WEBVTT - Does Our Solar System Contain a Primordial Black Hole?

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<v Speaker 1>Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff,

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<v Speaker 1>Lauren bog ol Bomb. Here there's something big lurking in

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<v Speaker 1>the frozen hinterlands of our Solar System that appears to

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<v Speaker 1>be tugging at the tiny worlds beyond the orbit of Neptune.

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<v Speaker 1>The object is assumed to be a hypothetical world called

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<v Speaker 1>Planet nine, which has an extremely far flung orbit around

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<v Speaker 1>the Sun and causes all kinds of gravitational chaos out

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<v Speaker 1>there in the dark. But as the search for Planet

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<v Speaker 1>nine wears on and astronomers have yet to so much

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<v Speaker 1>as get a glimpse of it, some researchers are pondering

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<v Speaker 1>what else the object could be. Might it not be

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<v Speaker 1>a planet at all? Could it be a primordial black hole?

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<v Speaker 1>The Solar System is a big place, and while our

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<v Speaker 1>astronomical techniques are rapidly advancing, many tiny bodies in the

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<v Speaker 1>outer Solar System have yet to be found. Planet nine

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<v Speaker 1>is thought to be a rather more substantial object, however,

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<v Speaker 1>with a massive around five to ten Earth masses scooting

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<v Speaker 1>around the Sun at an average distance of four to

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<v Speaker 1>eight hundred astronomical units or a US, since one AU

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<v Speaker 1>is the average distance at which Earth orbits the Sun.

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<v Speaker 1>That's ten to twenty times the orbital distance at which

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<v Speaker 1>Pluto orbits the Sun, So if it exists, planet nine

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<v Speaker 1>takes between ten thousand and twenty thousand years to complete

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<v Speaker 1>just one orbit. The possibility of a large world orbiting

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<v Speaker 1>the Sun at such a huge distance is captivating. Studies

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<v Speaker 1>of other star systems reveal that exoplanets between the masses

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<v Speaker 1>of Earth and Neptune are relatively common. Why our Solar

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<v Speaker 1>System doesn't contain a world with this mass range is

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<v Speaker 1>a puzzle. But if Planet nine really is out there,

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<v Speaker 1>it would be a profound historic discovery that would reshape

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<v Speaker 1>our understanding of the system of planets that orbit our Sun.

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<v Speaker 1>Suffice to say, any planet with an orbit this extreme

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<v Speaker 1>would be very difficult to spot, but astronomers are scouring

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<v Speaker 1>infrared surveys with hopes of seeing a distant object slowly

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<v Speaker 1>crawl across the sky. If it's out there, planet nine

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<v Speaker 1>should be emitting infrared radiation entered leaking from the planet

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<v Speaker 1>since its formation, but so far, apart from the gravitational

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<v Speaker 1>effects of something in the outer Solar System, there's precious

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<v Speaker 1>little direct evidence for Planet nine existence. Enter the black

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<v Speaker 1>hole hypothesis. In September of twenty nineteen, astronomer's Jacob Schultz

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<v Speaker 1>of Durham University and James Unwin of the University of

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<v Speaker 1>Illinois Chicago published a new study describing their alternative hypothesis

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<v Speaker 1>that the gravitational weirdness in the outermost reaches of the

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<v Speaker 1>Solar System isn't being caused by a planet at all. Instead,

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<v Speaker 1>they pointed to the potential presence of a primordial black hole,

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<v Speaker 1>a theory that's caused a bit of a stir No.

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<v Speaker 1>This kind of black hole does not pose a danger

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<v Speaker 1>to the rest of the Solar System, it would be

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<v Speaker 1>too small for that, but in the distant regions of

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<v Speaker 1>our Solar System its impact would be significant. The only

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<v Speaker 1>evidence we have for Planet nine existence are the gravitational

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<v Speaker 1>effects it's having on trans neptune objects, and black holes

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<v Speaker 1>are the most gravitationally endowed objects in the universe. After all,

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<v Speaker 1>Primal real black holes are the most ancient kind of

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<v Speaker 1>black hole. They're hypothesized to have formed right after the

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<v Speaker 1>Big Bang. Density fluctuations in the early universe would have

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<v Speaker 1>rapidly formed black holes of all masses. These ancient objects

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<v Speaker 1>would have been flung throughout the cosmos, and over time

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<v Speaker 1>they would have slowly evaporated via Hawking radiation, smaller ones

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<v Speaker 1>popping out of existence first. But let's back up a step.

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<v Speaker 1>Why designed to think that some extreme object is out there?

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<v Speaker 1>In planet Hunter's Constantine, Batiguon and Mike Brown of Caltech

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<v Speaker 1>announced their discovery of a group of very distant trans

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<v Speaker 1>Neptunian objects that were all strangely clustered and moving with

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<v Speaker 1>similar orbital alignments. Their orbital alignment was also weirdly tilted,

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<v Speaker 1>so it appeared they were all being corralled by gravitational

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<v Speaker 1>interactions with a larger planetary body. But no other large

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<v Speaker 1>planetary body exists in that region, So Batigan and Brown

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<v Speaker 1>hypothesized than an as get to be discovered planet was

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<v Speaker 1>out there, and so the hunt began. While many theories

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<v Speaker 1>of cosmic evolutions suggest that primordial black holes should exist,

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<v Speaker 1>we have yet to directly observe one, though there is

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<v Speaker 1>some compelling indirect evidence. Take, for example, micro lensing events,

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<v Speaker 1>the transient brightening of stars caused by a massive object

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<v Speaker 1>passing in front of them, causing a brief brightening via

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<v Speaker 1>the curvature of space time, creating a sort of magnifying lens.

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<v Speaker 1>Analysis of these micro lensing events suggests that there's a

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<v Speaker 1>population of small black holes out there with no other

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<v Speaker 1>visible clues except for their gravitational impact on space time.

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<v Speaker 1>Schultzon Unwin took a fresh look at the trans Neptune

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<v Speaker 1>object peculiarities and simulated what would happen if a black

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<v Speaker 1>hole with a mass of between five and ten Earth

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<v Speaker 1>masses had an extreme orbit around the Sun. Sure Enough,

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<v Speaker 1>their models suggest that a primordial black hole with a

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<v Speaker 1>mass within this range would cause orbital perturbances like the

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<v Speaker 1>ones already observed in the population of trans Neptune objects.

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<v Speaker 1>This could also explain why little optical or infrared observational

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<v Speaker 1>evidence for planet nine exists. A primordial black hole would

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<v Speaker 1>generate neither signal. In fact, if a black hole is nearby,

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<v Speaker 1>it may also be dragging around a cloud of dark

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<v Speaker 1>matter that could be generating different types of radiation. The

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<v Speaker 1>researchers therefore suggest, based on their findings, that the experimental

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<v Speaker 1>program needs to be expanded, including searches for high energy

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<v Speaker 1>cosmic rays like X rays and gamma rays coming from

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<v Speaker 1>moving sources. While this is an interesting avenue of study,

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<v Speaker 1>replacing a hypothetical planet with a hypothetical type of black hole,

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<v Speaker 1>maybe over complicating the mystery of planet nine. We spoke

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<v Speaker 1>with Mike Brown. He said, could a black hole explain

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<v Speaker 1>the gravitational effects we are seeing in the outer Solar System? Absolutely?

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<v Speaker 1>All we know is that there is a six earth

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<v Speaker 1>mass something out there, and we don't know what the

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<v Speaker 1>something is. Brown points out that a planet would be

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<v Speaker 1>the most obvious something, but as long as it has

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<v Speaker 1>a mass of a few earths, it could be anything.

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<v Speaker 1>But the plausibility of it being an anything other than

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<v Speaker 1>a planet is extremely low, to say the least. With

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<v Speaker 1>tongue in cheek, Brown added, it might be a six

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<v Speaker 1>earth mass hamburger or a burrito, but yes, it might

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<v Speaker 1>also be a six earth mass black hole. The physics,

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<v Speaker 1>of course, don't care one bit what the six earth

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<v Speaker 1>masses are made of. You could equally well hypothesize that

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<v Speaker 1>every exoplanet that we only detect via the radial velocity

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<v Speaker 1>method is a black hole. Is it possible? Yes? Does

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<v Speaker 1>it make any sense in the universe? No. While investigating

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<v Speaker 1>other gravitational sources of what may be messing with transniptune

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<v Speaker 1>objects is good science, it's more likely the planet nine

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<v Speaker 1>is a planet and not a primordial black hole. Astronomers

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<v Speaker 1>just have to keep searching, and there's a growing consensus

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<v Speaker 1>that it will be discovered in the not so distant future.

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<v Speaker 1>We'll keep you updated. Today's episode was written by Dr

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<v Speaker 1>Ian O'Neill and produced by Tyler Klang. Brain Stuff is

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<v Speaker 1>production of I Heart Radio's How Stuff Works. For more

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<v Speaker 1>on this and lots of other topics that are surprisingly

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<v Speaker 1>dense for their size, visit our home planet, how stuff

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