Pratique du Shadowing: The Black Hole Bomb and Black Hole Civilizations - Apprendre l'anglais à l'oral avec la vidéo
Création de la leçon...
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Black holes are the largest collections of pure violent energy in the universe.
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If you come too close, they'll devour you and add your energy to their collection.
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And so, the energy is lost to us forever.
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Or is it? It turns out there's a universe cheat code.
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A way of powering civilizations until the very death of everything, or of constructing the largest bomb in the universe.
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But how? Didn't we learn that all energy is trapped forever in black holes, even light?
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This is true.
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Everything you think you know about the weirdest thing in the universe is about to get weirder, for one simple reason: Black holes are spinning.
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When really really massive stars die, their cores collapse under their own gravity into black holes.
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This means something very big becomes very, very tiny. Like the tiniest anything can be in this universe.
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But stars are rotating and a fundamental property of our universe is that things that are spinning don't want to stop spinning.
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We call this: angular momentum.
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And this angular momentum can't go away. A big thing that spins and becomes smaller, spins faster.
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So, as the core of a star collapses, its momentum makes it spin faster and faster and faster, until it collapses into a black hole .
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And the black hole keeps on spinning, inconceivably fast.
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Some of them spin millions of times a second.
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Just like non spinning black holes, ...spinning black holes have an event horizon and a singularity at their core, where all of their mass is concentrated.
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The singularity is usually described as a single infinitely small point with no surface area.
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But points can't rotate, so a rotating singularity can't be a point.
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Instead, it's a RINGularity.
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A ringularity is a ring with a thickness of zero and no surface, spinning extremely fast, containing all the mass of the black hole.
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The black hole is spinning so fast, that it morphs space and time itself.
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It literally drags space with it, such is its power.
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This creates a new and super weird region of space-time: the Ergosphere, which envelops the black hole.
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If space and time are completely broken inside the event horizon, then they're only half broken inside the ergosphere.
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Inside the ergosphere, nothing makes sense.
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It's possible to enter it and then leave it again, but it's probably not a great experience.
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You can imagine it like this: Falling into a static black hole is like sliding down a hole.
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Being inside the ergosphere of a spinning black hole is like spiraling down a deadly drain.
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The black hole transfers its own kinetic energy in the form of rotation, to everything that enters the ergosphere.
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The ringularity makes you dance whether you want to or not.
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You need to move faster than the speed of light just to stand still here, which is impossible.
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But here's our cheat code: We can steal this energy, and there's a lot of energy to steal.
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Take the supermassive black hole at the center of the Milky Way.
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We could steal as much energy from it as every single star in the Milky Way emits in a billion years combined.
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The easiest way to steal this energy is, oddly enough, to drop something into the black hole.
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We've seen that the ringularity forces energy on us when we enter the ergosphere, ...which is a lot like being in a whirlpool, with space-time rushing around and around.
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If you're clever you can use the water to your advantage, and swim faster than before.
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In practice, this means sending a rocket into the ergosphere, and making a trade with the black hole: We give it some mass-energy, and it gives us some of its rotational energy.
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But it's not a fair trade, we get the better deal.
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Normally, if you fire a rocket, you exchange chemical energy for kinetic energy.
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This is like pushing yourself forward in a swimming pool.
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But if you fire a rocket inside the ergosphere, it's like pushing yourself forward in a wave pool.
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The rotational energy of the waves gives you a much stronger boost than you could get just by pushing yourself.
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The boost from the rotation of the back hole is so big, that you leave the ergosphere with much more energy than you entered it.
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The black hole gives a tiny amount of its rotational energy to you, and slows down a little.
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Obviously, this requires a lot of food.
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Fortunately, black holes aren't picky eaters.
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An advanced future civilization would probably harvest asteroids to drop them into the black hole when they needed an energy boost.
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But there's an even better way to get energy from a black hole, and oddly enough, it builds the biggest bomb any living thing could ever hope to build: We only need two things to build a black hole bomb: a fast-spinning black hole, and a big mirror.
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The mirror has to completely envelop the black hole, ...which is similar to a Dyson Sphere, a mega structure that harvests the energy of an entire star.
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Although, our mirror would be easier to build.
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Mirrors are simpler, and black holes are much, much more compact than stars.
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If we made the mirror 10 centimeters thick, the metal of a big asteroid would probably be enough material for a black hole with the mass of our Sun.
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Once our mirror is in place, we only need to open a window, and shoot electromagnetic waves at the black hole.
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You can imagine what happens next, by imagining tossing a ball at a wall, and it coming back faster than a bullet.
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The waves hit the black hole at light speed.
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A small proportion of the waves falls past the event horizon to disappear forever.
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But a much larger amount sloshes through the ergosphere, ...where the black hole forces some of its rotational energy on them, and amplifies them.
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They now begin superradiant scattering, which are fancy science words meaning: "Bouncing around between mirror and black hole and getting stronger." Every time they go around, they are getting exponentially stronger.
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By opening some windows in the mirror, we can extract the energy from the waves as fast as they grow.
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Which we could use, in theory, to create what would be for all practical purposes, an endless source of energy for trillions of years.
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Or, we could blow it up.
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If the waves are not released, they will continue to get stronger and stronger, ...and take more and more energy from the black hole, until the mirror shatters.
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A supermassive black hole would release as much energy as a supernova, ...making the bomb the largest explosion any living being could ever create.
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The beauty of the black hole bomb, the Penrose process, and the super radiant scattering, is that they are not science-fiction.
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In the far far future, this might be the only way to survive in our dying universe.
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After all the red dwarfs have cooled down, and all the white dwarfs transformed into black dwarfs, the universe will turn dark forever.
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Rotating black holes might be the only sources of energy in the entire universe that life could harvest.
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If so, the last living being in existence might one day end its life around a black hole.
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Which is equally chilling and uplifting.
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It turns out that even without any light, there are places we can go.
About This Lesson
In this lesson, you will practice your English listening and speaking skills by engaging with a fascinating discussion about black holes and their implications for energy and civilization. By shadowing the transcript from the video "The Black Hole Bomb and Black Hole Civilizations," you will enhance your ability to comprehend complex scientific concepts and improve your pronunciation and fluency. This practice will be beneficial in grasping both technical vocabulary and the rhythm of spoken English, allowing you to effectively learn English with YouTube.
Key Vocabulary & Phrases
- Black Hole: A region in space where the gravitational pull is so strong that nothing can escape from it.
- Angular Momentum: The quantity of rotation of a body, which is conserved in a closed system.
- Ergosphere: The region outside a rotating black hole's event horizon, where objects can gain energy.
- Singularity: A point in a black hole where density becomes infinite and the laws of physics as we know them cease to function.
- Ringularity: A rotating singularity that exists as a ring, affecting surrounding space-time.
- Energy Boost: An increase in energy gained, often through a specific action or process.
- Harvest Asteroids: To gather and utilize asteroids for resources, such as energy, in advanced civilizations.
- Black Hole Bomb: A theoretical weapon that utilizes the energy from a fast-spinning black hole.
Practice Tips
To effectively use the shadowing technique with this video, focus on matching the speaker's speed and tone. The discussion about black holes involves scientific terminology that requires clarity and precision in your speech. Here are some tailored tips:
- Start Slowly: Play the video at a slower speed first. This will help you grasp the vocabulary and structure before attempting to match the natural speed.
- Repeat Often: Listen to short segments multiple times. After you hear a sentence, pause the video and repeat it aloud, mimicking the speaker’s intonation and rhythm.
- Use a Shadowing App: To track your progress effectively, utilize a shadowing app that allows you to record your voice alongside the video. This will help you identify areas where you need improvement.
- Practice in Context: As you shadow, visualize the concepts being discussed. Understanding the subject matter can enhance retention and pronunciation.
- Incorporate Key Vocabulary: Integrate the key terms from the vocabulary list into your sentences during practice. This will help solidify your understanding and enable you to use scientific language accurately.
By actively engaging with the material and utilizing these strategies, you can significantly enhance your English speaking abilities and confidence in a variety of contexts. Happy learning!
Qu'est-ce que la technique du Shadowing ?
Le Shadowing est une technique d'apprentissage des langues fondée sur la science, développée à l'origine pour la formation des interprètes professionnels. Le principe est simple mais puissant : vous écoutez de l'anglais natif et le répétez immédiatement à voix haute — comme une ombre suivant le locuteur avec un décalage de 1 à 2 secondes. Les recherches montrent une amélioration significative de la précision de la prononciation, de l'intonation, du rythme, des liaisons, de la compréhension orale et de la fluidité.