If we could hear the sounds of these explosions directly where it was happening, how loud would each of these events be?
4$\begingroup$ Hi. We are expected to show some research effort with our Questions. What would happen if you were near a supernova? $\endgroup$– Keith McClaryMay 19, 2021 at 17:14
1$\begingroup$ A related question on our sister site: Would we be able to hear the sun if space were full of air? $\endgroup$– PM 2RingMay 19, 2021 at 19:44
$\begingroup$ Sound is a compression wave, and highly compressed things get hot and squashed, it's safe to say that the gas and water would instantly be expelled from your planet and your body, so your ears would perhaps turn into hot dust within a few seconds. It would depend if you are looking forward or sideways if your ears would be squashed together or blown away in different directions. Because the planets would actually change orbits and disintegrate it's not really sound. $\endgroup$– bandybabboonMay 20, 2021 at 3:29
This is a kind of silly question because you are dealing with object (stars, etc) that cannot exist in an atmosphere so treat the whole below as a bit of a lark.
The decibel scale is logarithmic. 120 dB is one joule of sound energy. 130 Joules is ten times more: 10 Joules, 140 is 100 Joules etc. (Source)
The loudest sound on Earth is said to be Krakatoa at 180 dB. This is a megaJoule of sound energy. (source) But Krakatoa released 840 PetaJoules in total (source) or 840 billion MegaJoules. So 1/840000000000 of the energy was converted to sound.
If we suppose that the same fraction of a supernova's energy is converted to sound, and a supernova releases 1044 joules, That means that about 1044/(840 billion) = 1032 Joules of sound energy, thirty-two orders of magnitude greater than 120 dB, or about 440 decibels. This means that the sound energy would be enough to vaporise the Earth.
A kilonova is smaller, by a factor of 10 to 100, so 420 to 430 decibels, and a hypernova (really just a very large supernova) might be bigger by a factor of 10, so about 450 decibels.
These are all "silly numbers". You can't actually put that much energy into sound waves. So there is nothing "realistic" about this calculation.
$\begingroup$ If someone created an artificial wormwhole leading into the body of hte exploding supernova, a recording device and transmitter sent though the wormhole into the supernova could record the sound inside the supernova for a tiny fraction of a second before being destroyed. There is no vacumn inside a star, so there should be some unimaginable type of sound within a supernova. Of course creating artificial wormholes is almost certainly impossible. $\endgroup$ May 20, 2021 at 18:08