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What if Planet 9 is a Primordial Black Hole?
- mugwort13 6y agoPluto is planet 9.
- wrnr 6y agoA person should be allowed to dream sometimes, how freaking cool would this be. A block hole right in our neighbourhood, even closer than Alpha Centauri. Just imagine what kind of things can be learned from studying it.
- 127 6y agoCool, and absolutely terrifying.
- wlesieutre 6y agoOn the flip side, you wouldn't be any less dead if you fell into Jupiter and that's a lot easier to get to
- behnamoh 6y agoFalling into Jupiter is an eye-opening experience tho, esp. if you fall into the "big eye" (pun intended). Just the sheer massive size of a turbulent, harsh planet that covers all the horizon... The world becomes flat much faster near such a planet.
- p1mrx 6y agoWe're already on a planet that covers the horizon; some say there's more beyond the horizon. Would Jupiter look subjectively bigger, if you couldn't also see the Earth for comparison?
- m_mueller 6y agoI guess it wouldn't, but it probably would be a much longer fall until either pressure is crushing you or your heatshield fails.
- mhh__ 6y agoCrossing into the event horizon of a black hole has a very profound poetry to it in that you will never be able to communicate back your findings. I find the romance of the destruction of knowledge very intriguing - falling into a black hole is similar to shooting a mathematician in the head in that regard. Great way to go, all things considered.
- aaomidi 6y agoYes you'd be dead.
- mhh__ 6y agoI am prepared to put down MTW and dream
- FreeFull 6y agoExcept that with a black hole this small, you'll be pulled apart by the tidal forces long before you even reach the event horizon. If you want to make it across the event horizon intact, you need a much larger black hole, like the one in the centre of our galaxy.
- koheripbal 6y agoWhich conversely means that supermassive black holes allow you to pass through the event horizon unharmed.
- manigandham 6y agoNot sure if you meant it that way but information actually can't be created or destroyed in quantum mechanics. This is known as the no-hiding theorem [1] which has been experimentally proven and which leads to the black hole information paradox. [2] 1. https://en.wikipedia.org/wiki/No-hiding_theorem https://en.wikipedia.org/wiki/No-hiding_theorem 2. ttps://en.wikipedia.org/wiki/Black_hole_information_paradox
- bouncycastle 6y ago
- scotth 6y agoIn what sense? It poses no threat to us.
- Konohamaru 6y agoThis is not scary. Yes the event horizon will expand the more matter falls into its gravity well, but otherwise a black hole acts like a normal planet orbiting the Sun.
- onlyrealcuzzo 6y agoIs there a theoretical limit on the minimum mass of a black hole? It's counter-intuitive to me that something could get dense enough to form a black hole and not have more mass than the Sun, or at least enough mass to steal Pluto.
- Robotbeat 6y agoYeah, the event horizon the size of a Planck unit. Again, unless you get super close, it acts identical to a regular planet of the same mass.
- gizmo686 6y agoDo we actually have a theory that predicts a theoretical minimum size of a Planck length? Black holes are an artifact of gravity and the theory of relativity. The planck unit comes up as a result of quantum mechanics. Without a working theory of quantum gravity, we do not have a description of what happens in scenerios where both theories are relevent.
- QuesnayJr 6y agoThere's an approximation that's expected to hold, semiclassical gravity, where both theories are relevant. This is the background against which calculations of Hawking radiation and black hole evaporation are made.
- tfigment 6y agoI don't think so. With the various colliders there was talk of black holes but they would be small and super short lived. The question may be more interesting if we talk about stable black holes at least by human time scales.
- dehrmann 6y agoNo more terrifying than any gravity well.
- galaxyLogic 6y agoYes the cool thing about black holes is that the terrible things inside them can never get out. It's like a prison-planet with the most terrible criminals in there, but they can never escape. Laws of Physics prohibit that
- dodobirdlord 6y agoLess scary than most, since the paper predicts it would be somewhere in the range of 5cm diameter. Very difficult to hit, even if you were trying.
- sporkologist 6y agoAcrophobia, anyone?
- deepspace 6y agoAgree with cool, but not with terrifying. According to the paper, the mass would be ~5-15 M⊕ at a distance of 300-1000AU, so not a threatening object in any way.
- behnamoh 6y agowait, 2020 is not over yet...
- kzrdude 6y agoI assume M-plus means Mass of earth?
- NamTaf 6y agoYes. Similarly, M with a dot in the circle is the sun.
- dyslexit 6y agoAnd at 5M⊕ would have a diameter of about 9cm (or at 10M⊕ about the size of a bowling ball).
- echelon 6y agoHow would we ever find that? Gravitational lensing of the background stars? Do we stand a chance of uncovering it at all? Edit: from the abstract, > The observational constraints on a PBH in the outer Solar System significantly differ from the case of a new ninth planet. This scenario could be confirmed through annihilation signals from the dark matter microhalo around the PBH Wild.
- senectus1 6y agoits hung about out there for a few millennia, I doubt it's going to be a problem for us in a the entire lifespan of the human race...
- aaron695 6y agoA fun way to not be terrified - "What would happen if the Moon were replaced with an equivalently-massed black hole?" https://what-if.xkcd.com/129/ https://what-if.xkcd.com/129/ Also need one for lava, but looking up quicksand is one of the few that might make it worse for you.
- PhantomGremlin 6y agoCool, and absolutely terrifying. Sibling comments are questioning this. But ... what if the black hole's orbit around the sun isn't something approximately circular? What if the orbit resembles a long-period comet? Highly elliptical? What if it puts in an appearance near the sun every 100,000 years? How would we know? What in the historical record could we study?
- QuesnayJr 6y agoThey have a pretty good idea of what the orbit would look like to explain the eccentric orbits of TNOs. It's not circular, but it's not that eccentric: https://en.wikipedia.org/wiki/Planet_Nine#/media/File:Planet_nine-etnos_now-new3.png https://en.wikipedia.org/wiki/Planet_Nine#/media/File:Planet...
- LoSboccacc 6y agosomehow it never occurred to me that black hole could actually orbit what does it mean for the event horizon to move one side is fairly predictable as space gets swallowed as the black hole advances but the space at the rear side would just sort of pop out of the event horizon or be stretched from the previous position what would happen to the space behind a black hole moving at relativistic speed? Bet there some paper I cannot understand about it somewhere
- dreamcompiler 6y agoMuch less terrifying than a 5-Earth-mass planet. Such a planet would be quite easy for a spacecraft to crash into. But if all that mass is the size of a tennis ball, it would be very easy to miss. Unless your aim was perfect you'd just slingshot around it.
- keyle 6y agoit's not more terrifying than a planet or a sun, it's just more dense and invisible to the eye :)
- mseepgood 6y agoI don't see how this is more terrifying than, say, have a sun in the neighbourhood.
- tobmlt 6y agoSeconded.
- dmead 6y agoshouldn't this be something we can look for without resorting to additions to the standard model?
- wyldfire 6y agoSo would this PBH orbit the Sun? > This scenario could be confirmed through annihilation signals from the dark matter microhalo around the PBH. How long does this experiment take to construct, and to execute? Days/weeks/decades? BTW has anyone thought of getting in touch with the Lectroids? They're bound to know more about Planet 9 than we do.
- czbond 6y agoPlanet X and the Annunaki. I really enjoy some of those 'out there' outer space/alien documentary shows because even if untrue, they expand my mind with ideas. Sort of the mind expansion of getting "high", without the substance part. They have an episode on Planet X and Annunaki and predict a black hole is Planet X. https://www.amazon.com/The-Annunaki/dp/B07JW478HG/ref=sr_1_12?dchild=1&keywords=Anunnaki&qid=1596081149&sr=8-12 https://www.amazon.com/The-Annunaki/dp/B07JW478HG/ref=sr_1_1...
- Causality1 6y agoannihilation signals from the dark matter microhalo around the PBH. What? Since when do we know enough about dark matter to say something like that? Even if we did the diameter of a black hole with the mass of a dozen earths is smaller than a beach ball and the density of dark matter in the outer solar system is one AMU for every three cubic centimeters. I'm skeptical we have equipment sensitive enough to detect such a small number of interactions at the distance of 500+ AU.
- dumbfoundded 6y agoThat part seemed more speculative. I imagine most likely this is being used as an alternative hypothesis if we search for the undiscovered planet and fail to find it. Simultaneously if we become more certain about the observed gravitational effects, the probability of a PBH would increase.
- Causality1 6y agoThere's speculation and then there's fantasy. Hypothetically you could build a detector sensitive enough and a set of algorithms robust enough to observe the vibrations of a single crystal and decode from them every sound being made on the entire surface of the earth. Just because something is not physically impossible does not make it realistic or keep it from being foolish.
- smitty1e 6y agoAre we still allowed full verbal use of the spectrum, or should we say "singularity" here? Asking for Nathan Poe.
- ISL 6y agoOne should not miss Figure 1 of the arXiv preprint, which is, alas, absent from the final PRL. https://arxiv.org/pdf/1909.11090.pdf https://arxiv.org/pdf/1909.11090.pdf It is among the rarest journal-article figures in physics. If I'd been asked to referee the paper, I'd have campaigned hard to keep it in.
- modzu 6y agothank you for this, i laughed out loud
- themodelplumber 6y agoFascinating. And kind of funny. I wonder, are there any YouTubers who walk through the math in papers like this? Asking because it seems really interesting and sometimes it's fun to learn bits here and there from applied math rather than always working up from the fundamentals.
- autokad 6y agoI really doubt Pluto is a black hole.
- p1mrx 6y agoYeah, anchoring a Mass Relay to a black hole would be too hazardous.
- xingyzt 6y agoIf true, would this be the smoothest planet in the solar system?
- sidcool 6y agoSince it's a black hole, it's gravitational effect would be at least as much as the Sun. Is there evidence to support this tug of war?
- iNic 6y ago> While an M⊕ object is too light to be an astrophysical black hole formed by stellar collapse, PBHs arise from over densities in the early universe [15, 16] and as a result can be substantially lighter than M . Normally black holes do have at least the mass of ~1.4 times our sun because they are formed by stellar collapse. That is why here they are considering Primordial Black Holes which a) formed differently and b) radiated some of their mass away
- sidcool 6y agoI guess I mixed PBH with a regular black hole.
- 317070 6y agoBlack holes do not have more gravity per mass than any other object. Put the other way, if the sun would suddenly change into a black hole without losing a lot of mass, the earth would still follow the exact same orbit.
- teslaberry 6y agono it wouldn't because the other planets affect our orbit and the collapse of the sun would affect mercury and venus very directly in their orbits. also the black hole polar jets would be beautiful, imagine a dark sun with two long well lit streamers cutting both ways across the sky. we'd all be dead, but it would be beautiful
- sidcool 6y agoThat's true. My point was that if there were a solar mass object beyond Pluto, it would have significant effect on orbits of all planets. But apparently PBHs can be lighter
- jug 6y agoThe interesting bit about this to me, if this is happening in our immediate neighborhood, is if it’s an indication that it’s actually a commonplace phenomenon and further - an explanation of our missing matter to bind galaxies. A primordial black hole is not visible but it would interact gravitationally, potentially with multiple of them clustering up in groups. Dark matter work this way seemingly including clustering. Some galaxies seem to be made up by a ton of the stuff, others by barely anything. Could that be due to random chance; i.e. primordial black holes distributed unevenly since the cosmic inflation era, much like the non-uniform distribution of matter at large?
- teslaberry 6y agowhat if we knew how old black holes were. we don't. not directly. we cannot 'age test' black holes. hawking radiation is mostly bullshit. blackholes may be like diamonds. they are forever. but when were they born? we've only seen a neutron start or black hole born last year for the first time. and we really don't even know which one it was. https://www.sciencefocus.com/news/birth-of-a-black-hole-witnessed-for-first-time/ https://www.sciencefocus.com/news/birth-of-a-black-hole-witn... there is a LOT of good experimental observation science left to do . let alone all the 'simulations' we have to run. the fact is, we know precious little about our own outer solar system let alone black holes, the closest of which we know is 3300 light years away, ---https://en.wikipedia.org/wiki/A0620-00---- https://en.wikipedia.org/wiki/A0620-00---- this is not even anywhere close to our local area of the galaxy, which is 50-100 light years radius from our sun. the truth is , while all this science is awesome, we have a proclivity to believe we have more certainty in our knowledge than we do. and no where is this procilivity more often seen as exaggerated , than in astronomy, where the physics of space time and distance work against our understanding reality more than in any other area of study.
- geoffmunn 6y agoI've been wondering - if the black hole was very small (I've read elsewhere that it would be grapefruit sized), would it be possible to build some kind of box around it so you couldn't accidentally go into the event horizon?
- Sharlin 6y agoThere's no material that you could make the box or shell out of that could withstand the gravitational forces near the black hole. Even the gravity differential (tidal forces) is strong enough to rip anything apart (the so-called spaghettification). And if you made the shell large enough (planet-diameter), it would collapse into a spherical body just from its self-gravity, never mind the additional gravity of the PBH.
- geoffmunn 6y agoBut given that it's so small, what would the gravitational forces be if you made a shell with a 100km radius? Or pick a number - surely at some point it might be practical to build something.
- xingyzt 6y agoSize of the object doesn’t matter. Gravitational force depends on its mass and how far away you are from the black hole. Standing on a shell ~6300 km above a black hole with the mass of the Earth is equivalent to standing on the Earth itself.
- jborichevskiy 6y agoI have a hard time really accepting this concept given how unintuitive it is to me but I found your comment helpful in that regard.
- lmilcin 6y agoIf this was true, this would be extremely fortunate for our civilization if we can figure out not to kill ourselves in next couple hundred years. Black holes offer about the most effective process to extract energy from matter, orders of magnitude more efficient than fusion and it is not picky about what kind of matter you put in. You can put a Dyson sphere/swarm around small black hole and extract something on the order of up to 40% of mass-energy equivalent of the falling matter. With BH of the mass of Earth the sphere would be pretty small and easy to make.
- wcoenen 6y ago"Small" Dyson sphere is relative. The tidal forces at 50km from an earth-mass black hole would still be pretty significant, so it probably couldn't be smaller than that. E.g. to pick something on the scale of a human, the difference in gravitational acceleration (being GM/(r^2)) between two points at 50000 and 50002 meters from such a black hole would be about 1.6 G.
- pas 6y agoWhat does that do? I mean you can walk in 1G just fine, so probably we could go there, take a walk/sit there in 1.6G, and leave, right? That means that if we put a 100km wide structure around it, we can service it easily(?) even without robots.
- wcoenen 6y agoYou can't "walk" in this 1.6G. You'd experience it while floating freely in space. And the stress on your body would be tension instead of compression. I guess it would feel like hanging upside down, except that your blood rushes to both your feet and your head.
- deleted 6y ago[deleted]
- juped 6y agoThe difference in gravitational acceleration between two points, not the gravitational acceleration at the points.
- thunderrabbit 6y agoAssuming its location can be determined, what experiments would you like to try in its vicinity?
- jbotz 6y agoThis paper has been on Arxiv since nearly a year ago; surprisingly it apparently didn't make HN at the time, even though it did get a bit of publicity then, including the MIT technology review[0]. Despite the sense of humor evident in the included to-scale "picture" of a black hole, the paper is quite serious... it may be speculative, but it's science. Also, the authors are not the first to speculate that the OGLE microlensing events could be best explained by a population of primordal black holes[1]. However, Planet 9 could still just easily just be an ordinary planet.. the final point of the paper is that we should look for both, the two requiring different search strategies. Anyway, no matter how plausible or implausible, this post made my day. A mini black hole, close enough that we could send a probe there? How cool is that?! [0] https://www.technologyreview.com/2019/09/30/410/is-planet-9-actually-a-primordial-black-hole/ https://www.technologyreview.com/2019/09/30/410/is-planet-9-... [1] https://arxiv.org/abs/1901.07120 https://arxiv.org/abs/1901.07120
- T-A 6y ago> This paper has been on Arxiv since nearly a year ago; surprisingly it apparently didn't make HN at the time https://news.ycombinator.com/item?id=21078068 https://news.ycombinator.com/item?id=21078068
- rishav_sharan 6y agoWe know that most heavy elements in the solar system come from a supernova explosion. I have always thought that the 9th "planet" was the remnant of this explosion and that this dead was the ancient binary companion of sun. But yeah. Just fanciful thoughts here and no evidence, or even, good arguments to back it up. :)