Narrator:

The earliest time measurements were observations of cycles of the natural world, using patterns of changes from day to night and season to season to build calendars.

More precise time-keeping, like sundials and mechanical clocks, eventually came along to put time in more convenient boxes.

But what exactly is it that we’re measuring?

Is time something that physically exists, or is it just in our heads?

At first the answer seems obvious — of course time exists; it constantly unfolds all around us, and it’s hard to imagine the universe without it.

But our understanding of time started getting complicated thanks to Einstein.

His theory of relativity tells us that time passes for everyone, but doesn’t always pass at the same rate for people in different situations, like those traveling close to the speed of light or orbiting a supermassive black hole.

Einstein resolved the malleability of time by combining it with space to define spacetime, which can bend, but behaves in consistent, predictable ways.

Einstein’s theory seemed to confirm that time is woven into the very fabric of the universe.

But there’s a big question it didn’t fully resolve:

Why is it we can move through space in any direction, but through time in only one?

No matter what we do, the past is always, stubbornly, behind us.

This is called the arrow of time.

When a drop of food coloring is dropped into a glass of water, we instinctively know that the coloring will drift out from the drop, eventually filling the glass.

Imagine watching the opposite happen.

Here, we’d recognize time as unfolding backwards.

We live in a universe where the food coloring spreads out in the water, not a universe where it collects together.

In physics, this is described by the Second Law of Thermodynamics, which says that systems will gain disorder, or entropy, over time.

Systems in our universe move from order to disorder, and it is that property of the universe that defines the direction of time’s arrow.

So if time is such a fundamental property, it should be in our most fundamental equations describing the universe, right?

We currently have two sets of equations that govern physics.

General relativity describes the behavior of very large things, while quantum physics explains the very small.

One of the biggest goals in theoretical physics over the last half century has been reconciling the two into one fundamental “theory of everything.”

There have been many attempts — none yet proven — and they treat time in different ways.

Oddly enough, one contender called the Wheeler-DeWitt equation doesn’t include time at all.

Like all current theories of everything, that equation is speculative.

But as a thought experiment, if it or a similarly time-starved equation turned out to be true, would that mean that time doesn’t exist at the most fundamental level?

Could time just be some sort of illusion generated by the limitations of the way we perceive the universe?

We don’t yet know, but maybe that’s the wrong way of thinking about it.

Instead of asking if time exists as a fundamental property, maybe it could exist as an emergent one.

Emergent properties are things that don’t exist in individual pieces of a system, but do exist for the system as a whole.

Each individual water molecule doesn’t have a tide, but the whole ocean does.

A movie creates change through time by using a series of still images that appear to have a fluid, continuous change between them.

Flipping through the images fast enough, our brains perceive the passage of time from the sequence of still images.

No individual frame of the movie changes or contains the passage of time, but it’s a property that comes out of how the pieces are strung together.

The movement is real, yet also an illusion.

Could the physics of time somehow be a similar illusion?

Physicists are still exploring these and other questions, so we’re far from a complete explanation.

At least for the moment.

🧠 Vocabulário

Inglês	Português
time measurement	medição do tempo
cycle	ciclo
sundial	relógio de sol
mechanical clock	relógio mecânico
time-keeping	medição / marcação do tempo
unfold	desenrolar-se / acontecer
theory of relativity	teoria da relatividade
pass at the same rate	passar na mesma velocidade
close to	próximo de
supermassive	supermassivo
malleability	maleabilidade / capacidade de mudar
spacetime	espaço-tempo
woven into	entrelaçado a
fabric	tecido / estrutura
stubbornly	teimosamente / persistentemente
arrow of time	seta do tempo
drift	deslocar-se lentamente
eventually	eventualmente / com o tempo
disorder	desordem
entropy	entropia
fundamental property	propriedade fundamental
govern	reger / governar
reconcile	conciliar
contender	candidato / teoria concorrente
speculative	especulativo
thought experiment	experimento mental
illusion	ilusão
emergent	emergente
individual piece	parte individual
fluid	fluido / contínuo
sequence	sequência
string together	encadear / juntar
at least for the moment	pelo menos por enquanto

⭐ Expressões e estruturas importantes

Come along

More precise time-keeping eventually came along…

Aqui come along significa surgir / aparecer.

New technologies came along and changed the way we communicate.

Unfold

Time constantly unfolds all around us.

Unfold pode significar algo que se desenrola ou acontece gradualmente.

Events unfolded very quickly.

= Os acontecimentos se desenrolaram muito rapidamente.

Woven into

Time is woven into the very fabric of the universe.

Literalmente, algo está “tecido” dentro de outra coisa.

No sentido figurado:

estar profundamente integrado ou incorporado a algo.

No matter what

No matter what we do, the past is always behind us.

Significa:

“Não importa o que…”

No matter what happens, I’ll be there.

= Não importa o que aconteça, eu estarei lá.

Turn out to be

If it … turned out to be true…

Significa acabar se mostrando / revelar-se.

The experiment turned out to be successful.

= O experimento acabou sendo bem-sucedido.

Some sort of

Could time just be some sort of illusion?

Significa algum tipo de / uma espécie de.

É extremamente comum no inglês falado.

Far from

We’re far from a complete explanation.

Aqui significa longe de.

We’re far from finished.

= Estamos longe de terminar.

Yet

The movement is real, yet also an illusion.

Nesse contexto, yet significa “e ainda assim” / “porém”.

É uma ótima estrutura para contrastar duas ideias.

🧩 Grammar & Language Focus

Present perfect + ever since

The universe has been expanding ever since.

O present perfect aparece para conectar uma situação iniciada no passado com o presente.

Comparatives

People traveling close to the speed of light.

Faraway galaxies…

More precise time-keeping…

O vídeo oferece vários exemplos de estruturas comparativas e de intensidade.

Question structures

O vídeo utiliza várias perguntas para construir a explicação:

What exactly is it that we’re measuring?

Is time something that physically exists?

Why is it we can move through space in any direction?

Could time just be some sort of illusion?

Esse tipo de construção é particularmente útil para alunos avançados porque mostra como perguntas são utilizadas naturalmente em uma explicação argumentativa.

❓ Questões de compreensão

1. How did humans originally measure time?

2. What did Einstein’s theory of relativity change about our understanding of time?

A) Time stopped existing.
B) Time always passes at exactly the same rate.
C) Time can pass at different rates depending on the situation.
D) Time only exists on Earth.

3. What is the “arrow of time”?

Explique em inglês.

4. Why does the video use food coloring spreading through water as an example?

5. What does the Second Law of Thermodynamics say about disorder and entropy?

6. What are the two major sets of equations currently used to describe physics?

7. Why is reconciling general relativity and quantum physics such an important goal?

8. What is unusual about the Wheeler-DeWitt equation?

9. What does the video mean by an “emergent property”?

10. Why is the movie analogy used to explain the concept of emergent time?

11. What does “far from a complete explanation” mean?

A) Scientists have completely explained time.
B) Scientists are close to explaining everything about time.
C) Scientists still have a long way to go before completely explaining time.
D) Scientists have stopped studying time.

12. According to the video, do we currently know whether time fundamentally exists?

Explain your answer.

✍️ Writing Practice

Imagine someone asks you:

“Do you think time is a real physical thing or an illusion created by our brains?”

Write 8–10 sentences in English explaining your opinion.

Try to use at least 5 expressions from the lesson:

unfold · woven into · no matter what · some sort of · turn out to be · far from · yet · eventually