text: The time evolution of the radius of one of these objects can be approximated with less than one percent error by the expression "one minus t squared raised to the two-fifths power".
full_question: The time evolution of the radius of one of these objects can be approximated with less than one percent error by the expression "one minus t squared raised to the two-fifths power". The Keller-Miksis equation models these objects, which have a natural frequency proportional to the square root of the adiabatic index times pressure divided by density, a value called the Minnaert resonance. Bjerknes forces contribute to the emission of light from these objects when they are forced to oscillate by standing acoustic waves in a phenomenon known as sonoluminescence. These objects are described by the Rayleigh-Plesset equation, which is derived from the Navier-Stokes equations under spherical symmetry. For 10 points, name these objects that form and implode via cavitation and can form from soap films.
first_sentence: The time evolution of the radius of one of these objects can be approximated with less than one percent error by the expression "one minus t squared raised to the two-fifths power".
raw_answer: bubbles [or liquid bubbles; or soap bubbles]