Des scientifiques ont récemment découvert un trou noir avec une masse 33 fois celle de notre Soleil, et il est étonnamment proche de la Terre—relativement parlant, bien sûr ! Ce trou noir massif, situé dans une galaxie proche à environ 1 500 années-lumière, est le plus proche que nous ayons jamais découvert. Ce qui est vraiment fascinant, c'est que c'est un trou noir "dormant", ce qui signifie qu'il n'absorbe pas activement de matière ni ne crée ces immenses jets d'énergie lumineux que nous voyons parfois dans l'espace. Les chercheurs ont utilisé un puissant télescope pour le détecter en observant comment sa gravité affectait une étoile à proximité. Découvrir des trous noirs comme celui-ci aide les scientifiques à mieux comprendre comment les étoiles vivent et meurent. C'est un peu effrayant, mais heureusement, même s'il est proche selon les normes cosmiques, il est suffisamment éloigné pour que nous soyons complètement en sécurité ! Animation créée par Sympa. ---------------------------------------------------------------------------------------- Musique par Epidemic Sound https://www.epidemicsound.com Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna ---------------------------------------------------------------------------------------- Nos réseaux sociaux : Facebook: https://www.facebook.com/sympasympacom/ Instagram: https://www.instagram.com/sympa.officiel/ Stock de fichiers (photos, vidéos et autres): https://www.depositphotos.com https://www.shutterstock.com https://www.eastnews.ru ---------------------------------------------------------------------------------------- Si tu en veux encore plus, fais un tour ici: http://sympa-sympa.com
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00:00Astronomers have discovered the stellar black hole, the most massive ever spotted in our galaxy, the Milky Way.
00:07This space monster is 33 times larger than the Sun and is 2,000 light years away from us.
00:14Until now, the largest stellar black hole we knew inside our galaxy was about 20 times larger than our star in terms of mass.
00:23As for the stellar medium black hole, it is generally 10 times larger than the Sun.
00:29The scientists of the Australian European Observatory's Gaia mission spotted this giant black hole after a star began to oscillate while it was in orbit in this area.
00:40The black hole was named Gaia BH3.
00:44The proximity of this space object to Earth makes it the second closest black hole to our planet ever discovered.
00:51The closest one is called Gaia BH1. It is about 1,560 light years away from us.
00:58This unassuring neighbor has a mass of about 9.6 times that of the Sun.
01:04This means that it is much smaller than the newly discovered black hole.
01:09Gaia BH3 is located in the constellation of the Eagle.
01:13From Earth, it seems to have the shape of this raptor.
01:17It is interesting to note that astronomers did not expect a large black hole to be so close to Earth and remain undetected for so long.
01:26It is true, we can probably admit that this stellar black hole is nothing compared to supermassive black holes like the one that dominates the center of the Milky Way.
01:36It is Sagittarius A.*.
01:40The mass of this space giant is 4.2 million times greater than that of the Sun.
01:46While a stellar black hole is formed when a star collapses, supermassive black holes have their own way of seeing the day.
01:54It usually results from the fusion of black holes whose size has not ceased to grow.
01:59But we will talk about it later.
02:01First of all, let's talk a little more about the formation of stellar black holes.
02:05When the stars approach the end of their life, they swell, lose a lot of mass and cool down to form what are called white dwarfs.
02:15We think that stellar black holes as massive as Gaia BH3 are formed when a star does not contain heavy elements and does not lose as much mass over its life.
02:25These stars are called poor in metal.
02:28So, instead of cooling down to white dwarfs, this star collapses into black holes.
02:35The companion of Gaia BH3 is a very poor star in metal.
02:39This suggests that the star that collapsed and formed BH3 was also poor in metal.
02:45Astronomers know about fifty stellar black holes in the Milky Way.
02:50Some black holes are larger than others.
02:54You see, the universe is full of black holes.
02:57Some are randomly scattered in the galaxies.
03:00Others, these giants that we call supermassive black holes, are in the center of the galaxies.
03:07While stellar black holes are usually only a few times larger than the Sun, these space monsters can weigh between one million and one billion solar masses.
03:17Although they are much heavier than our star, they are concentrated in a relatively small area.
03:23On a cosmic scale, of course, the size of our solar system.
03:28Some astronomers think that supermassive black holes could form as a result of the collision and simultaneous collapse of several stars.
03:36While other experts claim that these space objects began to develop several billion years ago.
03:43At first, a small seed appears somewhere in space.
03:46Then, its mass gradually increases until it forms a black hole.
03:51This seed gets there thanks to the accretion process, which consists of gathering more and more matter around it.
03:58In addition to the lack of precise information on the formation of black holes, there is also what is called the paradox of information.
04:06If a black hole has a certain mass, and as we know, these space objects have a lot of it.
04:12Then, according to the first law of thermodynamics, it should have a temperature.
04:17And according to the second law of thermodynamics, it should also emit heat.
04:23Stephen Hawking has shown that black holes are also supposed to emit radiation.
04:27Today, this type of radiation is called Hawking radiation.
04:32It would form, according to him, at the border of a black hole.
04:35But after demonstrating this, Hawking has raised a paradox.
04:38If a black hole is able to evaporate, it means that part of the information it contains evaporates too, forever.
04:46The problem is that the information contained in the thermal radiation of a black hole is degraded.
04:51It does not repeat any information related to the engulfed matter.
04:55Such an irreversible loss of information contradicts one of the basic principles of quantum mechanics.
05:01Physical systems that change over time cannot create or destroy information.
05:08This means that something is missing.
05:11Physicists and mathematicians have tried to find different ideas, but they have led to quite strange results.
05:18Some have even claimed that the universe could be holographic.
05:22This means that the universe we know and love is in fact the result of mysterious interactions at the infinitely distant border.
05:30I told you, black holes are really strange.
05:34At the same time, we have found spatial objects that seem to have the same properties as black holes.
05:41For example, look at this image of the black hole M87.*
05:46It really looks like a physical object.
05:49And if, in fact, black holes did not exist?
05:53There is an idea that black holes are actually gravastars, a mixture of gravity, vacuum and stars.
06:00This theory was first proposed in 2001 by Émile Mottola and Paweł Omazur.
06:06They hypothesized that at some point, when a large star collapses, intense gravity could transform its matter.
06:15This phenomenon is similar to the one that occurs when atoms are cooled to such a level that they begin to behave like a single super-atom.
06:24A star could therefore collapse to the point of no return, and its matter would then be transformed into a new state.
06:33It would exert enough external pressure to prevent the star from collapsing into a singularity, thus defying the laws of physics.
06:41In gravastars, an indestructible ultra-thin, ultra-cold and ultra-dark shell surrounds a space-time strongly enveloped.
06:50This new form of matter is very durable.
06:53But it is also a bit flexible, like a bubble.
06:56Thus, everything that is trapped by the intense gravity of a gravastar and that collapses, is obliterated and then assimilated to the shell of this strange spatial structure.
07:07One of the advantages of the theory of gravastars is that it allows us to overcome paradoxes related to information and singularities.
07:15But even if this idea seems pretty cool, it does not explain the phenomena that we observe.
07:20And we have indeed observed something that looks like black holes.
07:25On the other hand, look at this shadow. It is not caused by the trapped light in the horizon of events.
07:31It is a slightly different phenomenon, known as the gravitational redshift.
07:37This phenomenon loses energy to light when it crosses a region with a powerful gravitational field.
07:43It could therefore be a gravastar.
07:46When the light emitted by the nearby regions of these alternative objects reaches our telescopes,
07:51most of its energy is already lost in the gravitational field, which causes the appearance of this shadow.
07:58And yet, like black holes, things get complicated when we add rotation to the equation.
08:04Many experts are convinced that gravastars could not remain stable during their rotation.
08:10But wait, it's getting weirder and weirder.
08:13Some suggest that the interior of gravastars could contain a whole series of thicker shells.
08:19These shells are known as nestars, a bit like a Matryoshka doll.
08:24Of course, these theories are not yet perfect.
08:27Astronomers still have to make a lot of effort to build functional models.
08:31It is also possible that black holes exist next to gravastars.
08:35In this case, we are faced with another problem.
08:38How to distinguish between the two?
08:40According to some theories, these different types of space objects should emit very different gravitational rays.
08:47It is by observing these rays that we could determine whether we are in the presence of a gravastar or a classic black hole.