[HN Gopher] Astronomers confirm the existence of a lone black hole
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Astronomers confirm the existence of a lone black hole
Author : wglb
Score : 86 points
Date : 2025-04-21 18:36 UTC (4 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| wglb wrote:
| Astrophysical Journal article:
| https://iopscience.iop.org/article/10.3847/1538-4357/adbe6e
|
| Earlier article about first discovery:
| https://iopscience.iop.org/article/10.3847/1538-4357/ac739e/...
| pizzathyme wrote:
| Does anyone else find this...unsettling? Floating around in the
| void of space, alone, is an almost invisible monster that can
| gobble planets and stars.
| hyperhello wrote:
| Relax, it's probably traveling in a straight path at constant
| velocity.
| mytailorisrich wrote:
| It can't gobble planets and stars any more than any stars of
| the same mass.
| jsbisviewtiful wrote:
| For sure - The largest threat would be traveling by our solar
| system close enough to throw off the orbits of earth or any
| of our nearby neighbors.
| saltcured wrote:
| I'm trying to picture intersecting paths though. Does a
| faster moving black hole cause more or less damage to a
| target?
|
| Imagine a black hole on the quite small end, intersecting the
| core of a planet. Unlike regular matter, it can't really
| produce bow shock through collisions, right? All the target
| matter in the direct path just "falls in" and in elastically
| reduces the black hole momentum a tiny bit?
|
| Some matter outside the direct path could be accelerated
| towards the black hole but slingshot behind it, rather than
| into it. So this material could produce an impressive wake,
| with material spraying outward from the collision path and
| interacting with the remainder of the target.
|
| But, all this visible chaos comes from gravity rather than
| more direct kinetic interactions, right? If the black hole is
| moving faster, doesn't the target's material gets less
| gravitational acceleration as it spends less time in the near
| field? So, if the blackhole is moving very fast, does it bore
| a smaller hole and have less interaction with the target? Or
| do other effects of relativity make this more convoluted to
| think about?
|
| I'm imagining a cylindrical plug of a planet
| "instantaneously" disappearing, and then the remainder of the
| planet collapsing inward to fill the void, bouncing off
| itself, and ringing like a bell.
| psunavy03 wrote:
| It can't really "gobble" anything any more than a star
| "gobbles" things that fly into its photosphere or a planet
| "gobbles" things that crash into it.
|
| Unless you cross its event horizon, its gravity works just like
| any other celestial object. Maybe at worst it slingshots you
| off in a different direction.
| deadbabe wrote:
| He technically did not say the invisible monster was a black
| hole.
| stouset wrote:
| I think the concern is that if a star was headed in our
| direction we'd see it coming. We don't see one, so we know
| there is no anticipated threat.
|
| A small, lone black hole could be on an intersecting
| trajectory with us within a few years and we'd be completely
| oblivious.
| pixl97 wrote:
| I wonder if a few solar mass black hole would bend light
| far enough around it that it would show up at some point.
|
| With all that said, maybe it's better off if we were
| completely oblivious.
| robofanatic wrote:
| > maybe it's better off if we were completely oblivious.
|
| even that would be a slow death I suppose. Don't think
| the Earth would just vanish instantly.
| alabastervlog wrote:
| I'd wager such an encounter is way more likely to result
| in any of:
|
| 1) the Earth being flung out of the Sun's orbit
|
| 2) planetary orbits becoming disrupted such that an
| encounter with another planet over the coming years or
| millennia becomes likely,
|
| 2.1) which could eventually have the same "flinging away
| from the Sun" effect,
|
| 2.2) or (unlikely, but possible) result in a collision
|
| 2.3) or result in the Earth being shredded into asteroids
|
| 2.4) or _other_ planets suffering that fate and then
| showering the Earth with dangerously-large asteroids over
| a period of decades or centuries until it 's nearly, or
| actually (think: outright crust liquefaction from
| impacts) lifeless.
|
| than the Earth actually getting swallowed up, by at least
| an order of magnitude.
|
| IOW, the most-likely "we're all dead" outcomes for us,
| from a close encounter with a massive rogue _anything_
| really, including a black hole, might take years and
| years to play out.
| jazzcomputer wrote:
| I wonder what the chances are if there's a few of them
| within the Bootes void. It's pretty big.
| cactacea wrote:
| Schwarzschild radius of a 10 stellar mass black hole is
| ~20 miles. It would need to be pretty close in order to
| resolve optically.
| pyfon wrote:
| Yet they detected a lone black hole in the article. Maybe
| detection isn't guaranteed though?
| snowwrestler wrote:
| A mass of 6x to 7x our sun (size of this object) would
| start messing with solar system orbits well before it got
| here. Not that that would be much better for us!
| Loughla wrote:
| Yeah it wouldn't just sneak up on us. We would have years
| and years to worry and hypothesize before finally just
| dying.
| louthy wrote:
| We'd see the lensing soon enough, but couldn't do anything
| about it
| Ancalagon wrote:
| As if there were any different actions that could be taken
| to avoid a star vs a black hole.
|
| I'd probably welcome the quicker demise tbh
| stouset wrote:
| It's less about actions we could take and more about
| knowing we don't have to worry about colliding with a
| star for the moment.
| Ancalagon wrote:
| You probably wouldn't want society to know we were about
| to collide with a star-sized mass, visible or not.
| Swizec wrote:
| > wouldn't want society to know we were about to collide
| with a star-sized mass
|
| I may be misunderstanding the distances involved but
| wouldn't such a collision take centuries if not thousands
| of years to play out? For the most part it would just
| look like we had 2 suns, one of which gets a few
| millimeters bigger (to the naked eye) every year.
| hinkley wrote:
| If we saw a star coming toward us...
|
| Have you seen the Walking Dead?
| idiotsecant wrote:
| Fortunately space is really, really, really, really,
| really, really, REALLY big. The chance of this happening is
| so infinitesimal we might as well worry about spontaneously
| transforming into a whale or potted flower manifested a
| mile above the surface of our planet.
| gmuslera wrote:
| That brings me memories of Cosmos 1999. The moon left Earth's
| orbit to outer space because explosions, but being
| slingshoted away because a nearby massive enough object
| passing by looks like a more possible scenario, not explored
| enough by sci-fi.
| omnibrain wrote:
| > Cosmos 1999
|
| Space: 1999. Do you happen to be french or polish?
|
| In Germany they called it "Mondbasis Alpha". As I child I
| really liked this series and it's predecessor UFO made by
| the same team (Gerry and Sylvia Anderson of Thunderbirds
| fame).
| Mountain_Skies wrote:
| The basic premise of the show that an explosion at a
| nuclear waste dump could produce enough energy to push the
| Moon out of the Solar System to wander the galaxy is an
| interesting product of its time. Concerns over the power of
| nuclear explosions was high and casual access to knowledge
| about the plausibility of such a scenario was somewhat
| limited.
|
| There's a fan driven update called Space: 2099 that
| improves some of the more dated aspects of the show,
| including showing the Moon enter some type of portal or
| wormhole to make suspension of disbelief easier. While the
| Special Edition releases of Star Wars often suffered from
| updating certain aspects, especially special effects, the
| Space: 2099 changes were generally good for the show. Too
| bad they're unable to fund raise enough and get permission
| to do the entire series.
|
| https://www.youtube.com/watch?v=wPTZaSv9Bxk
| jonah-archive wrote:
| Fritz Leiber, "A Pail of Air": https://www.gutenberg.org/cach
| e/epub/51461/pg51461-images.ht...
| casenmgreen wrote:
| In practical terms, not so very far away from the NEAs that we
| have no idea of, and which we notice _after_ they 've just
| skimmed by the Earth.
| tejtm wrote:
| No, not me anyway. we are all floating (falling) in the (nigh)
| void of space (equally) alone ... which is great protection
| from all the monsters everywhere!
|
| Deliberately hitting things in space is hard, accidentally,
| more-so.
|
| Consider the chance of our sun getting whacked when the entire
| Andromeda galaxy gets here ... billions or more likely
| trillions to one. The chance of a single mass in our own galaxy
| getting us should be less than that.
|
| edit: as far as I know the only difference between getting
| gobbled by a black hole v.s. anything else is our atoms won't
| get to continue their evolution into larger atoms in this
| universe. (or maybe see it as our atoms get to complete their
| evolution in this universe)
| sega_sai wrote:
| The size of the black hole described in the paper is ~ 20 km,
| so it is tiny. Even we have millions of such objects (and most
| likely we do), the chance of hitting something, given the
| enormous size of the galaxy is negligible.
| rad_gruchalski wrote:
| Would we notice if it was to point in our direction?
| windsurfer wrote:
| The black hole in the paper is also ~7 solar masses. If that
| passed between the Earth and the Moon it would rip apart the
| earth from just the tidal forces.
| belter wrote:
| Are you worried? :-) I bit like bringing sunscreen to the
| apocalypse no? :-)
| hnuser123456 wrote:
| It would be nice to get a rigorous estimate on how big and
| nearby a black hole could be before we'd notice it with routine
| sky surveys or orbital deviations. A 6-solar-mass black hole
| only has a radius of around 18km or 11 miles. How often will
| one pass in front of a star precisely enough for OGLE and MOA
| to detect it, as they did with this one?
|
| Apparently the Roman Space Telescope will be great at detecting
| these, if it doesn't get cancelled.
| thangalin wrote:
| > gobble planets and stars
|
| Direct interaction isn't needed for havoc. A supermassive
| object sweeping by the Solar System could destabilize Jovian
| orbits. In the Nice model, Neptune flung Kuiper belt asteroids
| sunward, gifting the inner planets with a late heavy
| bombardment.
|
| Rogue gas giants, brown dwarfs accelerated to relativistic
| speeds, giant asteroids approaching from the Sun's direction,
| Carrington Events, an ill-directed gamma ray, etc. So many ways
| life on Earth can see its 250 million remaining years cut
| short, and those are only a few of the cosmic threats we can
| imagine.
|
| A black hole with a Schwarzschild radius of 20 km would weigh
| about 6.8 Solar masses. It wouldn't even need to get super
| close to affect the Solar System.
| vanattab wrote:
| Where is the 250 million years come from?
| ftrobro wrote:
| Perhaps a reference to Pangea Proxima?
|
| https://en.wikipedia.org/wiki/Pangaea_Proxima
|
| Life might very well exist on earth even through those
| conditions, but not to the extent we have today.
| thangalin wrote:
| https://www.nature.com/articles/s41561-023-01259-3
| ajb wrote:
| There are many theoretical astronomical risks. For example, if
| we happened to come into the path of a relatively nearby gamma-
| ray burst, it could eliminate all life. Given that life has
| existed on the earth for quite some time, the 'Lindy effect'
| suggests that the sum of these presumably-constant risks is
| small. We are much more likely to become extinct due to an
| anthropogenic cause.
| SllX wrote:
| No more unsettling than space in general is. It's pretty
| hostile to life. We're not just making turns around the orbital
| racetrack setup around the Sun, we're also flying through space
| following the gravitational trail of the Sun as it races
| forward without a destination.
|
| I was playing with Universe Sandbox over the weekend trying to
| figure out how to terraform Venus. Changing its axial rotation
| period to a day to match the Earth while I screwed around with
| its chemistry was enough to cause Europa and some of the other
| famous moons of Jupiter and Saturn as well as Charon to yeet
| themselves outside of the solar system within about 10 or 20
| years of simulated time.
| danparsonson wrote:
| Why would changing the rotation speed of Venus have any
| noticeable effect on the outer planets? That sounds more like
| a limitation of the model than anything else. Especially over
| such a short time! 20 years is nothing to the orbit of
| Charon.
| SllX wrote:
| Probably, but if a Venus-sized mass showed up in the inner
| solar system because the Sun just picked it up along the
| way, it might not be instant death but we're probably in
| for a rough time. It doesn't have to be a black hole that
| does us in, it could be something much smaller that still
| strips the Moon away or causes Earth to readjust its own
| position in a way we, as in life, but also maybe we as in
| humans or we as in mammals just don't like very much in a
| very short amount of time temporally speaking, and we
| couldn't do anything about it anymore than we could do
| anything about a black hole because we're just not the
| captains of this ship. We're just some homegrown stowaways.
|
| But for what it's worth, it's also just so incredibly
| unlikely it's not a scenario worth thinking about either,
| and thinking about it too much just invites existential
| dread.
| dreamcompiler wrote:
| I don't. If the sun were replaced by a black hole of equal mass
| next Tuesday at noon, the only thing we would notice is that it
| suddenly got very dark and very cold. We would continue
| orbiting the thing while freezing to death over the next few
| days.
| OsrsNeedsf2P wrote:
| > Prior to this new finding, all the black holes that have been
| identified have also had a companion star--they are discovered
| due to their impact on light emitted by their companion star.
| Without such a companion star, it would be very difficult to see
| a black hole.
|
| It seems like we think there's many more of these black holes,
| but we just can't see them
| adastra22 wrote:
| Lone stars are actually the exception, so not radically more as
| you might think. But there are also binary black holes.
| btilly wrote:
| This only covers stellar black holes. (Note that this black
| hole is believed to be a stellar black hole.) Those
| statistics could change quickly if you add to it a currently
| unknown number of primordial black holes that arose around
| the Big Bang.
|
| If those primordial black holes are mostly on their own, and
| are both numerous and small, they make a potential candidate
| for dark matter. They could also be potentially small enough
| to be evaporating in our current era. This has been suggested
| as a potential source of a very high energy neutrino that was
| found in February. See
| https://www.livescience.com/space/black-holes/evidence-
| for-s....
|
| (Note that this is just a single observation. We are a very
| long way from being able to obtain strong experimental
| evidence for such speculative theories.)
| MichaelZuo wrote:
| I thought there were too many constraints to make PBHs a
| significant contributor?
| chasil wrote:
| A type-1a supernova peer would produce this effect, leaving
| only the black hole (or the oversize star that would become
| it). I don't know any other types where the star is completely
| destroyed.
| cogman10 wrote:
| I'm sure I'm not the only one that's thought of this, but could
| this be "dark matter"? Is the universe simply filled with these
| rouge black holes?
| tomrod wrote:
| > rouge black holes
|
| They makeup much of the stylish universe in the cosmos ;-)
|
| Just kidding, I know you meant rogue.
|
| I would assume we'd see a lot of more tricks of light bending
| if they did. Light lensing was used to confirm relativity by
| looking for multiple super novae signatures from the same
| event, which passed by large black holes on their way here!
| cogman10 wrote:
| Depends on the size, position, and number of black holes,
| right? We see lensing currently because of super massive
| black holes that we know about. But if there's a bunch that
| are basically as massive as our sun (or less) then we are
| dealing with event horizons ~3km or less. It'd be pretty hard
| to spot those as the diffraction would be rounding errors.
| saltcured wrote:
| But are there enough of them that we're really the rogue
| matter that is abnormal?
| 7thaccount wrote:
| I can't remember who I heard talk about this, but scientists
| have considered this. I think there was a good reason for why
| it doesn't seem to match observations.
| nxpnsv wrote:
| If a significant portion of dark matter was made of these we
| would see a lot more gravitational lens distorions of distant
| objectes. There are further hard limits on how much baryonic
| dark matter there can be from big bang nuceleo synthesis. I
| think that would also put limits on contributions from lone
| black hole contribution.
| nabakin wrote:
| That was my first thought too. A cursory search indicates we
| would see a lot more gravitational lensing in our observations
| if that was the case.
|
| Found a couple of videos on it too
|
| https://youtu.be/qy8MdewY_TY
|
| https://youtu.be/d0wV5frSb6s
| MattPalmer1086 wrote:
| There are some theories that primordial black holes could be
| dark matter. It's not a mainstream view though.
| danparsonson wrote:
| These would be 'primordial' black holes:
| https://en.m.wikipedia.org/wiki/Primordial_black_hole
| hinkley wrote:
| This would certainly be some of it but the awkward fact is that
| we've positively identified so very little of the matter that
| makes the universe the shape that it appears to us to be that
| we could double the known matter in the universe with black
| holes and we'd still only be a 10th of the way there.
|
| However if we could eliminate the false signals from invisible
| (singularity) matter I am hopeful that will give us a clearer
| idea of whatever the rest is.
| mirekrusin wrote:
| What I don't understand is how big bang could exist if such
| relatively "small" mass concentration creates black holes?
| elchananHaas wrote:
| The layman's answer is that since everywhere was very dense
| there wasn't a gravitational pull to one direction or another
| since it all cancelled out.
| btilly wrote:
| Except that this answer does not make sense. General
| Relativity predicts that if you fill flat space-time with
| matter, it will start to contract due to gravity. It is not
| uniform density by itself that prevented the early Universe
| from forming a giant black hole.
|
| In fact one of the proposed cosmological models for our
| universe is that it has sufficient density to some day
| reverse its expansion and then fall in on itself into a giant
| black hole. See https://en.wikipedia.org/wiki/Big_Crunch for
| more.
| btilly wrote:
| Excellent question.
|
| Gravity pulls things in by causing space-time to accelerate in
| a particular direction. In other words we accelerate towards
| the Earth at 9.8 meters per second per second because that is
| what space-time itself does. The space-time that is in our
| frame of reference accelerates down, carrying us with it. The
| floor pushes up on us, causing us to accelerate up. Balancing
| things out so that we remain where we are.
|
| A dense mass will cause flat space-time to start falling in.
| Enough mass, densely enough, will cause it to fall in so fast
| that not even light can escape. This is a black hole.
|
| However the Big Bang wasn't a flat space-time. The space-time
| that was the structure of the universe was moving apart
| extremely quickly. There was more than enough mass around to
| create a black hole today. But what it did is cause the
| expansion rate to slow. Not to stop, reverse, and fall back in
| on itself into a giant black hole.
| hinkley wrote:
| One of the theories is that the properties of the Higgs Field
| changed and so the laws of physics changed. And that if they
| ever change again that we'll likely be dead before we know to
| be afraid, since the change would propagate through the
| universe at the speed of light. We wouldn't even see the stars
| blink out before the molecules in our bodies stopped being the
| molecules in our bodies.
| dreamcompiler wrote:
| "There is another theory which states that this has already
| happened."
|
| --Douglas Adams
| YeGoblynQueenne wrote:
| You'd be "lone" too if you ate all your neighbours.
| pyfon wrote:
| More like it eats the dust that brushes pass the front door,
| but neighbours are safe.
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