跟读练习: Sunlight is way older than you think - Sten Odenwald - 通过YouTube学习英语口语
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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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31 句
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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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在这段精彩的讲演中，讲者Sten Odenwald探讨了太阳光的旅程，以及阳光如何经过数十万年的演变才能最终抵达地球。此视频不仅使我们重新思考阳光的历史，还揭示了光线在太阳内部的复杂过程。这为学习英语的同学们提供了一个极好的机会，通过观察科学演讲练习语言技能，同时理解信息的深度和背景。这种类型的讲座特别适合通过看YouTube学英语的方法来进行shadowing练习。
日常交流的五个短语
- 光速 - 这是描述光传播速度的术语，对于科学讨论非常重要。
- 随机行走 - 这是一个用来描述光子在太阳核心中的运动方式的概念。
- 核反应 - 在讲座中提到太阳核心的能量来源。
- 辐射区 - 这是太阳内部的区域，光子在此经过能量转换。
- 时间跨度 - 用于描述从太阳核心到地球的光旅程，感知时间的重要性。
逐步跟读指南
对于想要提高英语口语能力的同学们，尤其是采用shadow speech的方法，以下步骤可以帮助您更有效地练习:
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通过以上步骤，你将能更有效地掌握这段讲座所传达的科学内容，同时在英语口语能力上也会有显著提升。在学习的过程中，不妨试试shadow speak的技巧，让每次学习变得更加生动有趣。
什么是跟读法？
跟读法 (Shadowing) 是一种有科学依据的语言学习技巧，最初开发用于专业口译员的培训，并由多语言者Alexander Arguelles博士普及。这个方法简单而强大：您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同，跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性，语调，节奏，连读，听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。