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.
> 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.
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.
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.
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...
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.
Yes! And still, gravity is so weak that that immense amount of energy translates to just a relative contraction of less than 10^-20, or about a hair's width in the distance from the Earth to the Moon.
This is because space is _stiff_. Recall Hooke’s law from high school physics. The k constant represents the stiffness of the object. A rubber band is about 50. A sky scraper, about a million. Space? About 10^46 if I recall correctly. So it takes a truly enormous amount of energy in the form of gravitational waves to be able to move space enough for it to be detectable on Earth. And the only objects that can do that are the most massive ones moving at close to the speed of light: black holes, neutron stars, supernovae (the latter would have to be very close for us to see gravitational waves from - close enough that we’d likely see it with the naked eye as well).
I was disappointed to learn that it would require billions of solar masses of energy from a black hole merger to be able to ride the gravitational wave starting at a distance of a few Schwarzschild radii. It seems like riding a plasma jet might be better.
Converted into energy and then escape the black hole, from which light can’t escape? That doesn’t seem to compute. And if it’s converted into gravity waves then we have an excellent obvious candidate for how most energy will escape a black hole. It won’t be waiting around for hawking radiation.
I think during the merger the event horizon must be changing rapidly, so I guess there's some(or a lot) of chance that matter can escape these merger events. The matter will already have high kinetic energy...
No mass escapes. It is purely gravitational waves that are emitted. There is no sneak peek behind the event horizon curtain during a black-hole merger.
Man, that is some seriously interesting phenomena:
"The black holes appear to be spinning very rapidly—near the limit allowed by Einstein's theory of general relativity," explains Charlie Hoy of the University of Portsmouth and a member of the LVK. "That makes the signal difficult to model and interpret. It's an excellent case study for pushing forward the development of our theoretical tools."
The rotating mass drags space time around it, called frame dragging, which is different from gravitational waves. Gravitational waves consists of oscillations, which is caused by change of mass, wobbling of spinning objects, or several masses orbiting around a barycentre.
A month ago, the proposed NSF budget would shut down one of the two LIGO observatories in the US, wrecking its ability to triangulate the location of events such as this black hole merger. A shutdown would also severely damage the noise margins and detection rate. Does anyone know if the shutdown is still planned? (I couldn't find any recent info.)
I believe the proposed budget is being marked up tomorrow (July 15th, 12:00). Currently the NSF budget is set to be ~$7 billion, a 23% cut compared to FY2025. I'm not sure how this affects LIGO exactly.
I was last week at an event in Pisa at virgo ego (basically ligo's cousin). It was to celebrate the 10th anniversary of finding gravitational waves iirc. There were an actress reading from the book the director of the Italian program wrote accompanied by the sound of waves made with sax. I can't describe it with words but it was truly moving.
There were also moments dedicated to interviewing a science communicator and the director of the virgo center, and he was, let's say, quite angry at the thought of ligo losing funding. Rightfully so
the collaboration to be able to triangulate is composed of LIGO, Virgo and now KAGRA. KAGRA is not yet fully ready for longer observation runs, so for now it's basically LIGO and Virgo - and if you take offline one of three, triangulation becomes nearly useless
I think all the previous events were announced with a big delay. They have a long pipeline of checks. The signals have too much noise and it's difficult not to cheat and find fake signals in the noise. IIRC they even have a team that adds secretly fake signals to ensure the pipeline is working and after it's detected the team disclose if it's real or fake, before publication.
It's only spherical in a Schwarzschild (non-rotating) black hole. A rotating black hole is called a Kerr black hole, and stuff gets weird, such as there being an oblate event horizon, a weird outer horizon called an ergosphere where spacetime gets dragged along such that it's impossible to stand still and you can accelerate objects using the black hole, a weirder inner horizon called the Cauchy horizon where time travel is possible, and a singularity in the shape of a ring. Your intuition is correct that during a merger it would be weirder still.
Edit: Updated the bit about about horizons as I research a bit more. It's complicated, and I'm still not positive I have it exactly right, but I think it's now as good as I can get it.
No matter how chaotic the merger looks, the event horizon must asymptotically become either spherical (Schwarzschild) or oblate (Kerr). The mass distribution inside doesn’t change this, general relativity doesn’t allow static “lumpy” horizons.
It’s wild how much happens in those milliseconds though. Numerical relativity papers like the one you shared from arxiv.org show the horizon “sloshing” before it stabilizes.
It is difficult to talk about the shape of the event horizon because the ordinary definition of a sphere is "surface where all points are equidistant from a given point" is already complex in a differentiable manifold, but even more so when the distance is infinite because of a singularity (or the point doesn't exist/isn't unique because of geodesic structure). So you switch to a definition of "surface of constant scalar curvature with the topology of a sphere", the topology being important to distinguish it from a plane and a hyperboloid.
From there, I haven't personally done or seen the calculations of the shape of the horizon for Kerr or merging black holes, but my intuition is that it would be indeed peanut shaped for a merger (there are likely some saddle points). The coordinate shape certainly is but you can choose coordinates so that a Schwarzschild black hole is a coordinate peanut so coordinates aren't very meaningful.
Edit: "The Kerr metric also predicts the existence of an inner and outer event horizon, with the shape of these horizons being oblate rather than perfectly spherical due to the rotation."
Kind of. Because the black hole drags space around with it you need to go faster near the ‘equator’ than the poles just to stand still. So the event horizon is fatter at the equator.
From our perspective there is no event horizon since the collapsing star has not reached the black hole state. In fact it takes infinite amount of time from the point of view of an external observer for the event horizon to form.
In almost all situations it does matter as the collapsing star will behave as it is a black hole. But for the merge of black holes it is significant as it allows to release energy as there is no event horizon.
I'm no physicist but what I've learned on the internet through osmosis, I'd wager that black holes aren't spherical per-se, but they appear sphere-like to us dimensionally challenged beings. It's more like a manifold (mobius-gate? not a mobius surface), that changes your spatial directions to parallel temporal directions to spatial ones all leading to the singularity.
So, if two black holes, each with mass M, were moving at nearly the speed of light and collided head-on (resulting in a final velocity of zero), what would happen to all that momentum? Would the resulting black hole have a mass greater than 2M? If so, how and why would this occur?
The thing is that the spacetime around blackholes get curved to the actual extremes.
When we imagine flying "at nearly the speed of light" towards something thats traveling the same speed towards you, we tend to imagine a collision at high speeds.
But for blackholes that turn space into time and time into space, they can see the other blackhole slowing to a complete stop as its about to touch. Or it can look differently, it all depends on the position and speed of an observer.
We cant even agree on the basics like: "It doesnt matter how it looks, but they must collide", since if we look at something falling into a blackhole (which I pressume could be another blackhole just as well), we see it slow towards 0 at the edge and fade away in redshift instead of seeing it actually fall trough.
The escape velocity from inside the event horizon is faster than the speed of light, which is the highest possible speed in the universe.
So black holes cannot approach each other faster than the speed of light. And if their trajectories intersect perfectly, they won’t be able to escape each other’s gravity.
A black hole can’t pass “through” another black hole like two bullets hitting each other. More like two incredibly strong magnets hitting each other in midair.
I'm in dire need of good news, so help me see it in an optimistic lens: can you imagine a path (even very indirect) where this kind of discovery ends up having a practical use that makes real life better here on Earth ?
(I'm not in the age-old debate about "is research useful ?" - I agree the answer is yes ; I just have a failure of imagination that prevents me from answer the question "how is this research going to be useful in the long run ?")
Just an amateur interested person here, but I think there is something very positive about these developments. There are probably more, that experts can chime in on, but one I know about is that gravitational waves can give us a signal of what happened when the universe came into existence. The cosmic microwave background radiation (CMB) is a similar thing with photons - it is a signal from the earliest photons to be emitted after the Big Bang / inflation. But the universe was opaque to photons for the first 300000 or so years. Even so cosmological theories have been confirmed and falsified based on this data. But gravitational waves are signals that originated right from the start, and are not blocked by anything unlike photons, and so likely give us much clearer information on the state of the universe when it was created. This might make new insights in fundamental physics possible (quantum mechanics, relativity).
This overlaps with the fascinating topic of multi-messenger astronomy: observing an event using photons, neutrinos, and now: gravitational waves, leading to triple-messenger astronomy, leading to (hand waves) more insights than.. otherwise.
How this might make real life better ln earth: that is a gamble, but progress in fundamental physics has frequently made life better on earth.
I wish you All the best in feeling better about the world.
> "how is this research going to be useful in the long run ?"
We don't know.
However, black holes are close to the limit of our scientific knowledge. We don't know what happens on the other side of an event horizon (and we may never know, at least not experimentally). Learning more about them means learning more about the universe, and every once in a while we make a breakthrough that leapfrogs our technology. There's nothing else that we can do with so much potential.
Most of the time though, the progress is quite 'boring', at least if you are not in a related field.
>practical< usefulness of this type of research isn't results per se - but methods of getting to them
LIGO needs extremely precise lasers, stationary platforms, extreme positioning precision, tons of supporting software - even if things "exist", the _need_ for results provide advances and improvements
astronomy itself already gave us cmos sensors (aka digital cameras) - but using your phone camera doesn't really make you think "this is caused by distance measurement to the stars"
> but using your phone camera doesn't really make you think "this is caused by distance measurement to the stars"
Maybe it should!
There's so many technologies that we use today that derive from astronomy, space exploration and similar. We don't do a good job making that point to folks.
Most rich civilization, to show off how great they are, have built monuments. Basically saying, look we are so rich we can redirect a big part of our society's productivity to building a magnificent piece of art. Notice, how the ancient Egyptians are remembered thousands of years later.
You should think of some research in similar ways. This is us saying, look how rich and powerful we are, we can devote a significant part of our society's productivity on discovering the very essence of this universe with no practical benefit to us. Detecting blackhole mergers is an intellectual monument.
Readit News
Does this mean that 15 solar masses were converted into energy? Because that's a LOT of energy.
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
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.
[1] https://mastodon.social/@badastro/114852139083587160
[2] https://badastronomy.beehiiv.com/p/the-biggest-black-hole-me...
I'm not sure what happens in black hole merger.. is it an annihilation like event or is just fusion...
(Just planning my next trip.)
I don't think much else would escape the black hole environment.
"The black holes appear to be spinning very rapidly—near the limit allowed by Einstein's theory of general relativity," explains Charlie Hoy of the University of Portsmouth and a member of the LVK. "That makes the signal difficult to model and interpret. It's an excellent case study for pushing forward the development of our theoretical tools."
https://www.science.org/content/article/trump-s-proposed-cut...
https://appropriations.house.gov/sites/evo-subsites/republic...
Then again, your file has less drastic reductions on nsf budget so who knows what would be the impact on ligo
Interesting that they break this news today. Props to them for playing the game.
There were also moments dedicated to interviewing a science communicator and the director of the virgo center, and he was, let's say, quite angry at the thought of ligo losing funding. Rightfully so
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But my physics intuition tells me that as two of them merge, the resulting BH should have a "peanut" shape, at least initially.
And maybe it can keep having an irregular shape, depending on the mass distribution inside it?
https://en.wikipedia.org/wiki/Kerr_metric
https://arxiv.org/pdf/0706.0622
https://en.wikipedia.org/wiki/Ergosphere
https://en.wikipedia.org/wiki/Cauchy_horizon
Edit: Updated the bit about about horizons as I research a bit more. It's complicated, and I'm still not positive I have it exactly right, but I think it's now as good as I can get it.
It’s wild how much happens in those milliseconds though. Numerical relativity papers like the one you shared from arxiv.org show the horizon “sloshing” before it stabilizes.
https://youtu.be/1agm33iEAuo
From there, I haven't personally done or seen the calculations of the shape of the horizon for Kerr or merging black holes, but my intuition is that it would be indeed peanut shaped for a merger (there are likely some saddle points). The coordinate shape certainly is but you can choose coordinates so that a Schwarzschild black hole is a coordinate peanut so coordinates aren't very meaningful.
I think so?
https://archive.ph/VrzwW
Edit: "The Kerr metric also predicts the existence of an inner and outer event horizon, with the shape of these horizons being oblate rather than perfectly spherical due to the rotation."
In almost all situations it does matter as the collapsing star will behave as it is a black hole. But for the merge of black holes it is significant as it allows to release energy as there is no event horizon.
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Because nothing can ever leave the event horizon black holes are essentially perfectly sticky.
If Hawking radiation turns out to be non existent, yes.
Also, we don't know if it's possible to 'crack' open a black hole. If anything, another black hole might be the perfect instrument for doing this.
Would they still fully merge, or might you get a mass exchange between them? Or even a smaller black hole spun off?
Black Hole brand adhesive: when you absolutely, positively need something stuck down for eternity.
When we imagine flying "at nearly the speed of light" towards something thats traveling the same speed towards you, we tend to imagine a collision at high speeds.
But for blackholes that turn space into time and time into space, they can see the other blackhole slowing to a complete stop as its about to touch. Or it can look differently, it all depends on the position and speed of an observer.
We cant even agree on the basics like: "It doesnt matter how it looks, but they must collide", since if we look at something falling into a blackhole (which I pressume could be another blackhole just as well), we see it slow towards 0 at the edge and fade away in redshift instead of seeing it actually fall trough.
Its just all very weird and unintuitive stuff.
So black holes cannot approach each other faster than the speed of light. And if their trajectories intersect perfectly, they won’t be able to escape each other’s gravity.
A black hole can’t pass “through” another black hole like two bullets hitting each other. More like two incredibly strong magnets hitting each other in midair.
(I'm not in the age-old debate about "is research useful ?" - I agree the answer is yes ; I just have a failure of imagination that prevents me from answer the question "how is this research going to be useful in the long run ?")
This overlaps with the fascinating topic of multi-messenger astronomy: observing an event using photons, neutrinos, and now: gravitational waves, leading to triple-messenger astronomy, leading to (hand waves) more insights than.. otherwise.
How this might make real life better ln earth: that is a gamble, but progress in fundamental physics has frequently made life better on earth.
I wish you All the best in feeling better about the world.
We don't know.
However, black holes are close to the limit of our scientific knowledge. We don't know what happens on the other side of an event horizon (and we may never know, at least not experimentally). Learning more about them means learning more about the universe, and every once in a while we make a breakthrough that leapfrogs our technology. There's nothing else that we can do with so much potential.
Most of the time though, the progress is quite 'boring', at least if you are not in a related field.
LIGO needs extremely precise lasers, stationary platforms, extreme positioning precision, tons of supporting software - even if things "exist", the _need_ for results provide advances and improvements
astronomy itself already gave us cmos sensors (aka digital cameras) - but using your phone camera doesn't really make you think "this is caused by distance measurement to the stars"
Maybe it should!
There's so many technologies that we use today that derive from astronomy, space exploration and similar. We don't do a good job making that point to folks.
You should think of some research in similar ways. This is us saying, look how rich and powerful we are, we can devote a significant part of our society's productivity on discovering the very essence of this universe with no practical benefit to us. Detecting blackhole mergers is an intellectual monument.