With the Gravitational perturbations among Neptune, Uranus & pluto, Is there anyway to know conclusively that there is no rogue Blackhole roaming the solar system? The Event Horizon may be very small, so no Mass falling in right now or for millions of years to increase the Surface Area, thereby, the Event Horizon...Thanks!
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1$\begingroup$ I think that scientists believe that the smallest black hole would be 1.5 - 3 times the mass of the sun. Surely astronomers would have noticed the gravitational pull of such an object on the other planets. symmetrymagazine.org/breaking/2008/04/01/… $\endgroup$– foolishmuseCommented Aug 21, 2023 at 22:10
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2$\begingroup$ @foolishmuse that would be assuming it was a collapsed star that formed the black hole 'recently.' If it were created ages ago & emitting Hawking radiation, it could be much smaller now. Either way, the remainder of your comment is correct: a sufficiently large object would be quite easily detected via gravitational forces. $\endgroup$– Kyle KanosCommented Aug 21, 2023 at 22:17
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$\begingroup$ @KyleKanos If the smallest possible star collapsed to the smallest possible astrophysical black hole at the earliest possible time after the Big Bang (and if the Hawking radiation actually existed), then the amount of the evaporation by now would be unmeasurably small. Thus, your comment applies only to hypothetical primordial black holes whose existence is a mere speculation. $\endgroup$– safesphereCommented Aug 23, 2023 at 3:21
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$\begingroup$ But then, that does not preclude us in thinking & building any preventive measures 'just-in-case' there exists one. We (Solar System) are going through the Galactic Space where once a Supernova explosion has happened ( for the past 15 years or so is what I read) as there are remnants detected..could there have been Blackholes created then Lurking? $\endgroup$– Gopal AnantharamanCommented Aug 23, 2023 at 20:10
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$\begingroup$ to support my case... "Experts suspect that the Local Bubble was “carved” by multiple supernovae in the Scorpius-Centaurus OB Association star cluster. Material from the stars in this cluster are thought to have contributed to the formation of the stellar dust clouds that make up the local interstellar cloud." Here...cosmic.news/… $\endgroup$– Gopal AnantharamanCommented Aug 23, 2023 at 21:17
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There is no way to conclusively rule out the presence of a black hole in the Solar System. Sure, we can rule out the presence of large, stellar mass black holes because they would cause large and very obvious perturbations to observed orbits, even if they were thousands of au from the Sun.
However, there may well be small gravitational perturbations indicating the possible presence of planetary mass objects in the outer Solar System well beyond Pluto. If such an object were a black hole it would not have been formed as the endpoint of stellar evolution, but as a "primordial black hole".
There are limits, from microlensing observations, that such objects are not likely to form a large fraction of dark matter, at least those of planetary masses. But that doesn't mean that one couldn't exist in the Solar System. Confirming the presence of such an object might be very difficult without flying some sort of probe towards its suspected location; the same perturbations could be caused by a small, dark planet. Proving the absence of such an object does not sound feasible
Ditto for even smaller black holes, which could be common and may form part of the non-baryonic dark matter. We might be lucky and discover one, but proving that none exists does not seem possible.
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$\begingroup$ “proving that none exists does not seem possible” - Exactly the same can be said about the existence of magical unicorns. Logically, one doesn’t need to prove that hypothetical things don’t exist. Anyone can come up with any number of things that he thinks may or should exist according to him. This puts no obligation on anyone else to prove that they don’t exist. This is unfalsifiable and therefore not a subject of science. From the standpoint of physics, hypothetical things don’t exist by default until they’ve been experimentally confirmed or at least proven to be predictive. $\endgroup$ Commented Aug 23, 2023 at 3:41