Scripture does not specify the reasons for the silence in heaven for that half an hour. But here are some possibilities:

1) The silence in heaven for the space of half an hour is a sign of deep respect and awe in the presence of the Judge of all the earth. Just as earthly courtrooms demand silence when the judge is presiding, so does the heavenly courtroom. “Be silent before the Sovereign LORD, for the day of the LORD is near” (Zephaniah 1:7). “The LORD is in his holy temple; let all the earth be silent before him” (Habakkuk 2:20).

2) The half-hour silence in heaven is the result of somber reflection on what has just been revealed. When Jesus Christ breaks the seventh seal, the scroll of God’s judgment is fully revealed for the first time. Now all heaven can see God’s plan to judge the wickedness of the earth, destroy the kingdom of the beast, and set things right. All heaven remains silent as God’s righteousness is on display. At the sight of full scroll and all the judgments about to fall, the denizens of heaven take their cue from Job, who, faced with God’s awesome presence, said, “I am unworthy—how can I reply to you? I put my hand over my mouth” (Job 40:4).

3) The silence in heaven is due to the severity of the actions the Lord God is about to take. With the scroll fully open, heaven can now see the trumpet judgments (in the next verse, seven nearby angels are handed seven trumpets of judgment, Revelation 8:2) and the bowl judgments (which the seventh trumpet introduces). These judgments are more terrible than anything the world will have ever seen (Mark 13:19–20). The final catastrophes are about to befall the earth, and silence and stillness fill the time of tense expectation. “Be silent, all flesh, before the LORD, for he has roused himself from his holy dwelling” (Zechariah 2:13, ESV).

In a way, the silence in heaven could be seen as the calm before the storm—the storm of final judgment coming upon the earth. The silence emphasizes the importance and impressiveness of the seventh and final seal. With the opening of the seventh seal comes a climax in the Day of the Lord. Evil has had its day; now the Lord will have His.