2. On the Curious Difficulty of Being Two Things at Once

The Senior Common Room at St Anselm's

The following evening. The rain has ceased. Professor Quillibrace is reading near the fire while Mr Blottisham paces beside a sideboard bearing an alarming quantity of biscuits. Miss Elowen Stray is writing notes in a small notebook.

Blottisham: I have corrected yesterday's misunderstanding.

Quillibrace: Which one?

Blottisham: The quantum one.

Quillibrace: Ah. All of it then.

Blottisham: I now understand superposition perfectly.

Quillibrace: How dreadful.

Blottisham: It means a thing occupies two states at once.

A pause.

Quillibrace: Remarkable.

Blottisham: Thank you.

Quillibrace: No, remarkable that one can misunderstand something with such efficiency.

Blottisham: Really, Quillibrace, I fail to see your objection. Everyone says this.

Quillibrace: Everyone also says one can "catch cold," as though influenza lurks in hedges waiting to leap upon passers-by.

Blottisham: That's entirely different.

Quillibrace: Not structurally.

Blottisham: Well then, explain.

Quillibrace: Very well. Tell me: when you say two states at once, what exactly are you imagining?

Blottisham: A particle here and there simultaneously.

Quillibrace: Mm.

Blottisham: Existing in multiple possibilities at once.

Quillibrace: Mm.

Blottisham: Like a sort of ghost spread across reality.

Quillibrace: Ah yes—the famous quantum ectoplasm interpretation.

Blottisham: You mock, but I detect no alternative explanation forthcoming.

Quillibrace: The difficulty is that your picture imports classical assumptions before the discussion has even begun.

Blottisham: Such as?

Quillibrace: Such as assuming there are already distinct states available for occupation.

Blottisham: Naturally there are.

Quillibrace: Naturally?

Blottisham: Well... yes.

Quillibrace: Classical physics assumes reality always exists in a condition of closure.

Blottisham: Closure.

Quillibrace: At any moment a system possesses a complete state.

Properties are simultaneously determinate.

Evolution proceeds from one completed condition to another.

Blottisham: Quite sensible.

Quillibrace: Sensible perhaps. Necessary, no.

Elowen: The assumption is stronger than it first appears.

Blottisham: How so?

Elowen: It assumes reality is always already settled.

Quillibrace: Exactly.

Elowen: Even uncertainty becomes a temporary defect in us rather than a feature of structure.

We merely fail to know the already completed state.

Blottisham: Naturally.

Quillibrace: Stop saying naturally. Nature is receiving an undeserved reputation.

Blottisham: Then quantum mechanics says—

Quillibrace: Quantum mechanics says closure itself becomes questionable.

Blottisham: So we lose knowledge of the closed state?

Quillibrace: No.

Blottisham: Then we lose—

Quillibrace: The requirement that such a state exists prior to actualisation.

Blottisham frowns at the fire as if suspecting conspiracy.

Blottisham: I dislike this already.

Quillibrace: Superposition does not mean multiple actual states.

It means non-closure.

Blottisham: Non-closure.

Quillibrace: The system has not stabilised into a single coherent regime of determination.

Blottisham: That's infuriatingly abstract.

Quillibrace: Reality bears no obligation to assist pictorial thinking.

Blottisham: Then what exactly is present?

Quillibrace: Constraint.

Structured relational potential.

Multiple admissible ways the system might become determinate.

But no prior selection among them.

Blottisham: So it is both A and B—

Quillibrace: No.

Blottisham: Neither A nor B—

Quillibrace: Also no.

Blottisham: You appear determined to eliminate all available conjunctions.

Quillibrace: I am attempting to eliminate misplaced ones.

Elowen: It sounds less like both and more like not yet one.

Quillibrace turns slowly toward her.

Quillibrace: Yes.

Precisely.

Blottisham: That's it?

Quillibrace: That's the entire disaster, yes.

Elowen: Classical thinking wants alternatives to exist in advance as separate completed possibilities.

Quillibrace: Mm.

Elowen: But a superposed system hasn't yet entered a regime where one coherent determination exists.

Quillibrace: Quite so.

Blottisham: So reality itself remains... unresolved?

Quillibrace: Temporarily non-closed.

Blottisham: Which sounds suspiciously like unresolved with spectacles on.

Quillibrace: There is a difference.

Unresolved suggests deficiency.

Non-closure describes structure.

Blottisham: Hmph.

Then what of measurement?

We look, and reality finally tells us what was true.

Quillibrace: Ah yes. We have arrived once again at extraction.

Blottisham: Extraction?

Quillibrace: Your persistent fantasy that reality contains hidden objects in drawers waiting for inspection.

Blottisham: A perfectly respectable fantasy.

Quillibrace: Measurement does not reveal completed facts.

It imposes closure.

Blottisham: Imposes?

Quillibrace: A previously non-closed relational structure enters a determinate regime.

Nothing hidden emerges.

The system simply resolves into one admissible organisation.

Blottisham: Good Lord.

Quillibrace: Quite.

Silence settles for a moment.

Blottisham: Then all these years I have imagined quantum mechanics as reality being indecisive.

Quillibrace: Yes.

Blottisham: Whereas the difficulty is that I insisted on asking reality to finish a sentence it had not yet begun.

A faint smile appears on Quillibrace's face.

Quillibrace: Mr Blottisham—

that is dangerously close to understanding.

Elowen: Then perhaps superposition is only paradoxical because we keep demanding closure too early.

Quillibrace: Miss Stray, I believe you have once again committed the regrettable act of arriving quietly at the centre of the discussion.

Blottisham: I still preferred the ghost.

Quillibrace: Of course you did.

Ghosts at least have the decency to possess properties.