Q: When a tree falls in the forest and nobody is around to hear it, does it make a sound?<\/p>\n\n\n\n
A: Yes. <\/p>\n\n\n\n
That’s an easy question to answer. It’s not a 3000-year-old philosophical conundrum with no answer<\/a>. Sound is simply a pressure wave moving through some medium (e.g. air, or the ground). A tree falling in the forest will create a pressure wave whether or not there is someone there to listen to it. It pushes against the air, for one. And it smacks into the ground (or other trees), for two. These will happen no matter who is around. As long as that tree doesn’t fall over in the vacuum of space (where there is nothing to transmit the sound waves and nothing to crash into), that tree will make “a sound”. (There are also sounds that humans cannot hear. Think of a dog whistle. Does that sound not exist because a human can’t hear it?) <\/p>\n\n\n\n What if it’s not a tree? What if it’s 120 million metric tons of rock falling onto a glacier? Does that make a sound? To quote a former governor, “You betcha!”<\/a> It even causes a 2.9 magnitude earthquake<\/a>!<\/p>\n\n\n\n That’s right! On 28 June 2016, a massive landslide occurred in southeast Alaska. It was picked up on seismometers all over Alaska<\/a>. And, a pilot who regularly flies over Glacier Bay National Park<\/a> saw the aftermath: <\/p>\n\n\n\n