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，量子策动机的策动单位就像量子粒子同样，它不错同期处在整个这些位置上。

要想确保量子策动机能够可靠地运行，这种位置的粗粉碎是必要的。因为只消这么，策动机才能在动量粗率度较小的情况下准确地实践下一步行径。淌若策动机不测深刻了位置散布的信息，就会裁汰位置的粗率度。把柄省略情味旨趣，这势必会导致动量粗率度升高，从而龙套行径实践的可靠性。

在我刚初始念念考若何哄骗量子寰宇的省略情味——某种进度上，也不错被称为“无知”——的技能，我还是合计这是量子寰宇特有的奇特表象。但我迟缓清醒到这是一个更为平日的主张，它明晰地揭示了咱们与周围寰宇换取的许多神志其实并不浮浅。

比如，让咱们想一想咱们通常是何如鉴别出某个东说念主的。当光子投射到视网膜上，尔后经大脑惩办产生的图像会受到诸多要素的影响，比如这个东说念主的位置、朝向、她是否被其它物体保密、她的穿戴等等。尽管如斯，咱们仍然能够判断出“这是贝茜”。显明，在这个经过中咱们摄取性地忽略了许多细节，而这么作念是有利的。

还有一个问题也败露着无知的价值 ：为什么不是整个东说念主都有竣工的音准呢？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（履行上是特定的毛发）来对特定的曲调产生反应。通过这种神志，耳朵不错采集到整个的信息，但只消小数一部分东说念主能够皆备哄骗它们。关于咱们这些莫得竣工音准的东说念主来说，概略大脑在运作时，不测志地“摄取”了无知——疏远那些曲调的信息，好让咱们专注于愈加有效的信息上。

在圣经故事中，亚当和夏娃因为吃了“划分善恶树”上的果实而受到刑事包袱。不论你何如看待这个故事，它都纯真地教唆咱们 ：无知是一项值得钟情的摄取。

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.

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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教师、量子色能源学的奠基东说念主之一。因发现了量子色能源学的渐近解放表象，他在2004年取得了诺贝尔物理学奖。

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