Quantum magic

I like Richard Feynman for many reasons, and one of them is that he sincerely did not want to be Nobel Prize laureate. He enjoyed what he was doing and considered this enjoyment to be enough reward in itself. Later he proved to be right when the glorious title took more of his time than paid back in some advantage. Apparently, Richard was not a vain person at all – another reason to respect him.

He has many great sayings. I like this one, for example: “Do not keep saying to yourself, if you can possibly avoid it, ‘But how can it be like that?’ because you will get ‘down the drain’ into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that.”

Recently, I got in a bit of trouble by misquoting another Feynman’s statement. It was found on his blackboard at the time of his death: “What I cannot create I do not understand.”

When I have read it the first time, it impressed me by the expressing what I felt about our knowledge.

As far as I know, no person had a chance to hear Feynman’s explanation of what he meant by this, so I came up with my interpretation: “If you can build something, then you understand it.”

Over time, this my rewording substituted the original one in my memory, and I started quoting Feynman my way.

Three weeks ago, I attended a meeting of Denver Physics Study Group, recently founded by Mike Witt. He had a good experience with such a group in Portland, so he started a similar group in Denver. Several people were present discussing “Can a particle really be in two places at once?”

During the discussion, while making some point, I (mis)quoted Feynman, as I described above and Doug Morrow, one of the participants, later responded to my statement on the group blog. When I saw the quote written, it felt not right. I quickly went to the source, and sure enough, the original wording was different. But I stand by my interpretation even if Richard Feynman meant something different. And here it is.

I think that the phrase “If you can build something, then you understand it” provides the criteria, if not the definition of “knowledge.” The presence of the applicability – that we can use something for the successful prediction of the results (that is, in my view, the synonym of “building”) – is necessary for being categorized as knowledge. To illustrate, I can offer you to think about a compelling wordplay (there were plenty debunked theories in the past) that has nothing to do with the reality, because it falls apart as soon as we perform an experiment. But if we can use some statement for consistent generation of some practical results, then we can call it a piece of knowledge. Well, some knowledge can (and it has happened many times in the past) be debunked in the future and replaced with another one. But without passing the criteria of the applicability, it would never be qualified as knowledge in the first place.

Doug, on the other hand, uses another criterion. For him, to understand something means to be able to answer “how or why.” Since quantum physics, in his view, does not provide sufficient answers, he comes to the conclusion that “the quantum world will remain more like magic than science until new theories are developed and tested that give one, and only one explanation for why ‘wavicles’ have their dual nature, how electrons can tunnel and if entangled particles are really one thing or two. Until then, it’s just magic, all the way down.”

As an example of a theory that provides sufficient answers to “how or why”, Doug names plates tectonic theory. I think I understand what he meant. The plates tectonic theory is knowledge because it establishes causal effects between the big-scale (by comparison to the quantum) phenomena. But I offer you to apply the same “how or why” to each of the phenomena used in that theory. They must be able to yield some answers. Otherwise, by Doug’s definition, we do not have knowledge about them and, if so, do not have knowledge about the plates tectonic theory itself. So, here we go. “How or why” heat? “How or why” magma? “How or why” gravity?

I think you understand where I am heading. Eventually, we will drill down to the quantum level, which, according to Doug, is not understandable. Does it mean we do not understand plates tectonic? I think so, if we agree, of course, that quantum physics is not understandable. In other words, I am saying that quantum explanation underlies all other explanations. By stating that we do not understand the quantum world we also state that we do not understand anything. The way out, in my opinion, is the (Feynman’s) quote. Because we can use quantum theory for predictions and practical results in the same manner we can use plates tectonic for predicting the quakes (well, we do not do it as well today as we predict quantum results, but we are getting there).

I also would like to mention Mike’s explanation of the origin of the notion that quantum physics is not understandable. It is based on the desire of the quantum physicists to bring lay people onboard (and pay the bills) of the fundamental research. They use analogies and try to illustrate quantum phenomena with everyday ones. They say “wave” and people imagine, well, a wave. They say particle, and people imagine a small ball. The waves and balls feel very different in our everyday life and we get the confusion and mystery: how the same thing can be a soft wave and a hard ball at the same time?

Well, let us look at the clouds. Do you see a dog or a camel or any other image, including a wave? And the same cloud sometimes yields different images to different people (like Rorschach test). And yet, when we fly into the cloud, we realize it is just a vapor. In the same manner, if we dive deep enough into the wave and the ball, we will eventually encounter the same “quantum vapor.”

Can we say that the soft wave and the hard ball are different on that level? If yes, then on which level the difference manifests itself? That’s the origin of the myth about the “magic” side of quantum physics.

I did not work with quantum physics professionally (I studied it in the school only), but I met the folks who used quantum physics for the calculations they did for a living. They told me that after you do it for some time, you start gaining certain intuition that allows you to “feel” the results in the same manner (well, almost) you feel it in everyday life while manipulating some everyday objects. It is not as strong intuition as the one we were granted by the evolution, but it is there, and some people get it better than others even among the small group of the specialists.

And the last question. Have you experienced meeting with a professional in an alien to you trade, like meat packer, for example, or a marble carver or any other very specialized activity? If you did, you might have noticed that some of their recommendations or tricks they used every day were not intuitive to you at all. But try and ask them to explain to you “why” and you will hear all kinds of reasoning ranging from “the power of the mother-earth” to divine intervention. It does sound like magic, isn’t it? And yet, one cannot deny that these people understand what are they doing, don’t they?

A theoretical physicist and his friend are lost in the mountains.
The theoretical physicist pulls out a map, looks at it,
then puts it away and says to his friend:
“I know where we are.”
“Where?”
“Do you see that mountain over there?”
“Yes.”
“We are exactly on its summit.”