In reply to felt:
> 1. I read that this event for 20 microsecs (?) or something gave out more watts than the combined light output of all the stars in the visible universe (this number being, as I understand it, 100 billion galaxies with 100 billion stars each in them; so a lot of stars, a sort of yottaosram) for the same period. Given that these holes are at the end of the day not that big -- three suns? -- how can that possibly be the case?
This event is regarded as the most powerful ever witnessed (i.e not the most energetic). We can work it out with some back-of-an-envelope calculations. I'm going to use 0.5s as the time period for the observations since the graphs in the publication cover roughly that period:
http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.116.061102
1 solar mass (Ms) = 2x10^30kg. The radiated energy equivalent of 3Ms is 1.8x10^47 Joules (using E=mc^2). So the average power output is 3.6x10^47 Watts!
The Sun produces energy through nuclear fusion: A simplified version of the process is that 4 Hydrogen nuclei (single protons) come together and fuse to form a Helium nucleus (2 protons, 2 neutrons). The mass of the Helium nucleus is approximately 99.25% the mass of the original protons. The energy comes from the missing 0.75%.
Let's assume that during The Sun's main sequence lifetime, 10% of the Hydrogen gets converted to Helium. That's 0.00075Ms over 10 billion years. Compare with our black holes: (3/0.00075) x 10x10^9 x 365.25 x 24 x 3600 x 2. Averaged across the half second I used, our black hole merger was 2.5 x 10^21 times more powerful than The Sun (2.5 thousand billion billion).
If we approximate our Universe as consisting of 100 billion galaxies containing 100 billion Sun-like stars, then the average power output of our black hole merger is a quarter of the power output of the rest of the observable Universe. When we consider that the power output of the black hole merger was not uniform over the split-second but rose to a peak, then we can see that, for a small fraction of a second, it was more powerful than everything else put together.
> 2. It seems fishy to me that the moment this machine is switched on we somehow manage to catch the biggest event ever in the history of everything. Isn't this akin to never watching telly, then finding one in the attic, switching it on and just coinciding with us winning the Eurovision Song Contest or the World Cup or similar?
Well it tells us something about our Universe - that black hole mergers are perhaps more common than we previously thought. That's why this new window we have on the Universe is so exciting, there are many incredible discoveries waiting to be made. Apparently there are some more announcements in the works from LIGO, I can't wait