What you learned in school
Physics classes taught that sound waves require a medium like air or water to travel, and therefore sound cannot exist in the vacuum of space. Students learned that space is completely silent because there are no molecules to carry sound waves. Textbooks emphasized that astronauts could not hear explosions or other sounds in space due to the absence of air. This was presented as an absolute physical law with no exceptions or alternative forms of acoustic phenomena in space environments.
What we know now
Physics classes taught that sound waves require a medium like air or water to travel, and therefore cannot exist in the vacuum of space. Students learned that space is silent because sound needs matter to propagate. While traditional sound waves cannot travel through vacuum, space isn't completely empty. Electromagnetic waves can carry acoustic information, and plasma waves in space can behave similarly to sound. Additionally, spacecraft and space stations contain air where sound travels normally. The principle is correct for traditional acoustic waves, but space-based "sounds" do exist in other forms.