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Discovering evidence supporting the Big Bang Theory stands as Arno Allan Penzias' seminal contribution. Through meticulous observations using the Holmdel Horn Antenna, Penzias and his colleague Robert Wilson stumbled upon a faint cosmic microwave background radiation. This detection provided empirical validation for Theoretical predictions of the expanding universe and cemented the Big Bang Theory as the prevailing cosmological model, forever altering our understanding of the universe's origin and evolution.