3. The Particle with Too Many Properties

The Senior Common Room was unusually animated.

Several physicists from King's had recently delivered a seminar, leaving behind a trail of half-finished diagrams on the blackboard and a noticeable increase in the consumption of sherry.

Mr Blottisham entered carrying a notebook filled with equations.

Quillibrace looked up.

"You've taken to theoretical physics."

"I've taken," said Blottisham triumphantly, "to certainty."

"A dangerous hobby."

"This time, Professor, I have the experiments on my side."

"I should hope so."

"It's quantum mechanics."

Miss Stray looked up from her embroidery.

"This ought to be interesting."

Blottisham opened the notebook.

"Particles possess measurable properties."

Quillibrace nodded.

"They certainly participate in measurable phenomena."

"No."

Blottisham smiled.

"Properties."

"I heard you."

"Position."

"Indeed."

"Momentum."

"Yes."

"Spin."

"Quite."

"So."

Quillibrace waited.

"They have properties."

The Professor folded his spectacles.

"Tell me, Blottisham."

"Yes?"

"When does a particle have a position?"

Blottisham blinked.

"Always."

"I see."

"So measuring it merely reveals the position."

"Very good."

"And measuring momentum?"

"The same."

Miss Stray looked slightly puzzled.

"But Professor..."

"Yes?"

"I thought physicists couldn't always determine both."

"So they tell us."

Blottisham waved a hand.

"That's merely uncertainty."

Quillibrace smiled.

"Merely?"

"Well..."

The Professor stood and walked towards the window.

"Imagine a mountain."

Blottisham sighed.

"Oh dear."

"What is the mountain's northern side?"

"The side facing north."

"Excellent."

"And without north?"

"There would be..."

He hesitated.

"...no northern side."

"So north is..."

"A direction."

"A relation?"

"I suppose."

Quillibrace nodded.

"Does the mountain contain north?"

Blottisham laughed.

"Certainly not."

"It participates in a geographical relation."

"Yes."

The Professor turned.

"Now tell me."

"Yes?"

"What makes you so certain that position belongs to the particle rather than to the experimental relation?"

Blottisham frowned.

"Because..."

He stopped.

Miss Stray looked thoughtful.

"Position is always measured relative to something."

Quillibrace smiled.

"A useful beginning."

"The laboratory."

"Quite."

"The apparatus."

"Yes."

"A coordinate system."

"Indeed."

She paused.

"It seems rather relational."

Blottisham protested.

"That doesn't mean the particle lacks properties."

"No?"

"It merely means we need equipment to observe them."

Quillibrace returned to his chair.

"Suppose I ask whether this room is warm."

"It is."

"To whom?"

Blottisham looked around.

"To everyone."

Miss Stray smiled.

"Not necessarily."

"No?"

"I've just come in from outside."

"And?"

"It feels wonderfully warm."

She looked towards the open window.

"But Professor Quillibrace has been sitting by the fire for an hour."

Quillibrace nodded.

"I confess I was considering opening the window."

Blottisham laughed.

"So warmth is relative."

"Precisely."

"But mass isn't."

"No?"

"No."

"What is mass?"

Blottisham looked surprised.

"You know perfectly well."

"I should like to hear your account."

"It's..."

He frowned.

"...what a body has."

Quillibrace waited.

"How much body?"

"No..."

"What sort of thing?"

Blottisham sighed.

"You always do this."

"I hope consistently."

Miss Stray laughed quietly.

"I think Mr Blottisham has discovered the Professor's favourite question."

"Which one?"

"'What sort of thing is it?'"

Blottisham looked resigned.

"Very well."

He sat down.

"The experiments don't actually show particles carrying little collections of properties."

Quillibrace said nothing.

"They show..."

Another pause.

"...that particular properties become measurable under particular experimental arrangements."

The Professor inclined his head.

"A careful sentence."

"But surely the properties were already there."

"Were they?"

"They must have been."

"Why?"

"Otherwise..."

Blottisham stopped.

The room became very quiet.

Outside, a bell sounded across the quadrangle.

Miss Stray spoke almost to herself.

"It seems every time we ask where a property is..."

She looked up.

"...we quietly assume it belongs to something."

Quillibrace smiled.

"And if it doesn't?"

"Then perhaps..."

She searched for the words.

"...the property belongs to the event."

Blottisham looked from one to the other.

"I don't like how often that keeps happening."

"How often what happens?"

"The thing..."

He gestured vaguely.

"...keeps escaping."

Quillibrace chuckled.

"Escaping?"

"First nouns."

"Yes."

"Then information."

"Quite."

"Now properties."

"So it appears."

Blottisham stared into the fire.

"You know..."

"Yes?"

"If this continues..."

"I sincerely hope it will."

"...there won't be very much left inside anything."

For a long moment no one spoke.

Then Quillibrace said quietly,

"My dear Blottisham..."

"Yes?"

"That depends entirely upon whether the world was ever built from containers in the first place."

Miss Stray slowly closed her notebook.

"I have the odd feeling..."

"What is it?"

"...that we've spent centuries looking inside things..."

She glanced towards the rain beginning again beyond the windows.

"...when perhaps we should have been looking between them."

The fire crackled softly.

Quillibrace did not answer.

He merely smiled.