Zero decibels is not silence – it’s the quietest sound an average human can perceive, i.e. the quietest sound most of us can perceive. This means that it’s quite possible to have negative-decibel sounds (which some people, and many animals and machines, can detect).
The ‘quietest place in the world’ is an anechoic chamber; the one they have at the University of Salford achieves minus 12.4 decibels. It’s built with very thick walls (to exclude outside sound) and lined with thick wedges of insulating material (to minimise echo) and is one of several similar chambers around the world which are used for testing things like engines and radio antennae. Chambers used for testing heavy machinery are normally only semi-anechoic, because they need a solid floor.
If you stand in such a chamber you can’t perceive any external sound at all, but you can hear your own heartbeat, the blood circulating in your head, and a high-pitched hiss which is thought to be caused by spontaneous activity in the auditory nerve fibres within your brain. It’s quite disturbing - nobody has been able to tolerate it for more than 45 minutes.
The largest frog in the world, the Goliath frog of Cameroon is completely silent.
Like the greatest virtue and the worst dogs, the fiercest hatred is silent.
A ‘passalorynchite’ is a monk who takes a religious vow of silence.
Ambrose (ad 338-397), Bishop of Milan, appears to have been the first person in Europe who could read without moving his lips; or, at least, that’s the interpretation generally given to this passage from the Confessions of St Augustine of Hippo.
‘When [Ambrose] read, his eyes scanned the page and his heart sought out the meaning, but his voice was silent and his tongue was still. Anyone could approach him freely and guests were not commonly announced, so that often, when we came to visit him, we found him reading like this in silence, for he never read aloud.’
Although there are various references to it in antiquity (Henry Chadwick says that it was ‘uncommon, but not unknown’ – e.g. it is attributed by Plutarch to Julius Caesar and Alexander the Great, and there are characters in Greek plays who read silently on stage), silent reading seems to have been a lost art in Europe in Ambrose’s time. The passage from the Confessions doesn’t directly state that Ambrose was unique, of course, but it is clear that the scholarly Augustine regarded silent reading as being akin to a conjuring trick of some sort.
Jonathan Swift spent a full year in complete melancholic silence.
The notes I handle no better than many pianists. But the pauses between the notes - ah, that is where the art resides.
In space, no one can hear you scream, but that's not to say that there cannot be any noise in space. There are still atoms to carry the noise, but they're just further apart - close to the Earth, you get an almost-vacuum with atoms about 1cm apart. In areas between galaxies, the molecules are around 10 meters apart - so if the sound is loud enough, it can be carried a certain distance.
If the Sun blew up tomorrow, and we had a microphone sensitive enough, there's no reason that we wouldn't be able to pick up a small noise. However, that would be the least of humanity’s worries.