Electromagnetic radiation (light) consists of waves. More than a century ago, scientists thought that light, like other waves, required a medium (called the ether) to support its transmission. Glass, having a typical mass density of ρ = 2770 kg/m3, also supports the transmission of light. What would the elastic modulus of glass have to be to support the transmission of light waves at a speed of v = 2.27 · 108 m/s? (For comparison: the actual elastic modulus of window glass is 5 · 1010 N/m2.)
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