Pratique du Shadowing: Sunlight is way older than you think - Sten Odenwald - Apprendre l'anglais à l'oral avec YouTube

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You may know that it takes light a zippy eight minutes to reach us from the surface of the Sun, so how long do you think it takes light to travel from the Sun's core to its surface?
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You may know that it takes light a zippy eight minutes to reach us from the surface of the Sun, so how long do you think it takes light to travel from the Sun's core to its surface?
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A few seconds or a minute at most?
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Well, oddly enough, the answer is many thousands of years.
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Here's why.
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Photons are produced by the nuclear reactions deep in the core of our Sun.
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As the photons flow out of the core, they interact with matter and lose energy, becoming longer wavelength forms of light.
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They start out as gamma rays in the core, but end up as x-rays, ultraviolet, or visible light as they near the surface.
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However, that journey is neither simple nor direct.
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Upon being born, each photon travels at a speed of 300,000 kilometers per second until it collides with a proton and is diverted in another direction, acting like a bullet ricocheting off of every charged particle it strikes.
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The question of how far this photon gets from the center of the Sun after each collision is known as the random walk problem.
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The answer is given by this formula: distance equals step size times the square root of the number of steps.
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So if you were taking a random walk from your front door with a one meter stride each second, it would take you a million steps and eleven days just to travel one kilometer.
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So then how long does it take for a photon generated in the center of the Sun to reach you?
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We know the mass of the Sun and can use that to calculate the number of protons within it.
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Let's assume for a second that all the Sun's protons are evenly spread out, making the average distance between them about 1.0 x 10^-10 meters.
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To random walk the 690,000 kilometers from the core to the solar surface would then require 3.9 x 10^37 steps, giving a total travel time of 400 billion years.
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Hmm, that can't be right.
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The Sun is only 4.6 billion years old, so what went wrong?
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Two things: the Sun isn’t actually of uniform density and photons will miss quite a few protons between every collision.
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In actuality, a photon's energy, which changes over the course of its journey, determines how likely it is to interact with a proton.
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On the density question, our models show that the Sun has a hot core, where the fusion reactions occur.
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Surrounding that is the radiative zone, followed by the convective zone, which extends all the way to the surface.
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The material in the core is much denser than lead, while the hot plasma near the surface is a million times less dense with a continuum of densities in between.
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And here's the photon-energy relationship.
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For a photon that carries a small amount of energy, a proton is effectively huge, and it's much more likely to cause the photon to ricochet.
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And for a high-energy photon, the opposite is true.
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Protons are effectively tiny.
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Photons start off at very high energies compared to when they're finally radiated from the Sun's surface.
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Now when we use a computer and a sophisticated solar interior model to calculate the random walk equation with these changing quantities, it spits out the following number: 170,000 years.
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Future discoveries about the Sun may refine this number further, but for now, to the best of our understanding, the light that's hitting your eyes today spent 170,000 years pinballing its way towards the Sun's surface, plus eight miniscule minutes in space.
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In other words, that photon began its journey two ice ages ago, around the same time when humans first started wearing clothes.
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Why practice speaking with this video?

The video “Sunlight is way older than you think” presented by Sten Odenwald offers a fascinating exploration of the journey light takes from the core of the Sun to its surface. Engaging with this content through the shadowing technique can significantly enhance your English speaking practice. By repeating the speaker's phrases while focusing on pronunciation, intonation, and rhythm, learners can improve their fluency and confidence in speaking. This approach allows you to absorb complex scientific concepts while simultaneously elevating your language skills.

Grammar & Expressions in Context

Analyzing the language used in the video reveals several key grammatical structures and expressions that are useful for learners:

  • Present Simple Tense: Odenwald uses the present simple to state facts, e.g., “It takes light a zippy eight minutes...” This structure is foundational for discussing general truths or regular occurrences.
  • Conditional Sentences: Phrases such as “If you were taking a random walk...” illustrate how conditionals can set up hypothetical scenarios.
  • Passive Voice: The speaker often employs passive voice to emphasize actions over subjects, e.g., “Photons are produced...” which is essential for academic and scientific discourse.
  • Complex Sentences: Sentences with clauses provide details, e.g., “The Sun is only 4.6 billion years old,” helping learners understand how to construct more elaborate statements.

Common Pronunciation Traps

While practicing with this video, pay attention to the following pronunciation challenges:

  • “Photon”: The initial “ph” can confuse non-native speakers. Practice emphasizing the “f” sound.
  • “Gamma”: The soft “g” might be tricky; ensure you're articulating it correctly as /ˈɡæmə/ (GAM-uh).
  • “Proton” and “Collision”: Focus on the stress in these words. Stressing the first syllable helps in clarity.
  • “Ricochet”: This word is not only difficult to pronounce but also requires attention to the rhythm, as it has multiple syllables.

Utilizing the shadow speech practice along with this content will enhance your grasp of scientific vocabulary and improve your overall English speaking ability. Whether you’re a beginner or advanced learner, the principles behind this video can guide effective shadowing sessions through a dedicated shadowing site. Embrace the challenge of speaking and enjoy the process of 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.

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