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LIGO detects most massive black hole merger to date

(www.caltech.edu)
360 points Eduard | 4 comments | 14 Jul 25 20:06 UTC | HN request time: 0.001s | source
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WrongOnInternet ◴[14 Jul 25 21:27 UTC] No.44565549[source]▶
> the 225-solar-mass black hole was created by the coalescence of black holes each approximately 100 and 140 times the mass of the Sun.

Does this mean that 15 solar masses were converted into energy? Because that's a LOT of energy.

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aaronharnly ◴[15 Jul 25 00:27 UTC] No.44566715[source]▶
Let’s see — the Tsar Bomba nuclear weapon released the equivalent of converting about 2.3 kg of matter into energy (1).

One solar mass is about 2 x 10^30 kg, so round numbers this event released the same as 10^31 Tsar Bombas, which is … a lot of energy? That number is too big to be a good intuition pump.

Let’s try again: over the course of its entire lifetime of about 10 billion years, the sun will release about 0.034% of its mass as energy (2). So one solar mass of energy is about 3000 solar-lifetime-outputs.

So this event has released about as much energy as 45,000 suns over their entire lifetime. I’m not sure how much of the energy was released in the final few seconds of merger, but probably most of it? So… that’s a lot of energy.

(1) https://faculty.etsu.edu/gardnerr/einstein/e_mc2.htm

(2) https://solar-center.stanford.edu/FAQ/Qshrink.html

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1. dd_xplore ◴[15 Jul 25 10:13 UTC] No.44569654[source]▶
Also to put in perspective, most of the mass isn't converted to energy in either nuclear or hydrogen bombs, it's just the bond energy. Pure energy for a given quantity of matter is released only in case of annihilation-like event(merging with anti matter). So even fusion releases max 0.7% energy of the mass

I'm not sure what happens in black hole merger.. is it an annihilation like event or is just fusion...

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2. simonh ◴[15 Jul 25 14:17 UTC] No.44571413[source]▶
The black holes orbit each other, and get closer and closer. This emits gravity waves, and when they merge a large proportion of their combined mass gets emitted as gravity waves. These are what LIGO is detecting.
3. arbitrandomuser ◴[15 Jul 25 14:59 UTC] No.44571844[source]▶
The bond energy is also mass . Energy is mass , If you had a nuclear reactor surrounded by gas and this setup ran a turbine which compressed a humungous spring and this whole setup was completely sealed and sits on a gigantic weighing scale. You run the nuclear reactor, the spring compresses gaining potential energy, waste heat goes into the gas molecules as kinetic energy. As the reactor progresses converting "mass to energy" does the weighing scale become lighter ?
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4. deepsun ◴[15 Jul 25 20:37 UTC] No.44575557[source]▶
Well, weighing scale doesn't measure mass, it measures weight. It's just scales' UI converts it to kg/lb for usability, instead of showing N it actually measures (weight is a force, and force is measured in newtons).