[HN Gopher] LIGO detects most massive black hole merger to date
___________________________________________________________________
LIGO detects most massive black hole merger to date
Author : Eduard
Score : 351 points
Date : 2025-07-14 20:06 UTC (1 days ago)
(HTM) web link (www.caltech.edu)
(TXT) w3m dump (www.caltech.edu)
| perdomon wrote:
| What happens when black holes collide? Does one black hole
| "consume" the other? Do they become a larger black hole? Does it
| get more dense or just larger?
| chasil wrote:
| What happens inside cannot be known.
|
| As I understand it, black holes are defined by three
| quantities: mass, spin, and charge.
|
| I'm assuming that these quantities will be additive post-
| merger.
|
| Edit: "The black holes appear to be spinning very rapidly--near
| the limit allowed by Einstein's theory of general relativity."
|
| Perhaps the additive spin becomes asymptotic. Alternately, the
| gravitational waves might have departed with the energy of the
| excess spin.
| jameskilton wrote:
| My basic understanding is that they combine, basically you just
| add the masses together. That increased mass then means more
| gravity, so the event horizon is pushed further out.
| __MatrixMan__ wrote:
| They become a more massive one. The volume of a black hole
| (assuming you're measuring at the event horizon) is determined
| only by its mass, so the final density is the same as you'd get
| for any other black hole of that mass regardless of how it came
| to be.
|
| I don't know how to address the "consume" question. If you were
| pulling on a piece of fabric and two tears in it grew until
| they met each other to become one tear... would you say that
| the larger one consumed the smaller?
| a012 wrote:
| I think the GP meant "merge"
| dataflow wrote:
| > The volume of a black hole (assuming you're measuring at
| the event horizon) is determined only by its mass, so the
| final density is the same as you'd get for any other black
| hole of that mass regardless of how it came to be.
|
| Wait, really? So if you had a super massive disk that was
| just 1 electron away from having enough mass to become a
| black hole... and then an electron popped into existence due
| to quantum randomness... then it would become a sphere
| instantly? Wouldn't that violate the speed of light or
| something?
| gus_massa wrote:
| It's the https://en.wikipedia.org/wiki/No-hair_theorem ,
| but it only applies after a while, not instantly.
|
| Your disk will emit a lot of gravitational on
| electromagnetic radiation, and after a while it will be a
| nice sphere. (Unless it's rotating and it will be a nice
| somewhat-elipsoidal ball.)
|
| ---
|
| > _and then an electron popped into existence due to
| quantum randomness_
|
| I feel there is a huge can of worms of technical problems
| in this sentence that nobody know how to solve for now.
| Just in case replace the quantum randomness with a moron
| with a broken CRT used as an electron cannon.
| ars wrote:
| > and after a while it will be a nice sphere
|
| Time doesn't exist for black holes, so "after a while" is
| not something you can say about them.
| gus_massa wrote:
| Simulations linked in others comment:
|
| https://www.youtube.com/watch?v=Tr1zDVbSjTM
|
| https://www.youtube.com/watch?v=1agm33iEAuo
| ars wrote:
| The second one is much more correct, notice how it
| freezes before they actually merge because they time
| dilate out to infinity.
| gus_massa wrote:
| If they actually froze just before the merge, they will
| be peanut shaped like in the video.
|
| I'm not sure if we can measure the shape of black holes,
| but I'm sure everyone think they are spheres with a
| slight deformation due to rotation.
| gus_massa wrote:
| The algorithm choose this for me
| https://www.youtube.com/watch?v=fKgQYOlpxmo
| addaon wrote:
| > then it would become a sphere instantly
|
| Event horizons are non-physical. Better to think of it as
| "then a spherical event horizon would become apparent."
| When the mass within a given black-hole-shaped volume
| (spherical for non-rotating mass) is "one electron short"
| of being a black hole, then one can define a surface in the
| shape of the (future) black hole where the escape velocity
| is /just/ below the speed of light. In practice, all light
| emitted within that volume will already be captured by the
| mass, unless it's perfectly perpendicular to the (future)
| event horizon. When that extra electron is added, it
| becomes true that the escape velocity at that same surface
| is now the speed of light -- the definition of event
| horizon. But nothing needs to "form" to make this true.
| ars wrote:
| That electron would take an infinite amount of time to
| reach the edge, since time dilates to infinity with gravity
| that strong.
|
| > a sphere instantly
|
| The concept of instantly doesn't work with time dilation
| like this. What you see will be different depending on if
| you are also falling in, or if you are far away.
| __MatrixMan__ wrote:
| Long before your disc neared the mass where it would form
| an event horizon, the matter it's made of would collapse
| into neutron star material, which would form a sphere.
|
| Perhaps if it were exceptionally wide the whole disc
| wouldn't collapse. Maybe only the parts near it's center.
| In that case you'd end up with a large ring around a
| neutron star. Add a bit more mass and maybe it's now a ring
| around a black hole. The gravity of the ring might distort
| the event horizon in some way, I'm not sure quite how, but
| probably its possible to get a non-spherical hole in
| situations where the objects distorting the shape are still
| in the universe.
|
| But as for the matter lost into the hole, it's gone. If the
| hole were to retain some shape based on what's "inside" of
| it, that would be the kind of information leak that the
| laws of physics do not permit.
| magicalhippo wrote:
| The analogy I like goes something like this. Imagine you're
| paddling in a canoe on the river. You approach a waterfall.
| If you do nothing you'll get consumed by the waterfall. So
| you try to paddle away from the waterfall, but as you get
| closer to the edge of the waterfall, the current gets
| stronger.
|
| The event horizon is the imaginary line across the river
| which once passed, even if you paddle as quickly as you
| can, you won't be able to get away from the waterfall. Once
| you pass that line, you're bound to reach the waterfall
| eventually.
|
| Now, thanks to Maxwell and Einstein, we know there's a
| maximum speed that anyone can paddle, the speed of light,
| and so we define the event horizon to be relative to this
| speed.
|
| You can calculate the event horizon for just about
| anything. The main difference between a black hole and
| everything else, is that for a black hole the event horizon
| is larger than the object itself.
|
| For example, the event horizon of a neutron star with a
| mass of 1.4 solar masses and a radius of 10km is about 4.1
| km, well inside the neutron star. Thus you don't get the
| "black hole effect", since once you pass the surface of the
| neutron star the matter above you pulls you away from the
| center.
|
| The river analogy is actually not far off what they try to
| use as an analog for testing black hole predictions,
| effectively a large water tank with a drain hole. Sixty
| Symbols did a video on this way back[1], and this thesis[2]
| goes into the details. Some are going beyond water using
| liquid helium to simulate quantum black holes this way[3].
|
| [1]: https://www.youtube.com/watch?v=kOnoYQchHFw
|
| [2]: https://arxiv.org/abs/2009.02133
|
| [3]: https://pirsa.org/25010083
| gus_massa wrote:
| > _the "consume" question_
|
| My guess is that in some popular depictions black holes are
| like holes, and things fall in the holes, and even a small
| black hole can possible fall inside a bigger hole.
|
| A better image is too drops of water on a glass, add some
| black ink for bonus realism. They merge into a bigger drop.
| Except, obviously black holes are not filled with water. And
| the " _average density_ " of the new black hole is smaller
| then the " _average density_ " of both original black holes,
| unlike the density of water drops on a glass. So don't take
| this image too literaly.
|
| (There are some problems to define the "density" of a black
| hole, but let's ignore all of them.)
| hnuser123456 wrote:
| They become a larger black hole, mostly conserving mass, minus
| a few percent to gravitational waves. However, their mass is
| proportional to their radius, not volume, so it gets LESS
| dense. If you laid out a bunch of black holes in a line, just
| barely not touching, and let them merge, suddenly, the whole
| sphere of space enclosing the line becomes black hole. It also
| turns out that a black hole with the mass of the universe would
| have a volume about the size of the universe.
| JumpCrisscross wrote:
| > _turns out that a black hole with the mass of the universe
| would have a volume about the size of the universe_
|
| Mass and energy.
| gjm11 wrote:
| Is that intended to be a correction? (I don't think the
| original statement needs correcting, other than by
| replacing "universe" with "observable universe" in both
| places.)
| hnuser123456 wrote:
| Up until the universe was around a few billion years old,
| its Schwarzchild radius would have been larger than even
| the co-moving (not just observable) universe's radius,
| but the initial momentum from the big bang was high
| enough to prevent collapse.
| AnimalMuppet wrote:
| That sounds suspiciously like "they were inside a region
| with enough mass to form an event horizon, but they
| escaped because they had enough momentum", which in turn
| sounds like "we can escape from inside an event horizon
| if we just move fast enough". Can you explain how that's
| _not_ what you 're saying?
| hnuser123456 wrote:
| I wish I had a straightforward answer to that. I'm sure
| the answer is some combination of cosmic inflation and
| dark energy, but by all means it appears the early
| universe either narrowly escaped, or simply is a black
| hole, that singularities are a flawed concept, that
| nothing is escaping the universe, and we are all stuck
| moving forward in time, and that the infinite future is
| the singularity.
| AnimalMuppet wrote:
| I don't have an answer either. But in my amateur opinion,
| of the available options, I lean toward "is a black
| hole". If all the mass we can see adds up to a black hole
| the size of what we can seen, then if you add all the
| stuff outside the light cone, it should add up to enough
| mass to make a black hole radius that includes the
| distance out to there.
|
| But that leaves us with black holes forming inside a
| black hole, which I have absolutely no idea what to do
| with.
| jMyles wrote:
| Is that true though?
|
| Can't we generalize to say that we observe that black
| holes have a similar density (which is to say, proportion
| of mass to volume) any sample of the observable universe
| sufficiently large as to be roughly uniform?
|
| In other words, doesn't this observation scale both down
| (to parts of the universe) and up (beyond the
| cosmological horizon, presuming that the rough uniformity
| in density persists), at least for any universe measured
| in euclidian terms?
|
| It's very possible that I'm wrong here, and I'd love to
| be corrected.
|
| ...I also think we have to acknowledge that "similarly"
| is doing a fair bit of work here, as we're not accounting
| for rate of expansion - is that correct?
| JumpCrisscross wrote:
| Mass alone doesn't do it. You need energy, namely the
| CMB, to push the observable universe close to its
| Schwarzschild limits.
| gjm11 wrote:
| Ohh, I see, you mean "mass" should have been "mass and
| energy" rather than e.g. that (mass,volume) should have
| been replaced by (mass,energy) or something.
|
| I confess I just ... take it for granted in this kind of
| context that "mass" or "energy" or "mass+energy" all mean
| the same thing. Someone who wants to refer just to the
| total amount of _matter_ will say something like "the
| total mass of the matter in the universe".
|
| It's commonplace for physicists to write just "mass" when
| talking about this sort of thing. E.g.,
|
| P T Landsberg, "Mass scales and the cosmological
| coincidences", _Annalen der Physik_ , https://onlinelibra
| ry.wiley.com/doi/10.1002/andp.19844960203:
|
| "Theories involving the parameters h, c, G, H (in a usual
| notation) are considered. A huge ratio of 10^120 of the
| mass of the universe (m_u) to the smallest determinable
| mass m_0 in the period since the big bang occurs in such
| theories."
|
| (Not cherry-picked; I went to the Wikipedia article on
| "Black hole cosmology", noted that it just says "mass"
| rather than "mass-energy" or whatever, and followed the
| link in the attached footnote. Also, so far as I know,
| not crankery; Landsberg was an eminent physicist.)
| itronitron wrote:
| >> just barely not touching
|
| Which part of them is barely not touching?
| gjm11 wrote:
| The event horizons.
| dylan604 wrote:
| In cosmological terms, what is barely not touching? Is that
| distance measured in meters, kilometers, AUs, lightyears,
| parsecs?
| hnuser123456 wrote:
| In terms of creating a row of black holes where the space
| between each black hole is small relative to the size of
| the event horizon of each.
| hnuser123456 wrote:
| Maybe I should've linked my toy simulator in my initial
| comment.
|
| https://cybersystems.dev/gtc/gtc.html
| onestay42 wrote:
| BTW, the php in /chat2 seems to be broken, if you didn't
| know already. Great simulation, too.
| hnuser123456 wrote:
| Thanks, I was kinda curious why it wasn't full of spam.
| it's running on a super neglected rpi, really need to
| wipe it and spend a month refreshing myself on basic
| webhosting stuff
| marcosdumay wrote:
| The events horizon.
|
| Or in other words, black holes mergers conserve their total
| radius, not volume as one would get with normal matter.
| pantalaimon wrote:
| > minus a few percent to gravitational waves
|
| They actually convert up to 42% of their mass into energy,
| mostly radiation
|
| https://youtu.be/t-O-Qdh7VvQ
| foota wrote:
| I think this is over their lifetime, not when they merge?
| hnuser123456 wrote:
| For normal matter inspiraling, yes, but a black hole which
| is falling into a black hole doesn't get to glow in gamma
| rays to try to escape :) they can only lose mass/energy by
| making splashes in spacetime itself (or hawking radiation)
| ars wrote:
| My understanding is they just spiral into each other forever.
|
| From our point of view nothing can actually fall into a black
| hole, instead it time dilates into nothing. "It is true that
| objects that encounter the event horizon of a black hole would
| appear "frozen" in time"[1]
|
| So we would never actually see the black holes merge. In fact
| I'm not clear how a black hole can even form in the first
| place, since it would take an infinite amount of time to do so
| (again, from our POV).
|
| (And yes, I know that from the POV of the falling object, they
| just fall in like normal. But that doesn't help us, because
| we'll never see it.)
|
| [1] https://public.nrao.edu/ask/does-an-observer-see-objects-
| fro...
| ajross wrote:
| This is true, but it's not an observable distinction. It's
| true that in some sense those two black holes "haven't yet
| collided", but at this point they're well past the point of
| last observability and have now red shifted and time dilated
| into the invisible background. All the interesting stuff
| happens before that.
| cloudrkt wrote:
| I wonder how the singularities would merge with each other.
| Enginerrrd wrote:
| We can't REALLY answer questions about what's inside the event
| horizon, but some real work has been done on what BH mergers
| look like, though even that as I understand, is extremely
| difficult model.
|
| https://m.youtube.com/watch?v=5AkT4bPk-00
| TechDebtDevin wrote:
| What are the waves of gradient colors, gravity?
| 20k wrote:
| I'd guess its the weyl scalar w4, which is generally used
| to extract gravitational waves
| 20k wrote:
| These kinds of simulations inherently cannot model the
| singularity accurately whatsoever. At the singularity, the
| numerical technique used becomes knowingly invalid
|
| In fact, the entire interior of the event horizon is actually
| physically invalid in these simulations. The formalisms used
| _trap_ the errors inside the event horizon, as the errors
| turn out to be strictly causal. And because of that,
| _theoretically_ they can 't escape
|
| Of course that analysis breaks down in the face of
| discretisation, so errors tend to leak out a bit under low
| resolutions, so you have to handle things pretty careful.
| Either way, you shouldn't draw any conclusions about the
| interior
|
| Source: I've done a lot of these simulations
| MattPalmer1086 wrote:
| I wonder what would happen if one black hole shot through another
| one at high relativistic velocity, instead of spiralling towards
| one another.
| fsmv wrote:
| They would merge and produce a black hole with the sum of their
| momentums
|
| Because nothing can ever leave the event horizon black holes
| are essentially perfectly sticky.
| mkw5053 wrote:
| 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?
| mkw5053 wrote:
| I think I'm going to answer my own question by saying both
| momentum and energy are conserved. The momentum of the
| entire system was zero before and after the collision.
| Energy must also be conserved, and since the final object
| is at rest, all the kinetic energy gets converted into rest
| mass energy, minus what is radiated away as gravitational
| waves.
| photon_lines wrote:
| Correct. If you're curious about the 'essence' of what
| black holes are I actually just did a write-up on them
| which you can find here:
| https://photonlines.substack.com/p/an-intuitive-guide-to-
| bla...
| lkuty wrote:
| Thanks. Little typo "Let's inflate Earth once again to
| its regular size and see what impact placing a 10 kg
| weight on it has." Should be 1kg.
| alex-robbins wrote:
| I'm not a physicist, but I took a class on special
| relativity in college, and I still remember some of it
| ... If I'm remembering it right, we still have
| conservation of momentum and energy in special
| relativity, with the caveat that these are defined
| differently than in classical mechanics. Specifically, E
| = gmc^2 and p = mvg, where g = 1 / sqrt(1 - v^2/c^2) and
| m is the invariant mass (aka the "rest mass"). [1] Note
| that when v=0 (so g=1), this equation for momentum is the
| same as the classical p=mv, which is generally a good
| approximation when v << c.
|
| So, using those relativistic definitions for energy and
| momentum, I think you're exactly right, at least up to
| the part about "since the final object is at rest".
| However:
|
| - As I understand it, invariant mass, aka "rest mass"
| (which is equivalent to "rest energy", aka "rest mass
| energy"), is invariant, and it's the same before and
| after the collision, so the kinetic energy doesn't get
| "converted into rest mass energy". Rather, if the final
| object is at rest, then all of its kinetic energy has
| been radiated away; kinetic energy (E_K) is is total
| energy (E) minus rest energy (E_0 = mc^2, where m is
| invariant mass)
|
| - I have no idea whether gravitational waves are the
| _only_ way for the kinetic energy to be radiated away. I
| imagine other forms of energy could also be emitted.
|
| - In order to know that the final object is at rest/has
| no kinetic energy (in an inertial frame), I worry that we
| might need to have specified more in the original
| question. In particular, I don't know how to handle spin.
| (I know that black holes have some concept of "spin", but
| I don't know if this is like rotational spin, or more
| like quantum mechanical spin, or something else, and I
| don't know how it figures into the black holes' total
| energy.) If we change the original question to say that
| the black holes are not spinning, then I think we can
| ignore this (since the collision is head-on).
|
| [1]: https://en.wikipedia.org/wiki/Mass_in_special_relati
| vity#Rel...
|
| To reiterate, I'm not a physicist. I may be off base
| here, but that's my understanding.
| hnuser123456 wrote:
| My hunch is they would briefly pancake and much of the
| mass/energy contribution from their initial velocities
| would dissipate as incredibly high amplitude gravitational
| waves from the ring-down.
| dkural wrote:
| It would create a universe, obviously. First all the mass
| would attempt being squished at a singularity. WHILE the
| squishing continues, the first-in-line stuff would've
| already started to explode back-out inside the event
| horizon. From the inside viewpoint, this looks like the big
| bang. Once all the mass from the two black holes collide
| and loose momentum, the inside-universe no longer expands
| as fast. Things wobble a bit as all this happens, creating
| tangles and non-homogeneity. Could be caused by initial
| Planck-scale uncertainties even when having a perfect head-
| on collision.
| photon_lines wrote:
| Energy and momentum are always conserved in EVERY physical
| process. We can distinguish three types of collisions:
| "sticky" ones, in which the kinetic energy decreases
| (typically, it is converted into heat); "explosive" ones,
| where the kinetic energy increases; and elastic ones, in
| which the kinetic energy is conserved. Since the total
| energy (rest plus kinetic) is always conserved, it follows
| that rest energy (and hence also mass) increases in a
| sticky collision, decreases in an explosive collision, and
| is unchanged in an elastic collision. The resulting black
| hole in other words would have way more of a mass than 2M
| since you're talking about a 'sticky' collision in the
| above instance. You can see an example of why this is in
| Griffiths' text (Introduction to Elementary Particles
| (which I highly recommend)) -- page 101 contains a great
| example of what happens to the mass of particles in
| 'sticky' collisions: https://www.hlevkin.com/hlevkin/90Math
| PhysBioBooks/Physics/Q...
| dataflow wrote:
| > Energy and momentum are always conserved in EVERY
| physical process.
|
| Veritasium recently claimed otherwise
| https://www.youtube.com/watch?v=lcjdwSY2AzM
| r0uv3n wrote:
| That is about something entirely different. It more or
| less just says that energy might be lost if you have a
| flux towards infinity. It does not in any way claim e.g.
| that the divergence of the stress energy tensor is non-
| zero (which would be how I think most people would
| interpret energy/momentum conservation).
| lorenzohess wrote:
| They would cancel each other out and disappear, like a
| snake eating its own tail.
| fooker wrote:
| > 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.
| im3w1l wrote:
| When you say cracking open a black hole do you mean
| cracking the event horizon to form a naked singularity?
| fooker wrote:
| The answer would likely be worth a Nobel prize or two.
| fishsticks89 wrote:
| Hawking radiation occurs because black holes are sticky !!
| fooker wrote:
| Huh nice analogy
| labster wrote:
| > black holes are essentially perfectly sticky
|
| Black Hole brand adhesive: when you absolutely, positively
| need something stuck down for eternity.
| MattPalmer1086 wrote:
| What if the collision was only a grazing one, not head on?
|
| Would they still fully merge, or might you get a mass
| exchange between them? Or even a smaller black hole spun off?
| MattPalmer1086 wrote:
| To answer my own question, some lay research shows it seems
| it is technically possible for them not to merge if only a
| tiny portion of their apparent event horizons merge and for
| only very briefly.
|
| But this is because of a distinction between the Apparent
| Horizon [1] (which is coordinate-dependent) and the true
| global event horizon. So they appear to briefly merge but
| no true global event horizon forms to encompass both. I
| think!
|
| [1] https://physics.stackexchange.com/questions/38721/what-
| is-th...
| snowwrestler wrote:
| 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.
| MaxikCZ wrote:
| 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.
|
| Its just all very weird and unintuitive stuff.
| veunes wrote:
| Too bad we can't set up a cosmic particle accelerator to test
| this!
| ChrisArchitect wrote:
| [dupe] https://news.ycombinator.com/item?id=44555220
| mnemonk wrote:
| 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."
| veunes wrote:
| It's like nature handed us a stress test for general relativity
| amelius wrote:
| Does the spinning of a spherical object cause any gravitational
| waves?
| NL807 wrote:
| 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.
| WrongOnInternet wrote:
| > 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.
| andrepd wrote:
| 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.
| cgdl wrote:
| Do we know how far this event was from earth? Wouldn't that
| distance be the determiner of what the relative contraction
| observed on earth would be?
| sgustard wrote:
| estimated distance of 2.2 Gpc per
| https://en.wikipedia.org/wiki/GW231123
| irjustin wrote:
| That's how fast the millennium falcon goes
| BurningFrog wrote:
| That's 7.2 billion light years. More than halfway to the
| most distant galaxy the Webb telescope has found.
|
| So this event happened 7.2 billion years ago.
|
| There is no mention of in which direction. Maybe the
| triangulation wasn't working at the time. You need three
| LIGOs for that.
| UltraSane wrote:
| At 10 times the Schwarzschild radius Space literally
| stretches and contracts by 10-100%
| ssl232 wrote:
| 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).
| misja111 wrote:
| Sure but we are 7 billion lightyears away from the source of
| the waves. Imagine if we'd be a bit closer ..
| UltraSane wrote:
| Yes. Black hole mergers are the highest energy events in the
| universe in terms of watts.
| aaronharnly wrote:
| 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
| vjvjvjvjghv wrote:
| 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.
| aaronharnly wrote:
| 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.
| mytailorisrich wrote:
| 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.
| aaronharnly wrote:
| I appreciate this point - it would take quite a few Tsar
| Bombas to approach the binding energy of a planet.
| bravesoul2 wrote:
| 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.
| mr_toad wrote:
| 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.
| thechao wrote:
| All the stars in the universe, burning as brightly as
| they are, are the tiniest fraction of additional energy
| compared to the 2.73degK background temperature of space.
| The Big Bang was very warm.
| ordu wrote:
| 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
| ithkuil wrote:
| Space is big and quadratic function grows fast
| scrollop wrote:
| But, is it a small or large hydrogen bomb? And, what
| distance from your eyeball?
| vjvjvjvjghv wrote:
| I'll run some tests and let you know
| dredmorbius wrote:
| 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.
| spuz wrote:
| 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.
| aaronharnly wrote:
| Derp yes, pesky off-by-100 errors :) Fixed, thanks.
| lxe wrote:
| Is it physically limiting for a theoretical civilization to
| harness and use such energy?
| Thiez wrote:
| 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.
| ChuckMcM wrote:
| 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...
| 9991 wrote:
| In the visible universe. The universe may well be infinite.
| twothreeone wrote:
| Observable universe. Dark matter does not emit light.
| anton-c wrote:
| 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.
| jerf wrote:
| 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.
| dredmorbius wrote:
| 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.
| dtgriscom wrote:
| You mean "every single _star_ in the universe ", right?
| randomtoast wrote:
| > 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.
| dd_xplore wrote:
| 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...
| simonh wrote:
| 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.
| arbitrandomuser wrote:
| 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 ?
| deepsun wrote:
| 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).
| steve_adams_86 wrote:
| 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.
| conradev wrote:
| 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
| hansulu wrote:
| 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.
|
| (Just planning my next trip.)
| pixl97 wrote:
| Much better off just chucking 90% of your mass into the
| blackhole to get a hella kick.
| tashmahalic wrote:
| Into what form of energy is that mass converted?
| BurningFrog wrote:
| Maybe all of it is gravitational waves?
|
| I don't think much else would escape the black hole
| environment.
| misja111 wrote:
| Kinetic energy is another option
| jajko wrote:
| Need a bit of oomph to move the very fabric of this
| universe a bit. But energy conversation laws say its just
| then spread all over the place across time, just like
| ripples in pond, suspended into nothingness of its own
| little universe... or something
|
| Tells me a bit darker thing in between the lines - the
| chance some advanced civilization (or us in far future if
| we actually survive) traveling FTL by bending space
| massively is next to zero, we would see (or detect soon)
| the evidence... unless they do it on planck-level of
| precision and self-contain all ripples. Nah, it really
| seems c is the ultimate barrier so far... depressing.
| mr_toad wrote:
| > Need a bit of oomph to move the very fabric of this
| universe a bit.
|
| It's enough "oomph" that we can detect it more than half
| way across the universe.
| csomar wrote:
| Pure energy.
| doikor wrote:
| Can some of the mass escape as gas/mass flying out into space?
| Basically is energy the only way for mass to exit such an
| event?
| Thiez wrote:
| 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.
| veunes wrote:
| It's hard to wrap your head around, but that's more energy than
| all the stars in the observable universe combined put out
| during that instant
| richardw wrote:
| 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.
| dd_xplore wrote:
| 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...
| BurningFrog wrote:
| I've always thought the event horizon for a black hole has to be
| spherical.
|
| 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?
| itishappy wrote:
| 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.
|
| 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.
| AnimalMuppet wrote:
| Could you (or anyone) tell what the radius of the ring
| singularity is, in terms of mass and angular momentum? I
| haven't been able to find that.
| itishappy wrote:
| The math seems to suggest R=a, or simply the spin in terms
| of length. It's certainly an oversimplification, as the
| answer will depend on the choice of metric.
|
| Here's the best resources I've been able to find on the
| question. Roy Kerr himself responded to the Quora question:
|
| > There is no Newtonian singularity at the Center of the
| earth and there is no singularity inside a rotating black
| hole. The ring singularity is imaginary. It only exists in
| my solution because it contains no actual matter. When a
| star collapses into a black hole it keeps shrinking until
| the centrifugal force stabilizes it. The event shell forms
| between the star and the outside. In 57 years no one has
| actually proved that a singularity forms inside, and that
| includes Penrose. instead, he proved that there is a light
| ray of finite affine length. This follows from the "hairy
| ball theorem".
|
| The stack overflow answer seems to describe the problem in
| terms I can better understand:
|
| > It seems unlikely to me that you're going to be able to
| formulate a notion of diameter that makes sense here.
| Putting aside all questions of the metric's misbehavior at
| the ring singularity, there is the question of what
| spacelike path you want to integrate along. For the notion
| of a diameter to make sense, there would have to be some
| preferred path. Outside the horizon of a Schwarzschild
| black hole, we have a preferred stationary observer at any
| given point, and therefore there is a preferred radial
| direction that is orthogonal to that observer's world-line.
| But this doesn't work here.
|
| https://physics.stackexchange.com/questions/471419/metric-
| di...
|
| https://www.quora.com/What-is-the-typical-diameter-
| roughly-o...
| CGMthrowaway wrote:
| Simulation: https://www.youtube.com/watch?v=Tr1zDVbSjTM
| theGnuMe wrote:
| Everything is a fluid in the end and at scale right??
| grues-dinner wrote:
| What kind of timeframe does that animation happen over?
| TMEHpodcast wrote:
| 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.
| pavel_lishin wrote:
| Is it even sensible to talk about a "mass distribution"
| inside of an event horizon?
| kadoban wrote:
| Sure, especially consider if singularities are not real.
| Then what's inside the event horizon is just some bunch
| of unknown material in some actual shape. Why wouldn't it
| be?
|
| If singularities are real...same thing but more boring
| answer maybe? (the distribution just being: in the
| center).
| lisper wrote:
| > Why wouldn't it be?
|
| Because the whole concept of "shape" assumes properties
| of space that might not apply inside an event horizon?
| db48x wrote:
| There's no reason to expect that the properties of space
| are different inside the event horizon than outside. Of
| course the direction of time turns sharply as you go
| inside, but otherwise space is just space.
|
| You only get an asymmetric black hole during the
| milliseconds of a merger. And that asymmetry is entirely
| due to the mass distribution inside the black hole. The
| black hole only becomes spherical again once the
| singularities have merged. Or in the more common case of
| rotating black holes, they only become properly oblate
| again once their ringularities have merged. Either way it
| happens quite quickly.
| lisper wrote:
| > the direction of time turns sharply as you go inside
|
| Yeah, that's what I meant. It's hard for me to reconcile
| the concepts of "the direction of time turns sharply"
| with "space is just space".
| fc417fc802 wrote:
| I am certainly no physicist but I remember coming across
| academic papers in the past speculating about exactly
| your question. I recall one theorized about singularities
| being hollow with all of the mass (err was it space?
| spacetime?) compacted down into 2 dimensions on a shell
| at the surface (at least IIUC, which I probably didn't).
|
| I think that concept might fit with the infinite time
| dilation preventing a merger from ever actually
| occurring? I'd be curious how that might differ for
| matter that's already inside when the critical mass is
| reached. (I'd also be curious to know all the creative
| and wacky ways in which I got the above completely wrong
| given that's just about inevitable.)
| db48x wrote:
| Mass curves space. All mass curves space all the time.
| You are bending the fabric of spacetime even now! Don't
| try to deny it!
|
| What does curvature mean? It means that the direction of
| time's arrow is different in different places. To an
| observer outside of a large gravitational field, events
| inside the field appear to move more slowly than they
| would have outside of it. Black holes merely take this to
| an extreme. To an observer far from a black hole, a clock
| entering the black hole appears to slow down and finally
| _stop_ as it crosses the event horizon1. But
| simultaneously an observer traveling with the clock
| observes something different. They see everything outside
| the black hole slow down and stop instead, while they
| continue to coast smoothly along. They notice nothing
| strange at the horizon itself; it is simply empty space
| with weird visuals in the distance.
|
| This almost seems like a paradox, since the two observers
| each believe that the other's clock has stopped. The
| reason why it's not a paradox is that the space around
| the black hole is strongly curved, so strongly that the
| axis of time swaps place with one direction of space. At
| the horizon the axis of time flips over and points down
| into the black hole. The distant observer sees time stop
| because time is now edge-on, as it were. The observer
| falling into the black hole notices nothing weird near
| themselves, because both time and space still exist. Only
| the images of distant objects show any evidence of
| curvature. But the falling observer is doomed, for their
| own time axis now points at the singularity. Their
| timeline now ends abruptly, while the timeline of the
| distant observer extends potentially a vigintillion
| years.
|
| For some edutainment on the subject, I recommend The
| Science Asylum. He's done a bunch of videos on gravity
| and relativity, but here are two in particular:
| * Explaining Gravity Using Relativistic Time Dilation <ht
| tps://www.youtube.com/watch?v=F5PfjsPdBzg&list=PLOVL_fPox
| 2K83_36YgnGisn4rxNvgq1iR&index=7> * Why Can't You
| Escape a Black Hole? <https://www.youtube.com/watch?v=yPQ
| UtuTraxs&list=PLOVL_fPox2K-zpTeryROTkmzzsMssSMWp&index=6>
|
| 1 There are other effects too. The image of the clock
| _lingers_ on the horizon forever, since for it time has
| apparently stopped. But the redshift increases to
| infinity too, as the gravitational well becomes steeper,
| so no matter what wavelengths we observe in the image of
| the clock fades away beyond sight. Worse, the tidal
| forces caused by a real stellar-mass black hole will tear
| apart solid objects into a stream of plasma, even small
| objects. So the hypothetical black hole in our thought
| experiment must be very large indeed, to minimize the
| tidal forces enough that the clock survives the trip to
| the horizon intact and functional. And it can't be
| rotating either, since the rotation causes its own
| weirdness. This is the spherical cow of black holes.
| r0uv3n wrote:
| Eh, space inside or outside the horizon is only different
| in so far as to whether it can reach our timelike
| infinity. Locally you cannot even tell where any horizon
| might be (just look at a small patch of a Penrose diagram
| near a horizon), they are very much something related to
| global properties of the spacetime. In particular it's
| not problematic to talk about some extended volume in
| spacetime occupied by mass, as long as the divergence of
| the stress energy tensor is 0.
|
| The point where our notions of geometry would break down
| would be near the singularity, not near the horizon, and
| we don't even know if a volume enclosed by a horizon
| (i.e. anything you might call a black hole) necessarily
| has a singularity inside, it's just that our simple
| mathematical models all assume one.
| mr_toad wrote:
| Because having some observational knowledge of the inside
| is impossible, in a sense it doesn't matter.
| geysersam wrote:
| When water sloshes it ejects small droplets. Can the event
| horizon eject black hole droplets during a violent merger
| event?
| Thiez wrote:
| It cannot. The event horizon by definition prevents mass
| and energy from leaving (ignoring the exception of
| Hawking radiation here). I'm assuming your "black hole
| droplet" would be a tiny black hole? But if you could
| remove a little chunk from the black hole then you've
| effectively taken mass out of it, which is impossible.
|
| It is even the case that once two black holes have
| overlapping event horizons (so they "touch" in a way)
| they can't stop touching. So two black holes can zip past
| one another at a small distance, but if they high-five
| they can't stop merging.
| captainkrtek wrote:
| Here is an animation from MIT/CalTech of what a merger looks
| like:
|
| https://youtu.be/1agm33iEAuo
| chasil wrote:
| Does the black hole's spin deform the event horizon?
|
| 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."
| mr_toad wrote:
| 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.
| micw wrote:
| Is there a "mass distribution" inside? AFAIK a black hole is a
| singularity which means it's mass is in one (infinitely small)
| point.
| BlackFly wrote:
| 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.
| Permik wrote:
| 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.
| veunes wrote:
| But black holes are incredibly efficient at radiating away
| asymmetries via gravitational waves
| fpoling wrote:
| 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.
| kens wrote:
| 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.)
|
| https://www.science.org/content/article/trump-s-proposed-cut...
| ac794 wrote:
| 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.
|
| https://appropriations.house.gov/sites/evo-subsites/republic...
| amarcheschi wrote:
| I had read something less recent than what you posted, but in
| that is said about 40% of ligo funding would be cut
| https://www.science.org/content/article/trump-s-proposed-
| cut...
|
| Then again, your file has less drastic reductions on nsf
| budget so who knows what would be the impact on ligo
| bee_rider wrote:
| I wonder why Bezos doesn't just pick up the tab, he likes
| space, right?
| jedberg wrote:
| > I believe the proposed budget is being marked up tomorrow
| (July 15th, 12:00)
|
| Interesting that they break this news today. Props to them
| for playing the game.
| amarcheschi wrote:
| 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
| TMEHpodcast wrote:
| Keep an eye on whether the final FY 2026 appropriations bill
| keeps LIGO at two sites. Until then, it's a real risk, but
| salvageable.
| BurningFrog wrote:
| So maybe that is why this discovery from 2023 gets published
| right now.
| gus_massa wrote:
| 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.
| robin_reala wrote:
| Given that there's a handful of gravitational-wave
| observatories running globally at this point, why does the
| closure of one LIGO wreck triangulation?
| agos wrote:
| 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
| robin_reala wrote:
| Looking at their Grafana dashboard, it looks like GEO600
| and KAGRA are both observing?
| https://online.ligo.org/grafana/public-
| dashboards/1a0efabe65...
| HocusLocus wrote:
| Chirps or it didn't happen
| HenryBemis wrote:
| When I read 'news' like that, I 'compare' myself to the thing.
| And then I think how this 'thing' can swallow me, everyone around
| me, everything as far as the eye can see (thank you light
| pollution, we can only see the moon and perhaps 5-6 more 'things'
| out there (ffs!)) and then we will be 'no more'.
|
| But then I use the voice of Djimon Hounsou and the quote from the
| Gladiator "but not just yet".
| croemer wrote:
| Boring press release without any real details. I wish the paper
| would trend not an empty press release announcing the
| announcement.
| veunes wrote:
| Kind of amazing that LIGO/Virgo/KAGRA can even detect and decode
| something that extreme
| ck2 wrote:
| even the "sound" is spooky
|
| https://www.youtube.com/embed/QyDcTbR-kEA
| jcims wrote:
| In case it's not clear, that 'chirp' is exactly what we would
| hear if the merger was powerful enough to actually be
| detectable by our ears. It's the vibration induced in the final
| moments and the frequency is the speed at which the blackholes
| are orbiting each other before they merge. Things the size of
| multiples of our Sun dancing around each other a thousand times
| per second. It's insane to me.
| ck2 wrote:
| so I hate to have to ask this but must
|
| is the space version of LIGO, known as LISA (and will be far more
| sensitive)
|
| now doomed? because of the "savings" by DOGE?
|
| https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Ant...
| pantalaimon wrote:
| This is a project by ESA, it's not affected by DOGE
|
| https://www.esa.int/Science_Exploration/Space_Science/LISA/C...
| ck2 wrote:
| LISA is (was?) listed as a joint NASA-ESA project
|
| Both LISA and LIGO II were deleted from the last
| Congressional budget
|
| https://lisa.nasa.gov/
|
| https://bigthink.com/starts-with-a-bang/ligo-heaviest-
| black-...
| m3kw9 wrote:
| Everything in the universe is massive because we are just so
| small. Everywhere but within the confines of our solar system,
| calling something massive is a meaningless endeavour, it's so big
| nobody has any idea how to appreciate it, and then there is
| always going to be something bigger which makes that black hole
| look tiny
| phtrivier wrote:
| 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 ?")
| beng-nl wrote:
| 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.
| NooneAtAll3 wrote:
| >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"
| outworlder wrote:
| > 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.
| phtrivier wrote:
| Well, maybe it's because in the last two to three decades,
| for the layman, technology has been mostly delivering funny
| gadgets, small incremental improvements, and massive
| problems.
|
| We still need fusion reactors, flying cars, telepathy and a
| cure for cancer yesteryear.
|
| Instead we had 140 characters, PFAS in everything (which
| make the cure for cancer even more overdue) ; cars that got
| very much not flying but very bigger (and made the world
| hotter, and the fusion even more overdue) ; smartphone that
| makes spreading lies faster than even telepathy could ever
| do, etc...
|
| But, now, sure, our flying drones are guided with "A", so
| the authoritarian regimes only have to point in a vague
| direction to get innocent people bombed.
|
| No wonder "Yay, science" is getting a hard rep.
|
| Thank the FSM you Americans decided to stop doing science
| altogether. Maybe the world needs to see that "bad
| research" is worse than "no research at all".
|
| Last time we did that in Europe, it only lasted for 1000
| years, and got us cool looking castles and dramatic
| paintings. So, art, I guess ?
| abdullahkhalids wrote:
| 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.
| outworlder wrote:
| > "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.
| favflam wrote:
| What is the budget outlook for LIGO?
|
| Was the budget cut in the BBB passage last week?
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