“Once again, the electrons ‘knew’ how many slits were open … Each electron seemed to ‘know’ not only what the exact experimental set-up was at the time it made its flight through the apparatus, but also what happened to the electrons that went before it and the ones that would come after it.”— John Gribbin, Six Impossible Things
It is worth lingering over this sentence, because an extraordinary amount of conceptual work is being done by a single word: knew.
Gribbin’s use of the term is clearly metaphorical. Electrons do not possess minds, memories, or beliefs. Yet the metaphor is not ornamental. It is explanatory. It is introduced at precisely the point where ordinary physical description runs out, and where something must bridge the gap between two claims that Gribbin wishes to hold simultaneously: that electrons are detected one at a time, and that their detections nevertheless conform to a stable interference pattern determined by the experimental configuration.
The word knew functions as that bridge. It allows Gribbin to gesture at a relation between a single detection event and a global experimental structure without specifying what kind of relation this is. In doing so, it quietly imports a familiar cognitive schema—access to information, awareness of conditions, sensitivity to alternatives—into a domain where none of those notions properly belong.
To see how much is being smuggled in, consider what it would actually mean for an electron to know how many slits were open.
Knowing, even in its weakest everyday sense, presupposes at least three things:
A distinction between alternatives — there must be something it is possible to be wrong about.
Access to a comparison class — the knower must be situated such that different possibilities can, in principle, be discriminated.
A standpoint from which conditions are apprehended — knowledge is always knowledge for someone or something.
None of these conditions can be made sense of at the level of a single electron detection. There is no standpoint, no access, no discrimination of alternatives. There is only an event: a localised detection at a particular position on a screen.
Why, then, does the metaphor feel so natural?
The answer lies in the specific explanatory pressure created by the two-slit experiment. When electrons are fired one at a time, there is a strong temptation to treat each detection as an isolated occurrence whose properties must be explained solely in terms of what happens at that moment. But the observed distribution of detections is not arbitrary. It is constrained by the entire experimental arrangement: the number of slits, their geometry, and the measurement set-up as a whole.
Gribbin’s sentence attempts to register this constraint. The problem is that, lacking a clear account of how a single event can legitimately be described as constrained by a global structure, the explanation slips into anthropomorphic terms. The electron is said to know the configuration, because knowing is the everyday concept we use when an individual outcome reliably tracks a larger set of conditions.
This move has several immediate consequences.
First, it recasts structural constraint as epistemic access. Instead of asking how the experimental configuration defines the space of possible outcomes, we are invited to imagine an electron that somehow consults that configuration before deciding where to land.
Second, it introduces a temporal distortion. Gribbin does not merely say that the electron knows the current set-up; he says it knows about electrons that came before and electrons that will come after. Here the metaphor does even heavier lifting. What is really being gestured at is the stability of a distribution across many trials, but that stability is redescribed as though it were the result of memory and anticipation on the part of each individual event.
Finally, the metaphor reverses the direction of explanation. Instead of the interference pattern being understood as a property of the experimental construal that governs individual detections, the pattern begins to look like something produced by electrons somehow coordinating their behaviour across time.
At this point, the familiar rhetoric of mystery takes hold. How could a single electron possibly know all this? How could it be influenced by events that have not yet occurred? The sense of paradox is real—but it is a paradox generated by the metaphor itself.
In the posts that follow, we will argue that nothing in the two-slit experiment requires us to attribute knowledge, memory, or foresight to electrons. The appearance that it does arises from a deeper confusion about how patterns relate to events, and about how potential structures are instantiated in particular cases. Once those confusions are brought into view, the metaphor of knowing can be set aside—not because it is poetic, but because it is doing the wrong kind of explanatory work.
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