Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: EvaH on 12/10/2020 17:04:58

Title: Can sound be used to create gravitational waves?
Post by: EvaH on 12/10/2020 17:04:58
Marcus asks:

Can sound be used to create gravitational waves?

What do you think?
Title: Re: Can sound be used to create gravitational waves?
Post by: alancalverd on 12/10/2020 17:56:36
Sound pushes. Gravity pulls.
Title: Re: Can sound be used to create gravitational waves?
Post by: Bored chemist on 12/10/2020 18:11:24
It would need to be loud if we wanted to detect the waves produced.
Very loud.
We can just about detect the waves from some of the biggest events in cosmology; two neutron stars colliding.
This one
https://en.wikipedia.org/wiki/GW170817
was relatively near so we observed it, even though it was a relatively "small" event.
According to this
https://en.wikipedia.org/wiki/List_of_gravitational_wave_observations#List_of_gravitational_wave_events
it released energy equivalent to "only" about 0.04 times the mass of the Sun.
(the others in that table release energy equivalent to about the mas of the Sun, or more).

So it "dumped" 7x 10^48 J
By comparison the biggest H bomb ever released about 2 X 10^17 Joules

So the biggest H bomb that we ever set off is  ten thousand million million million million times too quiet for us to detect the gravity waves from it (at  that distance- about 40 Million parsecs).

On the other hand, anything that accelerates mass in any way produces gravity waves. that includes sound.
So, in principle, a pin dropping does create gravity waves- just rather weak ones.
Title: Re: Can sound be used to create gravitational waves?
Post by: Bored chemist on 12/10/2020 18:13:09
Sound pushes. Gravity pulls.
Ignorance sucks.
Title: Re: Can sound be used to create gravitational waves?
Post by: evan_au on 12/10/2020 21:54:36
Quote from: Hitch-Hiker's Guide to the Galaxy, by Douglas Adams
Disaster Area are a plutonium rock band from the Gagrakacka Mind Zones and are generally regarded as not only the loudest rock band in the Galaxy, but also as being the loudest noise of any kind at all.
As I recall, in the book they turned a star supernova as the final note in their performance...

And this really would create gravitational waves, if the supernova collapse was asymmetric.
- A spherically symmetric supernova does not create gravitational waves
- Recent supernova modeling on supercomputers has suggested that there is a lot of asymmetric oscillations inside a star going supernova, so an asymmetric supernova is fairly likely
- Now, we just need to wait for the next supernova in our own galaxy to find out - the last one observed was 400 years ago (even one in the Magellanic Dwarf galaxy would be good; the last one observed there was 1987. We may have to wait a while for the next one...)

See: https://hitchhikers.fandom.com/wiki/Disaster_Area
Title: Re: Can sound be used to create gravitational waves?
Post by: Bored chemist on 12/10/2020 22:17:14
it's only the end of the world again...