LIGO detects most massive black hole merger to date

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

I have read somewhere that an experiencing a supernova at sun distance would be the same as holding a hydrogen bomb to your eyeball. The energy released in these events is basically unimaginable.

Assuming your 0.034% figure is correct, then one solar mass is equivalent to 2941 lifetimes of a sun's output, not 30. So 15 solar masses would be more like 44115 solar-lifetimes.

Derp yes, pesky off-by-100 errors :) Fixed, thanks.

Probably here:

https://what-if.xkcd.com/73/

And it’s even more astonishing — the supernova at 1 AU would be the same as a billion hydrogen bombs at your eyeball.

Is it physically limiting for a theoretical civilization to harness and use such energy?

Yeah, it's alot alot :-). Over on Mastodon I asked Phil Plait (@badastro) if the "missing mass" in the universe might be a result of black holes converging[1]. He wrote up this event in his newsletter[2] and points out that when they merge, they emit more energy in that instant than every single start in the universe in the same instant. So kind of like an instant of double energy. Hard to fathom how much energy that is with my meager mammalian brain.

[1] https://mastodon.social/@badastro/114852139083587160

[2] https://badastronomy.beehiiv.com/p/the-biggest-black-hole-me...

In the visible universe. The universe may well be infinite.

But, is it a small or large hydrogen bomb? And, what distance from your eyeball?

> 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 me try:

To match this power with sequentially detonated bombs, one would need to set off about 10^13 Tsar Bombas (or one hydrogen bomb scaled up to 5% the mass of the Moon) every second since the Big Bang to match it. With that amount of energy, you could essentially destroy earth every second since the Big Bang.

I’ll run some tests and let you know

Another way to look at it is that a hydrogen bomb is very small at planetary scale and so microscopically small at any astronomical scale.

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...

But you are safe at a parsec. Showing how also incredibly big space is. Space's bigness makes it hard to blow up a galaxy. Big bang excepted.

The energy is emitted as gravitational waves which is probably tricky to convert into usable energy and you probably can't attend more than one in your life unless you have faster-than-light travel. You're much better off visiting a supernova.

But in general it's better to have a steady and stable source of power, rather than one enormous burst of energy that you have to spend on something instantly.

I don’t want to dismiss your memory of the anecdote, but it doesn’t hold up under fact-checking. https://www.snopes.com/fact-check/bono-of-contention/

For certain values of safe. It’s close enough to strip the ozone layer, significantly increase the risk of cancer, alter the climate, and possibly cause extinctions.

All the stars in the universe, burning as brightly as they are, are the tiniest fraction of additional energy compared to the 2.73°K background temperature of space. The Big Bang was very warm.

It depends on the kind of supernova. Type Ia[1] is really insane. 10^44 J is a thing, that I think can blind you, even you've chosen a spot for your picnic to watch a Big Boom at distance of 1 parsec. A white dwarf made mostly of carbon burns all the carbon into oxygen in matter of seconds, and then it burns some of oxygen that was a result of burning carbon. It would like to continue brewing more and more heavy elements, but can't, because it becomes so hot, that gravity is no longer enough to keep the matter from flying away.

[1] https://en.wikipedia.org/wiki/Type_Ia_supernova

Space is big and quadratic function grows fast

I can't even understand how supernovae emit like "more energy than than the sun over it's entire lifetime"

Just... how? I get what happens with fusion but the numbers are so mind boggling. And it makes what seems like a terrifying ball of fire appear as a space heater in comparison. It's nuts. The GW thing you mention is near incomprehensible to me.

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.

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 ?

I don't care about the anecdote and its origin (but I did read this and thank you for setting the record straight). I don't care about Bono either :) He's a singer in a band that once made great music, and got lots of money, and does some good things about it. It's the parallelism of the statements 'stop clapping' x 'stop setting off bombs' that cracked me up.

At this scale it can help to think in terms of mass rather than energy. The most energy the sun could ever emit over its lifetime is if it was completely converted into energy. However, this merger emitted 15 times the mass of the sun as energy. I don't have all the numbers on tap for supernovas but given that the sun won't convert all its mass to energy, it's not hard for a supernova to convert more mass in its explosion into energy than the sun ever will.

I appreciate this point – it would take quite a few Tsar Bombas to approach the binding energy of a planet.

One of the rather curious facts about the Sun is that its net energy emissions, on a unit-mass basis, are roughly the same as a mammalian metabolism.

That is, your body is converting mass to energy (the only way the conversion is possible) through chemical processes (ATP-mediated molecular breakdown in the Krebs cycle) at roughly the same rate that the Sun is converting mass to energy through fusion of hydrogen to helium (modulo some pathway hand-waving).

You'll need far more input chemical fuel (carbohydrates and fats, mostly) than the Sun needs of input hydrogen fuel. But the net energy release rate is roughly equivalent.

The biggest difference between you and the Sun is that it (presumably) weighs somewhat more than you do. So that per-unit-mass conversion is multiplied by a much greater mass.

At these scales, several orders of magnitude literally makes no difference.

Hydrogen bomb yields range from roughly 0.1 MT to 100 MT (the full design yield of the Tsar Bomba), or four orders of magnitude. They can be considered equivalent for the purposes of this comparison. The principle warhead of the US ICBM force, the W87 warhead, has yield of ~0.3 to 0.475 MT.

Even at a distance of several tens of metres from your eye, destructive effects would remain significant.

Observable universe. Dark matter does not emit light.

It's humbling to consider what an incredibly low-energy state we humans live in. The universe is capable of such immense energetic outputs. We're humming along at energy levels approaching zero compared to most bodies floating around in space. Crazy.

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).

If you consider orders of magnitude from the Planck scale all the way up to the observable universe, we are actually somewhere in the middle

You mean "every single star in the universe", right?

Yes the same reasons your jet wash can't water your entire garden at once.

I hadn't considered that! That makes me wonder... Is that likely to be true for most forms of life? I wonder if there's some physical constraint that makes this likely. I suppose I won't know in my lifetime. It's also probably not so significant that we're close to the middle; maybe it's just my ape brain finding significance in arbitrary figures.

If I were to guess before, I think I would have estimated humanity was in the lower 10%. I suppose I was mostly thinking in terms of the Kelvin scale.

It's fascinating to consider how staggering the scale goes in either direction, now. Absolutely bizarre.