Re 8:1 When He opened the seventh seal, there was silence in heaven for about half an hour.
Any answer to this will only be a speculation, and mine is no different. The silence in heaven for half an hour probably means that there are no Charismatics and Pentecostals there!
No, seriously. I think it's the silence of expectation and anticipation. They were all waiting to see what will take place at the opening of the seventh seal, and so, naturally, they become silent to see what happens.