A cloud of gas passes Earth at a high velocity of v $=0\mathrm{.}15$ c$.$ It contains traces of a particular heavy element, which in such a cloud would display a forbidden emission line with a lifetime $0=1\mathrm{.}1$ s$.$ What lifetime would an Earth$-$bound observer measure for that particular emission line?

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This is a classic problem of time dilation a key concept of Special Relativity Time dilation essenti... View the full answer