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      <video:description>Push an empty bicycle down a gentle slope and let go. It does not have to fall over. It can roll on, wobble, correct itself, and keep going with nobody aboard. Physicists call that self-stability.</video:description>
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      <video:description>At the shore: waves arrive, then retreat. Sometimes a retreating one meets the next one arriving.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/PX_3dgtwZ70</video:player_loc>
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      <video:description>Sand castles go up on beaches all over the world. Some are just a bucket turned over. Some take a whole afternoon.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/7vsFkx4jsEk</video:player_loc>
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      <video:description>Waves arrive at a shore all day, and the water is right there in front of you.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/SJeG5jCuyCY</video:player_loc>
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      <video:thumbnail_loc>https://teenscientists.org/images/videos/-ePraSDZBMc.jpg</video:thumbnail_loc>
      <video:title>Seashells: why that shape, those colors, those layers?</video:title>
      <video:description>Pick up a seashell. It is thin, hard, and it lasts.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/-ePraSDZBMc</video:player_loc>
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      <video:description>The sea surface carries many waves at the same time: a sum of lengths, each with its own height and its own direction. That is why a sea state gets written down as a spectrum rather than as a wave.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/hlkH6Gl9FmI</video:player_loc>
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      <video:title>Meteor shower traces: how much you can infer?</video:title>
      <video:description>A meteor leaves a track, and a track is data: a direction, a moment, a brightness that changes, a rate of slowing down.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/Cd7UjSbBh_Y</video:player_loc>
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      <video:title>Which headphones are best? Do you hear, know, or believe?</video:title>
      <video:description>Which headphones are best? Do you hear, know, or believe?</video:description>
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      <video:description>When we say a leaf is green, we are describing a *perception*, not the leaf itself. Light from the leaf contains a continuous spectrum of wavelengths.</video:description>
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      <video:description>When you aim to build something that works, you are doing engineering.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/5MyYMhf8WQg</video:player_loc>
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      <video:title>Physics of Watermelon Waves: Is It Ripe?</video:title>
      <video:description>Tap a watermelon and you hear a hollow thud. Physicists hear a lab experiment in disguise.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/v0RCtvUlyqE</video:player_loc>
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      <video:title>How Big Is a Rainbow You Never Saw?</video:title>
      <video:description>A rainbow keeps going past the red and past the violet, and what stops it at each end is a different thing entirely. Past the red it is the water: light has to travel into a droplet and back out, and far enough into the infrared the water absorbs all of it on the way. Past the violet the water is fine. It is the sunlight that gives out, because the atmosphere overhead has taken the far ultraviolet before it ever reaches the ground.</video:description>
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      <video:title>Lightning and Thunder: Still Carrying Secrets</video:title>
      <video:description>Most of the thunder you hear comes from one brief moment in the flash. A lightning channel takes tens of milliseconds to build itself downward, step by step, then unloads in a return stroke whose current rises in microseconds. The long, slow part is nearly silent. That was measured directly in 2023, in three flashes, at a site where lightning is triggered on purpose.</video:description>
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      <video:title>What Shape Is a Raindrop? Physicists Are Still Working on It</video:title>
      <video:description>Under about a millimeter, a raindrop is a sphere. Surface tension wins and nothing else gets a say. From one to five millimeters it flattens as it falls, rounded on top and flat or slightly hollowed underneath. Past about five millimeters the base caves in, the drop inflates into a bag and bursts.</video:description>
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    <loc>https://teenscientists.org/world-of-teen-science/videos/surely-youre-joking/a-train-hits-a-tennis-ball-frames-of-reference-explained/</loc>
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      <video:title>A Train Hits a Tennis Ball: Frames of Reference Explained</video:title>
      <video:description>A train doing 50 miles an hour meets a tennis ball sitting still.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/UJqEJxxN2uE</video:player_loc>
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      <video:title>Schrödinger's Cat on Franklin's Kite? The Cat Would Get Wet</video:title>
      <video:description>A proposal arrived in the comments under our Schrödinger's cat video: take the cat, put it on a kite, go discover lightning.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/oOCvD3z-a74</video:player_loc>
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    <loc>https://teenscientists.org/world-of-teen-science/videos/surely-youre-joking/why-a-crookes-radiometer-spins-both-popular-answers-are/</loc>
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      <video:title>Why a Crookes Radiometer Spins: Both Popular Answers Are Wrong</video:title>
      <video:description>A radiometer, or light mill: a glass bulb with a little gas left inside and vanes that are black on one side and white on the other. Light falls on it and the vanes spin.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/Ow5-Mg6D5Gs</video:player_loc>
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  <url>
    <loc>https://teenscientists.org/world-of-teen-science/videos/surely-youre-joking/a-story-of-a-levitating-frog/</loc>
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      <video:description>&quot;Flying frogs and floating magnets.&quot; That is a real paper title, in the Journal of Applied Physics.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/eeikQKVJ3xE</video:player_loc>
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    <loc>https://teenscientists.org/world-of-teen-science/videos/surely-youre-joking/is-light-a-wave-or-a-particle-two-experiments-two-answers/</loc>
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      <video:title>Is Light a Wave or a Particle? Two Experiments, Two Answers</video:title>
      <video:description>Is light a wave, or a particle?</video:description>
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    <loc>https://teenscientists.org/world-of-teen-science/videos/surely-youre-joking/what-is-a-black-body-the-sun-is-almost-a-perfect-one/</loc>
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      <video:thumbnail_loc>https://teenscientists.org/images/videos/agC00kmGvxY.jpg</video:thumbnail_loc>
      <video:title>What Is a Black Body? The Sun Is Almost a Perfect One</video:title>
      <video:description>A piece of coal in a cold fire pit looks black. Heat it and it glows red. To a physicist it was a black body the whole time, and the light coming off the hot one is black body radiation.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/agC00kmGvxY</video:player_loc>
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    <loc>https://teenscientists.org/world-of-teen-science/videos/surely-youre-joking/why-do-cats-always-land-on-their-feet-physicists-still/</loc>
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      <video:title>Why Do Cats Always Land on Their Feet? Physicists Still Argue About It</video:title>
      <video:description>In 2018 Hanno Essén and Arne Nordmark, at the Royal Institute of Technology in Stockholm, published &quot;A simple model for the falling cat problem&quot; in the European Journal of Physics. Physicists have been on this one since the time of Maxwell.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/NElBvU-JBA0</video:player_loc>
      <video:duration>75</video:duration>
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  <url>
    <loc>https://teenscientists.org/world-of-teen-science/videos/surely-youre-joking/schrodingers-cat-one-electron-two-slits-and-a-cat-in-the-box/</loc>
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      <video:thumbnail_loc>https://teenscientists.org/images/videos/layR9x-NJX4.jpg</video:thumbnail_loc>
      <video:title>Schrödinger's Cat: One Electron, Two Slits, and a Cat in the Box</video:title>
      <video:description>Erwin Schrödinger published the most famous cat in physics in 1935, and he published it as an objection.</video:description>
      <video:player_loc>https://www.youtube-nocookie.com/embed/layR9x-NJX4</video:player_loc>
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    <loc>https://teenscientists.org/world-of-teen-science/videos/surely-youre-joking/are-cats-solid-or-liquid-physicists-actually-studied-this/</loc>
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