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  • Black holes and dark matter are two topics that get science geeks pretty hyped, but sadly

  • they're not usually mentioned in the same sentence.

  • Now though you can feel twice the hype, because a new theory has proposed that we can detect dark matter using black holes.

  • Well, more accurately, using the gravitational waves that dark matter near a black hole would give off.

  • So make that three times the hype.

  • I am 99.9% positive that all of you watching are familiar with black holes, the superdense

  • points in space where matter is packed so tight and gravity is so strong that -all together now- not even light can escape.

  • You've probably also heard of gravitational waves.

  • First proposed by Einstein and confirmed in 2015 by the Laser Interferometer Gravitational-Wave

  • Observatory, or LIGO, they are ripples in spacetime and they''re caused when massive

  • objects turn space into a wibbly wobbly, timey-wimey...

  • Thing.

  • So far, these are well established phenomenon and we have a pretty good idea of what they are and why they happen.

  • But the third member in this science love triangle is the biggest question mark of them all: dark matter.

  • Evidence has shown that almost 85% of the matter in the universe is unaccounted for.

  • Beyond that, we have no solid lead what all that missing stuff actually is, so we just call it 'dark matter'.

  • One of the proposed culprits is a hypothetical subatomic particle called the axion.

  • These little guys were originally proposed to solve another mystery of physics called

  • the Strong CP Problem, but they might be the key to Dark Matter as well.

  • Score!

  • They're predicted to be a billionth the mass of an electron or lighter, but with enough of them they just might add up to all that missing mass.

  • Those are the key pieces: a black hole, gravitational waves, and a whole bunch of axions.

  • The way the researchers proposed they work together is really quite elegant.

  • Because the quantum world is a silly place, axion particles should also act like waves.

  • The lighter the particle, the longer the wavelength.

  • Hypothetically, if an axion is near a spinning black hole and its wavelength is as long as

  • the black hole's diameter, then things could get really crazy.

  • That's right we're not even at the crazy part yet!

  • A phenomenon called superradiance can kick in.

  • Superradiance is a process that has been shown to multiply photons, and axions and photons are thought to have some properties in common.

  • The spinning black hole would give the axion more energy and generate more axions in a runaway chain reaction like a Mr. Meeseeks box.

  • You can end up with 1080 axions around one black hole.

  • That's as many axions as there are atoms in the universe!

  • All these axions should give off a distinct signature that we can detect.

  • The researchers predicted they won't scatter randomly, but will form orderly clouds like electrons do around an atom.

  • And as they smash into each other, they should annihilate each other to produce gravitons,

  • another hypothetical particle that's never been confirmed.

  • These gravitons mediate the force of gravity, so we should be able to detect them coming

  • from these huge axion clouds as gravitational waves.

  • LIGO isn't quite sensitive enough to pick up these gravitational waves just yet.

  • But once it is, if LIGO detects gravitational waves with the same wavelengths from different

  • sources, then we'll know it's likely caused by these axions and all the pieces will fall into place.

  • Don't go thinking it fits completely perfectly just yet.

  • For the axions to have a long enough wavelength they'd have to be much lighter than what

  • we've been looking for with current lab experiments, anywhere from ten thousand to ten million times lighter.

  • At that mass they still might be too light to account for all the dark matter.

  • So pump the brakes on the hype train just a little, and let's wait until LIGO is a bit more sensitive.

  • Do you have a favorite candidate for dark matter?

  • Axions?

  • WIMPs?

  • MACHOs?

  • Let us know in the comments, don't forget to subscribe!

  • If you're still hung up on why Gravitational Waves should get you hyped, check out Julia's video on it right here.

  • One more thing, we got nominated for a Webby for sending a VR camera to the edge of space

  • and you can help us win, all you have to do is go to, search Seeker and click vote, simple as that or click the link down below.

  • And if you still haven't seen it, check out the video on Seeker VR.

  • Thanks for watching!

Black holes and dark matter are two topics that get science geeks pretty hyped, but sadly

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Black Holes And Gravitational Waves Might Help Us Find Dark Matter

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    Jerry Liu posted on 2019/05/06
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