0:07

Austrian physicist Erwin Schrödinger is one of the founders of quantum mechanics, but he’s most famous for something he never actually did: a thought experiment involving a cat.

0:17

He imagined taking a cat and placing it in a sealed box with a device that had a 50% chance of killing the cat in the next hour.

0:26

At the end of that hour, he asked, “What is the state of the cat?”

0:30

Common sense suggests that the cat is either alive or dead, but Schrödinger pointed out that according to quantum physics, at the instant before the box is opened, the cat is equal parts alive and dead, at the same time.

0:44

It’s only when the box is opened that we see a single definite state.

0:48

Until then, the cat is a blur of probability, half one thing and half the other.

0:54

This seems absurd, which was Schrödinger’s point.

0:56

He found quantum physics so philosophically disturbing, that he abandoned the theory he had helped make and turned to writing about biology.

1:04

As absurd as it may seem, though, Schrödinger’s cat is very real.

1:08

In fact, it’s essential.

1:10

If it weren’t possible for quantum objects to be in two states at once, the computer you’re using to watch this couldn’t exist.

Parte 2 — Superposition

1:18

The quantum phenomenon of superposition is a consequence of the dual particle and wave nature of everything.

1:25

In order for an object to have a wavelength, it must extend over some region of space, which means it occupies many positions at the same time.

1:34

The wavelength of an object limited to a small region of space can’t be perfectly defined, though.

1:39

So it exists in many different wavelengths at the same time.

1:43

We don’t see these wave properties for everyday objects because the wavelength decreases as the momentum increases.

1:50

And a cat is relatively big and heavy.

1:52

If we took a single atom and blew it up to the size of the Solar System, the wavelength of a cat running from a physicist would be as small as an atom within that Solar System.

2:03

That’s far too small to detect, so we’ll never see wave behavior from a cat.

2:08

A tiny particle, like an electron, though, can show dramatic evidence of its dual nature.

Parte 3 — The Double-Slit Experiment

2:13

If we shoot electrons one at a time at a set of two narrow slits cut in a barrier, each electron on the far side is detected at a single place at a specific instant, like a particle.

2:25

But if you repeat this experiment many times, keeping track of all the individual detections, you’ll see them trace out a pattern that’s characteristic of wave behavior: a set of stripes — regions with many electrons separated by regions where there are none at all.

2:40

Block one of the slits and the stripes go away.

2:42

This shows that the pattern is a result of each electron going through both slits at the same time.

2:49

A single electron isn’t choosing to go left or right but left and right simultaneously.

2:56

This superposition of states also leads to modern technology.

Parte 4 — From Quantum Physics to Computers

3:00

An electron near the nucleus of an atom exists in a spread out, wave-like orbit.

3:05

Bring two atoms close together, and the electrons don’t need to choose just one atom but are shared between them.

3:12

This is how some chemical bonds form.

3:14

An electron in a molecule isn’t on just atom A or atom B, but A+B.

3:21

As you add more atoms, the electrons spread out more, shared between vast numbers of atoms at the same time.

3:27

The electrons in a solid aren’t bound to a particular atom but shared among all of them, extending over a large range of space.

3:35

This gigantic superposition of states determines the ways electrons move through the material, whether it’s a conductor or an insulator or a semiconductor.

3:45

Understanding how electrons are shared among atoms allows us to precisely control the properties of semiconductor materials, like silicon.

3:53

Combining different semiconductors in the right way allows us to make transistors on a tiny scale, millions on a single computer chip.

4:01

Those chips and their spread out electrons power the computer you’re using to watch this video.

4:07

An old joke says that the Internet exists to allow the sharing of cat videos.

4:12

At a very deep level, though, the Internet owes its existence to an Austrian physicist and his imaginary cat.

📚 Vocabulary

English	Português
founder	fundador
quantum mechanics	mecânica quântica
thought experiment	experimento mental
sealed box	caixa lacrada
device	dispositivo
state	estado
alive	vivo
dead	morto
common sense	senso comum
definite	definido
blur	algo indistinto / borrão
probability	probabilidade
absurd	absurdo
disturbing	perturbador
abandon	abandonar
essential	essencial
phenomenon	fenômeno
superposition	superposição
particle	partícula
wave	onda
wavelength	comprimento de onda
occupy	ocupar
momentum	momento / quantidade de movimento
detect	detectar
electron	elétron
slit	fenda
barrier	barreira
stripe	faixa
pattern	padrão
simultaneously	simultaneamente
nucleus	núcleo
bond	ligação
solid	sólido
conductor	condutor
insulator	isolante
semiconductor	semicondutor
transistor	transistor
chip	chip

🗣️ Expressões e estruturas

“It’s only when…”

→ É somente quando…

It’s only when the box is opened that we see a single definite state.

Uma estrutura ótima para o aluno aprender a dar ênfase a uma condição.

“As absurd as it may seem…”

→ Por mais absurdo que possa parecer…

Essa é uma estrutura mais avançada, muito útil para inglês acadêmico e argumentativo.

“At the same time”

→ Ao mesmo tempo.

A single electron isn’t choosing to go left or right but left and right simultaneously.

“In order for…”

→ Para que…

In order for an object to have a wavelength…

Estrutura bastante comum em textos científicos.

“Far too…”

→ Muito além do necessário / longe demais para…

That’s far too small to detect.

“It turns out…”

→ Acontece que / descobriu-se que.

Muito útil em conversação e explicações.

“Bring something close together”

→ Aproximar algo.

Bring two atoms close together.

“Be bound to”

→ Estar ligado/restrito a.

The electrons aren’t bound to a particular atom.

🧠 Comprehension

Responda em inglês:

1. What was Schrödinger’s thought experiment about?
2. Why did Schrödinger consider the situation absurd?
3. What is superposition?
4. Why don’t we normally observe wave behavior in everyday objects?
5. Why can electrons demonstrate this behavior more clearly?
6. What happens in the double-slit experiment?
7. Why does the video say that an electron goes through both slits?
8. How does superposition relate to chemical bonds?
9. What is the difference between a conductor, an insulator, and a semiconductor?
10. How does quantum physics ultimately connect to the computer you’re using?

🎯 Desafio

Explique em 3–5 frases em inglês:

Why is Schrödinger’s cat important even though Schrödinger never actually put a real cat in a box?

✍️ Writing

Would you open the box?

Imagine that you are part of Schrödinger’s experiment.

Write 8–10 sentences in English answering:

If you knew there was a 50% chance the cat was alive and a 50% chance it was dead, would you open the box? Why or why not?

Tente utilizar pelo menos 5 palavras/expressões da aula.

Você pode começar:

If I were in this situation, I would probably…