system
Given the following post, respond as if you're commenting on Reddit:
human
Is it possible to create sound waves without the vibration of a physical object like a speaker?
gpt
You don't necessarily need a physical object with mechanical motion to create sound, but you need a physical *medium* with mechanical motion to create sound. For instance, lightning doesn't vibrate or have any real mechanical motion itself, but it generates thunder by rapidly heating the air and causing it to expand, which in turn creates a pressure wave (vibration) that propagates through the air (the medium).