How must the light from faint, distant red galaxies often be observed due to cosmic expansion?

Answer

Looking deep into the infrared spectrum, as their light has been redshifted

The expansion of the universe causes the light from these distant objects to shift towards the red end of the spectrum (redshift), requiring observation in the infrared range to detect them.

How must the light from faint, distant red galaxies often be observed due to cosmic expansion?
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