[ExI] Has the mystery of Dark Matter been solved?

John Clark johnkclark at gmail.com
Sat May 28 02:34:04 UTC 2016

On Fri, May 27, 2016 at 4:04 AM, Tomaz Kristan <protokol2020 at gmail.com>

​> ​
> We have at least one billion supermassive black holes around.

Supermassive black holes
​ with billions of solar masses are of trivial importance in cosmology,
​the important ones are Black Holes larger than 10 and less that 100 solar
masses because they could make up 85% of all matter in the universe.

> ​> ​
> Each has already swallowed many million to billion of stars (black holes)
> just to be as massive as it is.

​And LIGO can't even detect what ​
supermassive Black Holes are doing because the frequency of the
gravitational  waves they make would be too low.​ LIGO is deaf to Black
Holes larger than a few hundred solar masses.
And a Black Hole of any size in isolation that's just sitting there minding
its own business doesn't make an
gravitational waves at all.

​> ​
> It's less than 10^18 seconds since the Big Bang. So one such event per
> 1000 or there about seconds on average.

​I don't know where you got that figure. In the ​
10^18 seconds
​ that a pair of orbiting Black Holes exist they only make enough noise for
LIGO to detect it for a fifth of a second, and ​yet LIGO heard such a pair
in just 18 days.

> ​> ​
> I am quite certain that those colliding events are frequent.

​Apparently they ​
​are. Unless they LIGO people were astronomically lucky they are far more
frequent than anybody predicted. Most thought it would be decades before
they heard anything that good, and some thought they never would.

> ​> ​
> It's a question for me however, if there was a detection by LIGO, at all.

​Long ago people used General Relativity and computers to simulate what the
​merger of two ​30 solar mass black holes would look like, and the match
with what LIGO found couldn't be more perfect. Pure textbook.

 John K Clark

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