The numbers in the article suggest a violation of conservation of mass:
> Today, the LIGO Collaboration announced the detection of the most colossal black hole merger known to date, the final product of which appears to be a gigantic black hole more than 225 times the mass of the Sun.
> GW231123, first observed on November 23, 2023, seems to be an unprecedented beast of a black hole merger. Two enormous black holes—137 and 103 times the mass of the Sun—managed to keep it together despite their immense combined mass
Is the explanation here "225 is a nice round number, and 240 is technically 'more than' that", or "a lot of mass evaporates into other forms of energy when black holes merge", or "during a merge, it becomes possible for matter to escape an event horizon", or what?
OTOH whatever else may be outside the black holes near the merger and count towards their mass for astronomical purposes, such as accretion discs, should be much lighter weight than what's inside the event horizon.
The waves are actually made just to the outside of the event horizon.
Was my understanding wrong all along?
Time is halted inside the black hole, so the waves made inside it never show up. Static gravity does show up though, but changes do not.
How do we feel about this vis-a-vis action-at-a-distance?
The reason these waves are not generated from inside the black hole is that, to us, time stops there. For example these black hole mergers aren't actually merging, they are getting closer, and then they time dilate out of existence.
Why does it need to travel in waves at the speed of light? If one mass moves, a distant mass is unaffected until the information reaches it. That's the opposite of action at a distance.
Compare wikipedia:
> Under our modern understanding, the four fundamental interactions (gravity, electromagnetism, the strong interaction and the weak interaction) in all of physics are not described by action at a distance.
( https://en.wikipedia.org/wiki/Action_at_a_distance )
Or: https://en.wikipedia.org/wiki/Principle_of_locality
> This is an alternative to the concept of instantaneous, or "non-local" action at a distance.
> The idea is that for a cause at one point to have an effect at another point, something in the space between those points must mediate the action. To exert an influence, something, such as a wave or particle, must travel through the space between the two points, carrying the influence.
You'll note that "action at a distance" does in fact specifically mean that information travels faster than light!
But this understanding would seem to be incompatible with the idea that the mass inside a black hole can interact gravitationally with anything outside the black hole.
But here's something that might help: We'll use gravity for our example, and I'll be non-technical for ease of typing.
The gravitational force that leaves an object is constant and continuous, it never stops, and it never starts. It exists from before the beginning of time, and it will never stop. The only thing you can do with that force is move it. This is because it's impossible to destroy energy. If you move the mass (the energy actually if you want to be exact) then you have changed the location (but not the strength) of the gravitational force, and that CHANGE travels at the speed of light.
So the gravitational attraction of my hand has, right now, already reached the end of universe, out to infinity. When I move my hand, it sends a tiny gravitational wave that travels at the speed of light, indicating a change in where the force is.
So the gravity inside the black hole has already reached the end of the universe, when that matter starts to clump, a change in the location of the gravity is sent out saying "this gravity is now moving over here".
This is why it feels like it's moving faster than light - it's not, it's already there at the end of the universe.
This is also why the orbit of Mercury is different in relativity, the sun pulls on Mercury where it WAS in the orbit, not where it is (which would require faster than light travel). In Newtonian gravity it's instant (i.e. faster than light).
What part of your comment says something about gravity that is different from what I've already said about it?
How do you look at a quote stating explicitly that action at a distance is, by definition, instantaneous, and say "I'm not seeing where any of this requires faster than light travel"?
> So the gravitational attraction of my hand has, right now, already reached the end of universe, out to infinity.
And how has the gravitational attraction of your hand gone more than 200 light years from Earth?
I clicked to the Wikipedia article, I did not see this quote.
> And how has the gravitational attraction of your hand gone more than 200 light years from Earth?
My hand is made of mass collected on earth. Those atoms have been rearranged into the shape of my hand, but their gravity has existed since the beginning of the universe, just in difference shapes.
No need to go to that much effort; I pulled that quote in my comment.
>> This is an alternative to the concept of instantaneous, or "non-local" action at a distance.
> My hand is made of mass collected on earth. Those atoms have been rearranged into the shape of my hand, but their gravity has existed since the beginning of the universe, just in difference shapes.
So, as you acknowledge, zero information about your hand has gone much distance from the earth. Someone 1000 light years away who could resolve gravitational information into an image with perfect detail wouldn't be able to perceive your hand, you, or anything related.
Because gravity isn't a non-local force.
Notice the word "alternative", instantaneous action at a distance is a concept that was suggested at one point in the development of physics and discarded once relativity was figured out. Action at a distance these days is always at the speed of light.
> So, as you acknowledge, zero information about your hand has gone much distance from the earth.
No, not zero. All the gravity from the atoms in my hand is already out there.
> Someone 1000 light years away who could resolve gravitational information into an image with perfect detail wouldn't be able to perceive your hand, you, or anything related.
Correct, they would see the location of the atoms that make up my hand today, as those atoms looked 1000 years ago. (Probably in plants, and water.)
But remember: They do see the gravity from those atoms!!! Meaning the gravitational force my hand exerts, already exists 1000 years away, just in a different shape.
> Because gravity isn't a non-local force.
Are you saying gravity is a local force? Because that's not true.
https://en.wikipedia.org/wiki/List_of_most_massive_stars lists only 2 stars more massive than that
These aren't points; they are (literally) opaque volumes of space, and once their outer limits broach, they have collided.
By analogy, two warships can collide, even though their centers of mass don't.
But there is no matter at an event horizon. That's just an imaginary line in space. It's opaque, but not solid.
If the black holes were moving fast enough, it should be possible for their event horizons to cross and then uncross, although that would immediately raise the question of what would happen to matter in the zone of overlap. Perhaps "fast enough" would exceed the speed of light?
First define what you mean by "colliding".
By analogy, I'm defining it as the Event Horizons intersecting, at which point nothing in side "either" black hole has any physical meaning to us ever again. For all we know, the insides could be chocolate ice cream on one half of the now-double-sized Event Horizon, and pure neutronium on the other. It's meaningless to even pretend we know anything about that volume.
An event horizon has no mass or other existence and cannot collide with anything. Within the black hole, there is mass somewhere, but generally not at the event horizon. If you're not comfortable assuming that, we can make it a definition - take this to be an example where none of the internal mass lies within the region of overlap.
What is the obstacle to the black holes separating again?
No, that is not possible.
Also most black holes have matter on the event horizon, because something fell on them. Maybe it can even touch, because this matter is frozen slightly above even horizon.
I don't see a way to read your comment that allows for the possibility that a black hole might move, which is something they do.
I'm riiiiiiight on the edge of concluding that you are a poet and the only thing you know about the words is the way they sound. Is there more to it than that?
How black holes can move is an interesting question, but as you can see, in reality there are no infinities, since stuff slows down before that. Maybe infinities could exist for an observer inside black hole, but an observer outside of black hole sees only large slow down.
https://www.popularmechanics.com/space/deep-space/a65038572/...
... and give it a go: "Yo mama is so big she can't even collide with a black hole" (or something ...)
Or do we just call it a collision if they simply get as close to each other as to be within the event horizon of the other?
If the former and we see these true collisions, how is it not a proof the age of the universe is infinite ? If we see events that are supposed to take infinitely long to occur?
So the merger definitely happens from the point of view of the black holes. We might observe odd artifacts but they would eventually fade away.
Photons travel at the speed of light always, that's what Einstein told us.
So rather, the observed energy (frequency) of the photons decreases, and it takes longer between each photon.
At least that's my understanding.
https://en.wikipedia.org/wiki/List_of_most_massive_stars
Then again, the universe is really big and to paraphrase Pratchett, million-to-one chances happen nine times out of ten.
https://en.wikipedia.org/wiki/Phoenix_Cluster#Supermassive_b...
"Such a high mass may place it into a proposed category of stupendously large black holes (SLABs), black holes that may have been seeded by primordial black holes with masses that may reach 100 billion M or more, larger than the upper maximum limit for at least luminous accreting black holes hosted by disc galaxies of about 50 billion M[12]"
(which comes from a paper from one of my old lecturers).
If we accept that primordial black holes do indeed exist (the evidence against, is, I believe that they should be evaporating about now, but are as yet unobserved), there must therefore be a weight distribution of those, which means there are probably other 'solar mass' 'seeded' black holes lurking, that were never created by stellar collapse.
Black holes only become destructive/powerful when you are very close to them.
To elaborate: A black hole is mass, a sun is mass. From a distance there's no difference. The only difference is up close - you can get a lot closer to a black hole dramatically increasing the gravitational force.
But from a distance? Nothing special.
In a shrinking univers, they absolutely would. (But neither of these things would necessarily have already happened.)
In an expanding universe, some things will eventually so far away from black holes that they won't get "eaten". Also, they won't see them anymore, nor most of the rest of the universe.
That third option is, to our best knowledge, the one we live in.
An interesting implication is that, if intelligent life evolves several billion years from now in any given galaxy, it's galaxy might be so far away from its nearest neighbors that light from them will never reach it. That civilization's Hubble will never be able to test their crazy theory that "there could be more than one galaxy in the universe".
The wave moves your entire body, and the ground, all at the same time. You would not notice anything because it all moves together.
OK, not at exactly the same time - but you need specialized equipment to detect it, AKA the machines in the article. A person would not notice even a strong wave.
After digging around, the masses of these Black Holes are in the forbidden zone, where there shouldn't really be Black Holes of that size because of how they are formed.
They are usually either bigger or smaller depending on their origin. They could be second or third generation Black Holes, which would be unlikely due to the probability of them forming in close neighborhood. So what their reason for existing there are questions that should lead to some interesting answers if we ever get to the bottom of it.
So maybe both of these black holes formed from earlier mergers of smaller black holes. Or maybe there are other ways to make larger black holes we don't know about. They are in a range of mass we don't really expect to see theoretically.
Black hole merger challenges our understanding of black hole formation
The black hole is happening. So it exists. So either the observations are wrong or the undeying assumptions are wrong or math / physics we are using to make sense of the event is wrong.
Click-bait articles serve no purpose in advancing science.