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

  • knightly the Sneptaur@pawb.social
    12·
    4 days ago

    Sort of. The speed of light in a vacuum is the speed of causality, nothing can go faster than the maximum speed at which one part of the universe can effect another.

    It is possible for fluids to move faster than the speed of sound in the fluid around it, such as the exhaust products of a supersonic jet engine, but in these cases not all of the fluid is operating like a wave. The core of the jet experiences a laminar flow where all of the fluid is moving in the same direction and at roughly the same speed, like a laser instead of a flashlight. At the boundaries of this laminar flow exists a turbulent region where the fluid interacts with the surrounding medium and is slowed to subsonic speeds.

    • Cethin@lemmy.zipEnglish
      3·
      4 days ago

      I don’t know how this works, but wouldn’t the exhaust of the jet be moving at or slower than the speed of sound relative to the other particles in the exhaust. Sure, compared to other particles it’s moving faster, but that doesn’t really matter if we’re only looking at the exhaust. It’s not doing anything differently, though the exhaust and outside particles will have to interact at the boundary.