Learn Hardcore Portuguese (Brazil): Antes da peça começar, o teatro fica em silêncio; depois, o palco enche de aplausos. - Before the play starts, the theater becomes silent; afterward, the stage fills with applause.

The basic structure is antes de (before) + a noun or verb.
Peça (play) is feminine, and we normally use the definite article a with it: a peça (the play).
So: antes de + a peça → antes da peça.

More explicitly, the full, non‑contracted form is:

antes de a peça começar → in normal speech/writing becomes antes da peça começar.

Both are grammatically acceptable, but in Brazilian Portuguese the contracted form da is by far the most common in everyday language.

Why is começar in the infinitive (antes da peça começar) instead of a conjugated form like comece?

After antes de, Portuguese can use:

Infinitive:
- antes de / da peça começar
- Literally: before the play start (with an infinitive)
Subjunctive with que:
- antes que a peça comece

Differences:

Antes de + infinitive is very common and sounds natural and neutral in Brazilian Portuguese, especially in speech.
Antes que + subjunctive (comece) is also correct, a bit more formal or literary, and often used when you want to emphasize that something must happen (or not happen) before something else.

In this sentence, antes da peça começar is the most natural everyday option and sounds smooth and idiomatic.

Why is the verb fica (present tense) used in o teatro fica em silêncio if this describes something that happens repeatedly?

In Portuguese, the simple present often expresses:

habitual or repeated actions
general truths or typical behavior

So o teatro fica em silêncio means:

the theater becomes / is left silent in that situation, as a general, repeated fact.

English might use present simple too (the theater goes quiet), but sometimes English would use gets or becomes; Portuguese keeps the simple present fica to cover that meaning of repeated, typical behavior.

Why use ficar em silêncio instead of ser silencioso or estar silencioso?

The three verbs focus on different nuances:

ficar em silêncio
- Literally: to end up / become / remain in silence
- Emphasizes a change of state: the theater goes from noisy to silent and stays that way.
ser silencioso
- Describes a permanent characteristic: the theater is a quiet place (in general).
- That’s not the idea here; we’re interested in what happens before the play, not in the theater’s permanent nature.
estar silencioso
- Describes a temporary state, similar to English is being quiet right now.
- You could say o teatro está silencioso, but ficar em silêncio gives a stronger sense of the theater falling into silence and staying that way for that period, which matches the dramatic/temporal feel of the sentence.

So ficar em silêncio is a very idiomatic way to describe the moment when an environment goes quiet.

Why is it em silêncio and not no silêncio or just silencioso?

em silêncio = in silence (a state or manner)
- Very idiomatic in Portuguese: ficar em silêncio, permanecer em silêncio, esperar em silêncio.
no silêncio = in the silence
- Focuses more on the surrounding environment as a noun (the silence around them), not on the behavior/state of the theater.
silencioso = adjective quiet, silent
- o teatro é/está silencioso is possible, but em silêncio is the set phrase normally used with ficar to talk about people or places going quiet.

So fica em silêncio is the most natural collocation here.

Why is it enche de aplausos and not enche com aplausos?

With the verb encher (to fill), the standard and most idiomatic pattern in Portuguese is:

encher de + noun

Examples:

encher de água – to fill with water
encher de gente – to fill with people
encher de alegria – to fill with joy
encher de aplausos – to fill with applause

Encher com is much less common and often sounds less natural or slightly off. In everyday Brazilian Portuguese, you almost always say encher de when you mean to become full of something.

So o palco enche de aplausos literally means the stage fills up with applause.

What is the difference between o teatro and o palco in this sentence?

o teatro = the theater (the whole venue: building, audience area, space)
o palco = the stage (the platform where actors perform)

In the sentence:

antes da peça começar, o teatro fica em silêncio
- Before the play starts, the whole theater (especially the audience) goes quiet.
depois, o palco enche de aplausos
- Afterwards, the stage fills with applause (metaphorically: the whole space of the performance is flooded by applause; it evokes the center of action).

So the switch from o teatro to o palco highlights a shift of focus: first the entire room, then the performance area.

Why is there a semicolon () ; ) between the two parts instead of a comma or the word e?

The semicolon separates two closely related but independent clauses:

Antes da peça começar, o teatro fica em silêncio
depois, o palco enche de aplausos

You could write:

…, e depois o palco enche de aplausos.
or even with just a comma in less formal writing.

But the semicolon:

gives a slightly more formal or literary tone,
highlights the contrast between the quiet before and the applause after,
clearly marks that each part could stand as its own sentence.

It’s mostly a stylistic choice here, not a strict grammatical requirement.

Can we change the order inside antes da peça começar, like antes de começar a peça? Are both correct?

Yes, both are acceptable, with a small difference in emphasis:

Antes da peça começar, o teatro fica em silêncio.
- Focus: the play as the subject that starts.
- Structure: antes de + [subject] + infinitive.
Antes de começar a peça, o teatro fica em silêncio.
- Focus: the event of starting the play in a more general way.
- Structure: antes de + infinitive + object.

In meaning, they are essentially the same here, and both sound natural in Brazilian Portuguese. The version with da peça começar is perhaps a bit more formal or literary; antes de começar a peça may feel a little more conversational.

Could we say antes que a peça comece instead of antes da peça começar? Is there any difference?

Yes, you can say:

Antes que a peça comece, o teatro fica em silêncio.

Differences:

Antes da peça começar (infinitive)
- Very common, neutral, and widely used in speech and writing.
- Slightly simpler and more direct.
Antes que a peça comece (subjunctive)
- Also correct.
- Sounds a bit more formal, cautious, or literary.
- The conjunction que
  - subjunctive often emphasizes that something must or should happen (or not happen) before the other action.

In everyday Brazilian Portuguese, antes de + infinitive is often preferred unless there’s a specific stylistic reason to use antes que + subjunctive.

Why is aplausos in the plural? Could we say aplauso in the singular?

In Portuguese, aplausos is almost always plural when referring to clapping applause from an audience:

receber aplausos – to receive applause
muitos aplausos – lots of applause
o palco enche de aplausos – the stage fills with applause

The singular aplauso exists, but it usually refers to:

a single act of applause, or
a more abstract idea, often with a modifier, like um aplauso tímido (a timid applause).

So in this sentence, aplausos in the plural is the natural and idiomatic choice.

Why are the definite articles (o teatro, o palco, a peça) used here? Could we omit them?

Portuguese uses definite articles much more frequently than English:

o teatro – the theater
o palco – the stage
a peça – the play

In this context:

We are talking about a specific, known theater, stage, and play (the one involved in this event).
That naturally calls for the definite article in Portuguese.

If you omit them:

Antes de peça começar – ungrammatical; sounds wrong.
Antes de começar peça – also wrong; the noun peça almost always needs an article or other determiner here.

So the articles o / a are required in this sentence and are not optional the way English the sometimes can be.

Who is the subject of começar in antes da peça começar? Is peça really the subject even though it comes after the verb?

Yes, peça is the subject of começar.

The structure is:

antes de + [subject] + infinitive

Expanded:

antes de a peça começar
- a peça = subject
- começar = infinitive verb whose subject is a peça

In the contracted, natural form antes da peça começar, the grammar is the same; the subject just comes after the infinitive. This kind of structure (preposition + infinitive + its subject) is quite common and normal in Portuguese.

Does this sentence sound natural in Brazilian Portuguese, or is it overly poetic?

The sentence:

Antes da peça começar, o teatro fica em silêncio; depois, o palco enche de aplausos.

is perfectly natural and idiomatic in Brazilian Portuguese, but it does have a slightly literary or descriptive flavor because of:

the balanced structure (antes… depois…),
the semicolon,
the metaphor of the palco (stage) filling with aplausos.

You could easily hear or read this in:

a review of a play,
a descriptive passage in a book,
a more refined blog post or article about theater.

In everyday casual speech, people might say something simpler like:

Antes da peça, o teatro fica quieto; depois todo mundo aplaude.

But your original sentence is natural and stylistically elegant, not strange or incorrect.