英文版The Scientific Value of IgnoranceIn 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 ContinueAdam 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.
