# Thread: Sound of a supernova

1. Established Member
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## Sound of a supernova

The shock front of a newly created supernova remnant is the ultimate bang. What is its loudness in decibels?

2. Originally Posted by Tom Mazanec
The shock front of a newly created supernova remnant is the ultimate bang. What is its loudness in decibels?
I disagree. For things going on in the current universe, the loudest we get would be the shock from a short GRB. That being said, your question is hard to answer because the definitions of decibel don't normally account for things so loud that they change the phase of the matter that carries the signal... but I think that the answer will be between 400 and 500 decibels for a measurement taken near the event.

3. In decibels..? No, and I have no idea how to answer that. We can imagine a solar mass. We can measure its energy output.

Some of the thing we would need to know to calculate the energy release in a known moment is not known..

From what we know of nova events.. a large variance would be apparent.

That decibels are a method of measuring air shock moment momentum.. No air, no decibels. More correctly put.

Sound requires a medium to be transferred..

4. Originally Posted by astromark
That decibels are a method of measuring air shock moment momentum.. No air, no decibels. More correctly put.
No, the decibel is defined as sound pressure level by:

where the 20 comes from the squares that are actually in the Log. As there is plasma, which is a gas, there is gas pressure, and thus from the shock the level of decibels can be calculated.

5. Diffuse interstellar gas can transmit pressure waves like sound in our atmosphere, but only at vastly lower frequencies where the wavelength is large compared to the mean free path of the molecules. Shock waves of this sort are believed to trigger star formation around a supernova. In theory we could calculate the wavefront pressure in dynes per square centimeter and convert it to decibels as is done in Earth's atmosphere. When this reaches the hull of a hypothetical spacecraft I doubt very much that the crew would hear or even feel anything unless they were close enough to the blast to be roasted.

6. In his book, 'Extreme Cosmos', Bryan Gaensler indicates that a supernova explosion corresponds to a change in pressure equivalent to over 330 decibels (although he points out that even if you could somehow float in space with your ears exposed, the subjective experience would still be that the supernova was silent. For a creature whose "ears" were attuned to hearing in those rarefied conditions though, it would be utterly deafening!)

7. Order of Kilopi
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I would have thought that all the roiling around would be 330 dB, with the supernova being off the scale.

8. To try and state the obvious. Without creating a foolish argument.
If you think you can hear a NOVA event. You can not.
You might be able to measure the energy as it tears into and rips away Earth's atmosphere....
A sound I can not imagine and would never want to hear..
The OP clearly asks for "What is its loudness in decibels?"
In the context of sound being a shock wave change showing indication of sudden pressure wave change..
We do NOT hear sound from space..
because there is a insufficiency of medium to transfer such shock wave pressure front..
and from a science journal I quote:
" A hissing sound might be heard as the upper atmosphere is heated and energies absorbed. "

9. 08chile-span-articleLarge.jpg

and then there's this part of the spectrum.. It can be argued we do already hear Nova events..

10. In a nova, a vast amount of gas is hurled outward at great velocities. Isn't that a pressure wave that could be translated into decibles? You would have to specify the distance from the explosion.

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Originally Posted by astromark
To try and state the obvious. Without creating a foolish argument.
If you think you can hear a NOVA event. You can not.
You might be able to measure the energy as it tears into and rips away Earth's atmosphere....
A sound I can not imagine and would never want to hear..
The OP clearly asks for "What is its loudness in decibels?"
In the context of sound being a shock wave change showing indication of sudden pressure wave change..
We do NOT hear sound from space..
because there is a insufficiency of medium to transfer such shock wave pressure front..
and from a science journal I quote:
" A hissing sound might be heard as the upper atmosphere is heated and energies absorbed. "
Shouldn't the shock wave itself carry the pressure front? You start at basically 0 psi and then work your way up to X psi. For a change of 0 to 30 psi, a 15 psi swing,(max sinusoidal at sea level), the equivalent level is 194 dB. The nova doesn't have to be a periodic wave. I'm expecting a single pulse.

12. Originally Posted by tusenfem
No, the decibel is defined as sound pressure level by:

For some reason, our converter seems to like the tags close, and you forgot a parenthesis. I fixed it:

13. That from my friend 'Grapes' is a work of art I find No comfort in. I will explain;

Energised sub atomic particles.. ejected from a Nova event.

Might arrive upon Earth's atmosphere at very high velocity. Energies will be transferred.

If they were not previously absorbed or deflected by electro magnetic shielding fields..

That the arrival could disturb the upper atmosphere to a point of creating a shock wave front..

That might not be just heard, but felt. Measured and realized for what it might be.. Tested and retested..

The sound of a Nova event NO. The effect upon Earth's atmosphere, Yes.

14. Originally Posted by astromark
... The sound of a Nova event NO. The effect upon Earth's atmosphere, Yes.
Hi Mark, the OP was more about just trying to get a sense of the highest number of dB that might be real in any sense, and I'm pretty sure he was talking about the dB in the pressure wave inside the star as the supernova explodes... not because of sounds in our atmosphere, but just as an entertaining look at the units. He's also asked questions in the past about supernovae expressed in megatons, and other such things. This is perhaps not scientifically interesting, but it is a scale question, and so it can be instructive.

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Thank you Antoniseb for saving us those keystrokes.

Forget about earth and human hearing. Just imagine you're near a supernova going off. Find new ways to express the energy involved. Megatons, decibels, joules, whatever helps a person imagine how intense a nova really is.

16. With some regard for a language usage I do not understand..

I can not use decibels in space.. No transmission of sound in space.

and 'Antoniseb' has informed me of my complete miss understanding of this thread..

Here's me thinking from Earth.. No. Oops and sorry. dixi.

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