I was watching an XKCD “What-If” video recently and Randal off-handedly mentions the title fact as a given. Upon a further Google search I see explanations about why sound moves faster in liquids than gasses but nothing for my specific question. Is there an intuitive explanation for that fact or is it just one of those weird observable facts with no clear explanation

  • halcyoncmdr@lemmy.worldEnglish
    7·
    3 days ago

    Badically. “Liquid/fluid” and “gas” don’t necessarily mean the same thing scientifically as they do colloquially, they’re actually very close to the same thing.

    Fluid dynamics covers the study of liquids, gasses, and plasmas because they’re effectively the same.

    Note that the speed of sound isn’t a constant across various media. Just like the speed of light isn’t a constant on different media. The “speed of light” we usually refer to is specifically in a vacuum. Light travelling through a media like water or a prism actually changes speed, however slight.

    The same happens to sound. The speed of sound at altitude is different from sea level for instance, because of the atmospheric pressure difference. And sound doesn’t propagate at all in a vacuum because it requires the wave to move molecules, which don’t exist in a vacuum.

    • Cethin@lemmy.zipEnglish
      2·
      2 days ago

      Light travelling through a media like water or a prism actually changes speed, however slight.

      Colloquially, but not in actuality. Light still travels at the same speed technically, but it bounces off particles which makes it take a longer path so it takes longer to get from one point to another, but it’s speed is still constant.

      • Successful_Try543@feddit.org
        3·
        2 days ago

        but it bounces off particles which makes it take a longer path

        If I get the explanation on Wikipedia right, it’s not the photon taking a longer path, but the photon is absorbed by electons and re-emitted after a short delay. This effect is what decreases the effective speed of light in a transparent medium.

        In exotic materials like Bose–Einstein condensates near absolute zero, the effective speed of light may be only a few metres per second. However, this represents absorption and re-radiation delay between atoms, as do all slower-than-c speeds in material substances. As an extreme example of light “slowing” in matter, two independent teams of physicists claimed to bring light to a “complete standstill” by passing it through a Bose–Einstein condensate of the element rubidium. The popular description of light being “stopped” in these experiments refers only to light being stored in the excited states of atoms, then re-emitted at an arbitrarily later time, as stimulated by a second laser pulse. During the time it had “stopped”, it had ceased to be light. This type of behaviour is generally microscopically true of all transparent media which “slow” the speed of light.

    • Successful_Try543@feddit.org
      6·
      3 days ago

      “Liquid/fluid” and “gas” don’t necessarily mean the same thing scientifically as they do colloquially, they’re actually very close to the same thing.

      Both, liquids and gases, are fluids. The main difference is that liquid phases have a free surface, e.g. the level of water in a glas, whereas gases don’t. Their surface is equal to the surface of their compartment.