The Trouble with Quantum Questions: Dialogue V — On Entanglement

Characters:

Professor Quillibrace

Mr Blottisham

Miss Elowen Stray

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Blottisham:

At last! Entanglement.

Quillibrace:

I had hoped you might say that with less enthusiasm.

Blottisham:

This is the good part. The spooky part. Invisible threads across the cosmos!

Quillibrace:

Ah yes. The cosmic haberdashery.

Elowen Stray:

Entanglement does sound different, though. Not just misunderstanding, but real connection.

Blottisham:

Exactly! Two particles, one fate. Measure one—zap!—the other knows.

Quillibrace:

Particles are very bad at knowing things.

Blottisham:

Don’t quibble. The correlations persist no matter the distance.

Quillibrace:

Indeed. And that fact has survived far worse metaphors than yours.

Blottisham:

So you admit the connection is real.

Quillibrace:

The correlations are real.

Blottisham:

You slipped.

Quillibrace:

I was careful where you were careless.

Elowen Stray:

What’s the difference?

Quillibrace:

A connection suggests something travelling. A correlation suggests a shared condition.

Blottisham:

Shared how?

Quillibrace:

By being one system before being many.

Blottisham:

There it is—the mysticism.

Quillibrace:

No. The bookkeeping.

Blottisham:

You’re telling me two particles that fly apart are somehow still one thing?

Quillibrace:

I’m telling you they were never two independent things.

Elowen Stray:

So the mistake is assuming separateness too early?

Quillibrace:

Precisely.

Blottisham:

But they are separate in space.

Quillibrace:

Space is not the criterion you want it to be.

Blottisham:

Everything is somewhere!

Quillibrace:

Everything instantiated is somewhere. You keep forgetting that word.

Elowen Stray:

So before measurement, the system hasn’t split?

Quillibrace:

The description has not been cut into parts.

Blottisham:

And measurement does the cutting.

Quillibrace:

Yes. Not revelation—partition.

Blottisham:

Then why do the outcomes match?

Quillibrace:

Because the cut preserves the structure it cuts.

Blottisham:

That sounds suspiciously convenient.

Quillibrace:

It would be suspicious if it failed.

Elowen Stray:

So nothing is sent from one particle to the other?

Quillibrace:

Nothing is sent. Nothing needs to travel.

Blottisham:

Then Einstein was worried for nothing?

Quillibrace:

Einstein was worried about locality being asked to do a job it never agreed to do.

Blottisham:

Spooky action at a distance!

Quillibrace:

Spooky insistence on distance.

Blottisham:

If there’s no signal, no thread, no message—what is entanglement?

Quillibrace:

Entanglement is the refusal of a system to decompose cleanly into independent descriptions.

Blottisham:

That’s disappointingly abstract.

Quillibrace:

Reality often is, until metaphors arrive to entertain you.

Elowen Stray:

So the mystery isn’t faster-than-light influence…

Quillibrace:

…it’s our addiction to thinking in terms of influence at all.

Blottisham:

Then why can’t I assign properties to each particle individually?

Quillibrace:

Because the theory does not license that move.

Blottisham:

But surely they have properties!

Quillibrace:

They have properties only as outcomes of a cut that produces individuals.

Elowen Stray:

So individuation happens with measurement?

Quillibrace:

Yes. Not before it.

Blottisham:

You’re saying separateness is an achievement, not a given.

Quillibrace:

Now you’re listening.

Blottisham:

I don’t like it.

Quillibrace:

Understanding rarely consults preference.

Blottisham:

So entanglement isn’t a bond between things…

Quillibrace:

…it’s a reminder that the things were never the starting point.

Elowen Stray:

That feels… strangely elegant.

Blottisham:

It feels like the rug being pulled out.

Quillibrace:

Only because you insisted on standing on it.

(A pause.)

Blottisham:

Let me see if I have this. Entanglement doesn’t mean particles communicate.

Quillibrace:

Correct.

Blottisham:

It means we tried to describe one system as two too soon.

Quillibrace:

Precisely.

Blottisham:

And the universe refused to play along.

Quillibrace:

As it often does.

Elowen Stray:

So the trouble with entanglement…

Quillibrace:

…is that we mistook relation for linkage.

Blottisham:

And blamed physics for our impatience.

Quillibrace:

A long-standing tradition.

(Silence.)

Blottisham:

Very well. I will put away my threads.

Quillibrace:

Do keep the scissors, though. You’ll need them.