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What if Planet 9 is a Primordial Black Hole? (2019)
- pndy 3y agohttps://news.ycombinator.com/item?id=21078068 https://news.ycombinator.com/item?id=21078068 - 4 years ago, 346 comments https://news.ycombinator.com/item?id=23993716 https://news.ycombinator.com/item?id=23993716 - 3 years ago, 119 comments https://news.ycombinator.com/item?id=28167058 https://news.ycombinator.com/item?id=28167058 - 2 years ago, 153 comments
- sigmoid10 3y agoAnd it's still grasping at straws. The idea of a PBH as planet 9 itself is somewhat sound, but this particular paper assumes not just a significant population of MACHO dark matter, but also an additional WIMP-like particle DM that would produce a detectable signal. Is it theoretically possible? Yes. Would it be amazing to find evidence for it? Of course. Is it likely to happen? No. And we probably won't get a conclusive answer to this either way until we can easily send probes outside the solar system or at least have enormous telescopes on the moon's surface. Until then this topic is mostly an easy path to publishing papers to get tenure.
- ToDougie 3y agoQuestion for you -- how do we protect enormous telescopes on the moon's surface?
- andrewflnr 3y agoProbably pretty similar to how JWST is protected, which is to say not at all, but with enough redundancy to take a couple hits.
- PaulHoule 3y agoWhy do you mess around on the surface of the moon when something free floating can be much larger with light construction?
- huthuthike 3y agoYou can't just make something free floating bigger and bigger without introducing new issues. In particular, as objects get larger in zero gravity, it becomes harder to dampen oscillations. The lighter the object is the more problematic these oscillations become. You also run into issues with thermal expansion.
- giantrobot 3y agoAnd torsion effects when trying to move structures or reorient the whole structure.
- pyinstallwoes 3y agoCan you expand the oscillations part? I find that interesting.
- chaps 3y agoObjects have a resonant frequency and will jiggle in strange ways. The larger the object, the larger the possible jiggles. The larger the jiggles the larger the destruction.
- pyinstallwoes 3y agoAre you saying any object in space will naturally be resonating with itself at some frequency or that by proximity and interaction to another object it may cause resonance on another and therefore cause it to jiggle in strange ways. Thanks!
- chaps 3y agoThe latter. Basically [1] but not as exaggerated. Think of things like screws shaking loose over time which leads to structural failure. Plus, no easy means to release that energy like you would when you're attached to a planet. [1] https://www.youtube.com/watch?v=XggxeuFDaDU https://www.youtube.com/watch?v=XggxeuFDaDU
- dividedbyzero 3y agoMake it very modular and have little robots scurry over with a replacement module if one gets hit by a micrometeorite or otherwise fails.
- LASR 3y agoDo you play Factorio? I’m not sure how much of that is actually feasible.
- caymanjim 3y agoProtect them from what? We have enormous telescopes in space already. The moon is safer than where Hubble and JWST are now.
- dwaltrip 3y agoWouldn’t the moon’s gravity pull in more material, putting a telescope at higher risk?
- DrBazza 3y agoCorrect. A large hill/small mountain's worth of debris hits the Earth every year. That includes micrometeorites that without an atmosphere, would pepper the Earth's surface. It's also the reason why any Moon base would be buried under layers of regolith to protect it. Glass domes on the moon are sci-fi fantasy.
- OkayPhysicist 3y agoSince the moon is tidally locked, the side facing Earth and its far more massive gravity well would experience vastly less debris. It'd be a boring place to build your glass domed moon base, but I don't think it would be completely infeasible. Especially if it was built in a depression in the landscape, the approach angles would be greatly limited.
- ceejayoz 3y agoThe ISS gets hit with micrometeorites pretty regularly, without any regolith to protect it. Micrometeorites make correspondingly micro holes, which in said glass dome are patchable. A 2mm hole in a Soyuz docked to the station was fixed with a bit of Kapton tape and some epoxy, and was detected by a very small pressure drop in the crew spaces. Larger rocks are more of a problem, but quite rare. Your dome is much more likely to get smashed by someone mixing up the pedals in a rover. https://www.livescience.com/how-many-moon-meteorites https://www.livescience.com/how-many-moon-meteorites > "if you pick a square kilometer patch of ground, it will be hit by one of those pingpong-sized meteoroids once every thousand years or so" We've landed in visibly quite smooth areas; for example: https://www.flickr.com/photos/nasa2explore/48299974871 https://www.flickr.com/photos/nasa2explore/48299974871
- PaulHoule 3y agoIt’s the state of physics today. Einstein was able to predict how light was bent around the Sun and Eddington confirmed it right away, it was like Babe Ruth pointing to the stands and hitting a home run. The lag between a phenomenon being predicted or model sped by theoreticians and actually observed is getting longer and longer in fundamental physics, I mean neutrino oscillations were hypothesized in 1957. The fact that you can’t get a Nobel prize posthumously means a theoretician might never get a Nobel in fundamental physics ever again. So they’ve got to do something speculative like this to have a possibility of a legacy unless you are Ed Witten and can convince people you are a genius without any appeal to experiment whatsoever. It does point to a programme of observations to try to catch P9 in a gravitational snare and look really hard in that area with all kinds of telescopes and has the double prize of possibly finding non gravitational evidence for DM. Personally I think interstellar travelers would use FFPs as a resource but the question of how a civilization that lives on an FFP (imagine something like Pluto cut up into small (5000km) ringworlds) finds the next one seems pretty tough to me.
- irrational 3y agoExcept, I've never heard of Ed Witten and I'm pretty sure people had heard of Einstein during his lifetime.
- nonameiguess 3y agoI didn't recognize the name but figured he was the guy who came up with M-theory, and sure enough, that's him. I believe the point here is achieving a legacy within the academy, not being known in pop culture. I think there's a lot of ambivalence about his influence, but it's definitely been large. His papers revealing how the whole superstring thing can be constructed in a way that doesn't blatantly contradict observed reality diverted at least a generation of theorists into the search for the holy grail of a theory of everything, but because we have no means of experiementally probing anything at the scales involved, it has also turned a generation of physicists into algebraic topologists largely divorced from experimental practice. You can think of him maybe like the Velvet Underground of physicists. They never achieved much popularity themselves, but virtually every rock band of the past 40 years that has gotten popular cites them as an influence, and many artists would rather have that as a legacy than popularity. Similarity, I think a lot of physicists would rather be well known and influential to other physicists rather than becoming the next Michio Kaku or someone else who shows up on television a lot.
- swader999 3y agoAnd yet we can't escape debating this. Each time this is posted we get sucked in.
- pyinstallwoes 3y agoDo thoughts/ideas have inertia?
- swader999 3y agoThey create reality.
- pyinstallwoes 3y agoThat contemplation definitely has layers to it.
- bifftastic 3y agoIt would suck
- TheRealPomax 3y ago"clever joke" aside: why? Primordial black holes are a rather completely different category from super-massive black holes, with masses theorized as small as a single plank mass. Not a lot of sucking happens when PBH are involved.
- horsellama 3y agoFig1 in the paper shows the exact size of the PBH: > FIG. 1. Exact scale (1:1) illustration of a 5M⊕ PBH. Note that a 10M⊕ PBH is roughly the size of a ten pin bowling ball.
- danparsonson 3y agoIndeed; if the mass really were tiny, we'd have no idea that there was any object to look for.
- NoMoreNicksLeft 3y agoWouldn't a Planck mass black hole have evaporated immediately?
- TheRealPomax 3y agoThings are weird when dealing with Planck quantities, so "almost certainly", but only almost. The main point was that PBH are generally small and look nothing like what people think of if they've only heard of black holes from popular science and sci-fi.
- short_sells_poo 3y agoI suppose given the enormous force gradients around even a basketball sized black hole, it could potentially be turned into one of the most efficient ways to convert matter into energy by building an accretion disk around it?
- nameless912 3y agoEdit: the original comment I wrote was dumb and needlessly critical of an article I barely skimmed while on an airplane at 1 AM. That's my bad.
- seiferteric 3y agoIt's not an article, but a scientific paper exploring the idea.
- titzer 3y agoIt's a research paper, complete with a mathematical analysis. Take a gander. It's not "non-journalism."
- TheRealPomax 3y agoThere is nothing weird about this paper, the math works, and primordial black holes (which is a astronomical term, not just a plain English descriptor) are not the thing you're clearly thinking of given your rant. Checking to see if outer planetary motion can be explained in terms of PBH and working out the math as part of that is perfectly normal astrophysics, and good science. Read the paper, it's perfectly fine =)
- ryanmcbride 3y agodw bud I didn't read the paper either
- deleted 3y ago[deleted]
- ricardo81 3y agoGiven that a huge amount of mass in the universe is unaccounted for with current models, the idea of masses unaccounted for like this surely are still reasonable possibilities.
- didgeoridoo 3y agoThis is called the MaCHO (massive compact halo object) hypothesis, and it’s pretty close to dead based on the evidence we’ve been able to collect.
- jquery 3y agoOnly "dead" in the sense it can't explain all the missing matter.
- bashinator 3y agoI like Occam's razor as much as anyone, but it really is starting to seem like there might be more than one cause of the phenomenon called dark matter. My understanding is that WIMPs (weakly-interacting massive particles) are in trouble too, as the LHC has failed to produce them in the expected energy regimes.
- chorsestudios 3y agoOr perhaps it is more evidence that a variant of MOND theory is responsible for our observations and there is no dark matter.
- slowmovintarget 3y agoNo current MOND theories account for the state of our observations of the Cosmic Microwave Background, or the ratios of "things" left from nucleogenesis. The biggest gotcha for MOND is there's no way to reverse the direction of gravity, which would be needed to explain large scale structures without dark matter. (With dark matter, you see things moving toward where the matter is. Absent dark matter, you see things moving away from where matter is, because there is only ordinary matter.)
- wawwow 3y ago[flagged]
- nashashmi 3y agoI am convinced it is not a planet. It is the gravitational drag of a moving solar system moving around in a spiraling milky way galaxy around a theoretical black hole in the center.
- ToDougie 3y agohttps://binaryresearchinstitute.org/bri/ https://binaryresearchinstitute.org/bri/ We're in a binary star relationship with https://en.wikipedia.org/wiki/Barnard%27s_Star https://en.wikipedia.org/wiki/Barnard%27s_Star
- nashashmi 3y ago"The alternative explanation advanced by the Binary Research Institute is that most of the observable is due to solar system motion, causing a reorientation of the earth relative to the fixed stars as the solar system gradually curves through space (the binary theory or model)." Glad to know there is a similar theory being proposed.
- Apocryphon 3y agoI love precession and ancient knowledge, thank you for that
- whalesalad 3y agoI read the title as Plan 9 and I think it holds up.
- perihelions 3y agoThis is a very "dense" paper. So: if dark matter is something that annihilates itself, that's a two-particle interaction, so its macroscopic rate scales as density squared ρ². If there's a black hole in the solar system, the dark matter halo immediately surrounding it would be compressed far denser than around a normal object, so it'd have a much brighter annihilation signal. Nothing's known about dark matter annihilation. They speculate, if its cross section is large enough, this annihilation could be observable by gamma-ray telescopes like Fermi or the upcoming CTA. And that would distinguish a black hole from something else. That's all I could understand. It'd be a discovery of a solar system black hole, and new dark matter physics, two-for-one. I'm curious what math led to that funny exponent in eq.(5): ρ(r) ~ r^{-9/4}.
- kurthr 3y agoJust a thought, if a black hole that close were discovered there would be another space race to get there. It just sounds so cool to the politicians (who've seen the movies) that any scientist would have no problem convincing them to loosen the purse strings.
- deleted 3y ago[deleted]
- cgriswald 3y agoFor reference, if it exists, it’s closest approach to the sun is more than six times farther than Pluto’s furthest approach and it took New Horizons nearly a decade of travel time to reach Pluto. A probe would be a decades long project. Sending humans would be effectively impossible.
- cratermoon 3y agoPlanet 9 is Pluto.
- 1970-01-01 3y agoLaunch a probe already! If the anomaly is a planet, ~you've discovered a new planet~ If the anomaly is a black hole, then ~you've discovered a local black hole~ If there is literally nothing there, use the probe for interstellar science.
- codesnik 3y agolaunch where exactly?
- 1970-01-01 3y agoThat's the key, you absolutely need to design a probe where gravity is the guidance system. My take is a primary probe containing hundreds of hyper reflective microprobes, which scatter for billions of miles into space. After a few decades, the primary probe locates where the majority of mircoprobes went, and now you steer the primary probe into Planet 9's gravity well.
- smitty1110 3y agoI think you're underestimating the area you need to search. See the wiki page[1]. There's so much space to look near, you need a much better guess before you can send any probes. A 9k year orbit, that starts at 340 AU, and has a lot of uncertainty in all the parameters, just leaves too much volume to check naively. And that doesn't even get into the fact that there's not enough light out there to feasibly find probes from their reflections. 1: https://en.wikipedia.org/wiki/Planet_Nine https://en.wikipedia.org/wiki/Planet_Nine
- lamontcg 3y agoUhhhh, we've got all those "microprobes" which are all of the known objects in the Solar System. A couple of them are a bit macro though (Jupiter in particular).
- blindriver 3y agoIt would fly directly into the Sun
- readyplayernull 3y agoShouldn't this imply that many star systems also have small blackholes orbiting them, even in between other planets? Just like we found that there are many other earths. If something is possible it will happen again and again in the vast Universe.
- rishav_sharan 3y agoI always had a layman pet theory that Planet 9 is a BH, and not just any BH one but the one who's supernova remains seeded the solar system with heavier elements. Sort of like old grandpa blackhole looking after his/her small kid.
- sojuz151 3y agoBut the normal black holes have a mass greater than the sun
- bell-cot 3y agoSorry, but no. A supernova-born black hole ( https://en.wikipedia.org/wiki/Stellar_mass_black_hole https://en.wikipedia.org/wiki/Stellar_mass_black_hole ) would be far more massive than the sun - so the entire solar system would obviously revolve around it, not the sun. Also, the birth of such a black hole is a supernova explosion - which would not leave any solar-system-forming remains kicking around nearby.
- ballenf 3y agoQuestion from ignorance: if the planets are "moons" around the sun and the sun rotates around P9, how would we know?
- naikrovek 3y agoaren't papers supposed to advance scientific knowledge? this seems to be a paper describing something that could be true, probably isn't, and doesn't advance science as a whole at all.
- mxkopy 3y agoit's arxiv chill
- nequo 3y agoThe paper got published in Physical Review Letters in 2020: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125.051103 https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12... It advances scientific knowledge by providing a testable prediction. The prediction can be used to collect data and determine whether there indeed is a black hole orbiting the Sun beyond Neptune.
- naikrovek 3y ago"here's what we should do" is not advancing science. do the thing, get the results, and if they're significant, then author a paper. I think there is a lot of resume oriented science, these days, because publishing lots of papers looks good on your resume. i mean, we can't let actual science get in the way of our science careers, right? we gotta publish papers telling people what we're thinking about, and how to do those things.
- nequo 3y agoProposing theories and then testing them in data is what the scientific method is. Many theories were proposed before they were confirmed or refuted in data. Einstein's theory of general relativity is a famous example which was proposed before it could be confirmed by Eddington during a solar eclipse. Black holes themselves were also predicted by Penrose and Hawking before their existence was confirmed.
- Mimmy 3y ago
- autokad 3y agoplanet 9 is Pluto
- 303uru 3y agoIt would be cool, it would also be insanely hard to pin down. It would be about the size of a grapefruit but 5-10x the mass of the Earth. And it's way-way-way out there. Oh, and it's basically invisible. But, if we could find it, pin it down, and send out a probe imagine the science we could do!
- brucethemoose2 3y agoIf it was found, its amusing to think about how it could actually be studied. How close could a reinforced probe orbit? Would they just drop test masses in and observe what happens? Maybe drag a kuiper belt object in to make a little accretion disk?
- gigatexal 3y agoMake it a black hole but very big and the 2001 book gets even spookier
- A_D_E_P_T 3y agoFor what it's worth, a primordial black hole Planet 9 is the plot of Stephen Baxter's new book, "Creation Node," which was released about a week ago. (Well, it's the seed of the plot, and then things take a few turns. It's an interesting book!) As an aside, it takes the first visitors about 30 years to reach it, and they've got better tech than what's available to us today. It's pretty far out.
- andrewstuart 3y agoIf so, then it is clearly a gateway to the other civilisations in the galaxy, left there for us to find when our technology is sufficient.