Tuesday, October 8, 2019

A Nearby Black Hole?

About a week ago Salon put up an article suggesting the possibility that the hypothetical "planet nine" might be a small black hole. Small is relative here - planet nine is estimated to be between 5 and 15 times the mass of Earth based on gravitational anomalies measured by astronomers. But the size is also such that scientists believe said black hole would not be large enough to have formed from the usual process of stellar collapse. It must instead be a "primordial black hole" formed during the early days of our universe, an object that so far is only theoretical.

Now, a new scientific paper explores a very different theory: what if Planet 9 were not a planet at all, but rather a primordial black hole — a hypothetical type of small black hole that formed soon after the Big Bang, in the early Universe, as a result of density fluctuations. Such a novel idea might explain why powerful telescopes have never detected so much as a flicker from the theoretical distant, massive planet. Likewise, black holes do not emit visible light at all; rather, they absorb all photons that pass their event horizon, while occasionally emitting energy in the form of (theorized but never directly observed) Hawking Radiation.

In the paper, astronomers Jakub Scholtz of Durham University and James Unwin of University of Illinois at Chicago theorize that the elusive Planet 9 could be an old, very small black hole. "Capture of a free-floating planet is a leading explanation for the origin of Planet Nine, and we show that the probability of capturing a PBH [Primordial Black Hole] instead is comparable," the astronomers write in the paper. The two scientists reached this hypothesis in a novel way, by observing that two different phenomena could be related: first, the observation of peculiar orbits of trans-Neptunian objects (meaning bodies orbiting our sun beyond Neptune), which might be explained by the presence of a distant planet with 5 to 15 times Earth's mass; and second, the number of "microlensing events," meaning telescope images that had been distorted by gravitational lensing of the kind caused by black holes or other massive, compact objects.

"There is a growing body of observational anomalies connected to the orbits of trans-Neptunian Objects (TNOs)," the paper states. "These observations have been taken as evidence of a new ninth planet in our solar system, called Planet 9, with mass of [about] 5 − 15 [Earth masses] and orbiting around the Sun at a distance of 300−1000" times the Earth to Sun distance. Second, there is set of gravitational anomalies recently observed by the Optical Gravitational Lensing Experiment (OGLE)," they continue. "The lensing objects are located towards the galactic bulge, roughly 8 [kiloparsecs] away. These events correspond to lensing by objects of mass [of about] 0.5 [Earth masses] to 20 [Earth masses] and could be interpreted as an unexpected population of free floating planets or Primordial Black Holes."

While this is mostly a straight-up science story, there are some potentially interesting implications for esoteric disciplines like astrology if a black hole were actually found in orbit around the Sun. If we subscribe to a model of astrology based on optics, for example, no light would be directly projected by this object. However, the microlensing effects in which light traveling from outside the solar system can be "bent" in some cases by the gravitation could be significant. On the other hand, a model based on gravitation and/or orbital cycles would not be impacted at all.

There's one more scientific implication of this that is really fascinating, at least to me. Cosmologists have speculated on what it would take to build an actual time machine, and the only workable solution appears to be creating a black hole. We obviously don't have the technology to do that just yet, and even if we could the math supporting the concept includes a very specific limitation - you could never travel back in time to a moment before said black hole was created.

But a primordial black hole, that dates back to the beginning of the universe? That's a totally different thing. In theory, once we develop a spacecraft that can reach the black hole, travel in time is actually not that difficult. The black hole needs to be rotating (but it very probably is, like everything else in the solar system) and you need to map a helical course that passes in and out of the virtual event horizon (which is the point where you would be pulled in if the black hole were NOT rotating and therefore dragging space along with it) but basically that's the whole process.

You do need a spaceship capable of relativistic speeds to exploit this effect, so that's another technological limitation. The black hole itself would also be tiny at a mass of only 10-15 Earths. But in many ways the technological challenge is not nearly as insurmountable as the faster than light travel that would be needed to travel to Earth from distant star systems. If you're still following along, that in turn means that the "Repo Man" scenario of UFOs as time machines suddenly becomes a whole lot more plausible - because it requires less advanced technology than long-haul spaceflight.

It also could answer another question that UFOlogists haven't really been able to answer satisfactorily. If aliens are coming to Earth, why don't they just announce their presence in some public manner? There might be some sort of "prime directive" policy that they employ about not interfering, but if that's all it is I find it hard to believe that every alien and/or group of aliens would follow it - just like it's practically impossible for even three people to keep a conspiracy under wraps.

With time travel, though? Non-intervention would be paramount. Change the wrong thing or make too big a splash and you might never be able to get back home. That makes it in everyone's best interest to keep out of the spotlight, or even time visits to coincide with UFO sightings that are know to have occurred. The public doesn't take aliens seriously these days so they're the perfect cover - just like the idea of the fae, for example, might have been employed in the same way centuries ago. Or, say, "phantom airships" in the late 1800's, for which records of sightings also exist.

All of that might be premature, of course. We don't have much data supporting this new hypothesis, and probably the only good way to get it would be to send a space probe out to where "planet nine" is supposed to be located. Black holes in other parts of the universe are identified by detecting x-ray radiation emitted by their accretion disks. But the Kuipper Belt is a lonely place without much material for a black hole to consume. So that method is likely ruled out.

I'll keep following this story and keep all you readers apprised of any new developments. It it works out, this could be a huge discovery.

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