**Gravitational Chirp Death Zone**

LIGO detected the gravitational waves from a black-hole
merger. One hole was 39 solar masses, the other was 26, together they made a
62-solar-mass black hole; the 3 solar mass difference turned into gravitational
radiation in about a tenth of a second. That’s a powerful chirp; it outpowered
all the stars in the universe. One estimate was 10^24 sunpowers; that’s a
trillion trillion, or 1.6

*moles*of stars!
So I wondered how close your spaceship would have to be to
the black holes for the chirp to kill you. Here are my calculations:

Diameter
of proton = 8.77 * 10^-16 m

1/10000
of that = how far LIGO mirror moved = 8.77 * 10^-20 m

Length
of LIGO antenna = 4 * 10^3 m

Ratio
of those lengths = 2.19 * 10^-23

Gravitational
radiation goes by an inverse-square law. Also:

sqrt(2.19
*10^-23) = 4.68 * 10^-12

so
I presume that anything closer, by that factor, to the black hole merger
experienced gravitational-wave distortions on the order of the length of the
object itself. Anything that close gets pounded like pizza dough; squashed flat
in alternating perpendicular directions, 25 times in 0.1 seconds. That sounds
like a death-zone to me. All bones broken, total ship-systems malfunction,
planets explode, etc. CHIRP!

4.68*
10^-12 times 1.3 billion
light-years = 0.006 light-years = 2.16 light-days.

OK,
I’m staying at least that far away! But we’re not out of the woods yet. Note
the supermassive black holes at the centers of Milky Way and Andromeda
Galaxies. In a few billion years these galaxies will merge to form Milkomeda,
and then their black holes will merge and chirp. How loud?

Mass
of Milky Way black hole = 4.1 *
10^6 suns

Mass
of Andromeda black hole = 2.3 *
10^8 suns

The
recent black hole merger involved 29 and 36 suns. Assume that ‘our’ black hole
does most of the radiating; the ratio of it to 29 suns is about 141,379; so I
assume that the energy will be greater by that proportion.

Assuming
inverse-square law, the death-chirp zone is greater by a factor of
sqrt(141379) = 376

376
* 0.006 light-years is about
2.25 light years.

OK,
again I’m keeping my distance. But I wasn’t planning to go there anyway.

**Phew**. Frankly I was worried; my first, inaccurate, calculation had the death-chirp span Milkomeda. Frying when the Sun goes supergiant has some dignity; but death by chirp is an

**.**

*insult*
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