Is Planet Nine a Primordial Black Hole?

Two of the greatest mysteries of astrophysics
today is dark matter and black holes. Regarding dark matter, It’s simply not known
what this material is, other than that it has a profound effect gravitationally on the
rest of the universe. Candidates for what it could be include things
like undetected subatomic particles that only interact with other particles through gravity,
and no other way. But another candidate seems to stand out,
or at least may for a portion of the missing mass in the universe. It’s the concept of primordial black holes. And further, it’s plausible that one could
be rather close to us. Perhaps uncomfortably so. The concept of a primordial black hole goes
back to the 1960’s, and was first studied in depth by Stephen Hawking in the early 1970s. The idea is this, during the initial aftermath
of the big bang, literally about one second afte,r it’s thought, densities were such
that black holes could form that were far smaller than the stellar collapse black holes
that we’re most familiar with today. It’s thought that these types of black holes
would generally not have been very long lived in terms of the age of the universe under
a certain mass, and should have mostly evaporated by now. However, if string theory is correct, this
may lengthen the life of a tiny primordial black hole. But, above a certain mass, they might well
still be around. And with ones that are gaining mass in high
density areas, they may have even served as the seed cores for such things as supermassive
black holes at the centers of galaxies. But, the possibility of primordial black holes
explaining dark matter recently took a major hit. Earlier this year an international team studied
the Andromeda galaxy looking for microlensing events. The idea here is that the immense space between
us and Andromeda should be full of primordial black holes, and they would bend the light
from the stars in Andromeda behind them in such a way as to be detectable. The results were interesting to say the least. While they essentially eliminated primordial
black holes as a major component of dark matter through a lack of detections, they did see
one that might have been a primordial black hole. This would suggest that yes, they exist, but
they are significantly rarer than previous estimates. The team cautions however that certain other
phenomena might account for this single detection, and that further study is needed to determine
if it is indeed a primordial black hole. While contentious and hotly debated, as are
many things regarding black holes, the concept of primordial black holes is still out there,
if not a major candidate for dark matter. And if a recent paper ends up holding true,
there may be one much closer than anyone ever anticipated. In a paper by Jakub Scholtz and James Unwin,
they detail that the strange features seen with some of the objects in the outer solar
system may not be due to a ninth planet lurking out there at all, but rather a primordial
black hole. This ties into the Planet 9 story, see the
videos on this channel for that topic, and this hypothesis is based on two gravitational
anomalies of unknown origin that have been detected in the outer solar system and in
deep space. One is a strange gravitational effect on certain
transneptunian objects in the outer solar system, leading to speculation that there
may well be a ninth planet, or Planet 9, far out in the outer solar system. This planet has not yet been directly detected,
if it’s there at all, but could represent either a primordial planet ejected from somewhere
the inner solar system early in its history, or possibly even a captured rogue planet originally
from somewhere else entirely. Trouble is, it’s somewhat difficult to have
a planet in the predicted orbit, though not impossible. The problem is that to form a planet that
far out you need material, and the density of material in the outer solar system isn’t
very high, making it unlikely that a large planet could form that far out. Another option is that it might be either
an ejected planet from somewhere else in the solar system, or even a planetary core from
a forming gas giant that was tossed out, but again there are problems with the physics
of how it managed to go into an outer orbit without leaving the solar system entirely. The last option for a planet is the captured
rogue planet idea. Space is very likely full of wandering planets
that get tossed out of their original systems. It may be that the solar system captured one,
though it’s not very likely for such a thing to have happened, but it’s certainly not
impossible. The search for Planet 9 continues, but there’s
no reason to say that a primordial black hole couldn’t be captured in the same way, and
at similar odds. The other anomaly is something else entirely. These are distant, unexplained microlensing
events. Observed by the OGLE experiment, whatever
is causing these, they are near the galactic plane and are gravitationally microlensing
objects behind them. This could suggest a population of free floating
planets passing by in deep space, which is interesting enough, but could also be an indicator
for primordial black holes. The researchers noticed that the predicted
mass of planet 9 is very similar to the predicted mass of a primordial black hole, so the two
ideas may be linked. Perhaps most interestingly, the authors give
a way for how such a black hole might be detected. If it exists, the primordial black hole would
be surrounded by accumulated dark matter. If that dark matter were to annihilate with
anti-matter, then x-rays and gamma rays would be emitted, and should be detectable. But even if it weren’t detected directly,
if no evidence of planet 9 is ever found, and the anomalies in the outer solar system
continue to pile up, it will lead to a very interesting mystery indeed. On the other hand, if a tiny lack hole lurks
in the outer solar system, literally on our doorstep, it would revolutionize the study
of black holes as we know it. Thanks for listening! I am futurist and science fiction author John
Michael Godier currently requesting that the primordial black hole please vacate the solar
system to at least 10 light-years distance, or the nearest convenient empty patch of space
nowhere close to Earth. We have an enormous star that’s going to
red giant, two huge scary looking gas giants, asteroids, comets, interstellar oumuamuas
passing through, gamma ray burst possibilities … in other words, we have enough to worry
about already. We don’t need to add a lurking close black
hole to the list. Worries everywhere. So if you can’t sleep at night, try one
of my books which you can get at your favorite online book retailer, and subscribe to my
channels for regular, in-depth explorations into the interesting, weird and unknown aspects
of this amazing universe in which we live.


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