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If Planet Nine Is a Tiny Black Hole, This Is How to Find It
- deleted 6y ago[deleted]
- qubex 6y agoThis is both a very obvious and a very interesting proposal: locate an apparent source of gravitation by observing the gravitational effects it has upon a fleet of small (almost point-like) craft. However, there’s something that niggles me. If it’s a primordial black hole that has been captured by the sun, why is it (as far as I understand) apparently in the same plane (ecliptic) as all the other major bodies in the solar system? It makes sense for all planets & cetera to be in the same plane because they all originated in the same swirling (flat) planetary nebula... but a captured object could potentially orbit at any inclination (and, considering how massive it is, I doubt it would be coerced into being coplanar by comparatively minor intersections with light bodies such as those present in the Oort Cloud, which are arranged roughly spherically anyway).
- ianai 6y agoIt may have just happened to line up correctly. But gravity is going to pull it toward the center of mass for the whole solar system. If it were too massive to be pulled in like it wouldn’t be the hard to spot phenomenon that it has been to this point.
- 7373737373 6y agoIf SpaceX can afford to put a car into orbit around the sun as a publicity stunt during rocket testing, I wonder how much this would cost. Edit: Probably around $100MM: https://www.spacex.com/about/capabilities https://www.spacex.com/about/capabilities for the launch, several $100MMs for the (space based?) accelerator and spacecraft, and then a few more for operations and research. Yeah, $1 billion as described in the article seems like a good estimate: https://arxiv.org/pdf/1805.01306.pdf https://arxiv.org/pdf/1805.01306.pdf Since knowledge arising from this experiment will probably only be useful as a common good, there aren't really incentives for this to happen, unless governments decide to go through with it. NASA's 2020 budget is only $22.6 billion: https://en.wikipedia.org/wiki/Budget_of_NASA https://en.wikipedia.org/wiki/Budget_of_NASA The Apollo program cost $153 billion: https://en.wikipedia.org/wiki/Apollo_program#Costs https://en.wikipedia.org/wiki/Apollo_program#Costs Okay, this thing is ten times further away from the sun (400 AU) than Pluto (40 AU), 80 times the distance of Jupiter from the sun (5 AU), very far. Still, it's much closer than our next closest star, Proxima Centauri, which is 265612 AU away, or over 660 times the distance of Planet 9.
- ramraj07 6y agoIf we get actual evidence supporting that there could indeed be a black hole within our solar system, that seems like a true opportunity to advance our knowledge of physics. The potential to study a real black hole up close seems worth massive investments given what kind of breakthroughs could he possible from it.
- lenkite 6y agoAlso a lovely, future power-source.
- 7373737373 6y agoHow would this work?
- basementcat 6y agoAmplified superradiant scattering is one option. https://en.wikipedia.org/wiki/Black_hole_bomb https://en.wikipedia.org/wiki/Black_hole_bomb
- sbierwagen 6y agoIf it's rotating, you can extract its rotational energy using the https://en.wikipedia.org/wiki/Penrose_process https://en.wikipedia.org/wiki/Penrose_process Additionally, all black holes constantly emit Hawking radiation https://en.wikipedia.org/wiki/Hawking_radiation https://en.wikipedia.org/wiki/Hawking_radiation Unfortunately for the planet 9 black hole, it only loses mass on balance it's below a certain size, about 0.007 earth mass. Primordial black holes of that size, if they exist, would be quite useful. However, they would be monumentally hard to find: the black hole above would be 62 micrometres in radius, and have an event horizon temperature of 2.93K. Assuming no changes to the cosmic microwave background, this black hole is unstable: it will eventually radiate away all its mass and disappear. You'll be waiting a while for that to happen, at 20 picowatts, it'll take 1.9e35 gigayears to die.
- codethief 6y ago
- whatshisface 6y agoDisks minimize gravitational potential energy when angular momentum is held constant. Forming solar systems have ways of radiating energy, but they can't really radiate angular momentum. That's why galaxies and solar systems tend to be disk-shaped. The disk shape is very general and comes from fundamental principles, so I don't see why it couldn't continue to apply when one bit of mass in the system just so happens to be a black hole.
- infogulch 6y agoYes but the mechanism that makes the disk form from the general cloud is physical collisions, two "particles" that have opposite inclinations compared to the average hit each other and end up closer to that average plane. But basically nothing can hit a black hole that size so where would it get its momentum from?
- whatshisface 6y ago>But basically nothing can hit a black hole that size Why would that be true? Individual gas molecules manage to disk-ify and turn in to planets, I don't see why a black hole couldn't. This would presumably happen in the early stages of system formation when there was a lot of stuff flying around separately.
- qubex 6y agoObviously, nothing can ‘hit’ a black hole: anything that does just gets absorbed by it as it falls in. However, more broadly speaking, the angular momentum is conserved, so the result would be more or less the same. However, given the enormous, ridiculous difference of relative masses (and therefore angular momentum) in the case of black holes and some gas particles, I think my initial point stands.
- whatshisface 6y agoThe black hole would interact with many gas particles, not just one. How many would be reasonable? Well, Jupiter is a gas giant and it had to form somehow. Yes, conservation of momentum is the right way to think about that.
- beamatronic 6y agoIt’s the shotgun approach to detecting gravity, literally
- jayd16 6y agoCould such a black hole have influenced the current orbiting plane or do we believe it was captured too late?
- qubex 6y agoAbove he mentions that “if it were there from the start it would obey the same rules”... so I guess he does... though where evidence for this comes from isn’t clear from me (unless it’s some kind of circular logic along the lines of “if it is in the same plane then it must have been there from the start, and if the perturbations in the Oort Cloud objects is consistent with an object in the ecliptic plane, then it must be that if t’s a black hole it was captured early on”, or something like that. I dunno, to be honest. I don’t want to appear like I’m a polemicist with an axe to grind and sour grapes, but as I said in my original post... there’s something about this whole thing that just confuses me a bit.
- mabbo 6y agoI wonder if the influence of the rest of the solar system wouldn't impact it. Consider: the reason we think there is anything out there is because we see a lot of bodies that aren't following the expected pattern. For every action, there is an equal and opposite reaction, so perhaps those out-of-order bodies also pulled Planet 9 closer to the standard plane. Repeat a few billion times over a few billion years, each little tug moving it more in-line (and the rest of the solar system out-of-line). This still depends on it starting relatively close to the same plane, but there may be selection bias involved. Those bodies that met with the solar system and weren't aligned well with the plane may have been more likely to escape again. The one (or ones) remaining are the ones that were well-aligned.
- sandworm101 6y ago>>> about 5 centimeters across. Consequently, it is almost impossible to spot with a telescope. If it is 5cm across, then it should be rather bright (Hawking radiation). While still tiny, it wouldn't be black.
- speakeron 6y agoThis calculator[1] indicates that the temperature for a 2.5 cm radius black hole should be 0.007 K. So below the temperature of the cosmic background (2.7 K). [1] https://www.vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator https://www.vttoth.com/CMS/physics-notes/311-hawking-radiati...
- alextheparrot 6y agoDoes this mean that the cosmic background could be adding energy to the blackhole (Maybe helping with stability?)? I'm not sure how temperature and heat transfer would work in this context. Edit: For those interested, there is an entire article on "Black Hole Thermodynamics" on Wikipedia (https://en.wikipedia.org/wiki/Black_hole_thermodynamics https://en.wikipedia.org/wiki/Black_hole_thermodynamics)
- qubex 6y agoYou are correct: a black hole whose Hawking temperature is less than that of the cosmic background radiation is “colder” than the space it is immersed in and consequently absorbs energy (and mass-energy equivalence) from the heat bath it is immersed in. The easiest way to envision it is that the black hole swallows up photons of the microwave background radiation and is emitting less energy as Hawking radiation, leading to a net imbalance in the black hole’s favour. Of course eventually the expanding universe will drop the temperature of the cosmic background radiation further and the process will reverse.
- tjpnz 6y agoThe article talks about a scattergun approach and that detection would require getting within a few dozen AU of the object. That would require a huge number of probes and a means of coordinating beams spread across multiple continents. Wouldn't it be easier to determine the objects rough position ahead of time?
- jonshariat 6y agoSo could something like Starlink be used to detect things like this?
- qubex 6y agoNo. Who implied that?! Starlink will be a network of very near earth communication satellites. This black hole, if it exists, is far far further out than Pluto. The probes wouldn’t be even remotely reminiscent of Starlink satellites either.
- jonshariat 6y agoIt was a question. I am not an expert and so I asked. Also I said "like this". If you have a mesh of satellites around the earth and used that data along with other astronomy tools, I'm sure there are other things we can learn.
- nafey 6y agoDoes anyone else feels like that projects like these should be avoided unless we are certain that our corner of the galaxy is not part of a larger dark forest? The consequences of such actions can be catastrophic. If we do send out probes they should be designed to disintegrate after some fixed period of time.
- NikolaeVarius 6y agoI too choose to not use anything that radiates electromagnetic waves on the off chance aliens detect them.
- nafey 6y agoElectromagnetic waves will die off and become indistinguishable from background radiation after a certain distance. Not so much for physical objects.
- maxander 6y agoThe famous Douglas Adams quote is relevant: "Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." The odds of an alien civilization picking up one of our probes, even if we send out thousands of them, is preposterously small. Imagine trying to such an object if it had been left floating at an unknown point in the ocean; now consider how much bigger interstellar space is than Earth's oceans.
- gorgoiler 6y ago“It’s like trying to find your car keys in a field using a pair of binoculars.” I cannot remember where this quote came from, but I think it was something to do with a missing Russian cargo vessel in the Atlantic.
- qubex 6y agoThese a few tiny craft sent off into the depths of interstellar space. The chances of anybody ever picking one up are so ridiculously small, so utterly infinitesimal, it doesn’t even need to be thought about. Not only that, but even if they were picked up, they’d only ever be picked up after coasting through space for millions, possibly tends of millions of years, and in turn it will take hundred of thousands of years for them to make their way here (assuming they have highly relativistic propulsion systems). So... no.
- austincheney 6y agoCould a black hole orbit our tiny yellow dwarf sun? Even if it were tiny for a black hole it would be hard to imagine that it would have less mass than our sun. If it had more mass than our sun wouldn’t our system be a binary system, and if so it would suggest a black hole is not really a satellite of the sun. How small can a black hole be and still qualify as a black hole? I guess a better question is what is the least massive black hole observed and what is the smallest current theories allow? I have no idea what I’m talking about so all of that is probably wrong. I am just not able to wrap my head around it.
- qubex 6y agoAny gravitating body whose size is less than its Schwarzschild radius becomes a black hole. As the article remarks (can’t quote it exactly because I’m using a client that has an irksome modal interface) some of the ideas floated is that this black hole could be about fifteen centimeters across, and have the a mass of a very large planet. Science fiction fodder notwithstanding, from a suitable distance this kind of body would behave exactly like any other gravitationally interacting body, and would perfectly obey the usual laws of motion (Einstein’s General Relativity if you’re insisting on investigating it up close or in minute detail, classical Newtonian dynamics if you’re observing on a broader scale). It has mass, it has inertia, and it would be interacting gravitationally as the textbook “product of masses, reciprocal of square of distance” law. It would be a big, dark, featureless bowling ball with the mass comparable to a gas giant.
- maxander 6y agoThere were theoretical reasons to suspect that the Large Hadron Collider, by ramming particles together with sufficient force, could create microscopic black holes with approximately the mass of an atom. This turned out not to occur, but yes, at least in theory black holes can be very small indeed.
- Sharlin 6y ago"Theoretical" is overselling it, you need novel nonstandard physics to get black holes out of the LHC. Indeed standard physics cannot predict LHC black holes because the Standard Model and general relativity are famously incompatible at these scales. Moreover, if Hawking radiation exists, as is now widely believed, the lifetime of a hypothetical atom-mass black hole would be much, much less than a Planck time.
- lenkite 6y agoDiscovering a mini black-hole at the boundaries of our solar system would also mean discovering a lovely power source just waiting to be tapped, right ?
- the8472 6y agoBlack holes themselves do not generate power. If they have an accretion disk disk - i.e. they're feeding on matter - then that can be quite good at converting mass into radiation which you can then harvest. But you could also do that with the radiation of a more easily accessible mass-energy converter: the sun
- gorgoiler 6y agoYou are both talking about the Penrose Process, or perhaps only one of you is? https://en.m.wikipedia.org/wiki/Penrose_process https://en.m.wikipedia.org/wiki/Penrose_process
- Insanity 6y agoIt's such an unimaginable thing. 5cm across, yet "super" massive (not SMBH).
- knzhou 6y agoWhen the original paper about planet 9 being a black hole came out a year ago, everybody thought it was a cool-sounding but just completely wild idea -- both physicists and pop science articles. Not impossible by any means, but not within the top 250 new physics ideas in plausibility. Then the discussion died down. I figured it would end up being one of those forgotten but cool gems. Then the most authoritative string theorist in the world, who hasn't worked on anything relating to experiments in decades, suddenly writes a very short, simple, single-author paper to use this idea to promote Yuri Milner and Mark Zuckerberg's space probes. Now it's the conjunction of two crazy ideas, and it's really taking off. I just don't know why this is happening, or what to make of it.
- qubex 6y agoOf course if there was enough dust in interstellar space to reflect a laser beam (as happens when we see the traces of glowing beams shone through carbon dioxide gas) we could just prove the heavens with laser beams until suddenly we saw a beam bend. Unfortunately that isn’t the case so we have to fling stuff at it and see if they veer off track.
- Sharlin 6y agoWe do have microlensing though: https://en.wikipedia.org/wiki/Gravitational_microlensing https://en.wikipedia.org/wiki/Gravitational_microlensing
- robocat 6y agoYou can’t easily linearly scan space for a moving target, among other show-stopper problems.
- qubex 6y agoNo, but since using satellites on trajectories you hope will be perturbed is essentially ‘scanning’ anyway, it would be preferable to do it with a light-beam than with physical objects.
- T-A 6y ago
- tejtm 6y agoA well characterized black hole in our solar system would be our (one way) ticket out of here. The velocity we could gain would be limited to the vessel integrity. And thanks to math, being able to choose approach trajectories means we could go anywhere. Well worth looking real hard just in case it does exist.
- tqkxzugoaupvwqr 6y agoThe object is theorized to have between 5 and 10 times the mass of Earth. Jupiter has circa 1000 times the mass of Earth. Wouldn’t Jupiter be suited much better for slingshots?
- T-A 6y agoAssuming that you're thinking of the Oberth effect, it's no miracle worker. In the (non-relativistic) impulsive burn approximation you gain a speed factor sqrt(1 + 2*v_escape/delta_v) [1]. With v_escape = c and delta_v = 10 km/s that's a factor 245, for a final speed of 2450 km/s. That will get you to Alpha Centauri in 535 years. [1] https://en.wikipedia.org/wiki/Oberth_effect https://en.wikipedia.org/wiki/Oberth_effect
- Craighead 6y agoCan this be chained with other bodies in the solar system?
- tejtm 6y agoAlas I am not well enough educated on the subject to have ever come across that particular term. (I do wish KSP was available on *nix) And I do see your point as it pertains to solid matter. How ever as a layperson I am at least vaguely aware that there are hyper velocity stars, some observed w/delta-v close to 10% of C if memory serves ... Which would indicate to me that having a gravity well we can delve arbitrarly deep into has profound implications compared to gravity wells where it you go too deep you run into clouds or dirt. For example the vessel could be paired, co-orbiting with a sacrificial mass that is dumped into the hole while the vessel leaves at at factor greater than a few hundred.
- sbierwagen 6y agoFrom the paper: >However, the .01 c mission sketched in [10] has a spacecraft mass of only 6.6 mg, divided between the sail and the payload. Multiplying this by 100 while keeping the sail mass fixed leaves a payload mass of barely .65 grams. Oof. That's not a lot.
- mmmBacon 6y agoWouldn’t a black hole that small evaporate due to Hawking radiation?
- Dylan16807 6y agoNo. At even 1% of Earth's mass, a black hole's already down to 2 Kelvin of output, across a surface as big as a grain of very fine sand. It would take more than 10^44 years to evaporate on its own, but since the cosmic microwave background is 2.7K it would actually grow over time. For some other data points, a thousand ton black hole would explode in 84 seconds. A million ton black hole would last 2600 years as an unimaginably hot point five hundred times smaller than a proton. A billion ton black hole would last 2.6 trillion years as an unimaginably hot point twice as big as a proton.
- baja_blast 6y agoPlanet Nine is a Mass Effect Relay