00:00Astronomers have discovered the most MASSIVE stellar black hole ever spotted in our home
00:05Milky Way galaxy.
00:07This newly found space monster is 33 times bigger than the Sun and sits 2,000 light-years
00:13away from us.
00:15Until recently, the largest stellar black hole found residing in our galaxy has been
00:19around 20 times as big as our star in terms of mass.
00:23As for the average stellar mass black hole, it's usually about 10 times as hefty as
00:28the Sun.
00:29Scientists from the European Southern Observatory's Gaia mission spotted the giant black hole
00:35after a star started to wobble while orbiting in that area.
00:39The black hole got the name of Gaia BH3.
00:42The proximity of this space object to Earth makes it the second closest black hole to our
00:47planet ever discovered.
00:49The nearest one is called Gaia BH1.
00:53It's hanging out around 1,560 light-years away from us.
00:58This uncomfortably close neighbor has a mass of about 9.6 times that of the Sun.
01:04It means that it's way smaller than the newly found black hole.
01:08Gaia BH3 is located in the Aguila constellation.
01:13From Earth, it seems to have the shape of an eagle.
01:16Interestingly, astronomers didn't expect to find a high-mass black hole lurking so relatively
01:22close to Earth and remaining undetected for so long.
01:26Okay, we can probably admit that this stellar black hole is just a small fry compared to supermassive black holes,
01:32like the one that dominates the center of the Milky Way.
01:35I'm talking about Sagittarius A star.
01:39This space giant has a mass of 4.2 million times that of the Sun.
01:45While a stellar black hole forms when a star collapses, supermassive black giants have their
01:51own ways of seeing the light of day.
01:53They are usually the result of mergers of progressively larger and larger black holes.
01:58We'll talk about that later.
02:00First, let's speak a bit more about how stellar black holes form.
02:06When stars near the end of their lives, they typically inflate, lose a lot of mass, and
02:11cool to form what we know as white dwarfs.
02:14Such massive stellar black holes as Gaia BH3 are believed to form when a star doesn't contain
02:20heavy elements and loses not so much mass over its lifetime.
02:25Those stars are called metal-poor.
02:28Afterward, instead of cooling into a white dwarf, this star collapses into a black hole.
02:35The companion of Gaia BH3 is a very metal-poor star.
02:39It suggests that the star that collapsed and formed BH3 was metal-poor, too.
02:45Astronomers know of about 50 stellar black holes in the Milky Way.
02:51Some black holes are larger than others.
02:54You see, the universe is filled with black holes.
02:57Some of them are sprinkled randomly throughout galaxies.
03:00Others, those giants we know as supermassive black holes, sit at the center of galaxies.
03:07While stellar black holes are usually just a few times bigger than the Sun, such space
03:12monsters can weigh from a million to a billion solar masses.
03:17But even though they're so much heavier than our star, they're packed into a relatively
03:21small area.
03:23On a cosmic scale, of course.
03:25The size of our solar system or so.
03:28Some astronomers think supermassive black holes could form by several stars colliding and
03:33collapsing at once.
03:35While other experts state that such space objects might have started growing several billion years
03:40ago.
03:41At first, a small seed appears somewhere out there in space, which then gradually increases
03:47in mass to form a black hole.
03:50This seed does it through the process of accretion, which basically means gathering more and more
03:56matter around itself.
03:58Besides the absence of any precise information about the formation of black holes, there's
04:03also the black hole information paradox.
04:07If a black hole has some mass, and as we know, these spaced objects have a lot of it,
04:13then according to the first law of thermodynamics, it should have a temperature.
04:18And according to the second law of thermodynamics, it should also radiate heat.
04:23Stephen Hawking showed that black holes are supposed to emit radiation too.
04:28These days, this kind of radiation is called Hawking radiation.
04:32It should form at the boundary of a black hole, but after proving it, Hawking pointed out
04:36a paradox.
04:38If a black hole is capable of evaporating, some of the information it contains can be
04:43lost forever.
04:45The problem is that the information contained in thermal radiation emitted by a black hole
04:49gets degraded.
04:51It doesn't repeat any information about the matter swallowed by a black hole before.
04:56Such an irreversible loss of information contradicts one of the basic principles of quantum mechanics.
05:02Physical systems that change over time cannot create or destroy information.
05:09It means we must be missing something.
05:11Both physicists and mathematicians have tried to come up with different ideas, but they ended
05:16with pretty weird results.
05:18Some have even claimed that the universe could be holographic.
05:22It means that the universe that we know and love is actually the result of some mysterious
05:27interactions at the infinitely distant boundary.
05:30I told you, black holes are really strange.
05:35At the same time, we have definitely found space objects that seem to have the properties
05:40of black holes.
05:41For example, look at this image of black hole M87 star.
05:46It certainly looks like a physical object, but what if black holes don't exist at all?
05:54There's an idea that black holes are actually gravistars, a blend of gravity, vacuum, and stars.
06:01This theory was first proposed in 2001 by Emil Mottola and Pavel O. Mazur.
06:07They hypothesize that at one point during the collapse of a large star, intense gravity might
06:12transform its matter into a new state.
06:16It's similar to what occurs when atoms are cooled to such low energy states that they start
06:21acting like a single super atom.
06:24When we speak of gravistars, a star might collapse to the point of the event horizon, or the point
06:29of no return, and then its matter is transformed into a new state.
06:35It exerts enough outward pressure to prevent the star from collapsing into a physics-defying
06:39singularity.
06:41In gravistars, an ultra-thin, ultra-cold, and ultra-dark, indestructible shell surrounds
06:47heavily-wrapped space-time.
06:50This new form of matter turns out to be very durable, but it's also a bit flexible, like
06:55a bubble.
06:56So anything that's trapped by the intense gravity of a gravistar and smashed into it gets obliterated
07:02and then assimilated into the shell of this bizarre space structure.
07:07One of the benefits of the gravistar theory is getting away with those messy paradoxes
07:11connected with information and singularities.
07:15But even though this idea sounds kinda cool, it doesn't explain the phenomena we observe.
07:20And we've definitely observed something that looks like black holes.
07:25On the other hand, look at this shadow.
07:27It isn't caused by the trapping of light in the event horizon.
07:31It's a slightly different phenomenon known as the gravitational redshift.
07:35It makes light lose energy when it moves through a region with a powerful gravitational field.
07:41So, potentially, it could be a gravistar.
07:45When the light emitted from the regions close to the alternative objects reaches our telescopes,
07:50most of its energy is already lost to the gravitational field, which causes the appearance of this
07:56shadow.
07:57And still, like with black holes, things get complicated when you add rotation to the equation.
08:04Many experts are sure that gravistars would not be able to remain stable during rotation.
08:09But wait, it gets even more bizarre.
08:12There are suggestions that the insides of gravistars could contain a series of thicker shells.
08:19Those are known as nestars, something like a Matryoshka doll.
08:23Of course, these theories aren't perfect yet.
08:27Astronomers still have a lot of work trying to build functioning models.
08:30There's also a chance that both black holes and gravistars exist.
08:34But then, we've got another problem on our hands.
08:37How can we distinguish between the two?
08:40Some theories suggest that these different kinds of space objects should also emit very
08:44different gravitational radiation.
08:47It could allow us to figure out whether we're looking at a gravistar or a traditional black
08:52hole.
08:53So, let's see.
08:53Let's see.
08:54Let's see.
Comments