Quantum Computing - The Foundation of Everything - Part 1 - Extra History

Summary

In 1927, 29 physicists met in Brussels to debate quantum determinancy and the nature of light. The script explores the double-slit experiment, which initially supported the wave theory of light but later led to the photon theory. It delves into the quantum mystery of light behaving as both a particle and a wave, and how measurement affects its state. The concept of light as a 'wave of possibilities' is introduced, challenging our understanding of reality and setting the stage for quantum computing.

Takeaways

• 📅 In 1927, 29 physicists met in Brussels to discuss quantum determinancy and the nature of light.
• 🏆 17 of the attendees would later win a Nobel Prize, indicating the significance of the discussions.
• 🌌 The debate centered on whether light behaves as a particle or a wave, a question that has puzzled scientists for centuries.
• 🔬 Thomas Young's double-slit experiment in 1803 suggested light behaves like a wave, interfering with itself to create a pattern.
• 💡 Max Planck's quantum hypothesis in 1900 proposed that energy is absorbed or released in discrete units, challenging the continuous wave theory.
• 🌞 Einstein's theory of light quanta, or photons, explained phenomena like the photoelectric effect and earned him a Nobel Prize.
• 🤔 The double-slit experiment with individual photons revealed that light can exhibit both wave-like and particle-like properties.
• 📊 The interference pattern reappeared when many photons were fired through the slits, one at a time, suggesting a probabilistic nature.
• 🔍 The act of measuring which slit a photon passes through collapses its wave function, causing it to behave as a particle.
• 🧠 The concept of light as a wave of probabilities is a cornerstone of quantum physics, challenging our understanding of reality.
• 💻 The implications of these quantum properties are explored further in the context of quantum computing in future episodes.

Q & A

In what year did the gathering of physicists in Brussels take place?

The gathering of physicists in Brussels took place in 1927.

How many of the 29 physicists who gathered in Brussels eventually won a Nobel Prize?

17 of the 29 physicists who gathered in Brussels eventually won a Nobel Prize.

What was the main question that the physicists were wrestling with during the Brussels meeting?

The main question was about quantum determinancy, specifically whether the world at the quantum level operates as a fixed system or merely as a group of probabilities.

What is the double-slit experiment and why is it significant in physics?

The double-slit experiment is a demonstration that light and matter can display characteristics of both waves and particles. It's significant because it challenges the classical view of light as a simple wave and led to the development of quantum mechanics.

Who performed the original double-slit experiment, and what was the outcome?

Thomas Young performed the original double-slit experiment and observed an interference pattern, which supported the wave theory of light.

What was the strange phenomenon observed when light was used to eject electrons from a material?

The strange phenomenon was that light could force electrons to spew out of a material in a manner inconsistent with it being a continuous wave, as expected by classical physics.

What was Max Planck's contribution to the understanding of light and energy?

Max Planck proposed that energy could only be absorbed or released in discrete units, which was a radical departure from the continuous flow of energy as previously understood.

How did Albert Einstein expand on Max Planck's work, and for what was he awarded the Nobel Prize?

Albert Einstein proposed that light itself was quantized, existing as particles he called photons. He was awarded the Nobel Prize for this theory, not for his theories of relativity.

What happens in the double-slit experiment when photons are fired one at a time?

When photons are fired one at a time through the double-slit experiment, an interference pattern builds up over time, suggesting that each photon interferes with itself as if it were a wave.

What is the 'freaky' result when a detector is placed at the slits in the double-slit experiment?

When a detector is placed at the slits, the interference pattern disappears, and the photons behave as if they are particles passing through one slit or the other, suggesting that the act of measurement affects the outcome.

What is the concept of 'waves of possibility' in the context of the double-slit experiment?

The concept of 'waves of possibility' refers to the idea that before measurement, a photon exists in a superposition of states, represented as a wave function. This wave function collapses to a single point only upon measurement.

What is the implication of the double-slit experiment for the future of quantum computing?

The double-slit experiment highlights the principles of superposition and entanglement, which are fundamental to quantum computing. Understanding these principles is crucial for developing quantum computing technologies.

Outlines

00:00

🔬 Quantum Determinancy and the Double-Slit Experiment

In 1927, a gathering of 29 physicists in Brussels, 17 of whom would later win Nobel Prizes, discussed the quantum determinancy and the nature of light. The script introduces the double-slit experiment, initially performed by Thomas Young in 1803, which demonstrated light's wave-like behavior. However, later experiments showed that light could also eject electrons from materials, contradicting the wave theory. Max Planck's equation and Albert Einstein's photon theory suggested light could be quantized, behaving as both a particle and a wave. The script describes a modern version of the double-slit experiment where single photons are fired through slits and still produce an interference pattern, suggesting each photon interferes with itself, despite appearing at random points on the detection wall.

05:01

🌌 The Quantum Mystery of Wave-Particle Duality

The script delves into the paradox of light behaving as both a particle and a wave, as observed in the double-slit experiment. It explains that measuring which slit a photon passes through collapses its wave function, causing it to act as a particle. The concept of a 'wave of possibilities' is introduced, where the photon's wave-like nature represents potential locations rather than a definite position. Detection forces the photon to choose a location, thus becoming a particle. The interference pattern observed is due to these waves of probability interfering with each other, creating areas of high and low likelihood for photon detection. The script ends with a teaser for the next episode, which will explore the implications of energy quantization for quantum computing.

Keywords

💡Quantum determinancy

Quantum determinancy refers to the idea that the behavior of particles at the quantum level is determined by fixed laws rather than being random or probabilistic. In the video, this concept is central to the discussion among the physicists gathered in Brussels, as they debate whether the world operates on a fixed system or as a group of probabilities. It's a fundamental question that underlies the nature of reality at the smallest scales.

💡Double slit experiment

The double slit experiment is a classic physics experiment that demonstrates the dual nature of light as both a wave and a particle. In the script, Thomas Young's version of the experiment shows light creating an interference pattern, suggesting it behaves as a wave. However, when individual photons are fired through the slits, the same pattern emerges, which is a central mystery of quantum physics discussed in the video.

💡Interference

Interference is a wave phenomenon where waves superimpose to form a new wave pattern. When the peaks of two waves meet, they create a larger wave, and when the peak of one wave meets the trough of another, they cancel each other out. In the video, this concept is used to explain the pattern observed in the double slit experiment, where light waves interfere with each other to create alternating bright and dark lines.

💡Photon

A photon is a quantum of electromagnetic radiation, and it is considered both a particle and a wave. The video explains how photons, when passing through the double slit experiment, create an interference pattern as if they were waves, but upon detection, they behave as particles. This dual nature is a key aspect of quantum mechanics and is central to the video's narrative.

💡Wave-particle duality

Wave-particle duality is the concept in quantum mechanics that every particle or quantum entity can exhibit both wave and particle properties. The video script illustrates this with the double slit experiment, where light behaves as both a wave (creating an interference pattern) and as a particle (when detected at a specific point).

💡Max Planck

Max Planck was a German physicist who is considered one of the fathers of quantum theory. In the video, Planck's work is highlighted for his equation that explained how energy could be absorbed or released only in discrete units, which was a radical departure from the continuous flow of energy that was previously assumed. His work laid the foundation for the concept of quantization.

💡Quantization

Quantization refers to the property that a physical quantity can only take on certain discrete values. In the context of the video, quantization is exemplified by Max Planck's theory that energy is not continuous but comes in small, indivisible 'packets' or quanta, which was a pivotal concept in the development of quantum mechanics.

💡Albert Einstein

Albert Einstein is a renowned theoretical physicist, and his contributions to the understanding of light as quantized particles, or photons, are mentioned in the video. Einstein's explanation of the photoelectric effect, which won him the Nobel Prize, is a direct application of the photon concept and supports the wave-particle duality of light.

💡Probability

In the video, probability is discussed in the context of quantum mechanics, where the behavior of particles at the quantum level is not deterministic but probabilistic. This is exemplified by the double slit experiment, where the location where a photon lands is not predictable but follows a probabilistic pattern when many photons are fired.

💡Measurement problem

The measurement problem in quantum mechanics refers to the question of how the act of measurement affects the quantum system. The video script describes how placing a detector at the slits in the double slit experiment changes the outcome from an interference pattern to two distinct bands, illustrating the enigmatic impact of measurement on quantum phenomena.

💡Wave function collapse

Wave function collapse is a concept in quantum mechanics where a system's wave function, which describes all possible states of the system, collapses to a single outcome upon measurement. The video touches on this when discussing how a photon, which behaves as a wave of possibilities, 'decides' on a location when measured, thus collapsing to a particle.

Highlights

In 1927, 29 physicists gathered in Brussels to discuss quantum determinancy.

17 of the attendees would later win a Nobel Prize.

The debate centered on whether the world operates as a fixed system or as probabilities.

The discussion was rooted in the centuries-old problem of the nature of light.

Thomas Young's double-slit experiment suggested light behaved as a wave.

Young's experiment showed interference patterns, supporting the wave theory of light.

The discovery that light could eject electrons from materials contradicted the wave theory.

Max Planck proposed that energy is absorbed or released in discrete units.

Planck's equation was a radical departure from continuous energy flow.

Albert Einstein expanded on Planck's work, suggesting light is quantized.

Einstein's photon theory explained how light interacts with the world.

The photon theory reintroduced the double-slit experiment dilemma.

Single photons fired through slits one at a time still produced an interference pattern.

Each photon's impact point is random, yet as a group, they form an interference pattern.

The act of measuring which slit a photon passes through collapses its wave-like nature into a particle.

The photon behaves as both a particle and a wave, but not simultaneously.

The double-slit experiment suggests that photons interfere with themselves as waves of possibility.

The interference pattern is a result of peaks and troughs of possibility cancelling each other out.

The concept of waves of possibility leads to the idea of high and low probability lines for photon detection.

The implications of these findings are set to revolutionize quantum computing.

Transcripts

The year is 1927

29 people gather in Brussels to discuss physics

17 of those people will eventually win a Nobel Prize

and for a few short days

in the middle of Leopold Park

They will wrestle with the smallest question

or perhaps the biggest one

to ever face mankind

The question

at the foundation of everything.

[intro song]

For those few days

those 29 physicists

wrestled with the question

of the quantum determinancy

and whether our world at the minutest level

operates as a fixed system

or merely as a group of probabilities

Their question stemmed from one of the oldest problems in modern physics,

the problem of light

For nearly three centuries

since Newton wrote his famous treatise on optics

Physicists had debated whether light was a particle

or a wave

in 1803

this argument was thought to be put to rest

by one of the most beautiful and simple experiments ever created

the double slit experiment

Okay,

think of two buoys bobbing up and down in the water

as the waves spreading out from these buoys hit each other and overlap

They interfere with each other

if the peak of one wave

hits the peak of another

they'll amplify and become a bigger wave

Same with the troughs

but if a peak of one wave hits the trough of the other

they'll just flatten out

they'll combined back down to nothing.

A man named Thomas Young said,

Let's take that principle and apply it to light

And so he did the simplest thing imaginable

he took a monochromatic light,

to make sure that all the light had the same wavelength

and he shone it on a partition with two small slits cut into it

If light acted like a particle

he should simply see two columns of light on the wall on the other side

But

if light was a wave

then the waves coming through each of the slits

should interfere with each other

amplifying and cancelling each other out in places

And he would instead see a weird pattern of bright and dark lines as a result

And as he expected

he did indeed see that funky pattern

and that was that.

The particle theory of light was done and dusted

he'd solved the dang thing

Now everyone could finally move on to talking about just how smart he was

But then physicists in other labs

found something strange in their own experiments

They found that

when light strikes a material

it can force electrons to spew out of it

this wasn't that startling

but the way it happened was all wrong

and definitely not how it should have happened if light was the continuous wave they'd believed it to be

Then in 1900 a man named Max Planck

came up with an equation that fit

it made sense of what was happening

But as Planck himself would later say

it was an act of desperation

It went against everything he thought he knew

The only way he could get all of the math to work

was by treating energy as something that could only be absorbed or released in discrete units

How could this be? He thought.

How could energy not be continuous?

How could it not be a flow?

He had

no idea,

but then this fellow named Einstein took Planck's act of desperation and ran with it

He declared that light itself was quantized

That in many ways we

can think of it as a particle of zero mass

always moving at

well, the speed of light

And it is for this theory,

not for special or general relativity,

that Einstein was awarded his Nobel Prize

Because this concept, which we now call the photon

solved a number of lingering issues

with how light interacted with the world

But the photon brings us right back to the problem of Thomas Young's double-slit experiment

Because if light has both the properties

of a wave

and a particle

What happens if you fire those particles through the slits

one at a time?

Well, here is where this becomes the most astonishing and humble experiment

ever devised

Because if you shoot one photon at the slits and detect where it hits on the other side

You'll find that it impacts

some arbitrary point

just the way you think it should

And if you fire a second photon through,

you'll find that it too shows up at some other arbitrary point on the other side

But

if you do this enough times,

you'll eventually see the same interference pattern build up

that we got back in Thomas's original experiments.

That is madness

each individual photon, which should be completely independent of the rest

shows up at some seemingly random point on your wall

And exactly where they show up

will be different each time you run the experiments

And!

Knowing where the previous photon appeared in no way allows you to predict

where the next one will show up

yet when taken as a group

it's as if they're affected by how they

Should interfere with each other

This feels impossible

and yet it is experimental fact

And the reason for this phenomenon is one of the most hotly debated mysteries in physics

Because

the only way to conceptualize this

is that each photon passes through both slits as a wave,

interferes with itself

and then resolves down to a photon when it actually hits the wall

What is going on here?

What is this?

No, no, no,

this is magic.

This is magic !

[sine wave]

[meow]

No, you're right Zoe.

I should calm down because we are not done yet

because here

is where it gets

really freaky

Remember how when Thomas was first doing his experiment?

We said that if light were really a particle

we should just see two columns of light on the other side of his double slit paper?

Well,

if you put a detector on the slits,

so that you can determine which slit the photon you fired passes through

That is exactly what you get.

That's all you have to do

You don't have to change the experiment in any way or interfere directly with the photon

You simply have to measure which slit the photon

passes through.

Why does it do this?

Because a photon is a particle

and a wave

but it can't be both

simultaneously

The mere act of measuring which path the photon took

Forces it to resolve the wave-like nature of the photon into a particle

And this may be

the hardest thing to wrap your head around

in all of quantum physics

because the most common way to view this

is that the photon when acting like a wave

isn't a real

wave at all

but rather a wave of possibilities

That wave represents where the photon

could be but not where it is

It's only when something acts to detect the photon

whether it be your measuring device

or the wall on the opposite

side of your double slit experiment

That the photon is forced to,

for lack of a better term,

decide

on where it will actually be

and in doing so

becomes a particle

More unsettling still,

is the fact that these waves of possibility

interfere with each other just like normal waves

The interference pattern we see from firing particles

one at a time

through the double slit experiment

is caused by peaks and troughs of possibility

cancelling each other out

When you fire that photon and the wave of possibility hits your double slit paper

It is funneled through as two possibility waves

Just in the way

that any regular physical wave would be

and just like those regular waves

waves of possibility

interfere with each other

Essentially making it so there are places where it is more or less likely for a photon to land when detected

Thus

when you fire a lot of photons

one at a time through your double slit experiment

The bands you see are simply the high probability lines

playing out

But if you think we're done getting weird,

think again,

we're only on episode one

so join us next time as we get serious about this idea that energy only comes in discrete packets

and begin our journey on what this means

for the future of quantum computing.

We'll see you next time

or will we just

perceive you next time because would that mean we'd have to

watch you watching us

to know the

oh boy

[outro song]