Learn Russian: Там кто-то есть? Нет, никто не отвечает, там тишина. - Is someone there? No, no one answers, there is silence.

In Russian, double negatives are required! When you use a negative pronoun like никто (no one), you must also make the verb negative by adding не before it. Literally, this sentence says "no one doesn't answer."

How do кто-то and никто relate to each other here?

Both are based on the question word кто (who). Кто-то means "someone" or "anybody" and is used in the first part because you are asking if an unknown person is present. Никто means "no one" and is used in the reply to state that zero people are answering. In both clauses, they are the subject of the sentence, so they are in the Nominative case.

Why do we use есть in Там кто-то есть? but leave out the verb in там тишина?

In the present tense, Russian usually drops the verb "to be" when just linking a subject to a description, which is why там тишина literally means "there [is] silence". However, you use есть when you specifically want to ask about or state the existence or presence of something, like asking "is someone [actually present] there?"

Could I say там тихо instead of там тишина at the end?