Solon, why doesn't the clock inside a glass bell jar become invisible or least harder to see when the air is pumped out of the jar, even when the quality of the vacuum is sufficient to prevent me from hearing the alarm?
EDIT: Hey! Why not wire a photovoltaic cell and put in a bell jar and track the amount of electricity it generates while pumping the air out of the jar? Wouldn't this serve as a practical test of your claim, Solon?
EDIT 2: You could even put the apparatus in a dark room with a lamp to keep the amount of light as constant throughout the experiments.