A typical analogy explaining redshift involves a siren or a train whistle. So how do we know the same phenomenon works with light?

Question

A typical analogy explaining redshift involves a siren or a train whistle. So how do we know the same phenomenon works with light?

In: 2

Answer 1

Because both essentially travel in waves. And they can prove light redshift in other ways such as comparing something’s predicted spectral signature via its composition versus its observed one.