
Gravitational waves reveal collision of heavy and light black holes - jdnier
https://www.sciencemag.org/news/2020/04/gravitational-waves-reveal-unprecedented-collision-heavy-and-light-black-holes
======
clort
Are they saying that the frequency produced is the _same_ as the note in the
Elvis song or just that the ratio of the two notes in the song is the same as
the ratio of the two frequencies detected?

I mean, I am not sure what the frequencies generated by orbiting black holes
would be.. but ~260hz (middle C) sounds destructively fast to me so I'm
guessing the latter. What is the orbital frequency likely to be here?

~~~
tehsauce
260hz is not unreasonable, black hole mergers are unimaginably violent.

[https://youtu.be/9IdVyArDlZ4](https://youtu.be/9IdVyArDlZ4)

~~~
clort
yes but I'm imagining that when the orbital frequency gets to that kind of
level, the end would be extremely imminent?

(for the remote observer anyway haha)

~~~
Jabbles
Yes, but it's only when the black holes get extremely close that they produce
gravitational waves powerful enough for us to detect.

You're correct that for many years (millenia?) the black holes have been
orbiting each other much more slowly. We can't detect that though.

~~~
foota
I wonder what the right time scale is here. My gut reaction is million of
years?

~~~
enkid
I believe it depends on the specifics of the merger, but my understanding is
the reason black holes that orbit each other merge at all is because they
bleed energy to gravitational waves. While they are at a reasonable distance,
that's a very small amount of energy. I think some of these systems would be
stable for billions of years.

~~~
foota
Billions seemed too long to me, at that point you're talking about tenths of
the lifetime of the universe!

~~~
enkid
That's the timescale the solar system is stable on.

~~~
foota
Aw, sorry. I think I mis-interpreted your comment. I was thinking more of how
long the system has been falling apart for. It didn't make sense to me that
that could have been for billions of years, since the movement involved would
be so slow?

------
ttul
A link to the paper would be appreciated if anyone has it.

~~~
aspenmayer
It was a paid livestream of the virtual conference. Free slides available
below.

[http://meetings.aps.org/Meeting/APR20/Session/C06.2](http://meetings.aps.org/Meeting/APR20/Session/C06.2)

