The Question Tree

Your rating: None
0
No votes yet

QUANTUM SHORTS 2017: SHORTLISTED, OPEN CATEGORY

In early spring, they tie vibrantly colored ribbons to the branches of the tree. Most of them mark their ribbons–with some private symbol, or a name, or even a whole question. Sometimes a ribbon is left bare, and they count on remembering where they placed it. Or they don’t intend to check.
 
The girls mostly come together, in small groups, laughing and taking their time picking the best spots. Which spots are "best" is the subject of constant and passionate debate.
 
The boys mostly come alone, later in the evenings, and for them the goal is height. "Higher branches, better chances," one of them responded when I queried him. He had no deeper reasoning to offer.</em>
 
"Never mind that," Tanya said. I turned away from my terminal to look at her. "I am doing a much more important project."
 
"What would that be?" I asked.
 
"I am teaching quantum mechanics to Bruno."
 
I laughed. "Isn't this a little early? He's only nine."
 
She waved a hand, dismissing my objection. "I was younger when I started. Besides, nine is old for a dog."
 
"Oh yes, that little fact. That might also be a problem."
 
Bruno sauntered over to me. I gave him a scratch behind the ears.
 
"I don’t know if any dog could really understand QM," I said.
 
Tanya scoffed. "Is that different from any human?"
 
"Fair point," I said, returning to my report.
 
<em>Each spring the Question Tree blooms once. During the rest of the year it is an unremarkable plant, a common member of a species that makes up much of the deciduous forest surrounding the village. But during its week-long bloom, the Question Tree reveals an extraordinary phenotype. It flowers in two colors, in almost perfect balance: blue and white in seemingly random variation.
 
The blue flowers actually have a slight edge, comprising about 52% of the total each year. Still, the concurrence of two colors on the same tree is exceptional. There are millions of the Question Tree's species in the forest, and it alone blooms dichromatically. Consequently, its year-to-year variation provides a metric for validating the simulation's RAN5 algorithm—</em>
 
"Richard, what are you obsessing over? Watch our lesson. Bruno, come here."
 
I spun around again. Bruno trotted back to Tanya, an eager pupil.
 
"Okay, Bruno, observe this particle."
 
Tanya held out a dog biscuit. Bruno stared at it intensely.
 
"See, Bruno, you have observed its position. Now, if you observe again in the same way..."
 
Tanya closed her hand briefly, then opened it.
 
"...the position is the same. The wavefunction has collapsed. You may record this measurement."
 
She gave Bruno his treat. He crunched it happily as Tanya continued.
 
"Now, let us consider a system where position is unknown."
 
Tanya held out both her hands, both closed.
 
"What must we do?"
 
Bruno considered for a moment, then lifted a paw to Tanya's left hand. She opened it. Empty.
 
"Correct!" she said, "We make another observation, and detect nothing. But the particle must be somewhere, and so there is only one possibility left. The wavefunction has collapsed again."
 
She opened her right hand, revealing another biscuit.
 
"We can again record our measurement," she said, and tossed him the treat.
 
I clapped. "Excellent lesson. He’s learning quickly."
 
"Yes, we’ve worked hard," Tanya said, walking over. She sat down and glanced at the terminal. "What have you been playing at, while we worked? Torturing your little subjects?"
 
"Let's not argue," I said. "The simulants don't suffer any more than real beings do, and the development—"
 
“—of sapient species is a non-trivial feature of the universal life cycle - I've read your Ethics statement. It's cruel. But okay, no argument."
 
We sat silently for a while and I let the simulation run. The years passed in rapid succession. The Question Tree bloomed and withered, bloomed and withered.
 
"What’s that?" Tanya asked, noticing it on the terminal. I paused the simulation.
 
"An anomaly I'm using to track some parameters. It's a tree with two colors of flower, which appear in a different pattern every year. It’s unlike any other of its kind. Some simulants have developed rituals around it. They call it the Question Tree."
 
Bruno was rubbing against Tanya's leg, hoping for another lesson. She lifted him onto her lap. “Well? Why?"
 
"The flowers. They tie ribbons to the tree’s branches before it blooms - the ribbons represent questions they're asking. They tie them on and then check which color flower bloomed nearest their ribbon, and that’s their answer. There are only two possibilities: yes or no. A blue flower or a white one."
 
I displayed a single flower. It was white, and a purple ribbon was tied beside it.
 
"What was the question for this one?" Tanya asked.
 
"I don't know," I said. "Purple usually means a romantic question. Probably a boy from the village, asking if his sweetheart cares for him." I chuckled. "He’ll be disappointed. White means no."
 
Tanya frowned. "Has he seen it yet?"
 
"Unlikely," I said, checking the timecode. "Why?"
 
"Change it for him."
 
"What? No. I can't do that."
 
"Why not? Don't give me any nonsense about your algorithms. It won't affect anything."
 
I pointed at Bruno. "Have you forgotten his lesson? I've seen it. I can't change it now."
 
Tanya scoffed. "Nobody has seen it. You don't count. You're not in the simulation."
 
I hesitated.
 
"Oh, come on," Tanya said, "Give them a little joy for once. It won’t ruin the study."
 
With a sigh, I gave in, and entered a command. "Done," I said, "just for you."
 
I switched off the terminal and turned to Bruno.
 
"Now, I want to teach a lesson," I said. I grabbed a biscuit and held out my hands, palms closed.
 
Bruno pawed at the left. I opened it, and tossed him his well-observed treat.
 
"He’s a genius," Tanya said.
 
I stared at my left hand.
 
"Funny," I said, "I could have sworn it was in my right."
Share this fiction

Quantum Theories: A to Z

K is for ...
Kaon

These are particles that carry a quantum property called strangeness. Some fundamental particles have the property known as charm!

B is for ...
Bose-Einstein Condensate (BEC)

At extremely low temperatures, quantum rules mean that atoms can come together and behave as if they are one giant super-atom.

A is for ...
Act of observation

Some people believe this changes everything in the quantum world, even bringing things into existence.

F is for ...
Free Will

Ideas at the heart of quantum theory, to do with randomness and the character of the molecules that make up the physical matter of our brains, lead some researchers to suggest humans can’t have free will.

K is for ...
Key

Quantum Key Distribution (QKD) is a way to create secure cryptographic keys, allowing for more secure communication.

O is for ...
Objective reality

Niels Bohr, one of the founding fathers of quantum physics, said there is no such thing as objective reality. All we can talk about, he said, is the results of measurements we make.

C is for ...
Computing

The rules of the quantum world mean that we can process information much faster than is possible using the computers we use now.

S is for ...
Schrödinger Equation

This is the central equation of quantum theory, and describes how any quantum system will behave, and how its observable qualities are likely to manifest in an experiment.

A is for ...
Atom

This is the basic building block of matter that creates the world of chemical elements – although it is made up of more fundamental particles.

R is for ...
Randomness

Unpredictability lies at the heart of quantum mechanics. It bothered Einstein, but it also bothers the Dalai Lama.

Q is for ...
Quantum biology

A new and growing field that explores whether many biological processes depend on uniquely quantum processes to work. Under particular scrutiny at the moment are photosynthesis, smell and the navigation of migratory birds.

P is for ...
Probability

Quantum mechanics is a probabilistic theory: it does not give definite answers, but only the probability that an experiment will come up with a particular answer. This was the source of Einstein’s objection that God “does not play dice” with the universe.

D is for ...
Decoherence

Unless it is carefully isolated, a quantum system will “leak” information into its surroundings. This can destroy delicate states such as superposition and entanglement.

D is for ...
Dice

Albert Einstein decided quantum theory couldn’t be right because its reliance on probability means everything is a result of chance. “God doesn’t play dice with the world,” he said.

I is for ...
Information

Many researchers working in quantum theory believe that information is the most fundamental building block of reality.

V is for ...
Virtual particles

Quantum theory’s uncertainty principle says that since not even empty space can have zero energy, the universe is fizzing with particle-antiparticle pairs that pop in and out of existence. These “virtual” particles are the source of Hawking radiation.

C is for ...
Cryptography

People have been hiding information in messages for millennia, but the quantum world provides a whole new way to do it.

T is for ...
Teleportation

Quantum tricks allow a particle to be transported from one location to another without passing through the intervening space – or that’s how it appears. The reality is that the process is more like faxing, where the information held by one particle is written onto a distant particle.

M is for ...
Many Worlds Theory

Some researchers think the best way to explain the strange characteristics of the quantum world is to allow that each quantum event creates a new universe.

T is for ...
Tunnelling

This happens when quantum objects “borrow” energy in order to bypass an obstacle such as a gap in an electrical circuit. It is possible thanks to the uncertainty principle, and enables quantum particles to do things other particles can’t.

G is for ...
Gravity

Our best theory of gravity no longer belongs to Isaac Newton. It’s Einstein’s General Theory of Relativity. There’s just one problem: it is incompatible with quantum theory. The effort to tie the two together provides the greatest challenge to physics in the 21st century.

R is for ...
Reality

Since the predictions of quantum theory have been right in every experiment ever done, many researchers think it is the best guide we have to the nature of reality. Unfortunately, that still leaves room for plenty of ideas about what reality really is!

I is for ...
Interferometer

Some of the strangest characteristics of quantum theory can be demonstrated by firing a photon into an interferometer: the device’s output is a pattern that can only be explained by the photon passing simultaneously through two widely-separated slits.

W is for ...
Wave-particle duality

It is possible to describe an atom, an electron, or a photon as either a wave or a particle. In reality, they are both: a wave and a particle.

G is for ...
Gluon

These elementary particles hold together the quarks that lie at the heart of matter.

Y is for ...
Young's Double Slit Experiment

In 1801, Thomas Young proved light was a wave, and overthrew Newton’s idea that light was a “corpuscle”.

E is for ...
Entanglement

When two quantum objects interact, the information they contain becomes shared. This can result in a kind of link between them, where an action performed on one will affect the outcome of an action performed on the other. This “entanglement” applies even if the two particles are half a universe apart.

H is for ...
Hawking Radiation

In 1975, Stephen Hawking showed that the principles of quantum mechanics would mean that a black hole emits a slow stream of particles and would eventually evaporate.

H is for ...
Hidden Variables

One school of thought says that the strangeness of quantum theory can be put down to a lack of information; if we could find the “hidden variables” the mysteries would all go away.

U is for ...
Universe

To many researchers, the universe behaves like a gigantic quantum computer that is busy processing all the information it contains.

A is for ...
Alice and Bob

In quantum experiments, these are the names traditionally given to the people transmitting and receiving information. In quantum cryptography, an eavesdropper called Eve tries to intercept the information.

B is for ...
Bell's Theorem

In 1964, John Bell came up with a way of testing whether quantum theory was a true reflection of reality. In 1982, the results came in – and the world has never been the same since!

W is for ...
Wavefunction

The mathematics of quantum theory associates each quantum object with a wavefunction that appears in the Schrödinger equation and gives the probability of finding it in any given state.

J is for ...
Josephson Junction

This is a narrow constriction in a ring of superconductor. Current can only move around the ring because of quantum laws; the apparatus provides a neat way to investigate the properties of quantum mechanics and is a technology to build qubits for quantum computers.

S is for ...
Superposition

Quantum objects can exist in two or more states at once: an electron in superposition, for example, can simultaneously move clockwise and anticlockwise around a ring-shaped conductor.

R is for ...
Radioactivity

The atoms of a radioactive substance break apart, emitting particles. It is impossible to predict when the next particle will be emitted as it happens at random. All we can do is give the probability that any particular atom will have decayed by a given time.

Q is for ...
Qubit

One quantum bit of information is known as a qubit (pronounced Q-bit). The ability of quantum particles to exist in many different states at once means a single quantum object can represent multiple qubits at once, opening up the possibility of extremely fast information processing.

L is for ...
Light

We used to believe light was a wave, then we discovered it had the properties of a particle that we call a photon. Now we know it, like all elementary quantum objects, is both a wave and a particle!

S is for ...
Schrödinger’s Cat

A hypothetical experiment in which a cat kept in a closed box can be alive and dead at the same time – as long as nobody lifts the lid to take a look.

X is for ...
X-ray

In 1923 Arthur Compton shone X-rays onto a block of graphite and found that they bounced off with their energy reduced exactly as would be expected if they were composed of particles colliding with electrons in the graphite. This was the first indication of radiation’s particle-like nature.

Z is for ...
Zero-point energy

Even at absolute zero, the lowest temperature possible, nothing has zero energy. In these conditions, particles and fields are in their lowest energy state, with an energy proportional to Planck’s constant.

U is for ...
Uncertainty Principle

One of the most famous ideas in science, this declares that it is impossible to know all the physical attributes of a quantum particle or system simultaneously.

P is for ...
Planck's Constant

This is one of the universal constants of nature, and relates the energy of a single quantum of radiation to its frequency. It is central to quantum theory and appears in many important formulae, including the Schrödinger Equation.

L is for ...
Large Hadron Collider (LHC)

At CERN in Geneva, Switzerland, this machine is smashing apart particles in order to discover their constituent parts and the quantum laws that govern their behaviour.

M is for ...
Multiverse

Our most successful theories of cosmology suggest that our universe is one of many universes that bubble off from one another. It’s not clear whether it will ever be possible to detect these other universes.

N is for ...
Nonlocality

When two quantum particles are entangled, it can also be said they are “nonlocal”: their physical proximity does not affect the way their quantum states are linked.

Copyright © 2018 Centre for Quantum Technologies. All rights reserved.