00:00Tiny, tiny black holes capable of hollowing out entire planets might be tunneling through
00:06objects on Earth right at this moment.
00:09Could those earthly objects include your own body?
00:13Very likely.
00:14The trick is, in theory, black holes can have an enormous range of size, from those billions
00:19of times heavier to the Sun to minuscule far lighter than a paper clip.
00:24And those tiny black holes, aka primordial black holes, might be the ones zipping through
00:30your arm or leg right at this moment.
00:32Now, unfortunately, primordial black holes are so small that we have found no direct
00:38evidence of them.
00:39But a group of physicists have proposed a creative new approach, looking for their traces
00:44in everyday objects.
00:47Because although the primordial black holes are incredibly small, they are still large
00:52enough to see under a microscope.
00:55The chances of finding their traces are still exceedingly small, but, on the other hand,
01:00it wouldn't take many resources to search for them.
01:04What makes primordial black holes so special?
01:07They could have formed shortly after the Big Bang, in the extreme heat and density of the
01:11early Universe.
01:14Even cooler, they could be a key part of dark matter, the mysterious substance making up
01:1985% of all the matter in the Universe.
01:22Unlike black holes that form from collapsing stars or gas clouds, primordial black holes
01:28are likely to have originated from extremely dense pockets of subatomic particles, extremely
01:34small pieces of matter smaller than atoms, like protons, neutrons, or electrons, in the
01:39Universe's first moments.
01:41These tiny black holes could be as heavy as mountains, but no larger than a hydrogen atom.
01:47This combination of high mass and small size makes them incredibly hard to detect.
01:53Luckily, to help narrow the search, the researchers made some calculations to predict what signs
01:59primordial black holes might leave behind.
02:02And one intriguing possibility is that planets or asteroids might capture these black holes,
02:08which could then hollow out the insides of these objects.
02:12And then, if a planet or asteroid has a liquid core, a captured black hole might absorb the
02:17core material, which is denser than the outer layers.
02:21After consuming the core, the black hole might escape after a collision or impact shakes
02:26it loose.
02:27The result could be a hollowed-out planetary shell.
02:31If the object is small, about one-tenth the size of Earth, it might remain intact long
02:37enough for astronomers to spot it.
02:39But larger hollowed-out planets would collapse under their own weight.
02:43This offers another way to search for primordial black holes.
02:47If a small planet or moon has a much lower density than expected, it could be a sign
02:52that it's hollow and carved out by a black hole.
02:56Now we might not have to search space for clues.
03:00Researchers have also figured out what would happen if a primordial black hole were to
03:04pass through an object here on Earth.
03:06For example, a black hole, weighing about a ton, could carve a tunnel through an object,
03:11leaving an opening about 700 times thinner than a human hair.
03:16The coolest thing, though?
03:18If something moves faster than the speed of sound through a material, the material's
03:22molecules don't have time to react, and the material doesn't rip.
03:26It's like the difference between throwing a rock at a window, which shatters it, and
03:30shooting a bullet through it, which just leaves a clean hole.
03:34Researchers could examine billion-year-old rocks and even structures a few hundred years
03:38old for signs of these microscopic pathways.
03:42Of course, there's a catch.
03:44The odds of finding such a tunnel are very low.
03:47According to the researchers' calculations, there's only a 1 ten-thousandth of a chance
03:52that a primordial black hole would pass through any specific billion-year-old rock.
03:57Even so, the simplicity of the test makes it worth trying.
04:01Now let's talk about the risk to you, or your dog, if you're ever hit by a primordial
04:06black hole.
04:07First, let's be clear.
04:08The chances of this happening during your lifetime, or your dog's, are astronomically
04:13small.
04:14But if it did happen, there's no need to panic.
04:18Unlike planets or ancient rocks, your body, and your dog's body, have only a small amount
04:23of tension.
04:24It seems hard to believe that a primordial black hole could pass through you without
04:28you noticing.
04:30But here's a comparison.
04:32While you're watching this video, hundreds of trillions of neutrinos have passed through
04:36your body at the speed of light, and you didn't feel a thing now, did you?
04:40These particles also have another name – ghost particles.
04:44And that's for a reason.
04:45Maybe someday, we'll call primordial black holes ghost black holes.
04:51Even though now all of this might sound like pure speculation, studies like these are important.
04:57Many ideas that once seemed far-fetched are now accepted parts of science.
05:02Creative thinking is necessary to solve some of the biggest mysteries in physics.
05:07Like the true nature of dark matter, for example.
05:10The smartest people in the world have been trying to solve such problems for 80 years
05:14without success.
05:16So we don't just need minor changes to existing ideas.
05:20We need a completely new way of thinking.
05:24Back on the topic of black holes.
05:26Astronomers have found a lightweight black hole that's puzzling scientists.
05:30The thing is, there's a noticeable lack of black holes between about 2 and 5 times
05:35the Sun's mass.
05:37Scientists don't know if these smaller black holes are just difficult to detect, or if
05:41they're genuinely rare.
05:43Well, the new discovery might help solve the mystery.
05:47This black hole sits right in the middle of that size gap, with a mass of about 3.5 times
05:52that of the Sun.
05:54Researchers spotted it thanks to its companion, a large red giant star about 5,800 light-years
06:00away from Earth.
06:01The star, while only 2.5 times as heavy as the Sun, is about 13 times larger and shines
06:08100 times brighter.
06:11Astronauts made the discovery using data from the European Space Agency's Gaia spacecraft,
06:16which maps the movements of over a billion stars in the galaxy.
06:21Gaia is really good at tracking stars' 2D motion, which is side-to-side and up-and-down.
06:27But scientists needed ground-based telescopes to measure how the red giant was moving toward
06:32or away from Earth.
06:34And their observations revealed something surprising.
06:37Two objects were moving in a wide, nearly circular orbit around each other.
06:42And that orbit raised questions.
06:45The black hole must've formed because of a supernova, an insanely bright explosion
06:49of a star.
06:51The star would've lost a lot of its mass very quickly.
06:54Such a dramatic weight loss should've disrupted the orbit.
06:57It's a basic rule in orbital mechanics.
07:00If a binary system loses half its mass, the two objects should fly apart.
07:05And even if the mass loss wasn't quite that extreme in this case, it should've resulted
07:10in a stretched-out oval-shaped orbit, not the almost circular one we can observe.
07:16Another challenge to the theory is how supernova explosions behave.
07:20They aren't always perfectly even.
07:22If the explosion was lopsided, the leftover black hole could've been thrown off-course,
07:27which would've separated it from its companion star.
07:31This might explain why we spot so many small black holes.
07:35Most could be wandering the galaxy alone, invisible and unnoticed.
07:39That's why the discovery of this binary system is so intriguing.
07:44There's also another possible explanation.
07:47The black hole and the red giant might've originally been a triple-star system, with
07:52two massive stars at its center and the red giant orbiting further out.
07:57And the black hole we see now might've formed when the two central stars merged.
08:02It's also possible that the unseen object in the system contains two smaller compact
08:08objects instead of one.
08:10That's it for today, so hey, if you pacified your curiosity, then give the video a like
08:16and share it with your friends.
08:17Or if you want more, just click on these videos and stay on the Bright Side!
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