system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The science behind a classroom of commotion randomly going silent at the same time.

Really curious about this one.
gpt
Mathematically this is bound to happen. No one person is talking constantly but the noise level stays up because voices are constantly overlapping. All that needs to happen for a weird silence to occur would be for all the breaks in conversation to happen simultaneously. We can estimate some values to see how often this would happen in a class of average size. Say 20 students are all having conversions in which they are only actively talking about 30% of the time (groups of about 3 with a little transition time between speakers). And let's also say that it would take about a half second of pure silence to be noticeable. So given any half second interval there is a 0.7^20 or 0.08% chance that no one is talking. So now to figure out how long it would take before there is a 50% chance that an awkward silence has occurred we need to do 0.9992^x=0.5 or log (0.5)/log (0.9992)=x. So x is equal to 866 or 866 half second increments. So after about 7 and a half minutes we would expect about 1 random silence to have occurred. 
These are very rough estimates and a computer simulation could give a much more accurate answer.