Imaginez si le Soleil se transformait soudainement en trou noir—ça semble fou, non ? Tout d'abord, la Terre ne serait pas aspirée comme dans les films parce que la masse du Soleil ne changerait pas, donc notre orbite resterait la même. Mais les choses deviendraient très sombres et froides, rapidement. Sans la lumière du soleil, toutes les plantes mourraient et la température chuterait drastiquement, rendant la vie presque impossible. Nous verrions le Soleil rétrécir jusqu'à devenir un minuscule point, mais sa puissante gravité resterait. 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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00:00It would seem that the black holes may not be as unnoticeable as we thought before.
00:05They could be hidden within the stars themselves.
00:08The additional mass of some of these stars, acting like space lanterns,
00:13could explain unusual gravitational effects in the universe,
00:17while they were previously attributed to black matter.
00:20The black holes to which I refer could be those, tiny,
00:24that appeared in the dawn of time, when the universe was still young.
00:28These primordial black holes could still be found in the heart of giant stars.
00:33A team of scientists considers this hypothesis plausible,
00:37and astronomers could detect these trapped black holes
00:40thanks to the vibrations they induce at the surface of the stars.
00:44If these black holes are numerous in the universe,
00:46they could play the role of black matter, helping to maintain its cohesion.
00:52Most black holes come from massive stars that have collapsed on themselves,
00:57becoming incredibly dense.
00:59Their gravitational attraction is such that even light cannot escape their grip.
01:04Contrary to popular belief,
01:06black holes do not behave like vacuum cleaners that swallow everything in their path.
01:10They only absorb objects that approach stars from very close,
01:14generally those that cross their horizon of events.
01:17It is a point of no return where any escape becomes impossible.
01:22In 1971,
01:25the renowned physicist Stephen Hawking proposed an alternative origin for these black holes.
01:30According to him, in the first moments that followed the Big Bang,
01:34when the universe had just been born,
01:36some regions of a soup of dense particles
01:39could have reached a sufficient density to collapse into black holes.
01:43These so-called primordial black holes could vary in size,
01:47ranging from microscopic to gigantic.
01:49If they were sufficiently widespread and numerous,
01:52they could act like black matter,
01:54binding the cosmos by their immense gravity.
01:57It is estimated, moreover,
01:58that black matter would represent about 85% of the total matter of the universe.
02:05Astronomers try to detect the primordial black holes
02:08by searching for the flashes that would occur
02:11when they pass in front of distant and bright objects,
02:14amplifying their light as a lens would do.
02:16However, they have not yet observed any.
02:19If a primordial black hole was extremely small,
02:22with a mass similar to that of an asteroid
02:24and a diameter as small as a hydrogen atom,
02:27the flashes produced would not be bright enough
02:30to be detected by our current instruments.
02:33The team studying the primordial black holes
02:35then explored the implications of a universe
02:38where black matter would be made up exclusively of tiny black holes.
02:42They concluded that one of these small black holes
02:44could cross the solar system at any time.
02:47Some could even be trapped in gas clouds,
02:50thus participating in the formation of new stars
02:53and ending up nesting in their center.
02:56The researchers then built the model of a black hole
02:59at the heart of a star,
03:01where hydrogen atoms fuse to produce heat and light.
03:05Initially, they did not detect anything unusual.
03:08Even the core of a star,
03:09although extremely dense,
03:11is mostly made up of vacuum,
03:13making it difficult for a microscopic black hole
03:16to find matter to consume.
03:18This would explain why its growth would be extremely slow,
03:21to the point that it would take it more time
03:23than the age of the universe to swallow an entire star.
03:27But, what would happen if a larger black hole,
03:30with a mass comparable to that of Pluto
03:33or the asteroid Ceres,
03:34appeared at the center of a star?
03:36It could grow in a few hundred million years only.
03:39The stellar matter would spiral into the black hole,
03:42forming a disk heated by friction,
03:45which would emit radiation.
03:47When the black hole reached the size of Earth,
03:50it would emit even more radiation and shine intensely.
03:54This would disrupt the core of the star,
03:57which would then become an object fed by a black hole
04:00rather than by nuclear fusion.
04:02These objects were named Hawking stars.
04:06To cool down,
04:07the outer envelope of a Hawking star
04:09would turn into a red giant,
04:12a phase that our sun is destined to know as it ages.
04:15However,
04:16a red giant sheltering a primordial black hole in the center
04:20would be less hot than the one that would have reached this stage
04:22by conventional means.
04:24These stars are known under the name of red trennards.
04:29To determine whether these stars actually shelter a black hole,
04:32astronomers may have to focus on the frequency of their vibrations.
04:37Since a Hawking star mainly affects its core,
04:40rather than its external layers,
04:42it would resonate at a particular frequency.
04:44The generated waves could manifest themselves
04:47by variations in the pulsation and tingling of the star's light.
04:51Scientists will therefore have to examine the already identified red trennards
04:55to verify whether some present the characteristic vibrations of a black hole.
05:00Should we worry about our sun?
05:02Since it has not yet reached its phase of red giant,
05:05we cannot predict whether it will become a cold red trennard.
05:09What we know
05:10is that our star could contain these tiny black holes
05:13formed during the Big Bang.
05:15However,
05:16we currently have no way to confirm their presence.
05:21Currently,
05:22our star is about halfway through its lifespan.
05:25It produces energy continuously
05:27by fusing hydrogen atoms in its core.
05:30When it has exhausted its hydrogen,
05:32it will begin its phase of red giant
05:35and will begin to contract.
05:36This process will occur in about 5 billion years.
05:40So,
05:41don't worry too much.
05:42And this phase
05:43will last about 1 billion years
05:46before the star consumes its fusible materials
05:49and loses its external layers.
05:51It will leave behind a small white dwarf,
05:54having a mass equivalent to half that of the sun
05:57and a size comparable to that of our planet.
06:01In some cases,
06:02when a stellar nucleus completely collapses under the effect of gravity,
06:06it can turn into a black hole.
06:08However,
06:09it is not fate that awaits our sun.
06:12The fact is that it does not have enough mass to become a black hole.
06:17Several factors can influence the ability of a star
06:21to turn into a black hole,
06:23such as its composition,
06:24its rotation
06:25and the evolutionary processes it is subjected to.
06:28However,
06:29the main condition remains an adequate mass.
06:32Stars with a mass 20 to 25 times greater than that of the sun
06:36can potentially undergo the necessary gravitational collapse
06:40to become black holes.
06:42In other words,
06:43the sun is too small to turn into a black hole.
06:46But what would happen if that happened?
06:49One might think that if the sun became a black hole,
06:52our planet would inevitably be attracted to it.
06:56Nevertheless,
06:56it is important to remember that black holes do not work
07:00like gigantic space vacuum cleaners
07:02waiting for new objects to swallow.
07:05Black holes do not have an additional gravitational force
07:09beyond that generated by their incredible mass.
07:12Thus,
07:13even if the sun turned into a black hole,
07:16which is impossible,
07:17this hole would still have the same mass as our current star.
07:21The orbit of the Earth around this newly formed black hole
07:24would therefore not be altered.
07:26But many other aspects would change radically.
07:29The sun,
07:30which currently measures around 696,340 km of radius,
07:36would shrink to a radius of only 3 km.
07:40You would not really worry about the absence of the bright yellow sphere in the sky.
07:44Because other much more urgent problems would worry you.
07:47Our planet would lose its main source of heat,
07:50plunging us into a glacial darkness.
07:53Without this source of energy,
07:54photosynthesis would stop immediately,
07:57thus disturbing all food chains.
08:00In the end,
08:01life on Earth would be completely eradicated.
08:03But rest assured,
08:04our sterile and arid planet would continue to follow its orbit.
08:08That's the main thing, isn't it?